An industrial instrument switching power supply with a wide input voltage range

Abstract

This invention discloses a wide input voltage range industrial instrument switching power supply, including an EMI / EMS circuit, a rectifier circuit, a filter circuit, a spike suppression circuit, a switching transformer T, a switching power management chip U1, an output circuit, and a feedback control circuit. The secondary side of the switching transformer T has at least two independent secondary-side coils, one of which is a secondary-side auxiliary coil T_1. The secondary-side auxiliary coil T_1 is connected to the BP / M pin of the switching power management chip U1. The turns ratio of the primary-side coil T_0 to the secondary-side auxiliary coil T_1 of the switching transformer T is M, where M takes any value from 3 to 3.4. Through the synergistic effect of the above modules, this invention can operate normally under high voltage using the internal high-voltage starting circuit of the chip, and can also reliably start under low voltage relying on the auxiliary winding for self-powered operation, without any external switching circuit, significantly improving the adaptability of industrial instruments under different power supply environments.

Description

Technical Field

[0001] This invention relates to the field of switching power supply technology, and in particular to an industrial instrument switching power supply with a wide input voltage range. Background Technology

[0002] Currently, industrial instruments commonly use switching power supplies as their core power supply solution. Compared to traditional linear power supplies, switching power supplies have advantages such as strong anti-interference capability, high efficiency, and wide voltage input tolerance, and are therefore widely used in data acquisition and process control systems in various factory environments.

[0003] However, in actual industrial settings, some factories experience significant voltage fluctuations due to limited power grid infrastructure or the start-up and shutdown of large equipment (such as motors, frequency converters, and welding machines) on the same power grid. The effective voltage can vary between 20V and 265V. Furthermore, some scenarios only provide 24V DC power. Currently, the vast majority of industrial instruments on the market are equipped with switching power supplies whose nominal wide voltage input range is typically only AC 85V to 265V. This means that when the grid voltage drops below 85V (e.g., at the moment of motor startup or at the end of underground power lines in mines), or under DC power supply conditions below 85V, such power supplies will be unable to maintain normal operation, easily triggering undervoltage protection or causing direct power failure. This can lead to serious problems such as power-off resets, interrupted data acquisition, or control output failures in industrial instruments, affecting production safety and operational continuity. Summary of the Invention

[0004] The purpose of this invention is to provide an industrial instrument switching power supply with a wide input voltage range.

[0005] The technical solution to achieve the purpose of this invention is: an industrial instrument switching power supply with a wide input voltage range, including an EMI / EMS circuit, a rectifier circuit, a filter circuit, a spike suppression circuit, a switching transformer T, a switching power management chip U1, an output circuit, and a feedback control circuit. The EMI / EMS circuit, the rectifier circuit, the filter circuit, the primary winding T_0 of the switching transformer T, and the D pin of the switching power management chip U1 are connected in sequence. The spike suppression circuit is connected in parallel with the primary winding T_0 of the switching transformer T. The secondary side of the switching transformer T has at least two independent secondary windings, one of which is a secondary auxiliary winding T_1, and the rest are secondary output windings T_2. The secondary auxiliary coil T_1 is connected to the BP / M pin of the switching power management chip U1. The output circuit includes one or more output units. The number of secondary output windings T_2 is consistent with the number of output units in the output circuit. The secondary output windings T_2 are connected one-to-one with the output units in the output circuit. The output circuit, the feedback control circuit, and the EN / UV pins of the switching power management chip U1 are connected in sequence. The number of turns of the primary coil T_0 of the switching transformer T is N0, and the number of turns of the secondary auxiliary coil T_1 is N1. The turns ratio of the primary coil T_0 and the secondary auxiliary coil T_1 of the switching transformer T is M, where M = N0 / N1, and M is any value from 3 to 3.4.

[0006] Furthermore, the turns ratio M of the primary winding T_0 and the secondary auxiliary winding T_1 of the switching transformer T is 3.25. For example, the primary winding T_0 of the switching transformer T has 39 turns, and the secondary auxiliary winding T_1 has 12 turns, with a turns ratio M of 3.25. Considering the potential fluctuations in the actual signal, setting the turns ratio M of the primary winding T_0 and the secondary auxiliary winding T_1 of the switching transformer T to 3.25 further ensures reliable startup under low-voltage conditions.

[0007] Furthermore, the switching power supply management chip U1 is any one of the following models: TNY174P, TNY180P, TNY278P, LNK304D, and FSQ0165RN.

[0008] Furthermore, a current-limiting resistor R64 is connected in series on the connection line between the secondary auxiliary coil T_1 and the BP / M pin of the switching power management chip U1. The resistance value of the current-limiting resistor R64 can be, but is not limited to, 5.1 kΩ, with an accuracy of ±1%. By setting the above-mentioned current-limiting resistor R64, the current flowing into the BP / M pin of the switching power management chip U1 can be effectively limited to prevent overcurrent damage to the chip during low-voltage startup, while also ensuring that the switching power management chip U1 obtains a stable operating current over a wide input voltage range.

