Clock complementary sampling circuit with temperature compensation

Abstract

The utility model relates to the technical field of integrated circuits, and discloses a clock complementary sampling circuit with temperature compensation, which comprises a high-precision clock circuit and a main control circuit, the high-precision clock circuit comprises a real-time clock chip IC23, the main control circuit comprises a main chip U3, the main chip U3 is connected with the output end of the high-precision clock circuit, and the output end of the high-precision clock circuit is connected with the real-time clock chip IC23. The circuit further comprises a Vcap capacitor and bypass capacitor connecting circuit, and the Vcap capacitor and bypass capacitor connecting circuit is connected with a pin Vcap-1 and a pin Vcap-2 of the main chip U3. The main control chip reads the clock assignment of the clock circuit at each startup or 0 o'clock in the morning, the clock circuit is internally provided with a crystal oscillator and digital temperature compensation, the element matching error problem, the crystal oscillator temperature characteristic problem and the reliability problem caused by external connection of the crystal oscillator, a resonant capacitor and the like do not need to be considered, and meanwhile a power supply switching circuit is arranged in the clock circuit. When the module detects that the voltage of the main power supply VDD falls below the voltage of the rechargeable battery, the module is automatically switched to be powered by the rechargeable battery, and the real-time performance and the precision of the system are both considered.

Description

Technical Field

[0001] This utility model relates to the field of integrated circuit technology, and in particular to a clock complementary sampling circuit with temperature compensation. Background Technology

[0002] Today, real-time clocks are widely used, and almost all electronic products require a real-time clock output device. As the integration of electronic circuits increases and the size of electronic products decreases, the clock generators they use are gradually adopting a modular approach, and clock modules are becoming smaller and smaller, gradually forming several types of clock module series.

[0003] Chinese patent document CN209388211U discloses a "multi-channel synchronous sampling clock circuit". It employs integrated chips O3, O4, U82, and U78, an adjustable resistor R489, an inductor FB13, resistors R490, R491, R504, R505, and R507, and capacitors C702, C703, C704, C705, and C748. However, this technical solution cannot simultaneously achieve both real-time performance and accuracy in clock sampling. Summary of the Invention

[0004] This invention primarily addresses the technical problem that existing solutions cannot simultaneously achieve both real-time performance and accuracy in clock sampling. It provides a temperature-compensated complementary clock sampling circuit. The main control chip reads the clock value from the clock circuit each time the system powers on or at midnight. The clock circuit incorporates a built-in crystal oscillator and digital temperature compensation, eliminating concerns about component matching errors, crystal temperature characteristics, and reliability issues caused by external crystal oscillators and resonant capacitors. Furthermore, it includes an internal power switching circuit. When the module detects that the main power supply VDD has dropped below the rechargeable battery voltage, the module automatically switches to battery power. A bypass capacitor eliminates any AC noise in the DC signal, resulting in a cleaner and purer DC signal, thus balancing system real-time performance and accuracy.

[0005] The above-mentioned technical problems of this utility model are mainly solved by the following technical solution: This utility model includes a high-precision clock circuit and a main control circuit. The high-precision clock circuit includes a real-time clock chip IC23, and the main control circuit includes a main chip U3. The main chip U3 is connected to the output terminal of the high-precision clock circuit. It also includes a Vcap capacitor and a bypass capacitor connection circuit. The Vcap capacitor and bypass capacitor connection circuit is connected to pins Vcap-1 and Vcap-2 of the main chip U3.

[0006] Preferably, the real-time clock chip IC23 is model SD2506API. Pin 1 of IC23 is connected to the main chip U3, pin 4 is grounded, pin 5 is connected to the power supply through resistor R107, pin 6 is connected to the power supply through resistor R106, pin 7 is connected to the power supply through resistor R108, and pin 8 is grounded through parallel capacitors C63 and C65.

[0007] Preferably, the main chip U3 is an STM32F413VHT6. The pin I2C1_SDA of the main chip U3 is connected to pin 5 of IC23, the pin I2C1_CLK of the main chip U3 is connected to pin 6 of IC23, and the pin TIME_RES of the main chip U3 is connected to pin 7 of IC23.

