High-precision DC-DC voltage conversion circuit
By employing a topology of parallel main resistors and series auxiliary resistors, and resistors with different temperature coefficients, the voltage drift problem of DC-DC converters is solved, achieving high-precision voltage conversion stability and cost reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN K&D TECHONOLOGY
- Filing Date
- 2026-01-26
- Publication Date
- 2026-05-01
AI Technical Summary
Traditional DC-DC converters suffer from output voltage drift due to temperature coefficient (TCR), which is difficult to resolve. They also have complex layouts, high costs, and generate glitches during voltage switching.
The system employs a topology of parallel main resistor and series auxiliary resistor, and uses a temperature coefficient pairing method with the parallel main resistor. High-precision voltage conversion is achieved through a dual-channel synchronous buck converter chip U1, and the temperature coefficient pairing resistors R41 and R42 are used to reduce voltage drift caused by temperature changes.
It effectively reduces voltage drift caused by temperature changes, ensures the stability of output voltage, simplifies layout, and reduces costs.
Smart Images
Figure CN121966240A_ABST
Abstract
Description
A high-precision DC-DC voltage conversion circuit Technical Field
[0001] This invention discloses a high-precision DC-DC voltage conversion circuit, specifically relating to a resistor network system for a DC-DC converter. It is particularly suitable for power management integrated circuit designs that require multiple high-precision voltage outputs and belongs to the field of power electronics technology. Background Technology
[0002] In modern electronic systems, DC-DC converters are the most common power supply modules, and the output voltage accuracy of DC-DC converters directly affects system performance.
[0003] The output voltage drift problem caused by the temperature coefficient (TCR) of traditional DC-DC resistors has always been difficult to solve, and the layout is complex, sometimes requiring hundreds of resistors for adjustment, resulting in high costs. Voltage glitches are also generated when the resistors are switched. Summary of the Invention
[0004] To address the issue of temperature drift in existing DC-DC converters mentioned above, this invention provides a high-precision DC-DC voltage conversion circuit. It employs a topology of parallel main resistors and series auxiliary resistors, and uses a temperature coefficient pairing method with the parallel main resistors. This ensures stable output and effectively reduces voltage drift caused by temperature changes.
[0005] The technical solution adopted by this invention to solve its technical problem is: a high-precision DC-DC voltage conversion circuit, the voltage conversion circuit including a buck converter, a main output module and an auxiliary output module, the main output module and the auxiliary output module are respectively connected to the buck converter, the main output module is connected to the LX1 pin of the buck converter, the LX1 of the buck converter outputs the main power supply through the series-connected freewheeling diode D2 and resistor R36; the auxiliary output module is connected to the LX2 pin of the dual-channel synchronous buck converter chip U1, the LX2 pin of the dual-channel synchronous buck converter chip U1 outputs the auxiliary power supply through the series-connected freewheeling diode D1 and resistor R37.
[0006] The technical solution adopted by the present invention to solve its technical problem further includes: the buck converter adopts a dual-channel synchronous buck converter chip U1, and a capacitor C36 is connected between the power input pin of the dual-channel synchronous buck converter chip U1 and ground.
[0007] The VREF pin of the dual-channel synchronous buck converter chip U1 is the internal reference voltage output pin, and a filter capacitor C40 is connected between the VREF pin of the dual-channel synchronous buck converter chip U1 and ground.
[0008] The dual-channel synchronous buck converter chip U1 has an inductor L2 connected between LX1 and ground. The inductor L2 is connected in front of the freewheeling diode D2. The freewheeling diode D2 is connected in parallel with ground via capacitors C37, C46, and C47.
[0009] The main output module also includes a main voltage feedback and setting module, which is connected between the main power supply and the dual-channel synchronous buck converter chip U1. The main voltage feedback and setting module includes a capacitor C49, a resistor R44, a resistor R45, and a resistor R47. Resistors R45 and R47 are connected in series between the main power supply and the NON1 pin of the dual-channel synchronous buck converter chip U1. Resistor R44 and capacitor C49 are connected in series between the main power supply and the NON1 pin of the dual-channel synchronous buck converter chip U1. A resistor R29 is connected between the NON1 pin and the VREF pin of the dual-channel synchronous buck converter chip U1.
[0010] A resistor R46 is connected between the DIS1 pin of the dual-channel synchronous buck converter chip U1 and the main power supply.
[0011] An inductor L1 is connected between the LX2 pin and the HS2L pin of the dual-channel synchronous buck converter chip U1. The inductor L1 is connected in front of the freewheeling diode D1. Capacitors C38, C41 and C42 are connected in parallel between the freewheeling diode D1 and ground.