[0009] Furthermore, the EMI / EMS circuit includes a varistor RV, a thermistor F, a capacitor CX, a resistor R14, and a common-mode inductor L10. These components are arranged sequentially from front to back along the input direction. The varistor RV and capacitor CX are connected in parallel between the two input poles, while the thermistor F and resistor R14 are connected in series on a single input pole. The common-mode inductor L10 is mounted on both input poles. When the input voltage abnormally increases (such as due to lightning surges or grid overvoltage), the varistor RV quickly conducts, clamping the overvoltage within a safe range. This protects sensitive components such as the subsequent rectifier, filter, and switching power management chip U1 from overvoltage damage. Thus, under high-voltage input conditions, the varistor RV effectively absorbs overvoltage spikes on the high-voltage side, preventing breakdown of the internal MOSFET at pin D of the subsequent switching power management chip U1. The thermistor F has a high resistance at room temperature, effectively suppressing the surge current during power-on and preventing damage to the rectifier bridge and input capacitors due to excessive inrush current. At low voltage input, the initial resistance of thermistor F has little impact on low-voltage startup, but as the power supply operates normally and the temperature rises, the resistance of thermistor F automatically decreases to a minimum, preventing additional voltage drop from affecting energy transfer efficiency in low-voltage mode. Resistor R14 is connected in series with thermistor F on a single-pole line, acting as a current-limiting resistor to further limit the peak surge current. It also provides a backup current-limiting path or fault indication function in case of thermistor F failure, such as a short circuit or open circuit, enhancing the circuit's fault tolerance. Common-mode inductor L10 presents high impedance to common-mode interference current on the input line, effectively suppressing external common-mode noise from the power grid from entering the power supply, while preventing common-mode interference generated by the power supply itself from back-channeling to the power grid, thus improving electromagnetic compatibility performance in both directions. Capacitor CX is connected in parallel between the two input poles, forming an LC filter network with common-mode inductor L10. This provides a low-impedance bypass path for differential-mode conducted interference, further reducing the conducted emission level. The varistor RV, thermistor F, capacitor CX, resistor R14, and common-mode inductor L10 are arranged sequentially from front to back according to the input direction, forming a hierarchical protection effect. This hierarchical structure ensures that overvoltage protection comes first, surge suppression is in the middle, and filtering and purification come last. The components work together rather than interfere with each other, maximizing the overall EMI / EMS performance and effectively improving the electromagnetic compatibility, reliability, and lifespan of the switching power supply within a wide input voltage range (20V~265V).

[0010] Furthermore, the rectifier circuit is an integrated rectifier bridge. The model can be MB6S or ABS10. The integrated rectifier bridge encapsulates four rectifier diodes within a single component, reducing PCB footprint by approximately 50% compared to discrete diode solutions, which is beneficial for miniaturizing industrial instrument power supply modules. Moreover, the diode parameters within the rectifier bridge are highly consistent, resulting in uniform heat generation during operation, effectively reducing localized hotspots and improving the reliability of the power supply in high-temperature environments.

[0011] Furthermore, the filter circuit is a π-shaped LC filter circuit composed of capacitor E1, capacitor E2, and inductor L1. Capacitors E1, L1, and E2 are arranged sequentially from front to back according to the input direction. Capacitors E1 and E2 are connected in parallel between the two input poles, while inductor L1 is connected in series on a single input pole. Capacitor E1 primarily serves as the primary filter and energy buffer, absorbing high-frequency peak voltages from the rectifier circuit output and reducing the filtering burden on inductor L1. Inductor L1 exhibits high impedance characteristics to current changes, suppressing current surges, and simultaneously forming a low-frequency LC network with the preceding and following capacitors. Capacitor E2 further filters out residual high-frequency components and provides a stable near-end decoupling capacitor for the switching power management chip U1, ensuring a clean startup voltage at pin D of the chip. Capacitor E1, inductor L1, and capacitor E2 work together to form a two-stage low-pass filter structure. Compared with single-capacitor filtering, this structure has a higher attenuation coefficient for the high-frequency ripple component in the rectified pulsating DC, and can suppress the output voltage ripple to within mV. It effectively suppresses the ripple voltage and differential-mode conducted interference after rectification, meeting the strict requirements of industrial instruments for low noise and high purity of power supply. This makes the DC voltage after π-type LC filtering smoother, avoiding problems such as false triggering, repeated startup, or abnormal duty cycle jump of the switching power supply management chip U1 due to input voltage fluctuations or excessive pulsation after rectification. This improves the working stability and reliability of the power supply in a wide input voltage range (20V~265V).

[0012] Furthermore, the spike suppression circuit includes resistors R21 and R29, capacitor C7, and diode D3. A branch formed by the series connection of resistors R21, R29, and diode D3 is connected in parallel across the primary winding T_0 of the switching transformer T. Capacitor C7 is connected in parallel across resistor R21. The cathode of diode D3 is connected to resistor R29. During the steady-state phase after the spike energy has dissipated, when capacitor C7 is charged to a certain voltage, resistor R21 acts as a discharge resistor, gradually consuming the energy stored in capacitor C7 and preventing excessive voltage accumulation in capacitor C7 from affecting the absorption effect of the next spike. Capacitor C7, connected in parallel across resistor R21, exhibits low impedance characteristics at the moment the spike voltage appears, allowing most of the spike energy to be preferentially discharged through capacitor C7, reducing the transient current flowing through resistor R21. Diode D3, as a unidirectional conducting element, only conducts when the internal MOSFET of the switching power management chip U1 is turned off and the voltage polarity across the primary coil T_0 is reversed. This provides a low-impedance discharge path for leakage inductance energy, preventing voltage spikes from being applied to the drain of the internal MOSFET at pin D of the switching power management chip U1, thus avoiding overvoltage breakdown. Resistor R29 is connected in series with diode D3 to limit the peak value of the discharge current, preventing damage to diode D3 or the generation of additional electromagnetic interference due to excessive current. Resistor R21 and capacitor C7 are connected in parallel, and then in series with resistor R29 and diode D3, forming a two-stage impedance regulation. At the moment the voltage spike arrives, capacitor C7 provides a low-impedance path, quickly absorbing the spike energy and clamping the rate of voltage rise (dv / dt), protecting the internal switching transistor of the switching power management chip U1. After the spike, resistors R21 and R29 together provide a suitable impedance value, ensuring that the leakage inductance energy of the transformer is basically consumed before the next switching cycle, avoiding problems such as transformer core bias or secondary conduction of the switching transistor due to residual energy. This ensures that the internal switching transistor of the switching power management chip U1 can be reliably turned off in each cycle. The spike suppression circuit, through the reasonable configuration of resistors R21, R29, and capacitor C7, can prevent unnecessary power consumption due to excessive absorption when the input voltage is low and the spike energy is small, maintaining high conversion efficiency. When the input voltage is high and the spike energy is large, the circuit can provide sufficient absorption capacity to ensure that the voltage at pin D of the switching power management chip U1 is always within a safe range.

