Adjustable constant-current and constant-voltage SOURCE-SINK power supply

Abstract

The utility model aims to provide an adjustable SOURCE-SINK power supply with constant current and constant voltage. The power supply comprises a power supply chip, a PVIN end, an SW end and an RSP end of the power supply chip are respectively connected with an input stage, an output stage and a feedback stage, the input stage is connected with an external input power supply, the output stage is connected with an external product or load, and the feedback stage is connected with an external DAC chip; the feedback stage comprises a first resistor, a first amplifier and a second amplifier, the first resistor is connected with the SW end of the power supply chip, the input end of the first amplifier is connected with the first resistor, the output end of the first amplifier is connected with the input end of the second amplifier, and the output end of the second amplifier is connected with the output end of the second amplifier. The output end of the second amplifier and the RSP end of the power supply chip are connected with an external DAC chip. The utility model is applied to the technical field of equipment power supplies.

Description

Technical Field

[0001] This invention relates to the technical field of equipment power supplies, and particularly to an adjustable constant current and constant voltage source-sink power supply. Background Technology

[0002] SINK power supply: This indicates a negative power supply, capable of drawing external current into the power supply and allowing it to flow out from the input terminal. SOURCE power supply: This indicates a positive power supply; it is the source of energy, from which current flows out. Zero point: When the system input amplitude is not zero, and the input frequency causes the system output to be zero, this input frequency value is the zero point. Phase margin: The difference between the phase of the operational amplifier gain at the gain crossover frequency and the -180° phase. Transient response: The change in the system output from the initial state to the steady state under the action of a system signal input.

[0003] Source power supplies refer to commercially available DC regulated power supplies capable of providing various current and voltage specifications. Sink power supplies typically contain an input port for receiving electrical energy, along with corresponding circuitry to convert the received energy into the form required by the device. In some specialized applications, such as certain CCD imaging circuits, the power supply circuit is required to have both sink current capability and the ability to output a positive voltage. Existing sink power supplies, while possessing sink current capability, can only output a negative voltage. Existing DDR power supply chips, such as the TPS51200, have both sink current and source current capabilities, and can also output a positive voltage. However, the output voltage of DDR power supply chips is not adjustable, and the maximum output current is only 4.5A, resulting in strong specialization and poor versatility.

[0004] Current similar technologies include: (e.g., ...) Figure 7 As shown, the input terminal VIN of the SINK type voltage regulator is grounded, and the adjustment terminal ADJ is connected to the voltage VDD through a resistor, so that the output voltage is positive and adjustable, and has the ability to sink current.

[0005] Currently, a similar technology 2 is the TPS51200 device, a double data rate (DDR) termination regulator with both sink and source currents. It can meet all power requirements of DDR series terminations, supporting only 2.5V and 3.3V input voltages. The output voltage is not adjustable, with a maximum source current of 5.5A and a sink current of 5.5A. Application circuits for this chip include... Figure 8 As shown.

[0006] Currently, positive voltage linear regulators with sinking capability have limited load-carrying capacity, low efficiency, and low output power, making them unsuitable for high-dropout applications. Furthermore, most standard DC-DC power supplies lack sinking capability and have relatively low input and output ranges. This is primarily because DC-DC buck power supplies built with discrete components struggle to accept sinking current, have limited dynamic performance, and are difficult to adjust parameters.

[0007] Most power supply chips possess source current capability and adjustable output range, achieving high performance in key parameters such as ripple and transient response. Currently, power supplies requiring sink capability are relatively rare, with the market dominated by standard source power supplies. However, power supply chips capable of accepting negative current are scarce, and their negative current range is quite limited. Therefore, it is necessary to provide an adjustable constant current and constant voltage source-sink power supply that is small in size, has simple peripheral circuitry, is flexible in application, and highly adaptable, suitable for most onboard power supplies; its sink current capability can reach -20A; its source voltage output is adjustable in constant voltage and constant current mode; its source voltage accuracy is as high as 1‰; it has fast transient response; and its ripple is less than 20mV across the entire power range. Utility Model Content

[0008] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide an adjustable constant current and constant voltage source-sink power supply. It is small in size, has a simple peripheral circuit, is flexible in application, and has strong applicability. It is suitable for most onboard power supplies. The sink current capability can reach -20A. The source voltage output is adjustable in constant voltage and constant current mode. The source voltage accuracy is as high as 1‰, the transient response is fast, and the ripple is less than 20mV across the entire power range.

