A power supply device and method capable of changing output voltage

Abstract

The present invention relates to a power supply device and method capable of changing the output voltage. The power supply device comprises a power supply chip and an external resistor. The feedback pin of the power supply chip is connected to the external resistor. The output voltage of the power supply device is adjusted by changing the parameters of the external resistor. The design advantage of the circuit of the present invention is that the output voltage can be adjusted arbitrarily by adding a very small number of external devices, thereby improving the compatibility of the circuit. In the context of a long-term extreme shortage of power supply chips, the risk of the supply chain can be greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a power supply device and method capable of changing output voltage. Background Art

[0002] The power chip is a component that provides output voltage, and there are usually a large number of power chips that are versions with fixed output voltages. Figure 1 The power chip shown has an input of 2.4-5.5V and a fixed output of 1.0V. Since the output voltage is fixed, a power chip can only be used in applications with corresponding voltage requirements, and the scope of use of the power chip is greatly limited. At a time when power chips are extremely scarce, how to improve the utilization rate of power chips is an urgent problem to be solved. Summary of the invention

[0003] The object of the present invention is to provide a power supply device and method capable of changing the output voltage, so as to expand the application range of the power supply chip and improve the utilization rate of the power supply chip.

[0004] In order to achieve the above-mentioned object of the invention, the embodiment of the present invention provides the following technical solutions:

[0005] A power supply device capable of changing output voltage comprises a power supply chip and an external resistor. A feedback pin of the power supply chip is connected to the external resistor. The output voltage of the power supply device is adjusted by changing the parameters of the external resistor.

[0006] In one implementation manner, the external resistor includes a first external resistor, one end of the first external resistor is connected to a feedback pin of the power chip, and the other end of the first external resistor is connected to a switch output end of the power chip.

[0007] The first external resistor may be a single resistor or a plurality of resistors connected in series, so as to improve the combinability of the value of the first external resistor and thus increase the types of adjustable output voltages.

[0008] In another implementation manner, the external resistor further includes a second external resistor, one end of the second external resistor is connected to the feedback pin of the power chip, and the other end of the second external resistor is connected to the reference voltage.

[0009] The reference voltage may be provided by a voltage-adjustable digital-to-analog converter DAC, or may be a fixed off-chip reference voltage, thereby improving the flexibility of the adjustable output voltage and reducing the cost.

[0010] On the other hand, the present invention also provides a method for changing the output voltage of a power supply, wherein an external resistor is connected to a feedback pin of a power supply chip, and the output voltage of the power supply is adjusted by changing the parameters of the external resistor.

[0011] In one embodiment, the external resistor is a single resistor or a resistor unit composed of multiple resistors connected in series, and the output voltage of the power supply is adjusted by changing the resistance value of the resistor or the resistor unit. This embodiment can achieve any adjustment of the output voltage greater than the original power supply chip.

[0012] In another embodiment, the external resistor includes a first external resistor and a second external resistor, and the second external resistor is connected to a reference voltage, and the current flowing through the first external resistor is adjusted by adjusting the reference voltage and the resistance value of the second external resistor, and the output voltage of the power supply is adjusted by adjusting the resistance value of the first external resistor. This embodiment can realize that the power supply device outputs any voltage, further expanding the application range of the power chip.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: the design advantage of the circuit of the present invention is that by adding a very small number of external devices, the output voltage can be arbitrarily adjusted, the compatibility of the circuit is improved, and in the context of a long-term extreme shortage of power chips, the risk of the supply chain can be greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work, but they all belong to the scope of protection of the present invention.

[0015] Figure 1 The electrical schematic diagram of the power supply device in the prior art.

[0016] Figure 2 This is an electrical schematic diagram of the power supply device in Example 1 of the present invention.

[0017] Figure 3 This is the internal structure diagram of the power chip TPS6208818.