[0013] Furthermore, the output circuit is a DC rectifier and filter output circuit. The DC rectifier and filter output circuit can effectively reduce output voltage ripple and switching noise, improve the purity of the output power supply, and enhance load dynamic response performance. At the same time, it features highly versatile components and controllable costs, which is beneficial for improving the output quality and reliability of industrial instrument switching power supplies.

[0014] Furthermore, the number of output units in the output circuit is several. The output voltage of the output units in the output circuit is any one of 5V, 12V, and 24V. The TTL / CMOS logic level standard is 5V, compatible with most digital chips and microcontrollers; the standard voltage for industrial fieldbuses (RS-232, RS-485, CAN), analog front-ends, and fan cooling is 12V; the internationally common voltage for IEC61131-2 programmable controllers, sensors, and actuators is 24V. By setting up several output circuits and providing multiple standard industrial voltages such as 5V, 12V, and 24V, the diverse power supply needs of digital circuits, analog circuits, sensors, and actuators in industrial instruments can be met simultaneously with a single switching power supply; the outputs are isolated from each other, avoiding cross-regulation issues and improving the flexibility and system integration of the power supply; at the same time, the selection of standard voltage levels enhances compatibility with existing industrial instrument components and reduces user selection and usage costs.

[0015] Furthermore, an optocoupler U8 is provided on the connection line between the feedback control circuit and the EN / UV pin of the switching power management chip U1. The feedback control circuit includes a reference voltage source U9, and the primary side of the optocoupler U8 is connected to the reference voltage source U9. The reference voltage source U9 serves as a precision voltage reference source and error amplifier. It performs high-precision sampling of the output voltage, compares the sampled value with an internal reference voltage, generates an error signal, and transmits the error signal to the EN / UV pin of the switching power management chip U1 through the optocoupler U8, thereby adjusting the PWM duty cycle and stabilizing the output voltage. The optocoupler U8 is used to achieve electrical isolation between the primary and secondary sides, block ground loop interference, and improve the anti-interference capability of the feedback signal in complex electromagnetic environments. The combination of the optocoupler U8 and the reference voltage source U9 constitutes a high-precision isolated feedback network, which ensures both the adjustment accuracy of the output voltage and meets safety isolation requirements.

[0016] This invention provides an industrial instrument switching power supply with a wide input voltage range. By configuring the EMI / EMS circuit, the rectifier circuit, the filter circuit, the spike suppression circuit, the switching transformer T, the switching power management chip U1, the output circuit, and the feedback control circuit, and by connecting the primary winding T_0 and the secondary auxiliary winding T_1 of the switching transformer T to the D and BP / M pins of the switching power management chip U1 respectively, the switching power management chip U1 forms two independent startup power supply paths. Simultaneously, the turns ratio of the primary winding T_0 to the secondary auxiliary winding T_1 is set to 3~3.4.

[0017] Based on the above structure, the EMI / EMS circuit not only filters out conducted interference from equipment such as frequency converters and motor start-stop devices in industrial environments, ensuring that the switching power management chip U1 receives noise-free input power and avoiding chip mis-triggering or startup failure due to noise, but also suppresses transient surge voltages and provides comprehensive front-end protection for subsequent circuits by limiting startup surge current. With a clean input environment ensured, the rectifier circuit and filter circuit complete AC-DC conversion and bus voltage smoothing. Through capacitor energy storage and inductor smoothing in the filter circuit, instantaneous energy replenishment is provided at startup of the switching power management chip U1, compensating for potential power supply insufficiency, especially at low voltage inputs. Simultaneously, the switching transformer T, with an optimized turns ratio of 3~3.4, induces sufficient startup voltage in the secondary auxiliary coil T_1 at low voltage inputs, achieving low-voltage self-powered startup without relying on the chip's internal high-voltage startup circuit. This allows the switching power management chip U1 to automatically switch power supply paths and control switching actions based on the input voltage level. Meanwhile, the spike suppression circuit absorbs the spikes generated by the turn-off of the internal switching transistor in the switching power management chip U1, protecting the internal switching transistor and reducing electromagnetic interference; the output circuit provides a stable DC output; and the feedback control circuit forms a closed-loop voltage regulation control to ensure stable operation over a wide input voltage range.