[0009] The technical solution adopted by this utility model is as follows: This utility model includes a power chip, the PVIN terminal, SW terminal, and RSP terminal of the power chip are respectively connected to an input stage, an output stage, and a feedback stage. The input stage is connected to an external input power supply, the output stage is connected to an external product or load, and the feedback stage is connected to an external DAC chip. The feedback stage includes a first resistor, a first amplifier, and a second amplifier. The first resistor is connected to the SW terminal of the power chip, the input terminal of the first amplifier is connected to the first resistor, the output terminal of the first amplifier is connected to the input terminal of the second amplifier, and the output terminal of the second amplifier and the RSP terminal of the power chip are both connected to an external DAC chip.

[0010] As can be seen from the above solution, this application introduces a new power chip and peripheral circuit into the traditional power supply structure, which can realize bidirectional SOURCE-SINK conversion. It can not only achieve adjustable constant current and constant voltage output, but also has excellent performance advantages. In terms of size, it almost meets the needs of board-level power supplies on the market. It has a very strong competitiveness in a variety of application scenarios. By introducing the DAC input terminal into the voltage feedback terminal, the defect of non-adjustable voltage under constant current power supply conditions is solved.

[0011] In a preferred embodiment, the feedback stage further includes a second resistor and a first capacitor, one end of the first capacitor is connected to the first resistor, the other end of the first capacitor is connected to one end of the second resistor, and the other end of the second resistor is connected to the RSP terminal of the power chip.

[0012] In a preferred embodiment, the feedback stage further includes a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor, wherein the sixth resistor is connected to the output terminal of the second amplifier, and the third resistor, the fourth resistor, and the fifth resistor are all connected to the first resistor and the sixth resistor.

[0013] In a preferred embodiment, the input stage includes a second capacitor, a third capacitor, and a fourth capacitor connected in parallel, and the external PP_12V is connected to the PVIN terminal of the power chip through the second capacitor, the third capacitor, and the fourth capacitor.

[0014] In a preferred embodiment, the output stage includes an inductor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor, a tenth capacitor, a seventh resistor, and an eleventh capacitor. The SW terminal of the power supply chip is connected to the first resistor in sequence via the inductor, the fifth capacitor, the sixth capacitor, the seventh capacitor, the eighth capacitor, the ninth capacitor, and the tenth capacitor. The BOOT terminal of the power supply chip is grounded in sequence via the seventh resistor and the eleventh capacitor. Attached Figure Description

[0015] Figure 1 This is the circuit schematic diagram of this utility model;

[0016] Figure 2 This is the SINK current verification method of this utility model;

[0017] Figure 3 This is the ripple diagram of the 4V / 20A power output of this utility model;

[0018] Figure 4 This is the circuit simulation Bode plot of this utility model;

[0019] Figure 5 This is the transient response diagram of the power supply output of this utility model at 4.5V / 10A & 20A;

[0020] Figure 6 This is the power circuit layout diagram of this utility model;

[0021] Figure 7 This is a schematic diagram of a prior art positive voltage linear regulator with SINK capability;

[0022] Figure 8 This is a schematic diagram of a current-technology terminal voltage regulator. Detailed Implementation

[0023] like Figure 1 As shown, in this embodiment, the present invention includes a power chip U1. The PVIN, SW, and RSP terminals of the power chip U1 are respectively connected to an input stage, an output stage, and a feedback stage. The input stage is connected to an external input power supply, the output stage is connected to an external product or load, and the feedback stage is connected to an external DAC chip. The feedback stage includes a first resistor R1, a first amplifier U2, and a second amplifier U3. The first resistor R1 is connected to the SW terminal of the power chip U1, the input terminal of the first amplifier U2 is connected to the first resistor R1, the output terminal of the first amplifier U2 is connected to the input terminal of the second amplifier U3, and the output terminal of the second amplifier U3 and the RSP terminal of the power chip U1 are both connected to an external DAC chip.