[0008] Preferably, the Vcap capacitor and bypass capacitor connection circuit includes capacitor C23, one end of which is connected to pin Vcap-2 of the main chip U3 and the other end is grounded; capacitor C24, one end of which is connected to pin Vcap-1 of the main chip U3 and the other end is grounded; and capacitors C3, C4, C6 and C7 are connected in parallel between the power supply terminal and the ground terminal.

[0009] Preferably, an external watchdog circuit is also included. The external watchdog circuit includes a chip U4. Pin 1 of chip U4 is connected to the power supply terminal and grounded through capacitor C40. Pin 2 is grounded. Pin 3 is grounded through resistor R91. Pin 4 is connected to pin O_RST of the main chip U3 through resistor R77. Pin 6 is connected to pin 1 of P7. Pin 2 of P7 is connected to pin RESET of the main chip U3.

[0010] Preferably, a bypass capacitor circuit is also included, comprising capacitors C41, C42, C43, and C44 connected in parallel between the power supply terminal and the ground terminal.

[0011] Preferably, the chip also includes an internal RTC crystal oscillator circuit, which includes capacitors X3 connected to pins OSC32_IN and OSC32_OUT of the main chip U3, respectively. Pin OSC32_IN of the main chip U3 is grounded through capacitor C111, and pin OSC32_OUT is grounded through capacitor C110.

[0012] Preferably, the circuit also includes a power supply voltage detection circuit, which includes resistors R32 and R33 connected in series between the power supply terminal and the ground terminal, and resistor R33 connected in parallel with capacitor C18.

[0013] Preferably, the circuit also includes a quartz crystal oscillator circuit for the main chip. The quartz crystal oscillator circuit for the main chip includes a capacitor X1 connected to pin PH1 of the main chip U3 and pin PH0 of the main chip U3 respectively. The capacitor X1 is connected in parallel with the resistor R44. Pin PH1 of the main chip U3 is grounded through capacitor C20, and pin PH0 of the main chip U3 is grounded through capacitor C21.

[0014] Preferably, a reset circuit is also included, which includes a resistor R55 and a capacitor C28 connected in series between the power supply terminal and the ground terminal, and the resistor R55 and the capacitor C28 are connected to the RESET pin of the main chip U3.

[0015] The beneficial effects of this utility model are: the main control chip reads the clock value of the clock circuit every time it is powered on or at 0:00 AM. The clock circuit has a built-in crystal oscillator and digital temperature compensation, so there is no need to worry about component matching errors, crystal oscillator temperature characteristics and reliability issues caused by external crystal oscillators, resonant capacitors, etc. At the same time, it has an internal power switching circuit. When the module detects that the main power supply VDD drops below the rechargeable battery voltage, the module will automatically switch to rechargeable battery power. The bypass capacitor eliminates any AC noise on the DC signal, thereby generating a cleaner and purer DC signal, which takes into account both the real-time performance and accuracy of the system. Attached Figure Description

[0016] Figure 1 This is a high-precision clock circuit diagram of this utility model.

[0017] Figure 2 This is a main control circuit diagram of this utility model.

[0018] Figure 3 This is a circuit diagram showing the connection between a Vcap capacitor and a bypass capacitor according to this utility model.

[0019] Figure 4 This is a circuit diagram of an external watchdog circuit according to the present invention.

[0020] Figure 5 This is a bypass capacitor connection circuit diagram of this utility model.

[0021] Figure 6 This is a circuit diagram of the internal RTC crystal oscillator of a real-time clock chip according to this utility model.

[0022] Figure 7 This is a power supply voltage detection circuit diagram of this utility model.

[0023] Figure 8 This is a circuit diagram of a quartz crystal oscillator for a main chip according to this utility model.