[0018] This invention provides a wide input voltage range industrial instrument switching power supply. Through the synergistic effect of the above modules, it can operate normally under high voltage (85V~265V) using the internal high voltage start-up circuit of the chip, and can also reliably start under low voltage (20V~85V) by relying on the auxiliary winding for self-powered operation, without the need for any external switching circuit. This significantly improves the adaptability of industrial instruments in different power supply environments. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the industrial instrument switching power supply with a wide input voltage range according to the present invention. Detailed Implementation

[0020] The preferred embodiment of the industrial instrument switching power supply with a wide input voltage range of the present invention will be described in detail below with reference to the accompanying drawings.

[0021] like Figure 1As shown, an industrial instrument switching power supply with a wide input voltage range includes an EMI / EMS circuit 1, a rectifier circuit 2, a filter circuit 3, a spike suppression circuit 4, a switching transformer T, a switching power management chip U1, an output circuit 5, and a feedback control circuit 6. The EMI / EMS circuit 1, the rectifier circuit 2, the filter circuit 3, the primary winding T_0 of the switching transformer T, and the D pin of the switching power management chip U1 are connected sequentially. The spike suppression circuit 4 is connected in parallel with the primary winding T_0 of the switching transformer T. The secondary side of the switching transformer T has at least two independent secondary windings, one of which is a secondary auxiliary winding T_1, and the rest are secondary output windings T_2. The secondary auxiliary winding T_1 is connected in parallel with the primary winding T_0 of the switching transformer T. The BP / M pins of the power management chip U1 are connected. The output circuit 5 includes three output units (51, 52, 53). The number of secondary-side output windings T_2 is consistent with the number of output units in the output circuit 5. The secondary-side output windings T_2 are connected one-to-one with the three output units (51, 52, 53) of the output circuit 5. The output circuit 5, the feedback control circuit 6, and the EN / UV pins of the power management chip U1 are connected in sequence. The number of turns of the primary-side coil T_0 of the switching transformer T is N0, and the number of turns of the secondary-side auxiliary coil T_1 is N1. The turns ratio of the primary-side coil T_0 and the secondary-side auxiliary coil T_1 of the switching transformer T is M, where M = N0 / N1, and M is any value from 3 to 3.4.

[0022] This invention relates to a wide input voltage range industrial instrument switching power supply. The EMI / EMS circuit 1 is used to suppress electromagnetic interference (EMI) and improve electromagnetic immunity (EMS), including filtering high-frequency noise from the power grid, suppressing conducted interference generated by the power supply itself, and absorbing lightning surge energy, ensuring the power supply meets the electromagnetic compatibility standards of industrial instruments. The rectifier circuit 2 converts the AC input voltage into a pulsating DC voltage. The filter circuit 3 smooths and filters the rectified pulsating DC, reducing voltage ripple and providing a relatively stable DC bus voltage for the subsequent switching transformer T and the switching power management chip U1. The spike suppression circuit 4 absorbs the leakage inductance spike voltage generated by the primary winding T_0 of the switching transformer T at the moment the internal switching transistor of the switching power management chip U1 is turned off, protecting the internal switching transistor of the switching power management chip U1 from overvoltage breakdown. The switching transformer T is used for energy storage and transfer, voltage conversion, and electrical isolation between the primary and secondary sides. The primary side coil T_0 stores energy from the input terminal, the secondary side auxiliary coil T_1 provides operating power to the switching power management chip U1, and the secondary side output winding T_2 is connected to the output unit of the output circuit 5 to provide output voltage to the load. The switching power management chip U1 controls the operation of the entire power supply. Internally, the switching power management chip U1 integrates a high-voltage start-up switch and a PWM controller. It obtains operating power through pin D (high-voltage power supply pin) and pin BP / M (low-voltage power supply pin), receives feedback signals through pin EN / UV, and adjusts the PWM duty cycle to stabilize the output voltage. The output unit of the output circuit 5 rectifies and filters the high-frequency pulse voltage output from the secondary side output winding T_2, converting it into a smooth DC output voltage. For example, output unit 51 outputs 5V, output unit 52 outputs 12V, and output unit 53 outputs 24V for use by industrial instruments. The feedback control circuit 6 is used to transmit the output voltage to the EN / UV pin of the switching power management chip U1 to form a closed-loop control, ensuring that the output voltage remains stable under various operating conditions.

[0023] This invention provides an industrial instrument switching power supply with a wide input voltage range. The input voltage first enters the EMI / EMS circuit 1 for filtering and anti-interference processing, then is converted into a DC signal by the rectifier circuit 2. This DC signal is then smoothed into a relatively stable DC bus voltage by the filter circuit 3. This DC bus voltage is applied to the primary winding T_0 of the switching transformer T, and then further input to the switching power supply management chip U1 to start the switching power supply management chip U1 and put it into operation. After the switching power supply management chip U1 is started, its internally integrated switching transistor periodically turns on and off, causing the primary winding T_0 of the switching transformer T to... An alternating current is generated in the circuit, and the energy carried by this alternating current is transferred to the secondary side of the switching transformer T through electromagnetic induction. The high-frequency pulse voltage output by the secondary side output winding T_2 is rectified and filtered by the output unit of the output circuit 5 and converted into a smooth DC output voltage to supply the industrial instrument load. At the same time, the output voltage of the output circuit 5 is sampled by the feedback control circuit 6 and the feedback signal is transmitted to the EN / UV pin of the switching power management chip U1. The switching power management chip U1 adjusts the PWM duty cycle according to the feedback signal of the feedback control circuit 6 to stabilize the output voltage of the output circuit 5 at the set value.

