Method for evaluating power consumption of electric energy metering chip

Abstract

The invention discloses a power consumption evaluation method for an electric energy metering chip, relates to the technical field of semiconductor chips, and solves the technical problem of power consumption evaluation for the electric energy metering chip. The method comprises the following steps: selecting instruments and equipment according to the electrical characteristics of the electric energy metering chip, building a test circuit according to the selected instruments and equipment, a circuit is built according to a static condition given by an electric energy metering chip manual to measure static power consumption, data of voltage and current of the electric energy metering chip in different working modes along with time change is recorded by data acquisition equipment to measure dynamic power consumption, and data analysis is performed by a comparative analysis method. And the power consumption change of the electric energy metering chip during dynamic metering, different loads and switching of multiple working modes can be calculated in time. And the power consumption evaluation capability of the electric energy metering chip is improved.

Description

Technical Field

[0001] This invention relates to integrated circuit technology and power metering technology, and more specifically to a method for evaluating the power consumption of a power metering chip. Background Technology

[0002] Traditional methods for evaluating the power consumption of electricity metering chips are insufficient to fully reflect the chip's actual power consumption under different operating conditions. Existing technologies tend to focus on the chip's static power consumption, neglecting the power consumption changes of the electricity metering chip during dynamic metering, different loads, and switching between multiple operating modes.

[0003] To address the aforementioned issues, instruments and equipment were selected based on the electrical characteristics of the energy metering chip. A test circuit was then constructed using the selected instruments and equipment. The circuit was built according to the static conditions given in the energy metering chip's manual to measure static power consumption. Data acquisition equipment was used to record the voltage and current changes of the energy metering chip over time under different operating modes to measure dynamic power consumption. Comparative analysis was then used to analyze the data. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention discloses a method for evaluating the power consumption of an energy metering chip, comprising the following steps: Step 1: Select the appropriate instruments and equipment based on the electrical characteristics of the power metering chip; The instrumentation includes a power supply, an ammeter, a voltmeter, an oscilloscope, a breadboard, and DuPont wires; the oscilloscope is used to capture the power consumption characteristics of the power metering chip during transient and rapid changes, and the power characteristics include power measurement accuracy and power linearity. Step 2: Build the test circuit according to the selected instruments and equipment; The test circuit involves inserting the power metering chip into the breadboard shown, connecting the positive terminal of the power supply to the VCC pin of the power metering chip using the DuPont wire, and connecting the negative terminal of the power supply to the GND pin of the power metering chip; connecting the ammeter in series between the power supply and the VCC pin of the power metering chip; and connecting the voltmeter in parallel across the power supply pin of the power metering chip. Step 3: Build a circuit according to the static conditions given in the power metering chip manual to measure static power consumption; The static conditions include power supply voltage, reference voltage, reset circuit, and anti-interference capability. The power supply voltage is 5V; the reference voltage is 2.5V, and the external reference voltage during A / D and D / A conversion does not exceed 5V; the reset circuit uses a dedicated reset circuit chip and is a high-level reset; the anti-interference capability means that the interference voltage at the A / D and D / A conversion terminals must be less than 0.5mV. Step 4: Use data acquisition equipment to record the voltage and current changes of the power metering chip over time in different operating modes to measure dynamic power consumption; The data acquisition device includes the power supply, the ammeter, the voltmeter, and the data acquisition card; the operating modes include initialization mode, data acquisition mode, data processing mode, communication mode, and standby mode; The initialization mode resets and initializes the registers, controllers, and interfaces inside the power metering chip after it is powered on. The data acquisition mode includes continuous acquisition and triggered acquisition. The continuous acquisition is that the analog front end of the power metering chip is in a high-frequency working state, continuously converting analog signals into digital signals. The triggered acquisition is that the power metering chip performs data acquisition when an external trigger signal arrives and an internal timer is triggered. During the period when the power metering chip is waiting for a trigger signal, only the external interrupt detection circuit and the timer comparison circuit are working. The data processing mode uses a digital filter to filter the acquired data, and uses a digital signal processor and a microprocessor to perform effective value calculation, power factor calculation, active power calculation and reactive power calculation. The communication modes include SPI communication and UART communication. The SPI communication is the communication between the power metering chip and the microcontroller through the SPI interface, and the UART communication is the transmission and reception of data by the UART module of the power metering chip. The standby mode is when only the wake-up circuit of the power metering chip is active; Step 5: Perform data analysis using a comparative analysis method based on the power consumption measured in Step 3 and Step 4; The data analysis involves analyzing whether the power consumption of the power metering chip meets the design requirements and expected power consumption range, and comparing the power consumption differences under different operating modes.

[0005] Further, the step of measuring the static power consumption is as follows: 1) Set the power metering chip to a reset state; 2) Turn on the power supply and wait for ten minutes for the circuit to stabilize. Read the values ​​of the ammeter and voltmeter every ten seconds and record them. Record a total of ten sets. 3) Calculate the static power consumption based on the recorded voltage and current values. The static power consumption formula is: In formula (1) This refers to static power consumption, where j indicates static and i is the number of times the data is recorded. This is the recorded current, k is the temperature coefficient, and T is the current temperature. This is a reference temperature. The recorded voltage. Further, the dynamic power consumption includes switching power consumption and short-circuit power consumption; the switching power consumption is the power consumption generated when the transistor in the energy metering chip continuously switches from an on state to an off state and from an off state to an on state, and the load capacitor is charged and discharged when the transistor state changes; the formula for calculating the switching power consumption is: In formula (1) This refers to static power consumption, where j indicates static and i is the number of times the data is recorded. This is the recorded current, k is the temperature coefficient, and T is the current temperature. This is a reference temperature. The recorded voltage.