[0024] Figure 9This is a reset circuit diagram of this utility model. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this application will be further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only one preferred embodiment of this application and are only used to explain this application. They do not limit the scope of protection of this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] A real-time clock (RTC) is the clock that increments the date and time counter, typically at 32768Hz. The system clock is the microcontroller's internal main clock, providing the operating clock for all modules. The CPU clock is the clock that the CPU's PLL converts the system clock to its operating clock. In typical low-speed microcontroller systems, the system clock and CPU clock are roughly equal. In high-speed microcontroller systems, the CPU clock is much faster than the system clock. The RTC is only present in systems that require date and time information, and it is the lowest clock frequency available. Some systems also use it as the CPU clock during low-power operation.

[0027] The clock module is a real-time clock module with a built-in crystal oscillator, rechargeable battery, temperature compensation, and standard IIC interface. The CPU can use this interface to read and write 122 bytes of on-chip data (including time register, alarm register, control register, temperature register, battery level register, 70-byte user SRAM register, and 8-byte ID code register) via a 7-bit address.

[0028] Real-time clock (RTC) modules can be further subdivided into those with power consumption <0.5uA, >1uA, and 0.5-1uA. The automotive and consumer electronics industries are the main application areas for RTC modules.

[0029] Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe the operations (or steps) as sequential processes, many of the operations (or steps) can be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but it may also have additional steps not included in the figures; the process may correspond to a method, function, procedure, subroutine, subroutine, etc.

[0030] The technical solution of this utility model will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0031] Example: This example describes a clock complementary sampling circuit with temperature compensation, such as... Figure 1 As shown, the system includes a high-precision clock circuit and a main control circuit. The SD2506API stores the calibrated clock. Since the SD2506API uses an IIC interface, the clock value is read from the SD2506API and assigned to the RTC of the STM32F413VH at each power-on or at midnight. The STM32F413VH's RTC then supplies the system with a real-time clock. This is updated once daily at midnight. This balances system real-time performance with accuracy. The high-precision clock circuit includes a real-time clock chip IC23, and the main control circuit includes a main chip U3. The main chip U3 is connected to the output of the high-precision clock circuit and also includes a Vcap capacitor and a bypass capacitor connection circuit. The Vcap capacitor and bypass capacitor connection circuit are connected to pins Vcap-1 and Vcap-2 of the main chip U3. The real-time clock chip IC23 is model SD2506API. Pin 1 of IC23 is connected to the main chip U3, pin 4 is grounded, pin 5 is connected to the power supply through resistor R107, pin 6 is connected to the power supply through resistor R106, pin 7 is connected to the power supply through resistor R108, and pin 8 is grounded through parallel capacitors C63 and C65.

[0032] like Figure 2 As shown, the main chip U3 is an STM32F413VHT6. Pin I2C1_SDA of the main chip U3 is connected to pin 5 of IC23, pin I2C1_CLK of the main chip U3 is connected to pin 6 of IC23, and pin TIME_RES of the main chip U3 is connected to pin 7 of IC23. The STM32F413VHT6 operates from a 1.7V to 3.6V power supply, has a temperature range of -40℃ to 85℃, and its core includes a floating-point unit (FPU). Bit CPU, Adaptive Real-Time Accelerator (ARTAccelerator) TM It allows zero-wait execution from flash memory, with frequencies up to 100MHz, and features a memory protection unit, achieving 125 DMIPS (millions of instructions per second) / 1.25 DMIPS / MHz (Dhrystone 2.1 benchmark) and supporting digital signal processing (DSP) instructions. The main chip U3 is an STM32F413VHT6. Pin I2C1_SDA of the main chip U3 is connected to pin 5 of IC23, pin I2C1_CLK of the main chip U3 is connected to pin 6 of IC23, and pin TIME_RES of the main chip U3 is connected to pin 7 of IC23.

[0033] like Figure 3As shown, the Vcap capacitor and bypass capacitor connection circuit includes capacitor C23, one end of which is connected to pin Vcap-2 of the main chip U3, and the other end is grounded. It also includes capacitor C24, one end of which is connected to pin Vcap-1 of the main chip U3, and the other end is grounded. Additionally, it includes capacitors C3, C4, C6, and C7 connected in parallel between the power supply terminal and the ground terminal. A bypass capacitor is a capacitor that shorts the AC signal to ground, thus eliminating any AC noise appearing on the DC signal, resulting in a cleaner and purer DC signal. The bypass capacitor essentially bypasses the AC noise that may exist on the DC signal, filtering out the AC current, allowing a clean, pure DC signal to pass through with minimal AC ripple. A capacitor used to conduct AC current in the surrounding environment, either as a component or a group of components.