[0012] The auxiliary output module also includes an auxiliary voltage feedback and setting module, which is connected between the auxiliary output module and the dual-channel synchronous buck converter chip U1. The auxiliary voltage feedback and setting module includes resistors R41, R42, and R43. Resistors R41 and R43 are connected in series between the auxiliary power supply and ground. Resistors R42 and R41 are connected in parallel. Resistor R40, which is connected in series, and capacitor C48 are connected in parallel with resistor R41. The INV2 pin of the dual-channel synchronous buck converter chip U1 is connected to the common terminal of resistors R41 and R43.
[0013] The resistors R41 and R42 are paired using different temperature coefficients.
[0014] A resistor R35 is connected between the DIS2 pin of the dual-channel synchronous buck converter chip U1 and the auxiliary power supply. The VOUT2 pin of the dual-channel synchronous buck converter chip U1 is connected to the auxiliary power supply. The input power supply VDDA is connected to the VDDP pin of the dual-channel synchronous buck converter chip U1 through a series current-limiting resistor R38. Capacitors C43, C44, and C45 are connected between the current-limiting resistor R38 and ground.
[0015] The beneficial effects of this invention are: This invention adopts a topology structure of parallel main resistor and series auxiliary resistor, and the parallel main resistor is paired with a different temperature coefficient, which can ensure the stability of the output and effectively reduce the voltage drift problem caused by temperature changes.
[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description
[0017] Figure 1 is a circuit block diagram of the present invention.
[0018] Figure 2 is a circuit schematic diagram of the present invention. Detailed Implementation
[0019] This embodiment is a preferred embodiment of the present invention. All other embodiments that are the same as or similar to this embodiment in principle and basic structure are within the protection scope of the present invention.
[0020] Please refer to Figure 1. This invention mainly protects a high-precision DC-DC voltage conversion circuit, which mainly includes a buck converter, a main output module (defined as VOUT1 in this invention) and an auxiliary output module (defined as VOUT2 in this invention). The main output module and the auxiliary output module are respectively connected to the buck converter.
[0021] In this embodiment, the buck converter uses a dual-channel synchronous buck converter chip U1 (model BD81870) to output two different voltages (VOUT1 and VOUT2). The dual-channel synchronous buck converter chip U1 receives power from its power input pin (pin 1, VDDA), which is connected to the input power supply VDDA. A capacitor C36 is connected between the power input pin and ground for decoupling and filtering, making the input more stable. The control pins STB2 (pin 2), STB1 (pin 3), SEQON (pin 4), and HSWON (pin 5) of the dual-channel synchronous buck converter chip U1 are used to control the enable, timing, and standby modes of the two outputs. In this embodiment, the control pins STB2, STB1, SEQON, and HSWON are connected to the input power supply VDDA.
[0022] In this embodiment, the NC (pin 6) of the dual-channel synchronous buck converter chip U1 is a floating pin.
[0023] In this embodiment, the VREF (pin 7) of the dual-channel synchronous buck converter chip U1 is the internal reference voltage output pin. A filter capacitor C40 is connected between the VREF pin of the dual-channel synchronous buck converter chip U1 and ground to filter out noise and make the reference voltage more stable.
[0024] In this embodiment, the main output module adopts a synchronous buck circuit structure. The main output module is connected to LX1 (pin 10) of the dual-channel synchronous buck converter chip U1. LX1 of the dual-channel synchronous buck converter chip U1 outputs the main power supply (VSN, i.e., VOUT1) through the series-connected freewheeling diode D2 and resistor R36. In this embodiment, resistor R36 is a 0Ω resistor, and freewheeling diode D2 is a Schottky diode, which serves as a freewheeling tube to provide a freewheeling path for the inductor when the switching transistor is turned off. An inductor L2 is connected between LX1 of the dual-channel synchronous buck converter chip U1 and ground. Inductor L2 serves as a power inductor, used to store and transfer energy. Inductor L2 is connected in parallel with the stage before the freewheeling diode D2 (i.e., the side closest to the dual-channel synchronous buck converter chip U1). Capacitors C37, C46, and C47 are connected in parallel with the stage after the freewheeling diode D2 and ground. Capacitors C37, C46, and C47 serve as output capacitors, used for filtering and voltage regulation to reduce output ripple.