[0006] According to claim 1, a method for evaluating the power consumption of an energy metering chip is characterized in that: the dynamic power consumption in step four includes switching power consumption and short-circuit power consumption; the switching power consumption is the power consumption generated when the transistor in the energy metering chip continuously switches from the on state to the off state and from the off state to the on state, and the load capacitor is charged and discharged when the transistor state changes; the formula for calculating the switching power consumption is: In formula (2), It is the power consumption of switching. It is the parasitic capacitance between the two pins of the crystal oscillator. The total capacitance from the output pin of the crystal oscillator circuit to ground. The total capacitance from the input pin of the crystal oscillator circuit to ground, V is the power supply voltage, f is the signal switching frequency, a and b are constant parameters determined according to the specific characteristics of the chip, and T is the temperature; the short-circuit power consumption is the short-circuit current generated when the PMOS and NMOS transistors in the CMOS circuit are simultaneously turned on due to changes in the input signal; the formula for calculating the short-circuit power consumption is: In formula (3) It is short-circuit power consumption. It is short-circuit current. It is the temperature coefficient of the short-circuit current, where T is the current temperature. This is the reference temperature, and V is the power supply voltage. It is the short circuit time. It is the temperature coefficient of short-circuit time. This refers to the frequency of the input signal. Furthermore, the digital filter changes the relative proportions of the frequency components in the input signal and filters out frequency components through a set operational relationship. Filtering is achieved by the digital signal processor performing addition, subtraction, multiplication, division, shifting, and iterative operations on the input digital sequence. The filtered output formula is: In formula (4), This is the output signal at time n after filtering, where G is the gain factor and h is the filter coefficient. Here, k is the input signal, and k is the delayed sample at time n. This is quantization error. Further, the microprocessor performs the RMS value calculation when, for a periodic signal across the same resistor, the heat generated by the periodic signal is equal to the heat generated by a DC signal, and the RMS value is calculated using the following formula: In formula (5), It is the value of the DC signal. It is the sampling period. It is the signal period. It is the discrete current sample sequence acquired by the microprocessor. It is a gain amplifier. It's noise interference. Quantization error; The active power calculation refers to the actual electrical energy consumed per unit time, which is the power consumed by the resistive part in an AC circuit. The active power calculation formula is as follows: In formula (6), P is the active power. It is the number of points used within a cycle. It is a discrete sample sequence of voltage signals. It is a discrete sample sequence of the current signal; The power factor is calculated as the ratio of active power to apparent power, and the formula for calculating the power factor is: In formula (7), It is the number of points used within a cycle. It is a discrete sample sequence of voltage signals. It is a discrete sample sequence of current signals, where U is the effective value of voltage and I is the effective value of current; The reactive power calculation refers to the exchange of electric and magnetic fields within the circuit and the electrical power used to establish and maintain the magnetic field in electrical equipment. The reactive power calculation formula is as follows: In formula (8), Q is reactive power. It's inductance loss. RMS voltage value It's capacitor loss. RMS current value Power factor This refers to phase error. Further, the SPI communication includes a master device output, a slave device input, a master device input, a slave device output, a clock, and a chip select; the master device provides the clock signal via the clock and controls data transmission at the clock edge; the master device sends data to the slave device via the master device output, while the slave device returns data to the master device via the master device input, slave device output; the chip select selects a specific slave device for communication. The UART communication converts parallel data into serial data for transmission, and a data frame is composed of start bits, data bits, parity bits, and stop bits; the receiving end performs detection according to the same format and baud rate, and converts the serial data back into parallel data. Furthermore, the wake-up circuit wakes the low-power standby mode to the normal operating mode. When the wake-up circuit detects a new voltage and current signal change exceeding a preset threshold using a comparator, the input of the comparator is connected to the voltage and current signal collected by the chip after voltage division and current limiting processing, and the other input is connected to a fixed threshold voltage and current reference value. When the collected signal exceeds the reference value, the comparator issues a trigger signal, which is transmitted to the control logic part of the wake-up circuit. The control logic part determines whether the wake-up condition is met based on the trigger signal, and the trigger signal will generate an enable signal if the wake-up condition is met. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the overall architecture of the power consumption evaluation method for an energy metering chip according to the present invention; Figure 2 This is a test circuit diagram of a power consumption evaluation method for an energy metering chip according to the present invention; Figure 3 The flowchart of the power consumption calculation method for power metering chip according to the present invention is shown below. Figure 4 This invention provides a method for evaluating the power consumption of an energy metering chip. (Diagram of the energy metering chip power consumption method is included.) Figure 5 This is a flowchart of the wake-up circuit for a power consumption evaluation method for an energy metering chip according to the present invention. Detailed Implementation

[0008] The technical solutions in the embodiments described below will be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments described herein, and not all of them. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In addition, descriptions of well-known structures and technologies have been omitted in the description to avoid unnecessarily obscuring the concept of the invention.