[0034] like Figure 4 As shown, the external watchdog circuit includes chip U4. Pin 1 of chip U4 is connected to the power supply and grounded through capacitor C40. Pin 2 is grounded. Pin 3 is grounded through resistor R91. Pin 4 is connected to pin O_RST of the main chip U3 through resistor R77. Pin 6 is connected to pin 1 of P7. Pin 2 of P7 is connected to pin RESET of the main chip U3.

[0035] like Figure 5 As shown, the bypass capacitor circuit includes capacitors C41, C42, C43, and C44 connected in parallel between the power supply terminal and the ground terminal. A bypass capacitor is a capacitor that shorts the AC signal to ground, thus eliminating any AC noise present on the DC signal, resulting in a cleaner and purer DC signal. The bypass capacitor essentially bypasses AC noise that may be present on the DC signal, filtering out AC current and allowing a clean, pure DC signal to pass through with minimal AC ripple. Capacitors used to conduct AC current in the surrounding environment can be used as a component or a group of components.

[0036] like Figure 6 As shown, the internal RTC crystal oscillator circuit of the real-time clock chip includes capacitor X3 connected to pin OSC32_IN and pin OSC32_OUT of the main chip U3 respectively. Pin OSC32_IN of the main chip U3 is grounded through capacitor C111, and pin OSC32_OUT is grounded through capacitor C110.

[0037] like Figure 7 As shown, the power supply voltage detection circuit includes resistors R32 and R33 connected in series between the power supply terminal and the ground terminal, and resistor R33 is connected in parallel with capacitor C18.

[0038] like Figure 8As shown, the quartz crystal oscillator circuit for the main chip includes a capacitor X1 connected to pin PH1 and pin PH0 of the main chip U3, respectively. The capacitor X1 is connected in parallel with the resistor R44. Pin PH1 of the main chip U3 is grounded through capacitor C20, and pin PH0 of the main chip U3 is grounded through capacitor C21.

[0039] like Figure 9 As shown, the reset circuit includes a resistor R55 and a capacitor C28 connected in series between the power supply terminal and the ground terminal. The resistor R55 and the capacitor C28 are connected to the RESET pin of the main chip U3.

[0040] Example 2

[0041] This device is a real-time clock acquisition system. Unlike typical real-time clock acquisition systems, it balances accuracy and real-time performance, ensuring both real-time operation and accuracy (i.e., annual error of less than 2 minutes). The system units include: a main control chip STM32F413VH, bypass capacitors, and a temperature-compensated clock module SD2506API.

[0042] The STM32F413VHT6 is powered by a 1.7V to 3.6V supply, has a temperature range of -40℃ to 85℃, and its core includes a floating-point unit (FPU). Bit CPU, Adaptive Real-Time Accelerator (ARTAccelerator) TM It allows zero-wait execution from flash memory, with frequencies up to 100MHz, and features a memory protection unit, achieving 125 DMIPS (millions of instructions per second) / 1.25 DMIPS / MHz (Dhrystone 2.1 benchmark) and supporting digital signal processing (DSP) instructions. The main chip U3 is an STM32F413VHT6. Pin I2C1_SDA of the main chip U3 is connected to pin 5 of IC23, pin I2C1_CLK of the main chip U3 is connected to pin 6 of IC23, and pin TIME_RES of the main chip U3 is connected to pin 7 of IC23.

[0043] Up to 1.5 megabytes of flash memory, 320 kilobytes of static random access memory (SRAM), a flexible external static memory controller, and a 16-bit data bus supporting SRAM, pseudo-static random access memory (PSRAM), and NOR flash memory. Features include power-on reset (POR), power-down reset (PDR), a programmable voltage monitor (PVD), and undervoltage reset (BOR); clock, reset, and power management; internal 16MHz factory-calibrated RC circuitry; a calibrated 32kHz oscillator for real-time clock (RTC); and more.