[0024] This invention relates to an industrial instrument switching power supply with a wide input voltage range. The switching power supply management chip U1 integrates a high-voltage startup circuit. Specifically, when the input high voltage is 85V~265V, the switching power supply management chip U1 is directly powered through the high-voltage startup circuit inside its D pin. At this time, the capacitor connected to the BP / M pin is charged to its startup threshold voltage (typically 5.8V), and the chip completes startup and enters normal operation. When the input voltage is low, such as 20V~85V, the voltage at pin D of the switching power management chip U1 is too low. Its internal high-voltage startup circuit cannot provide sufficient charging current, causing the capacitor connected to pin BP / M to fail to be charged to the 5.8V startup threshold, and the chip cannot start in the normal way. At this time, the electrical energy on the primary side coil T_0 of the switching transformer T is transferred to the secondary side auxiliary coil T_1 through electromagnetic induction. Taking an input voltage of 20V as an example, the induced voltage on the secondary side auxiliary coil T_1 is above 5.88V. This voltage is higher than the 5.8V charging requirement of the capacitor connected to pin BP / M, and can charge the capacitor connected to pin BP / M to 5.8V. After the switching power management chip U1 detects that the voltage at pin BP / M has reached the startup threshold, it bypasses the internal high-voltage startup circuit, is powered by pin BP / M, and starts PWM switching.

[0025] This invention relates to a wide input voltage range industrial instrument switching power supply. The turns ratio M of the primary winding T_0 and the secondary auxiliary winding T_1 of the switching transformer T is 3 to 3.4. Taking a turns ratio M of 3.4 and an input voltage of 20V as an example, the induced voltage (RMS value) on the secondary auxiliary winding T_1 is approximately 20V / M ≈ 5.88V. This voltage is higher than the 5.8V startup threshold of the capacitor at pin BP / M, therefore, the switching power supply management chip U1 can be activated.

[0026] The present invention provides an industrial instrument switching power supply with a wide input voltage range. After low-voltage startup, the internal switching transistor of the switching power management chip U1 begins high-frequency switching operation, and the alternating current in the primary side coil T_0 increases; the induced voltage on the secondary side auxiliary coil T_1 increases accordingly and remains stable, continuously supplying power to the BP / M pin of the switching power management chip U1.

[0027] This invention provides an industrial instrument switching power supply with a wide input voltage range. When the input voltage decreases from high voltage (e.g., above 85V) to low voltage (e.g., below 85V), the high-voltage startup circuit at pin D of the switching power supply management chip U1 naturally shuts down, and pins BP / M continuously receive power from the secondary auxiliary coil T_1, allowing the power supply to smoothly transition to low-voltage mode. When the input voltage gradually increases from low voltage (e.g., below 85V) to high voltage (e.g., above 85V), the power supply at pins BP / M of the switching power supply management chip U1 continues to be the primary power source, while the high-voltage startup circuit at pin D of the switching power supply management chip U1 remains in standby mode, without affecting normal operation.

[0028] This invention provides an industrial instrument switching power supply with a wide input voltage range. It comprises the EMI / EMS circuit 1, the rectifier circuit 2, the filter circuit 3, the spike suppression circuit 4, the switching transformer T, the switching power management chip U1, the output circuit 5, and the feedback control circuit 6. The primary winding T_0 and the secondary auxiliary winding T_1 of the switching transformer T are connected to the D pin and BP / M pin of the switching power management chip U1, respectively, thus creating two independent startup power supply paths for the switching power management chip U1. Simultaneously, the turns ratio M of the primary winding T_0 and the secondary auxiliary winding T_1 is set to 3~3.4.

[0029] Based on the above structure, the EMI / EMS circuit 1 not only filters out conducted interference generated by equipment such as frequency converters and motor start-stop devices in the industrial field, ensuring that the switching power management chip U1 receives a noise-free input power supply and avoiding chip mis-triggering or startup failure due to noise, but also suppresses transient surge voltages and provides comprehensive front-end protection for subsequent circuits by limiting startup surge current. With a clean input environment ensured, the rectifier circuit 2 and the filter circuit 3 are used to complete AC-DC conversion and bus voltage smoothing. Through the capacitor energy storage and inductor smoothing of the filter circuit 3, instantaneous energy replenishment is provided at the moment of startup of the switching power management chip U1, compensating for potential power supply insufficiency, especially at low voltage inputs. Simultaneously, the switching transformer T, with an optimized turns ratio of 3~3.4, induces sufficient startup voltage in the secondary auxiliary coil T_1 at low voltage inputs, achieving low-voltage self-powered startup without relying on the chip's internal high-voltage startup circuit. This allows the switching power management chip U1 to automatically switch power supply paths and control switching actions according to the input voltage level. Meanwhile, the spike suppression circuit 4 absorbs the spikes generated by the turn-off of the internal switching transistor in the switching power management chip U1, protecting the internal switching transistor and reducing electromagnetic interference; the output circuit 5 provides a stable DC output; and the feedback control circuit 6 forms a closed-loop voltage regulation control to ensure stable operation over a wide input voltage range.

[0030] This invention provides a wide input voltage range industrial instrument switching power supply. Through the synergistic effect of the above modules, it can operate normally under high voltage (85V~265V) using the internal high voltage start-up circuit of the chip, and can also reliably start under low voltage (20V~85V) by relying on the auxiliary winding for self-powered operation, without the need for any external switching circuit. It can also be used with AC and DC input, significantly improving the adaptability of industrial instruments in different power supply environments.