[0009] like Figures 1-5 As shown, a method for evaluating the power consumption of an energy metering chip includes the following steps: Step 1: Select power consumption assessment and measurement instruments and equipment based on the electrical characteristics of the power metering chip; The instrumentation includes a power supply and an ammeter, voltmeter, oscilloscope, breadboard, and DuPont wires connected to the power supply; the oscilloscope is used to display the power consumption characteristics of the power metering chip during transient rapid changes. Step 2: Measure the power consumption parameters of the power metering chip using the selected power consumption evaluation and measurement instruments; The measurement method is as follows: the power metering chip is inserted into the breadboard through the test circuit; the positive terminal of the power supply is connected to the VCC pin of the power metering chip using the DuPont wire, and the negative terminal of the power supply is connected to the GND pin of the power metering chip; the ammeter is connected in series between the power supply and the VCC pin of the power metering chip; and the voltmeter is connected in parallel across the power supply pin of the power metering chip. Step 3: Build a circuit according to the static conditions given in the power metering chip manual to measure static power consumption; The static conditions include power supply voltage, reference voltage, reset circuit, and anti-interference capability. The power supply voltage is 5V; the reference voltage is 2.5V, and the external reference voltage during A / D and D / A conversion does not exceed 5V; the reset circuit uses a dedicated reset circuit chip and is a high-level reset; the anti-interference capability means that the interference voltage at the A / D and D / A conversion terminals must be less than 0.5mV. Step 4: Use data acquisition equipment to record the voltage and current changes of the power metering chip over time in different operating modes to measure dynamic power consumption; The data acquisition device includes the power supply, the ammeter, the voltmeter, and the data acquisition card; the operating modes include initialization mode, data acquisition mode, data processing mode, communication mode, and standby mode; The initialization mode resets and initializes the registers, controllers, and interfaces inside the power metering chip after it is powered on. The data acquisition mode includes continuous acquisition and triggered acquisition. The continuous acquisition is that the analog front end of the power metering chip is in a high-frequency working state, continuously converting analog signals into digital signals. The triggered acquisition is that the power metering chip performs data acquisition when an external trigger signal arrives and an internal timer is triggered. During the period when the power metering chip is waiting for a trigger signal, only the external interrupt detection circuit and the timer comparison circuit are working. The data processing mode uses a digital filter to filter the acquired data, and uses a digital signal processor and a microprocessor to perform effective value calculation, power factor calculation, active power calculation and reactive power calculation. The communication modes include SPI communication and UART communication. The SPI communication is the communication between the power metering chip and the microcontroller through the SPI interface, and the UART communication is the transmission and reception of data by the UART module of the power metering chip. The standby mode is when only the wake-up circuit of the power metering chip is active; Step 5: Perform data analysis using a comparative analysis method based on the power consumption measured in Step 3 and Step 4; The data analysis involves analyzing whether the power consumption of the power metering chip meets the design requirements and expected power consumption range, and comparing the power consumption differences under different operating modes.

[0010] In a specific embodiment, the collaborative deployment of multi-dimensional measurement devices Instrument and equipment selection logic Ammeters and voltmeters: High-precision models (such as Keysight 34465A, resolution 10nA / 1μV) are used to ensure accurate measurement of microampere-level current (such as standby mode current) and millivolt-level voltage fluctuations.

[0011] Oscilloscope: Select a high-bandwidth model (such as Tektronix MDO3054, bandwidth 500MHz, sampling rate 5GSa / s) to capture nanosecond-level current spikes (duration ≤100ns) during transient processes such as A / D conversion and SPI communication.

[0012] Breadboard and DuPont wires: Low impedance materials (silver-plated copper, impedance ≤1mΩ) are selected to reduce additional errors introduced by the measurement circuit (<0.1%).

[0013] Measurement circuit design Current measurement circuit: A four-terminal measurement method is used, with the ammeter connected in series in the VCC path to eliminate the influence of wire resistance on current measurement (formula: Voltage measurement circuit: A differential probe (such as Pico Technology TA049, CMRR≥100dB) is directly connected in parallel across the chip power supply pins to eliminate line voltage drop interference.

[0014] II. Precise Measurement of Static Power Consumption Static condition standardization Power supply voltage stability: A low-noise LDO power supply (such as Texas Instruments TPS7A4700, with output noise ≤10μVrms) is used to ensure that the voltage ripple is <50μV when the power supply is 5V.

[0015] Reference voltage control: A high-precision voltage reference source (such as Analog Devices ADR4550, temperature drift ≤2ppm / °C) is used to output 2.5V±0.01%, which meets the high stability requirements of A / D conversion for reference voltage.

[0016] Reset circuit design: Select a dedicated reset chip (such as Maxim MAX811) to generate a high-level reset pulse with a width of ≥200ms to ensure reliable initialization of the chip registers.

[0017] Measurement Implementation Under static conditions where the chip has no input signal (analog front-end grounded) and no communication operation (SPI / UART pin floating), record the current value after stabilization (measurement time ≥ 10s, take the average value).

[0018] Calculation formula: Typical values ​​are 2.7mW (5V power supply, quiescent current 540μA).

[0019] III. Timing Analysis of Dynamic Power Consumption Work mode decomposition and triggering Initialization mode: The power-on process of the chip is precisely controlled by a power timing controller (such as Linear Technology LTC2924), and the current curve from VCC reaching the threshold (such as 4.5V) to the chip completing the register configuration is recorded (the duration is about 15ms).

[0020] Data acquisition mode: Continuous acquisition: Input a 1kHz, 1Vrms sine wave signal to trigger a single capture of the oscilloscope and measure the current fluctuation when the analog front end is working continuously (typical values: peak current 1.2mA, average current 850μA).

[0021] Trigger acquisition: An external trigger signal (such as a 5V pulse with a width of 10μs) is synchronized with an oscilloscope to measure the current spike at the moment of triggering (rise time ≤20ns, peak current 1.8mA).

[0022] Data processing mode: Input a full-scale signal (e.g., 2.5Vrms), calculate power parameters through a digital filter (e.g., Butterworth filter, order 8), and record the current changes during DSP operation (typical value: average current 920μA, fluctuation period is related to sampling rate).

[0023] Power consumption characteristics of communication modes SPI communication: Set different baud rates (e.g., 1MHz, 4MHz, 8MHz) and measure the current consumption per clock cycle (formula: (where N is the number of bits to transmit).

[0024] UART communication: Send data packets of different lengths (e.g., 8 bytes, 64 bytes, 256 bytes) and analyze the differences in current distribution of start bit, data bit, and stop bit (typical value: the energy consumption for sending 1 byte of data is 3.2 μJ).

[0025] IV. Quantitative Analysis of Power Consumption Data Comparative analysis framework Design specification verification: Compare the measured values ​​with the nominal values ​​in the chip datasheet (e.g., static power consumption deviation ≤ ±5%, dynamic power consumption deviation ≤ ±10%).