[0044] In some implementations, bypass capacitors are capacitors that short-circuit AC signals to ground, thus eliminating any AC noise present on the DC signal and producing a cleaner, purer DC signal. Bypass capacitors essentially bypass AC noise that may be present on the DC signal, filtering out AC current and allowing a clean, pure DC signal to pass through with minimal AC ripple. Capacitors used to conduct AC current around the signal can be used as a component or a group of components. The Vcap capacitor and bypass capacitor connection circuit includes capacitor C23, one end of which is connected to pin Vcap-2 of the main chip U3, and the other end is grounded; it also includes capacitor C24, one end of which is connected to pin Vcap-1 of the main chip U3, and the other end is grounded; and it also includes capacitors C3, C4, C6, and C7 connected in parallel between the power supply and ground terminals. The bypass capacitor circuit includes capacitors C41, C42, C43, and C44 connected in parallel between the power supply and ground terminals.

[0045] The SD2506AP is a real-time clock module with a built-in crystal oscillator, rechargeable battery, temperature compensation, and a standard IIC interface. The CPU can use this interface to read and write 122 bytes of on-chip data (including a time register, alarm register, control register, temperature register, battery level register, 70-byte user SRAM register, and 8-byte ID code register) via a 7-bit address. The real-time clock chip IC23, model SD2506API, has pin 1 connected to the main chip U3, pin 4 grounded, pin 5 connected to the power supply via resistor R107, pin 6 connected to the power supply via resistor R106, pin 7 connected to the power supply via resistor R108, and pin 8 grounded via parallel capacitors C63 and C65.

[0046] The SD2506AP features a built-in crystal oscillator and digital temperature compensation, eliminating user concerns about component matching errors, crystal temperature characteristics, and reliability issues caused by external crystal oscillators and resonant capacitors. It achieves fully automatic, highly reliable temperature-compensated timing without user intervention within a wide temperature range (-30℃ to +80℃). The SD2506 guarantees a clock accuracy of ±3.8ppm (around 25℃), meaning an annual error of less than 2 minutes. The SD2506AP incorporates a rechargeable battery and charging circuit. With a fully charged battery at room temperature, the internal clock runs for approximately 8 months, accumulating over 550mAh of battery capacity, providing a battery life of 5-8 years. An internal power switching circuit automatically switches to battery power when the main power supply VDD drops below the rechargeable battery voltage.

[0047] The SD2506API stores the calibrated clock. Since the SD2506API uses an I2C interface, it reads the clock value from the SD2506API once each time the system is powered on or at midnight, and assigns it to the STM32F413VH's RTC. The STM32F413VH's RTC then supplies the system with a real-time clock. This is then updated once daily at midnight. This approach balances system real-time performance with accuracy.

[0048] 1) Basic module bypass capacitor: Low impedance and long life filter capacitors exceeding national standards by one order of magnitude are selected to filter out high frequency AC components.

[0049] STM32F413VH main control chip: STMicroelectronics-based main control chip; input voltage operating range 1.7V to 3.6V. Includes a real-time clock module.

[0050] 2) System power supply

[0051] This device supports external 8V-42V DC power supply. After being converted by a DC-DC power conversion module, it becomes a stable DC12V voltage. The DC12V voltage is then converted into DC5V voltage by the power conversion circuit to supply the processor and other related circuit modules.

[0052] 3) Equipment structural requirements

[0053] The overall shape of this device is cylindrical, and it is designed to be as compact as possible, with a diameter of 20mm and a length of approximately 70mm.