[0031] Furthermore, in the wide input voltage range industrial instrument switching power supply of this invention, the startup threshold of the capacitor at the BP / M pin of the switching power supply management chip U1 is 5.8V. When the input voltage is the lowest voltage of 20V, and 20V / M≥5.8V, i.e., M≤3.4, the chip can be started through the BP / M pin of the switching power supply management chip U1. Simultaneously, to avoid excessively high auxiliary winding voltage and increased power consumption due to an excessively small turns ratio (e.g., a value of 1), and to balance low-voltage startup performance with efficiency under high-voltage conditions, this invention further sets the value of M to ≥3. That is, this invention sets the turns ratio M of the primary side coil T_0 and the secondary side auxiliary coil T_1 to 3~3.4, which ensures reliable chip startup under low-voltage input while avoiding additional power consumption caused by excessively high auxiliary winding voltage, thus achieving a reasonable balance between startup reliability and conversion efficiency over a wide input voltage range.

[0032] In this invention, a wide input voltage range industrial instrument switching power supply is provided. Preferably, the turns ratio M of the primary winding T_0 and the secondary auxiliary winding T_1 of the switching transformer T is 3.25. For example, if the primary winding T_0 of the switching transformer T has 39 turns N0 and the secondary auxiliary winding T_1 has 12 turns N1, the turns ratio M of the primary winding T_0 and the secondary auxiliary winding T_1 of the switching transformer T is 3.25. Considering that actual signals may fluctuate, setting the turns ratio M of the primary winding T_0 and the secondary auxiliary winding T_1 of the switching transformer T to 3.25 can further ensure reliable startup under low voltage conditions.

[0033] This invention relates to an industrial instrument switching power supply with a wide input voltage range. The switching power supply management chip U1 is any one of the following models: TNY174P, TNY180P, TNY278P, LNK304D, and FSQ0165RN.

[0034] In this invention, an industrial instrument switching power supply with a wide input voltage range preferably includes a current-limiting resistor R64 connected in series on the connection line between the secondary auxiliary coil T_1 and the BP / M pin of the switching power management chip U1. The resistance value of the current-limiting resistor R64 can be, but is not limited to, 5.1 kΩ, with an accuracy of ±1%. By setting the aforementioned current-limiting resistor R64, the current flowing into the BP / M pin of the switching power management chip U1 can be effectively limited, preventing overcurrent damage to the chip during low-voltage startup, while also ensuring that the switching power management chip U1 obtains a stable operating current within a wide input voltage range.

[0035] This invention relates to a wide input voltage range industrial instrument switching power supply. Preferably, the EMI / EMS circuit 1 includes a varistor RV, a thermistor F, a capacitor CX, a resistor R14, and a common-mode inductor L10. The varistor RV, the thermistor F, the capacitor CX, the resistor R14, and the common-mode inductor L10 are arranged sequentially from front to back according to the input direction. The varistor RV and the capacitor CX are connected in parallel between the two input poles, the thermistor F and the resistor R14 are connected in series on a single input pole, and the common-mode inductor L10 is mounted on both input poles. The varistor RV rapidly conducts when the input voltage abnormally increases (such as due to lightning surges or grid overvoltage), clamping the overvoltage within a safe range and protecting sensitive components such as the subsequent rectifier, filter, and switching power management chip U1 from overvoltage damage. Thus, under high-voltage input conditions, the varistor RV can effectively absorb overvoltage spikes on the high-voltage side, preventing breakdown of the internal MOSFET at pin D of the subsequent switching power management chip U1. The thermistor F has a high resistance at room temperature, effectively suppressing the surge current during power-on and preventing damage to the rectifier bridge and input capacitors due to excessive inrush current. At low voltage input, the initial resistance of thermistor F has little impact on low-voltage startup, but as the power supply operates normally and the temperature rises, the resistance of thermistor F automatically decreases to a minimum, preventing additional voltage drop from affecting energy transfer efficiency in low-voltage mode. Resistor R14 is connected in series with thermistor F on a single-pole line, acting as a current-limiting resistor to further limit the peak surge current. It also provides a backup current-limiting path or fault indication function in case of thermistor F failure, such as a short circuit or open circuit, enhancing the circuit's fault tolerance. Common-mode inductor L10 presents high impedance to common-mode interference current on the input line, effectively suppressing external common-mode noise from the power grid from entering the power supply, while preventing common-mode interference generated by the power supply itself from back-channeling to the power grid, thus improving electromagnetic compatibility performance in both directions. Capacitor CX is connected in parallel between the two input poles, forming an LC filter network with common-mode inductor L10. This provides a low-impedance bypass path for differential-mode conducted interference, further reducing the conducted emission level. The varistor RV, thermistor F, capacitor CX, resistor R14, and common-mode inductor L10 are arranged sequentially from front to back according to the input direction, forming a hierarchical protection effect. This hierarchical structure ensures that overvoltage protection comes first, surge suppression is in the middle, and filtering and purification come last. The components work together rather than interfere with each other, maximizing the overall EMI / EMS performance and effectively improving the electromagnetic compatibility, reliability, and lifespan of the switching power supply within a wide input voltage range (20V~265V).

[0036] This invention relates to a wide input voltage range industrial instrument switching power supply. Preferably, the rectifier circuit 2 is an integrated rectifier bridge. The model can be MB6S or ABS10. The integrated rectifier bridge encapsulates four rectifier diodes within a single component, reducing PCB footprint by approximately 50% compared to discrete diode solutions, which is beneficial for miniaturization of industrial instrument power supply modules. Furthermore, the diode parameters within the rectifier bridge are highly consistent, resulting in uniform heat generation during operation, effectively reducing localized hotspots and improving the power supply's reliability in high-temperature environments.