[0026] Inter-mode difference assessment: Calculate the power consumption ratio of each mode (e.g., standby mode ratio < 5%, data processing mode ratio 40%), and identify high-energy-consuming components.

[0027] Timing characteristic analysis: Calculating instantaneous power using oscilloscope waveforms The evaluation assesses the chip's power consumption overshoot during state transitions (e.g., the peak overshoot during initialization to data acquisition mode is 2.3 times the normal current). The evaluation report output is shown in Table 1.

[0028] This application has a current resolution of 10nA, which can detect leakage current (typical value 25nA) in the chip's sleep state.

[0029] With a timing accuracy of 1ns, it accurately captures the clock edge current changes during SPI communication.

[0030] This application supports power consumption evaluation at different sampling rates (such as 500Hz, 2kHz, 8kHz), adapting to diverse application needs such as smart meters and industrial monitoring.

[0031] This application is compatible with multiple communication protocols (SPI, UART, I²C) and evaluates the chip's power consumption performance in the Internet of Things ecosystem.

[0032] This application guides algorithm optimization (such as reducing DSP operation frequency) by identifying high-energy-consuming modes (such as data processing modes).

[0033] Based on timing analysis results, power management strategies (such as inserting sleep cycles during SPI communication intervals) can be designed to reduce overall system power consumption by 15%-20%.

[0034] This evaluation method provides data support for low-power design optimization by quantitatively analyzing the power consumption characteristics of the chip under different operating states. It is especially suitable for power-sensitive battery-powered energy metering devices (such as wireless meter reading terminals and distributed energy monitoring modules).

[0035] Further, the step of measuring the static power consumption is as follows: 1) Set the power metering chip to a reset state; 2) Turn on the power supply and wait for ten minutes for the circuit to stabilize. Read the values ​​of the ammeter and voltmeter every ten seconds and record them. Record a total of ten sets. 3) Calculate the static power consumption based on the recorded voltage and current values. The static power consumption formula is: In formula (1) This refers to static power consumption, where j indicates static and i is the number of times the data is recorded. This is the recorded current, k is the temperature coefficient, and T is the current temperature. This is a reference temperature. The recorded voltage. The derivation logic and physical meaning of the above static power consumption calculation formula are as follows: I. Formula Structure and Physical Meaning Formula Prototype Core Items Instantaneous power consumption in a single measurement (basic power formula: The average value of multiple measurements is taken to reduce the impact of random noise and reflect the stability of static power consumption. Temperature compensation item: Used to correct for the effect of temperature on chip power consumption, where: k: the chip's temperature coefficient (unit: °C), reflecting the rate of change of current with temperature (e.g., leakage current in semiconductor devices typically increases with increasing temperature). T: the current measurement temperature. re Reference temperature (such as the standard test temperature in the chip datasheet, usually 25℃). The current value Ii at the current temperature is corrected to the equivalent current value at the reference temperature, thus eliminating the interference of temperature drift on power consumption assessment.

[0036] II. Background and Key Points of Formula Derivation: Assumption 1. Definition of static power consumption; Static power consumption is the power consumption of a chip in a non-operating state (such as the reset state), mainly caused by leakage current and standby circuits. At this time, the transistors inside the chip are in the cutoff or saturation state, and the current is usually small and stable, but may be significantly affected by temperature.

[0037] 2. The mechanism by which temperature affects power consumption; Semiconductor physical characteristics: Leakage current of the PN junction within the chip (such as reverse saturation current I) S It has an exponential relationship with temperature: in Where is the bandgap, and k is the Boltzmann constant. As temperature increases, leakage current increases, leading to increased static power consumption. Within a small temperature range (e.g., ...), The effect of temperature can be simplified to a linear relationship through a linear approximation (first-order Taylor expansion), that is: Where k is the linearized temperature coefficient (given by the chip manufacturer through actual measurement).

[0038] 3. The necessity of averaging multiple measurements Circuit stabilization time: After the chip is powered on, it needs to wait for the capacitor to charge and the register to reset ("wait ten minutes" in step 2) to ensure that it enters a stable static working state. Noise suppression: Data is read every 10 seconds (10 sets in total), and the impact of random noise such as power supply ripple and environmental interference on the measurement results is reduced by statistical averaging.

[0039] III. Key points for formula application: 1. Obtaining the temperature coefficient k: This is provided by the chip manufacturer in the datasheet (e.g., a chip may specify "static current temperature coefficient is +0.1% / ℃"). If the manufacturer does not provide this, k can be obtained by measuring the static current at different temperatures in a constant temperature chamber and fitting the data.

[0040] 2. Reference temperature T ref The selection is usually based on the standard temperature of the chip design (such as 25°C) to ensure that the evaluation results are comparable to the manufacturer's specifications.

[0041] 3. Difference from dynamic power consumption assessment: Static power consumption: focuses on the baseline power consumption under steady-state conditions, used to assess standby power consumption. Dynamic power consumption: captures transient current waveforms using an oscilloscope (as in step 4), analyzing the peak and average power consumption during operating mode switching.

[0042] This formula addresses two key issues in static power consumption assessment through temperature compensation and statistical averaging: 1. Environmental sensitivity: Eliminating assessment bias caused by temperature differences, ensuring comparability of test results under different conditions. 2. Measurement error: Improving the reliability of power consumption data through multiple sampling and mathematical averaging, meeting the needs of chip energy efficiency optimization and standby power consumption compliance testing. Using these methods, the power consumption level of an energy metering chip under ideal static conditions can be accurately quantified, providing data support for chip design iteration and low-power optimization.

[0043] The static power consumption includes leakage current power consumption and static bias current power consumption. The leakage current power consumption is caused by the small leakage current that still exists in the transistors of the power metering chip when it is in the off state. The power metering chip does not perform any signal processing or data conversion, and the leakage current continuously consumes current. The static bias current power consumption is the bias current required for the analog circuitry inside the power metering chip to maintain normal operation. This bias current generates power consumption when the power metering chip is in a static state. Static power consumption is shown in Table 2.