[0025] In this embodiment, the main output module also includes a main voltage feedback and setting module. The main voltage feedback and setting module is connected between the main power supply and the dual-channel synchronous buck converter chip U1. The main voltage feedback and setting module includes a capacitor C49, a resistor R44, a resistor R45, and a resistor R47. Resistors R45 and R47 are connected in series between the main power supply and the NON1 (pin 8) of the dual-channel synchronous buck converter chip U1. Resistor R44 and capacitor C49 are connected in series between the main power supply and the NON1 (pin 8) of the dual-channel synchronous buck converter chip U1. A resistor R29 is connected between the NON1 (pin 8) of the dual-channel synchronous buck converter chip U1 and the VREF (pin 7) of the dual-channel synchronous buck converter chip U1. The main power supply (VOUT1) is fed back to the internal part of the dual-channel synchronous buck converter chip U1 after being divided by resistors R44, R45, and R47, and compared with the reference voltage to achieve closed-loop voltage regulation.
[0026] In this embodiment, a resistor R46 is connected between DIS1 (pin 9) of the dual-channel synchronous buck converter chip U1 and the main power supply. Overcurrent protection can be achieved by detecting the inductor current through resistor R46. In this embodiment, resistor R46 is a 0Ω resistor.
[0027] In this embodiment, the auxiliary output module adopts a synchronous buck circuit structure. The auxiliary output module is connected to LX2 (pin 15) of the dual-channel synchronous buck converter chip U1. LX2 of the dual-channel synchronous buck converter chip U1 outputs auxiliary power (VSP, i.e., VOUT2) through a series-connected freewheeling diode D1 and resistor R37. In this embodiment, resistor R37 is a 0Ω resistor, and freewheeling diode D1 is a Schottky diode, which serves as a freewheeling tube to provide a freewheeling path for the inductor when the switching transistor is turned off. An inductor L1 is connected between LX2 of the dual-channel synchronous buck converter chip U1 and HS2L (pin 14) of the dual-channel synchronous buck converter chip U1. The inductor L1 serves as a power inductor for storing and transferring energy. The inductor L1 is connected in front of the freewheeling diode D1 (i.e., on the side closest to the dual-channel synchronous buck converter chip U1). Capacitors C38, C41, and C42 are connected in parallel between the stage after the freewheeling diode D1 and ground. Capacitors C38, C41, and C42 serve as output capacitors for filtering and voltage regulation to reduce output ripple.
[0028] In this embodiment, the auxiliary output module further includes an auxiliary voltage feedback and setting module. The auxiliary voltage feedback and setting module is connected between the auxiliary power supply and the dual-channel synchronous buck converter chip U1. The auxiliary voltage feedback and setting module includes resistors R41, R42, and R43. Resistors R41 and R43 are connected in series between the auxiliary power supply and ground. Resistors R42 and R41 are connected in parallel as the main resistors. Resistor R43 is the auxiliary resistor. Resistors R40 and C48, which are connected in series, are connected in parallel with resistor R41. The INV2 (pin 20) of the dual-channel synchronous buck converter chip U1 is connected to the common terminal of resistors R41 and R43. The auxiliary power supply (VOUT2) is fed back to the INV2 (pin 20) of the dual-channel synchronous buck converter chip U1 after being divided by resistors R41, R42, and R43, thus realizing closed-loop voltage regulation. In this embodiment, resistors R41 and R42 are paired with different temperature coefficients (e.g., resistor R41 is +100ppm and resistor R42 is -100ppm).
[0029] In this embodiment, a resistor R35 is connected between DIS2 (pin 18) of the dual-channel synchronous buck converter chip U1 and the auxiliary power supply. Overcurrent protection can be achieved by detecting the inductor current through resistor R35. In this embodiment, resistor R35 is a 0Ω resistor.
[0030] In this embodiment, VOUT2 (pin 17) of the dual-channel synchronous buck converter chip U1 is connected to the auxiliary power supply.
[0031] In this embodiment, the input power supply VDDA is connected to the VDDP (pins 11, 12, and 13) of the dual-channel synchronous buck converter chip U1 through a series current-limiting resistor R38. Capacitors C43, C44, and C45 are connected between the current-limiting resistor R38 and ground. Capacitors C43, C44, and C45 are connected in parallel to ensure stable power supply to the chip.
[0032] When this invention is in operation, the power transistor inside chip U1 operates in a high-frequency switching mode. By controlling the high and low levels of the LX1 and HS2L pins, it drives the external inductor and diode to perform energy conversion. When the internal power transistor is turned on, the input voltage supplies power to the load and stores energy through the inductor. When the internal power transistor is turned off, the inductor releases energy through the freewheeling diode to maintain the output voltage. The output voltage is fed back to the chip through the voltage divider resistor and compared with the reference voltage. By adjusting the duty cycle of the switching transistor, the output voltage is stabilized.