[0037] In this invention, an industrial instrument switching power supply with a wide input voltage range is preferably provided. The filter circuit 3 is a π-shaped LC filter circuit composed of capacitor E1, capacitor E2, and inductor L1. Capacitors E1, L1, and E2 are arranged sequentially from front to back according to the input direction. Capacitors E1 and E2 are connected in parallel between the two input poles, while inductor L1 is connected in series on a single input pole. Capacitor E1 primarily performs primary filtering and energy buffering, absorbing high-frequency peak voltages from the rectifier circuit output and reducing the filtering burden on inductor L1. Inductor L1 exhibits high impedance to current changes, suppressing current surges and forming a low-frequency LC network with the preceding and following capacitors. Capacitor E2 further filters out residual high-frequency components and provides a stable near-end decoupling capacitor for the switching power supply management chip U1, ensuring a clean startup voltage at pin D of the chip. Capacitor E1, inductor L1, and capacitor E2 work together to form a two-stage low-pass filter structure. Compared with single-capacitor filtering, this structure has a higher attenuation coefficient for the high-frequency ripple component in the rectified pulsating DC, and can suppress the output voltage ripple to within mV. It effectively suppresses the ripple voltage and differential-mode conducted interference after rectification, meeting the strict requirements of industrial instruments for low noise and high purity of power supply. This makes the DC voltage after π-type LC filtering smoother, avoiding problems such as false triggering, repeated startup, or abnormal duty cycle jump of the switching power supply management chip U1 due to input voltage fluctuations or excessive pulsation after rectification. This improves the working stability and reliability of the power supply in a wide input voltage range (20V~265V).

[0038] In this invention, a wide input voltage range industrial instrument switching power supply is provided. Preferably, the spike suppression circuit 4 includes resistors R21 and R29, capacitor C7, and diode D3. A branch formed by the series connection of resistors R21, R29, and diode D3 is connected in parallel across the primary winding T_0 of the switching transformer T. Capacitor C7 is connected in parallel across resistor R21. The cathode of diode D3 is connected to resistor R29. During the steady-state phase after the spike energy has dissipated, when capacitor C7 is charged to a certain voltage, resistor R21 acts as a discharge resistor, gradually consuming the energy stored in capacitor C7 and preventing excessive voltage accumulation in capacitor C7 from affecting the absorption effect of the next spike. Capacitor C7, connected in parallel across resistor R21, exhibits low impedance characteristics at the moment the spike voltage appears, allowing most of the spike energy to be preferentially discharged through capacitor C7, reducing the transient current flowing through resistor R21. Diode D3, as a unidirectional conducting element, only conducts when the internal MOSFET of the switching power management chip U1 is turned off and the voltage polarity across the primary coil T_0 is reversed. This provides a low-impedance discharge path for leakage inductance energy, preventing voltage spikes from being applied to the drain of the internal MOSFET at pin D of the switching power management chip U1, thus avoiding overvoltage breakdown. Resistor R29 is connected in series with diode D3 to limit the peak value of the discharge current, preventing damage to diode D3 or the generation of additional electromagnetic interference due to excessive current. Resistor R21 and capacitor C7 are connected in parallel, and then in series with resistor R29 and diode D3, forming a two-stage impedance regulation. At the moment the voltage spike arrives, capacitor C7 provides a low-impedance path, quickly absorbing the spike energy and clamping the voltage rise rate (dv / dt), protecting the internal switching transistor of the switching power management chip U1. After the spike, resistors R21 and R29 together provide a suitable impedance value, ensuring that the leakage inductance energy of the transformer is basically consumed before the next switching cycle, avoiding problems such as transformer core magnetization or secondary conduction of the switching transistor due to residual energy. This ensures that the internal switching transistor of the switching power management chip U1 can be reliably turned off in each cycle. The spike suppression circuit 4, through the reasonable configuration of resistors R21, R29, and capacitor C7, can prevent unnecessary power consumption due to excessive absorption when the input voltage is low and the spike energy is small, maintaining high conversion efficiency. When the input voltage is high and the spike energy is large, the circuit can provide sufficient absorption capacity to ensure that the voltage at pin D of the switching power management chip U1 is always within a safe range.

[0039] The present invention provides an industrial instrument switching power supply with a wide input voltage range. Preferably, the output units of the output circuit 5 all include DC filter circuits. The DC filter circuit effectively reduces output voltage ripple and switching noise, improves the purity of the output power supply, and enhances the dynamic response performance of the load. Furthermore, the components are highly versatile and cost-effective, which helps to improve the output quality and reliability of the industrial instrument switching power supply.

[0040] This invention relates to a wide input voltage range industrial instrument switching power supply. Preferably, the number of output units in the output circuit 5 is several. The output voltage of the output unit in the output circuit 5 is any one of 5V, 12V, and 24V. Preferably, the number of output units in the output circuit 5 is three, respectively denoted as output unit 51, output unit 52, and output unit 53. The output voltage of output unit 51 is 5V, the output voltage of output unit 52 is 12V, and the output voltage of output unit 53 is 24V. The TTL / CMOS logic level standard is 5V, compatible with most digital chips and microcontrollers; the standard voltage for industrial fieldbus (RS-232, RS-485, CAN), analog front-end, and fan cooling is 12V; the internationally common voltage for IEC 61131-2 programmable controller standard, sensors, and actuators is 24V. By setting up several output circuits and providing multiple standard industrial voltages such as 5V, 12V, and 24V, a single switching power supply can simultaneously meet the diverse power supply needs of digital circuits, analog circuits, sensors, and actuators in industrial instruments. Each output is isolated from the others, avoiding cross-regulation issues and improving the power supply's flexibility and system integration. At the same time, the selection of standard voltage levels enhances compatibility with existing industrial instrument components, reducing user selection and usage costs.