[0044] The data above shows that as the temperature, leakage current, and static bias current increase, the static power consumption also shows an upward trend.

[0045] Furthermore, the dynamic power consumption includes switching power consumption and short-circuit power consumption; the switching power consumption is the power consumption generated when the transistor in the power metering chip continuously switches from the on state to the off state and from the off state to the on state, and the load capacitor is charged and discharged when the transistor state changes; the formula for calculating the switching power consumption is: In formula (2), It is the power consumption of switching. It is the parasitic capacitance between the two pins of the crystal oscillator. The total capacitance from the output pin of the crystal oscillator circuit to ground. The total capacitance from the input pin of the crystal oscillator circuit to ground, V is the power supply voltage, f is the signal switching frequency, a and b are constant parameters determined according to the specific characteristics of the chip, and T is the temperature; the implementation of the switching power consumption formula (2) needs to be combined with the chip hardware characteristics, test environment setup and parameter calibration, which can be divided into the following steps: Parameter definition and retrieval; 1. Parasitic capacitance parameters (C) parasitic C out C in Source: C parasitic (Parasitic capacitance between crystal oscillator pins), C out (Output pin to ground capacitor), C in (Input pin to ground capacitance) is usually provided by the chip manufacturer in the datasheet, or can be measured in the following ways: LCR meter measurement: Disconnect the crystal oscillator circuit and directly measure the capacitance between pins and between pins and ground (this must be done after the chip is powered off and discharged).

[0046] Simulation tool extraction: Parasitic parameters are extracted using chip layout design tools (such as Cadence). Unit: Farad (F), typically at the picofarad (pF) level (e.g., C). parasitic =5pF), C out =10pF).

[0047] 3. Constant parameters (a) and (b) are provided by the chip design manufacturer through process models (such as the BSIM model) and reflect nonlinear effects such as charge injection and reverse recovery during transistor switching. If the manufacturer does not provide them, experimental calibration is required: Under standard test conditions with known power consumption (such as fixed frequency and voltage), measure the actual power consumption and deduce the values ​​of (a) and (b). Example: Assume that the measured switching power consumption of a chip at V=5V and f=1kHz is 100W. Substituting these values ​​into the formula, the combined value of (a) and (b) can be calculated.

[0048] 4. Temperature Measurement Tool: The ambient temperature is monitored in real time using an integrated temperature sensor (such as an internal chip sensor) or an external thermocouple, measured in Kelvin (K) or degrees Celsius (°C). Purpose: Temperature affects transistor threshold voltage and carrier mobility, requiring a temperature compensation term to be included in the formulas (e.g., variations in (a) and (b) with temperature), or the test temperature can be controlled using a constant temperature chamber (e.g., a standard 25°C environment).

[0049] Test Environment Setup 1. Circuit Connection Use the test circuit from step two (breadboard, DuPont wire, power supply, ammeter, voltmeter), focusing on the integrity of the crystal oscillator circuit (ensuring the crystal oscillator starts oscillating normally). If you need to measure the switching power consumption in a specific working mode (such as communication mode), you need to activate the mode through a logic control signal (such as the SPI enable pin). 2. Data Acquisition Use a high-speed data acquisition card (such as NI USB-6356, sampling rate ≥1MS / s) to synchronously record the power supply voltage (V) and current I(t), or directly capture the waveform parameters of key signals (such as frequency, duty cycle) through an oscilloscope. For periodic working modes (such as timed data acquisition), you need to collect signal data within the complete cycle to calculate the average switching frequency f. III. Formula Substitution and Calculation 1. Parameter Substitution Substitute the measured or acquired parameters into formula (2): Example: Assume C parasitic =2pF, C out =8pF, C in =2pF, V=3.3V, f=100kHz, a=0.8, b=0.002 / ℃, (T=25℃), then: 2. Temperature Compensation: If the test temperature deviates from the standard value (e.g., 25℃), parameters a and b need to be recalibrated, or the calculation results need to be corrected through the chip temperature characteristic curve. For wide-temperature operating scenarios (e.g., -40℃ to 85℃), the values ​​of (a) and (b) at different temperatures can be measured in segments to establish a temperature-power consumption mapping table.

[0050] The actual dynamic power consumption P was calculated by comparing the results of the dynamic power consumption measurement method in step four (recording voltage and current data under different modes). dynamic And the switching power consumption P calculated by formula (2) switch Comparison: If Short-circuit power consumption (which needs to be measured separately) verifies the formula's validity. If significant deviations exist, check for parameter acquisition errors (e.g., inaccurate parasitic capacitance measurement) or whether other power consumption sources (e.g., resistive power consumption) have been overlooked. 2. Optimization Directions: If switching power consumption exceeds the limit, optimization can be achieved through the following methods: Reduce the power supply voltage V (within the chip's operating voltage range); Reduce the signal switching frequency f (e.g., optimize the communication protocol to reduce data transmission rate); Optimize the chip layout design to reduce parasitic capacitance C. parasitic C out C in .

[0051] The core of implementing the switching power consumption formula (2) lies in accurately obtaining parasitic capacitance parameters, dynamically monitoring the operating frequency and voltage, and improving calculation accuracy through temperature compensation and experimental calibration. This method can help users quantitatively evaluate dynamic power consumption during chip design or selection, providing data support for low-power optimization. The switching power consumption is shown in Table 3. Based on the above data, it can be seen that when the current, voltage, load capacitance, and switching frequency remain constant, the switching power consumption increases with increasing temperature, and the influence of temperature on the switching frequency is smaller than that of the switching voltage, load capacitance, and switching frequency; the switching power consumption increases with increasing voltage, increasing load capacitance, and increasing switching frequency.