[0054] The specific embodiments described herein are merely illustrative examples illustrating the spirit of the invention. The above embodiments only express several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art to which this application pertains can make various modifications or additions to the described specific embodiments or use similar methods to replace them, but without departing from the spirit of this application or exceeding the scope defined by the appended claims. For those skilled in the art, multiple variations and improvements can be made without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A clock complementary sampling circuit with temperature compensation, characterized in that, It includes a high-precision clock circuit and a main control circuit. The high-precision clock circuit includes a real-time clock chip IC23, and the main control circuit includes a main chip U3. The main chip U3 is connected to the output terminal of the high-precision clock circuit. It also includes a Vcap capacitor and a bypass capacitor connection circuit, which are connected to pins Vcap-1 and Vcap-2 of the main chip U3.

2. The clock complementary sampling circuit with temperature compensation according to claim 1, characterized in that, The real-time clock chip IC23 is model SD2506API. Pin 1 of IC23 is connected to the main chip U3, pin 4 is grounded, pin 5 is connected to the power supply through resistor R107, pin 6 is connected to the power supply through resistor R106, pin 7 is connected to the power supply through resistor R108, and pin 8 is grounded through parallel capacitors C63 and C65.

3. The clock complementary sampling circuit with temperature compensation according to claim 2, characterized in that, The main chip U3 is an STM32F413VHT6. The I2C1_SDA pin of the main chip U3 is connected to the 5th pin of IC23, the I2C1_CLK pin of the main chip U3 is connected to the 6th pin of IC23, and the TIME_RES pin of the main chip U3 is connected to the 7th pin of IC23.

4. A clock complementary sampling circuit with temperature compensation according to claim 1, 2, or 3, characterized in that, The Vcap capacitor and bypass capacitor connection circuit includes capacitor C23, one end of which is connected to pin Vcap-2 of the main chip U3 and the other end is grounded. It also includes capacitor C24, one end of which is connected to pin Vcap-1 of the main chip U3 and the other end is grounded. It also includes capacitors C3, C4, C6 and C7 connected in parallel between the power supply terminal and the ground terminal.

5. A clock complementary sampling circuit with temperature compensation according to claim 1 or 3, characterized in that, It also includes an external watchdog circuit, which includes chip U4. Pin 1 of chip U4 is connected to the power supply and grounded through capacitor C40. Pin 2 is grounded. Pin 3 is grounded through resistor R91. Pin 4 is connected to pin O_RST of the main chip U3 through resistor R77. Pin 6 is connected to pin 1 of P7. Pin 2 of P7 is connected to pin RESET of the main chip U3.

6. A clock complementary sampling circuit with temperature compensation according to claim 1 or 3, characterized in that, It also includes a bypass capacitor circuit, which includes capacitors C41, C42, C43 and C44 connected in parallel between the power supply terminal and the ground terminal.

7. A clock complementary sampling circuit with temperature compensation according to claim 1 or 3, characterized in that, It also includes an internal RTC crystal oscillator circuit for the real-time clock chip. The internal RTC crystal oscillator circuit for the real-time clock chip includes capacitors X3 that are connected to pins OSC32_IN and OSC32_OUT of the main chip U3, respectively. Pin OSC32_IN of the main chip U3 is grounded through capacitor C111, and pin OSC32_OUT is grounded through capacitor C110.

8. A clock complementary sampling circuit with temperature compensation according to claim 1 or 3, characterized in that, It also includes a power supply voltage detection circuit, which includes resistors R32 and R33 connected in series between the power supply terminal and the ground terminal, and resistor R33 connected in parallel with capacitor C18.

9. A clock complementary sampling circuit with temperature compensation according to claim 1 or 3, characterized in that, It also includes a quartz crystal oscillator circuit for the main chip, which includes a capacitor X1 connected to pin PH1 of the main chip U3 and pin PH0 of the main chip U3 respectively. The capacitor X1 is connected in parallel with the resistor R44. Pin PH1 of the main chip U3 is grounded through capacitor C20, and pin PH0 of the main chip U3 is grounded through capacitor C21.

10. A clock complementary sampling circuit with temperature compensation according to claim 1 or 3, characterized in that, It also includes a reset circuit, which includes a resistor R55 and a capacitor C28 connected in series between the power supply terminal and the ground terminal. The resistor R55 and the capacitor C28 are connected to the RESET pin of the main chip U3.

Images