[0024] The power chip U1 is a TPS543B20. The input stage is used for input power and receiving SINK current; the output stage is used for outputting voltage and current and serving as a path for receiving SINK current; the feedback stage implements the functions of adjusting the output voltage and constant current / constant voltage. The input stage consists of an input power supply and a capacitor; the output stage consists of a bootstrap circuit and energy storage components (inductor and capacitor); the feedback stage consists of a DAC output, remote feedback, loop compensation, constant current feedback network, and sampling resistors; the power chip U1 mainly functions as a PWM controller.

[0025] like Figure 1 As shown, PP12V is the input power supply for the entire circuit, with a voltage of 12V, providing energy to the power chip U1; OUTPUT is the output terminal of the power circuit, outputting voltage and current, and connecting to external products or loads; OUTPUT_S+ and S- are connected to the positive and negative terminals of the external product, introducing the voltage of the product to the feedback terminal to ensure that the voltage of the product is the set voltage and will not cause voltage drop due to load effect; DAC_SET is connected to an external DAC chip, outputting a control voltage to make the circuit output voltage adjustable.

[0026] The first resistor R1 serves as a sampling resistor, converting the changing output current into voltage and collecting it at the feedback terminal; the first amplifier U2 amplifies the voltage across the sampling resistor by 25 times; the second amplifier U3 compares the amplified voltage with 1.8V. When the voltage is less than 1.8V, the output terminal is in a constant voltage state; when the voltage is greater than 1.8V, the output terminal is in a constant current state.

[0027] like Figure 1 As shown, in this embodiment, the feedback stage further includes a second resistor R9 and a first capacitor C13. One end of the first capacitor C13 is connected to the first resistor R1, and the other end of the first capacitor C13 is connected to one end of the second resistor R9. The other end of the second resistor R9 is connected to the RSP terminal of the power chip U1. The first capacitor C13 and the second resistor R9 provide a zero point for the circuit, increasing the phase margin of the loop and improving the loop crossover frequency.

[0028] like Figure 1 As shown, in this embodiment, the feedback stage further includes a third resistor R12, a fourth resistor R13, a fifth resistor R14, and a sixth resistor R15. The sixth resistor R15 is connected to the output terminal of the second amplifier U3. The third resistor R12, the fourth resistor R13, and the fifth resistor R14 are all connected to the first resistor R1 and the sixth resistor R15. The third resistor R12, the fourth resistor R13, and the fifth resistor R14 all serve as a feedback resistor network, working together at the feedback terminal of the chip to control the output voltage.

[0029] like Figure 1 As shown, in this embodiment, the input stage includes a second capacitor C10, a third capacitor C11, and a fourth capacitor C12 connected in parallel. External PP_12V is connected to the PVIN terminal of the power chip U1 via the second capacitor C10, the third capacitor C11, and the fourth capacitor C12. The second capacitor C10, the third capacitor C11, and the fourth capacitor C12 all serve as input capacitors, playing a role in energy storage, voltage regulation, filtering, and protection.

[0030] like Figure 1 As shown, in this embodiment, the output stage includes an inductor L1, a fifth capacitor C1, a sixth capacitor C2, a seventh capacitor C3, an eighth capacitor C4, a ninth capacitor C5, a tenth capacitor C6, a seventh resistor R6, and an eleventh capacitor C9. The SW terminal of the power chip U1 is connected to the first resistor R1 via the inductor L1, the fifth capacitor C1, the sixth capacitor C2, the seventh capacitor C3, the eighth capacitor C4, the ninth capacitor C5, and the tenth capacitor C6 in sequence. The BOOT terminal of the power chip U1 is grounded via the seventh resistor R6 and the eleventh capacitor C9 in sequence.

[0031] The inductor L1 primarily functions as a filter, stores energy, and suppresses output voltage ripple. The fifth capacitor C1, the sixth capacitor C2, the seventh capacitor C3, the eighth capacitor C4, the ninth capacitor C5, and the tenth capacitor C6 all stabilize the output voltage at the desired value, reducing voltage fluctuations. The seventh resistor R6 reduces the charging current to the eleventh capacitor C9, thereby slowing down the turn-on time of the high-side MOSFET and reducing switching ringing. The eleventh capacitor C9 serves as a bootstrap capacitor, providing drive voltage to the high-side MOSFET inside the chip.