[0052] The short-circuit power consumption is generated when changes in the input signal cause both the PMOS and NMOS transistors in the CMOS circuit to conduct simultaneously, resulting in a short-circuit current. The formula for calculating the short-circuit power consumption is: In formula (3) It is short-circuit power consumption. It is short-circuit current. It is the temperature coefficient of the short-circuit current, where T is the current temperature. This is the reference temperature, and V is the power supply voltage. It is the short circuit time. It is the temperature coefficient of short-circuit time. This refers to the frequency of the input signal. In a specific embodiment, 1. The complementary conduction characteristics of the CMOS transistor. CMOS circuits are composed of complementary PMOS (P-type metal-oxide-semiconductor) and NMOS (N-type metal-oxide-semiconductor) transistors: Static state: When the input signal is high, the NMOS is turned on and the PMOS is turned off; when the input signal is low, the PMOS is turned on and the NMOS is turned off. Ideally, there is no DC path. Dynamic transition region: When the input signal transitions between high and low levels (i.e., during the rising / falling edge phase), due to the transistor threshold voltage (V... THP / V THN Due to the influence of signal edge slope, PMOS and NMOS will enter a subthreshold conduction state, forming a brief DC path (from power supply V to ground GND), generating a short-circuit current I. SC When calculating the temperature sensitivity of short-circuit current, the short-circuit current I... SC It has an exponential relationship with temperature T: I SC ∝exp(T−T0 ) / α T This is the temperature coefficient of the short-circuit current (unit: K), reflecting the change in carrier mobility with temperature: as temperature increases, the intrinsic carrier concentration of the semiconductor material increases, leading to an increase in subthreshold leakage current. The reference temperature T0 is usually taken as room temperature (25℃, i.e., 298K) to normalize the temperature effect. When relating short-circuit time to signal frequency, t... SC The rise / fall time of the corresponding input signal is directly limited by the transistor size and the load capacitance: t SC =β T .C L / k p +k n ; β T C is the temperature coefficient of short-circuit time (process-dependent). L For the load capacitance, k p / k n This represents the conductivity factor of PMOS / NMOS. The input signal frequency f determines the number of switching operations per unit time, and the short-circuit power consumption increases linearly with frequency. Formula (3) can be expanded as follows: The power supply voltage V directly determines the theoretical upper limit of the short-circuit current. ) Ron is the on-resistance. Temperature correction term: via I SC (T) and t SC (T) reflects the dual effect of temperature on the amplitude and duration of short-circuit current, with short-circuit power consumption increasing significantly under high-temperature conditions. Frequency f: Reflects the number of short-circuit events per unit time. High-frequency circuits (such as high-speed digital signal processing) have a higher proportion of short-circuit power consumption. When controlling the input signal edge, a buffer is used to optimize the rise / fall rate of the input signal (e.g., shortening the edge time from 5ns to 2ns) to reduce the overlap time t when the PMOS / NMOS is turned on simultaneously. SC Adding a Schmitt trigger to the FPGA interface circuit accelerates signal conversion and reduces the width of the transition region through its hysteresis characteristic. Transistor size matching requires adjusting the width-to-length ratio (W / L) of the PMOS / NMOS transistors to match their threshold voltages and conductivity, thus shortening the time window for simultaneous conduction. For 0.18μm processes, this is typically designed... Wp / Wn≈2−3 to balance the turn-on speed of NMOS / PMOS. Power supply voltage grading uses low-voltage power supplies for non-critical path circuits (e.g., core logic modules V=1.2V, I / O modules V=1.8V), directly reducing the short-circuit current amplitude I. SC . On-chip temperature sensor integration: A thermistor or PTAT (proportional-to-absolute temperature) circuit is deployed inside the chip to acquire the temperature T in real time. The temperature coefficient parameter in the formula is dynamically adjusted via a digital signal processor (DSP). The power consumption model is corrected in real time. (Note: Typical temperature coefficient α) T ≈100K (The specific value needs to be determined through process corner simulation). During SPICE-level power consumption simulation; Using tools such as Hspice / PSpice, input the actual signal waveform (including rising / falling edges) to simulate the overlapping conduction process of PMOS / NMOS and extract the short-circuit current waveform I. SC (t). Key parameters: Robustness analysis was performed by setting process angle (TT / FF / SS), temperature (-40℃~85℃), and power supply voltage fluctuation (±5%). Power consumption test after tape-out: By injecting a square wave signal of a specific frequency through a probe station, the average current at the power supply terminal is measured to separate short-circuit power consumption from dynamic switching power consumption. ). In high-speed interface circuits above 1GHz, short-circuit power consumption can account for 15%-25% of the total power consumption (70% for dynamic power consumption and 5%-10% for static power consumption). Pre-emphasis technology is used to increase the signal edge rate, and dynamic voltage frequency scaling (DVFS) is introduced to reduce the power supply voltage when operating at low frequencies. Add heat sinks during PCB layout and dynamically adjust the input signal frequency using software algorithms (e.g., reduce the frequency from 500MHz to 300MHz when the temperature exceeds 80℃). A subthreshold logic design (V < Vth) is employed, sacrificing speed for extremely low short-circuit current, and pulse amplitude modulation (PAM) is used to reduce the number of signal transitions, thereby improving application performance. Short-circuit power consumption is shown in Table 4.

[0053] The data above shows that as the power supply voltage decreases, the short-circuit power consumption decreases; and as the temperature and short-circuit current increase, the short-circuit power consumption increases.

[0054] The process for calculating the power consumption of the energy metering chip is as follows: First, the chip is initialized, and the received current and voltage data are analyzed to determine whether the energy metering chip is in a high-load or low-load operating mode. If it is in the high-load operating mode, the dynamic power consumption calculation is performed on the energy metering chip. If it is in the low-load operating mode, the static power consumption calculation is performed on the energy metering chip. The dynamic power consumption and the static power consumption are then combined into the total power consumption.