[0033] This invention employs a topology of parallel main resistor and series auxiliary resistor, and uses a temperature coefficient pairing method with the parallel main resistor to ensure output stability and effectively reduce voltage drift caused by temperature changes.
Claims
1. A high-precision DC-DC voltage conversion circuit, characterized in that: The voltage conversion circuit includes a buck converter, a main output module, and an auxiliary output module. The main output module and the auxiliary output module are respectively connected to the buck converter. The main output module is connected to the LX1 pin of the buck converter. The LX1 pin of the buck converter outputs the main power supply through a series-connected freewheeling diode D2 and a resistor R36. The auxiliary output module is connected to the LX2 pin of the dual-channel synchronous buck converter chip U1. The LX2 pin of the dual-channel synchronous buck converter chip U1 outputs the auxiliary power supply through a series-connected freewheeling diode D1 and a resistor R37.
2. The high-precision DC-DC voltage conversion circuit according to claim 1, characterized in that: The buck converter uses a dual-channel synchronous buck converter chip U1, and a capacitor C36 is connected between the power input pin of the dual-channel synchronous buck converter chip U1 and ground.
3. The high-precision DC-DC voltage conversion circuit according to claim 2, characterized in that: The VREF pin of the dual-channel synchronous buck converter chip U1 is the internal reference voltage output pin, and a filter capacitor C40 is connected between the VREF pin of the dual-channel synchronous buck converter chip U1 and ground.
4. The high-precision DC-DC voltage conversion circuit according to claim 2, characterized in that: The dual-channel synchronous buck converter chip U1 has an inductor L2 connected between LX1 and ground. The inductor L2 is connected in front of the freewheeling diode D2. The freewheeling diode D2 is connected in parallel with ground via capacitors C37, C46, and C47.
5. The high-precision DC-DC voltage conversion circuit according to claim 2, characterized in that: The main output module also includes a main voltage feedback and setting module, which is connected between the main power supply and the dual-channel synchronous buck converter chip U1. The main voltage feedback and setting module includes a capacitor C49, a resistor R44, a resistor R45, and a resistor R47. Resistors R45 and R47 are connected in series between the main power supply and the NON1 pin of the dual-channel synchronous buck converter chip U1. Resistor R44 and capacitor C49 are connected in series between the main power supply and the NON1 pin of the dual-channel synchronous buck converter chip U1. A resistor R29 is connected between the NON1 pin and the VREF pin of the dual-channel synchronous buck converter chip U1.
6. The high-precision DC-DC voltage conversion circuit according to claim 2, characterized in that: A resistor R46 is connected between the DIS1 pin of the dual-channel synchronous buck converter chip U1 and the main power supply.
7. The high-precision DC-DC voltage conversion circuit according to claim 2, characterized in that: An inductor L1 is connected between the LX2 pin and the HS2L pin of the dual-channel synchronous buck converter chip U1. The inductor L1 is connected in front of the freewheeling diode D1. Capacitors C38, C41 and C42 are connected in parallel between the freewheeling diode D1 and ground.
8. The high-precision DC-DC voltage conversion circuit according to claim 2, characterized in that: The auxiliary output module also includes an auxiliary voltage feedback and setting module, which is connected between the auxiliary output module and the dual-channel synchronous buck converter chip U1. The auxiliary voltage feedback and setting module includes resistors R41, R42, and R43. Resistors R41 and R43 are connected in series between the auxiliary power supply and ground. Resistors R42 and R41 are connected in parallel. Resistor R40, which is connected in series, and capacitor C48 are connected in parallel with resistor R41. The INV2 pin of the dual-channel synchronous buck converter chip U1 is connected to the common terminal of resistors R41 and R43.
9. The high-precision DC-DC voltage conversion circuit according to claim 8, characterized in that: The resistors R41 and R42 are paired using different temperature coefficients.
10. The high-precision DC-DC voltage conversion circuit according to claim 2, characterized in that: A resistor R35 is connected between the DIS2 pin of the dual-channel synchronous buck converter chip U1 and the auxiliary power supply. The VOUT2 pin of the dual-channel synchronous buck converter chip U1 is connected to the auxiliary power supply. The input power supply VDDA is connected to the VDDP pin of the dual-channel synchronous buck converter chip U1 through a series current-limiting resistor R38. Capacitors C43, C44, and C45 are connected between the current-limiting resistor R38 and ground.