[0032] In this embodiment, the present application has a sink current capability. The power chip U1 is a TPS543B20, and its negative current limit threshold is -23A. Therefore, under negative input current, the chip switches from output BUCK to input Boost, and the output voltage will boost in reverse to the input power supply voltage. The chip can still work normally and output a positive voltage, so it has a sink current capability. When it is necessary to sink current to the chip, two conditions must be met:

[0033] 1. The power input terminal needs to consume the current that SINK comes in from the output terminal;

[0034] 2. Current limiting is required at the output terminal to prevent excessive current from causing the chip's OCP (Optical Current Capability) to malfunction.

[0035] Therefore, the verification method is as follows: Figure 2 As shown, when the chip is operating, the E-Load is connected in series with the input power supply and the output terminal to provide constant current. At this time, a negative current is injected into the chip's input terminal. Since the input terminal provides power to the negative current, the current path forms a closed loop, and the function of SINK current is realized. When the SINK current needs to be above -20A, it is necessary to ensure that the power loop in the layout is minimized.

[0036] In this embodiment, as Figure 1 As shown, this application has the advantage of adjustable constant voltage and constant current SOURCE voltage output. The SOURCE voltage output is determined by three parts: the output voltage, the DAC output voltage, and the current feedback voltage. Due to the small chip size and limited output power, when the output current exceeds the threshold, it will automatically enter a constant current state to limit the maximum output power. At this time, if the output current continues to increase, the output voltage will decrease synchronously. Figure 1Given that U2 has a gain of 25 and a sampling resistor of 4mR, the current feedback voltage increases by 0.1V for every 1A increase in output current. When the output current reaches 18A, the power supply enters a constant current state. VCUR is the current feedback voltage in the constant current state; VDAC is the input voltage of the external DAC, which allows the output voltage to remain adjustable in the constant current state, meeting the voltage requirements of some special application scenarios.

[0037] According to the superposition theorem, the influence of each voltage source can be calculated separately and then superimposed.

[0038] Transfer function of individual output voltage:

[0039]

[0040] Transfer function of DAC output voltage:

[0041]

[0042] Transfer function of output current feedback voltage:

[0043]

[0044] Therefore, the output voltage transfer function is:

[0045]

[0046] Substituting R12=R13=R15=6K, R14=1K, and VFB=0.6V into the transfer function, we get:

[0047]

[0048] Assuming the required power output is 3.3V 30A, the power supply enters a constant current state, and VCUR is 1.2V. Therefore, VDAC needs to be set to 0.9V simultaneously to meet the requirements.

[0049] In this embodiment, as Figures 3 to 5 As shown, this application has the advantage of excellent performance. Figure 1 The circuit has a source output voltage ripple of less than 20mVpp, fast transient response, and an accuracy of 1‰.

[0050] (1) Low ripple voltage: Output capacitors C2~C6 are made of MLCC material, and multiple capacitors connected in parallel can reduce ESR and ESL; the switching frequency of the power supply chip is 1.6MHz, which can reduce the ripple caused by capacitor charging and discharging. Figure 3 As shown, the power supply has a ripple of 17.6mV at 4V / 20A. Figure 3 Ripple diagram for 4V / 20A power output.

[0051] (2) Good transient response: The output capacitors C1~C6 have sufficiently large capacitance to reduce the transient voltage drop caused by capacitor discharge; the parallel AL capacitor reduces the capacitor bias voltage drop, and the parallel connection of multiple capacitors can reduce ESR and ESL. The C3-R9 loop compensation device is introduced, which adds a zero point to the loop and improves the phase margin of the loop to 105°, making the transient response faster. The simulation results are as follows. Figure 4 As shown. The test results are as follows. Figure 5 As shown, the transient voltages at outputs of 4.5V / 10A and 4.5V / 20A are 120mV and 200mV, respectively, with a response time of 600us.