[0041] In this invention, an industrial instrument switching power supply with a wide input voltage range is preferably provided with an optocoupler U8 on the connection line between the feedback control circuit 6 and the EN / UV pin of the switching power management chip U1. The feedback control circuit 6 includes a reference voltage source U9, and the primary side of the optocoupler U8 is connected to the reference voltage source U9. The reference voltage source U9 serves as a precision voltage reference source and error amplifier. It performs high-precision sampling of the output voltage, compares the sampled value with an internal reference voltage, generates an error signal, and transmits the error signal to the EN / UV pin of the switching power management chip U1 through the optocoupler U8, thereby adjusting the PWM duty cycle and stabilizing the output voltage. The optocoupler U8 is used to achieve electrical isolation between the primary and secondary sides, block ground loop interference, and improve the anti-interference capability of the feedback signal in complex electromagnetic environments. The combination of the optocoupler U8 and the reference voltage source U9 constitutes a high-precision isolated feedback network, which ensures both the adjustment accuracy of the output voltage and meets safety isolation requirements.

[0042] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent process transformations made using the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An industrial instrument switching power supply with a wide input voltage range, characterized in that: The circuit includes an EMI / EMS circuit, a rectifier circuit, a filter circuit, a spike suppression circuit, a switching transformer T, a switching power management chip U1, an output circuit, and a feedback control circuit. The EMI / EMS circuit, the rectifier circuit, the filter circuit, the primary winding T_0 of the switching transformer T, and pin D of the switching power management chip U1 are connected sequentially. The spike suppression circuit is connected in parallel with the primary winding T_0 of the switching transformer T. The secondary side of the switching transformer T has at least two independent secondary windings, one of which is a secondary auxiliary winding T_1, and the rest are secondary output windings T_2. The secondary auxiliary winding T_1 is connected to the switching power transistor... The BP / M pins of the power management chip U1 are connected. The output circuit includes one or more output units. The number of secondary-side output windings T_2 is consistent with the number of output units in the output circuit. The secondary-side output windings T_2 are connected one-to-one with the output units in the output circuit. The output circuit, the feedback control circuit, and the EN / UV pins of the power management chip U1 are connected in sequence. The number of turns of the primary-side coil T_0 of the switching transformer T is N0, and the number of turns of the secondary-side auxiliary coil T_1 is N1. The turns ratio of the primary-side coil T_0 and the secondary-side auxiliary coil T_1 of the switching transformer T is M, where M = N0 / N1, and M is any value from 3 to 3.

4.

2. The industrial instrument switching power supply with a wide input voltage range according to claim 1, characterized in that: The turns ratio M of the primary winding T_0 and the secondary auxiliary winding T_1 of the switching transformer T is 3.

25.

3. The industrial instrument switching power supply with a wide input voltage range according to claim 1, characterized in that: The switching power supply management chip U1 is any one of the following models: TNY174P, TNY180P, TNY278P, LNK304D, or FSQ0165RN.

4. The industrial instrument switching power supply with a wide input voltage range according to claim 1, characterized in that: A current-limiting resistor R64 is connected in series on the connection line between the secondary auxiliary coil T_1 and the BP / M pin of the switching power management chip U1.

5. The industrial instrument switching power supply with a wide input voltage range according to claim 1, characterized in that: The EMI / EMS circuit includes a varistor RV, a thermistor F, a capacitor CX, a resistor R14, and a common-mode inductor L10. The varistor RV, the thermistor F, the capacitor CX, the resistor R14, and the common-mode inductor L10 are arranged sequentially from front to back according to the input direction. The varistor RV and the capacitor CX are connected in parallel between the two input poles, the thermistor F and the resistor R14 are connected in series on the single input pole, and the common-mode inductor L10 is mounted on the two input poles.

6. The industrial instrument switching power supply with a wide input voltage range according to claim 1, characterized in that: The rectifier circuit is an integrated rectifier bridge.

7. The industrial instrument switching power supply with a wide input voltage range according to claim 1, characterized in that: The filter circuit is a π-shaped LC filter circuit composed of capacitor E1, capacitor E2 and inductor L1. Capacitor E1, inductor L1 and capacitor E2 are arranged in sequence from front to back according to the input direction. Among them, capacitor E1 and capacitor E2 are connected in parallel between the two input poles, and inductor L1 is connected in series on the single input pole.

8. The industrial instrument switching power supply with a wide input voltage range according to claim 1, characterized in that: The spike suppression circuit includes resistors R21 and R29, capacitor C7, and diode D3. A branch formed by the series connection of resistors R21, R29, and diode D3 is connected in parallel across the primary winding T_0 of the switching transformer T. Capacitor C7 is connected in parallel across resistor R21. The cathode of diode D3 is connected to resistor R29.

9. The industrial instrument switching power supply with a wide input voltage range according to claim 1, characterized in that: The output circuit is a DC rectifier and filter output circuit; the number of output units in the output circuit is several.

10. The industrial instrument switching power supply with a wide input voltage range according to claim 1, characterized in that: An optocoupler U8 is provided on the connection line between the feedback control circuit and the EN / UV pin of the switching power management chip U1. The feedback control circuit includes a reference voltage source U9, and the primary side of the optocoupler U8 is connected to the reference voltage source U9.

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