[0055] Furthermore, the digital filter changes the relative proportions of frequency components in the input signal and filters out frequency components by setting operational relationships. Filtering is achieved by the digital signal processor performing addition, subtraction, multiplication, division, shifting, and iterative operations on the input digital sequence. The filtered output formula is: In formula (4), This is the output signal at time n after filtering, where G is the gain factor and h is the filter coefficient. Here, k is the input signal, and k is the delayed sample at time n. This refers to quantization error. The working principle of a digital filter is to perform preset mathematical operations on the input digital signal sequence to selectively change the relative proportions of each frequency component or filter out specific frequency components, thereby adjusting the signal's frequency characteristics. Its core is based on a digital signal processor (DSP) performing operations such as addition, subtraction, multiplication, division, shifting, and iteration on the input digital sequence.

[0056] Furthermore, the microprocessor performs the RMS value calculation when, for a periodic signal across the same resistor, the heat generated by the periodic signal is equal to the heat generated by a DC signal, and the RMS value is calculated using the following formula: In formula (5), It is the value of the DC signal. It is the sampling period. It is the signal period. It is the discrete current sample sequence acquired by the microprocessor. It is a gain amplifier. It's noise interference. Quantization error; The active power calculation refers to the actual electrical energy consumed per unit time, which is the power consumed by the resistive part in an AC circuit. The active power calculation formula is as follows: In formula (6), P is the active power. It is the number of points used within a cycle. It is a discrete sample sequence of voltage signals. It is a discrete sample sequence of the current signal; The power factor is calculated as the ratio of active power to apparent power, and the formula for calculating the power factor is: In formula (7), It is the number of points used within a cycle. It is a discrete sample sequence of voltage signals. It is a discrete sample sequence of current signals, where U is the effective value of voltage and I is the effective value of current; The reactive power calculation refers to the exchange of electric and magnetic fields within the circuit and the electrical power used to establish and maintain the magnetic field in electrical equipment. The reactive power calculation formula is as follows: In formula (8), Q is reactive power. It's inductance loss. RMS voltage value It's capacitor loss. RMS current value Power factor This refers to phase error. Further, the SPI communication includes a master device output, a slave device input, a master device input, a slave device output, a clock, and a chip select; the master device provides the clock signal via the clock and controls data transmission at the clock edge; the master device sends data to the slave device via the master device output, while the slave device returns data to the master device via the master device input, slave device output; the chip select selects a specific slave device for communication. The UART communication converts parallel data into serial data for transmission, and a data frame is composed of start bits, data bits, parity bits, and stop bits; the receiving end performs detection according to the same format and baud rate, and converts the serial data back into parallel data. Furthermore, the wake-up circuit wakes the low-power standby mode to the normal operating mode. When the wake-up circuit detects a new voltage and current signal change exceeding a preset threshold using a comparator, the input of the comparator is connected to the voltage and current signal collected by the chip after voltage division and current limiting processing, and the other input is connected to a fixed threshold voltage and current reference value. When the collected signal exceeds the reference value, the comparator issues a trigger signal, which is transmitted to the control logic part of the wake-up circuit. The control logic part determines whether the wake-up condition is met based on the trigger signal, and the trigger signal will generate an enable signal if the wake-up condition is met.

[0057] The wake-up circuit operates as follows: it uses a comparator to determine whether the change in current or voltage signal is greater than a preset threshold. If the change is greater than the threshold, a trigger signal is issued; if the change is less than the threshold, the signal is not received. The trigger signal is transmitted to the control logic section, which determines whether the trigger signal meets the wake-up conditions. If the conditions are met, the control logic section generates an enable signal to complete the wake-up operation; otherwise, the trigger signal is sent back to the comparator for re-comparison.

[0058] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these specific embodiments are merely illustrative. Those skilled in the art can omit, substitute, and modify the details of the above methods and systems in various ways without departing from the principles and essence of the present invention. For example, combining the above method steps to perform substantially the same function and achieve substantially the same result according to substantially the same method falls within the scope of the present invention. Therefore, the scope of the present invention is defined only by the appended claims.

Claims

1. A method for evaluating power consumption of an electric energy metering chip, characterized by: The method comprises the following steps: Step one: select power consumption evaluation measuring instrument according to the electrical characteristics of the electric energy metering chip; The instrument includes a power supply and a voltmeter, an ammeter, an oscilloscope, a breadboard and a DuPont wire connected to the power supply; the oscilloscope is used to display the power consumption characteristics of the electric energy metering chip during transient rapid change; Step two: measure the power consumption parameters of the electric energy metering chip according to the selected power consumption evaluation measuring instrument; The measurement method is: through the test circuit, the electric energy metering chip is inserted into the breadboard, the positive electrode of the power supply is connected to the VCC pin of the electric energy metering chip using the DuPont wire, and the negative electrode of the power supply is connected to the GND pin of the electric energy metering chip; the ammeter is connected in series between the power supply and the VCC pin of the electric energy metering chip; the voltmeter is connected in parallel across the power supply pins of the electric energy metering chip; Step three: build a circuit according to the given static conditions of the electric energy metering chip standard value to measure the static power consumption; The static conditions include power supply voltage, reference voltage, reset circuit and anti-interference ability, the power supply voltage is 5V; the reference voltage is 2.5V, and the external reference voltage during A / D and D / A conversion does not exceed 5V; the reset circuit uses a special reset circuit chip, and is a high level reset; the anti-interference ability is that the interference voltage at the A / D and D / A conversion end is less than 0.5mV; Step four: use data acquisition equipment to record the voltage and current data of the electric energy metering chip changing with time in different working modes to measure the dynamic power consumption; The data acquisition equipment includes the power supply, the ammeter, the voltmeter and a data acquisition card; the working modes include initialization mode, data acquisition mode, data processing mode, communication mode and standby mode; The initialization mode resets and initializes the registers, controllers and interfaces in the electric energy metering chip after the electric energy metering chip is powered on; The data acquisition mode includes continuous acquisition and trigger acquisition, the continuous acquisition is that the analog front end of the electric energy metering chip is in a high frequency working state, constantly converting analog signals into digital signals, the trigger acquisition is that the electric energy metering chip performs data acquisition when the external trigger signal arrives and the internal timer triggers, and only the external interrupt detection circuit and the timer comparison circuit work during the waiting period of the trigger signal; The data processing mode uses a digital filter to filter the collected data, and uses a digital signal processor and a microprocessor to calculate the effective value, power factor, active power and reactive power; The communication mode includes SPI communication and UART communication, the SPI communication is that the electric energy metering chip communicates with the microcontroller through the SPI interface, and the UART communication is that the UART module of the electric energy metering chip transmits and receives data; The standby mode is that only the wake-up circuit of the electric energy metering chip works; Step five: use comparative analysis method to analyze the data measured in steps three and four. The data analysis is to analyze whether the power consumption of the electric energy metering chip meets the design requirements and the expected power consumption range, and compare the power consumption difference in different working modes.