[0052] (3) High precision: The voltage of the remote load can be introduced to the feedback terminal through S+ and S-, so that the output voltage can be accurately output under load conditions and will not decrease due to the increase of load. In addition, the resistance accuracy of the transfer function is 1‰, which can significantly reduce the influence of resistance.

[0053] In this embodiment, as Figure 6 As shown, this application has the advantage of small size. The power chip is relatively small, and the peripheral circuit components are simple. 0201 components can be used to further reduce the size. However, it requires high precision in component layout and design, necessitating a minimum current loop area to achieve optimal performance. Overall, this power circuit is small in size, and all components can be placed within a 2.5cm x 2.5cm board frame. Figure 6 As shown in the diagram, this power supply circuit can meet the power supply needs of almost all industrial equipment and is also a good choice for power supply design of various precision testing equipment. Due to its size advantage, it saves a lot of space compared to traditional power supplies, which is particularly advantageous in automated testing equipment.

[0054] In this embodiment, the present application has the following advantages:

[0055] 1. The sink current capability can reach -20A or higher;

[0056] 2. Adjustable SOURCE voltage output in constant voltage and constant current mode;

[0057] 3. Small size, simple peripheral circuitry, suitable for most onboard power supplies;

[0058] 4. The source voltage accuracy is as high as 1‰, with good transient response and ripple of less than 20mV across the full power range. This structure incorporates loop compensation, making it suitable for most application scenarios. It has high adjustability and allows parameters to be adjusted according to individual needs.

Claims

1. An adjustable constant current and constant voltage source-sink power supply, characterized in that: It includes a power chip (U1), whose PVIN, SW, and RSP terminals are respectively connected to an input stage, an output stage, and a feedback stage. The input stage is connected to an external power supply, the output stage is connected to an external product or load, and the feedback stage is connected to an external DAC chip. The feedback stage includes a first resistor (R1), a first amplifier (U2), and a second amplifier (U3). The first resistor (R1) is connected to the SW terminal of the power chip (U1), the input terminal of the first amplifier (U2) is connected to the first resistor (R1), the output terminal of the first amplifier (U2) is connected to the input terminal of the second amplifier (U3), and the output terminal of the second amplifier (U3) and the RSP terminal of the power chip (U1) are both connected to an external DAC chip.

2. The adjustable constant current and constant voltage source-sink power supply according to claim 1, characterized in that: The feedback stage also includes a second resistor (R9) and a first capacitor (C13). One end of the first capacitor (C13) is connected to the first resistor (R1), and the other end of the first capacitor (C13) is connected to one end of the second resistor (R9). The other end of the second resistor (R9) is connected to the RSP terminal of the power chip (U1).

3. The adjustable constant current and constant voltage source-sink power supply according to claim 1, characterized in that: The feedback stage also includes a third resistor (R12), a fourth resistor (R13), a fifth resistor (R14), and a sixth resistor (R15). The sixth resistor (R15) is connected to the output terminal of the second amplifier (U3), and the third resistor (R12), the fourth resistor (R13), and the fifth resistor (R14) are all connected to the first resistor (R1) and the sixth resistor (R15).

4. The adjustable constant current and constant voltage source-sink power supply according to claim 1, characterized in that: The input stage includes a second capacitor (C10), a third capacitor (C11), and a fourth capacitor (C12) connected in parallel. External PP_12V is connected to the PVIN terminal of the power chip (U1) through the second capacitor (C10), the third capacitor (C11), and the fourth capacitor (C12).

5. The adjustable constant current and constant voltage source-sink power supply according to claim 1, characterized in that: The output stage includes an inductor (L1), a fifth capacitor (C1), a sixth capacitor (C2), a seventh capacitor (C3), an eighth capacitor (C4), a ninth capacitor (C5), a tenth capacitor (C6), a seventh resistor (R6), and an eleventh capacitor (C9). The SW terminal of the power chip (U1) is connected to the first resistor (R1) in sequence through the inductor (L1), the fifth capacitor (C1), the sixth capacitor (C2), the seventh capacitor (C3), the eighth capacitor (C4), the ninth capacitor (C5), and the tenth capacitor (C6). The BOOT terminal of the power chip (U1) is grounded in sequence through the seventh resistor (R6) and the eleventh capacitor (C9).

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