2. The method of claim 1, wherein: The step of measuring the static power consumption in step three is: 1) set the electric energy metering chip to a reset state; 2) turn on the power supply, wait for ten minutes to stabilize the circuit, read the values of the ammeter and voltmeter every ten seconds, and record them, a total of ten groups; 3) calculating the static power consumption from the recorded voltage and current values, the static power consumption formula being: ; In equation (1) is the static power consumption, j indicates static, i is the number of recordings, is the recorded current, k is the temperature coefficient, T is the current temperature, is the reference temperature, the recorded voltage.

3. The method of claim 1, wherein: The dynamic power consumption in the fourth step includes switch power consumption and short circuit power consumption; the switch power consumption is the power consumption generated by charging and discharging the load capacitor when the transistor in the electric energy metering chip is constantly switched from the on state to the off state and from the off state to the on state; the switch power consumption calculation formula is: ; In formula (2), is the switching power consumption, is the parasitic capacitance between the two pins of the crystal oscillator, is the total capacitance from the output pin of the crystal oscillator circuit to ground, is the total capacitance from the input pin of the crystal oscillator circuit to ground, V is the power supply voltage, f is the signal flip frequency, a and b are constant parameters determined according to the specific characteristics of the chip, and T is the temperature; the short-circuit power consumption is caused by the simultaneous conduction of the PMOS and NMOS tubes in the CMOS circuit due to the change of the input signal, and a short-circuit current is generated; the short-circuit power consumption calculation formula is: ; In equation (3) is the short-circuit power consumption, is the short-circuit current, is the temperature coefficient of the short-circuit current, T is the current temperature, is the reference temperature, V is the supply voltage, is the short-circuit time, is the temperature coefficient of the short-circuit time, is the frequency of the input signal.

4. The method of claim 1, wherein: The digital filter in the fourth step is to change the relative proportion of the frequency components contained in the input signal and filter out the frequency components through a set operation relationship, and the filtering is realized through addition, subtraction, multiplication, division, shift and iteration operations on the input digital sequence based on a digital signal processor; the output formula after filtering is: ; In Equation (4), is the output signal after filtering at time n, G is a gain factor, h is a coefficient of the filter, is an input signal, k is a delayed sample at the current time n, is a quantization error.

5. The method of claim 1, wherein: The microprocessor in the fourth step performs the effective value calculation. For a periodic signal, the heat generated by the periodic signal on the same resistance is equal to the heat generated by a direct current signal. The value of the direct current signal is the effective value of the periodic signal. The effective value calculation formula is: In formula (5), is the value of the direct current signal, is the sampling period, is the signal period, is the current discrete sample sequence collected by the microprocessor, is the gain amplifier, is the noise interference, quantization error; The active power calculation is the actual consumed electric energy per unit time, which is the power consumed by the resistance part in the alternating current circuit, and the active power calculation formula is: ; P is the active power in equation (6) is the number of samples taken in one period, is the sequence of discrete samples of the voltage signal, is the sequence of discrete samples of the current signal; The power factor calculation is the ratio of active power to apparent power, and the power factor calculation formula is: In formula (7), is the number of points in a cycle, is the discrete sample sequence of the voltage signal, is the discrete sample sequence of the current signal, U is the voltage effective value, and I is the current effective value. The reactive power calculation is the exchange of electric field and magnetic field in the circuit and the electric power for establishing and maintaining the magnetic field in the electrical equipment, and the reactive power calculation formula is: ; In equation (8), Q is the reactive power, is the inductive loss, the voltage effective value, is the capacitive loss, the current effective value, the power factor, is the phase error.

6. The method of claim 1, wherein: The SPI communication in step four includes master device output, slave device input, master device input, slave device output, clock and chip selection; the master device provides the clock signal through the clock, controls the data transmission at the clock edge; the master device sends data to the slave device through the master device output slave device input, while the slave device returns data to the master device through the master device input slave device output; the chip selection selects a specific slave device for communication; The UART communication is to convert parallel data into serial data for transmission, and a frame of data is composed of a start bit, a data bit, a parity bit and a stop bit; the receiving end detects according to the same format and baud rate, and converts the serial data back to parallel data.

7. The method of claim 1, wherein: The wake-up circuit in step four is to wake up the low-power standby mode to the normal working mode; the wake-up circuit detects the change of the new voltage and current signal exceeding the preset threshold value through the comparator, the input end of the comparator is connected to the voltage and current signal collected by the chip after the voltage and current signal is processed by voltage division and current limiting, the other input end is connected to a fixed threshold voltage and current reference value, the collected signal exceeding the reference value triggers the comparator to send a trigger signal to the control logic part of the wake-up circuit, the control logic part judges whether the trigger signal meets the wake-up condition, and the trigger signal meeting the wake-up condition will generate an enable signal.

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