[0018] Figure 4 This is an electrical schematic diagram of the power supply device in Example 2 of the present invention. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0020] The present invention provides a power supply device capable of changing the output voltage, comprising a power supply chip and an external resistor, wherein a feedback pin of the power supply chip is connected to the external resistor, and the output voltage of the power supply device is adjusted by changing the parameters of the external resistor.

[0021] In one implementation, the external resistor is a single resistor or a resistor unit composed of a plurality of resistors connected in series, and the output voltage of the power supply is adjusted by changing the resistance value of the resistor or the resistor unit.

[0022] In another embodiment, the external resistor includes a first external resistor and a second external resistor, and the second external resistor is connected to a reference voltage, and the current flowing through the first external resistor is adjusted by adjusting the reference voltage and the resistance value of the second external resistor, and the output voltage of the power supply is adjusted by adjusting the resistance value of the first external resistor.

[0023] It should be noted that the first external resistor and the second external resistor may be a single resistor respectively, or may be a resistor unit composed of a plurality of resistors connected in series.

[0024] The following will provide a more detailed description with two specific embodiments.

[0025] Example 1

[0026] See also Figure 2 As shown, the power supply device capable of changing the output voltage provided in this embodiment includes a power chip, a resistor R3, a resistor R1, a capacitor C1, a capacitor C2, a capacitor C3 and an inductor L1, the two ends of the resistor R3 are respectively connected to the power input pin VIN and the power indication pin PG of the power chip, one end of the capacitor C1 is connected to the power input pin VIN of the power chip, and the other end is grounded. The switch output pin SW of the power chip is connected to one end of the inductor L1, the capacitor C2, the capacitor C3 and the resistor R1 are all connected to the other end of the inductor L1, and the other ends of the capacitors C2 and C3 are grounded. Figure 2The resistor R1 in the figure can be a resistor, and the output voltage of the power supply device can be changed by changing the resistance value of the resistor R1; the resistor R1 can also be a resistor unit composed of multiple resistors connected in series, and the output voltage of the power supply device can be changed by changing the combination of the resistor units (for example, the number of resistors connected in series).

[0027] The following is a calculation explanation using TI's TPS6208818, a power chip with a fixed output of 1.8V. However, please note that the solution of the present invention is not limited to TI's TPS6208818, but is generally applicable to all power chips of this type of connection in which the Rup resistor pin P2 is connected to the FB pin.

[0028] Figure 3 The figure shows the internal block diagram of the power chip. For the convenience of description, some annotations are made on the figure. As described in the data sheet of the power chip, the power chip has a fixed output of 1.8V. The internal S1 switch connects the FB pin to the P2 point, which is connected to the internal voltage regulation resistor network. The resistance values ​​of the resistors Rup and Rdown of the internal resistor network are 5000k ohms and 2500k ohms respectively. The internal reference voltage V REF =0.6V.

[0029] In the absence of external resistor R1, the output voltage of the power chip can only be a fixed output voltage. According to the node current theorem, Vout = V REF +Rup*V REF / Rdown=0.6+5000*0.6 / 2500=1.8V.

[0030] After adding an external resistor R1, according to the node current theorem, Vout = V REF +(Rup+R1)*V REF / Rdown=0.6+(5000+R1)*0.6 / 2500=1.8+0.6*R1 / 2500 (Equation 1).

[0031] According to equation 1, the output voltage can be adjusted to above 1.8V by adjusting the size of resistor R1, thereby improving the flexibility of the circuit and the compatibility of the power chip, and alleviating the pressure of the shortage of power chip supply.

[0032] Example 2

[0033] See also Figure 4As shown, the power supply device capable of changing the output voltage provided in this embodiment includes a power supply chip, a resistor R3, a resistor R2, a resistor R1, a capacitor C1, a capacitor C2, a capacitor C3 and an inductor L1, the two ends of the resistor R3 are respectively connected to the power input pin VIN and the power indication pin PG of the power supply chip, one end of the capacitor C1 is connected to the power input pin VIN of the power supply chip, and the other end is grounded. The switch output pin SW of the power supply chip is connected to one end of the inductor L1, the capacitor C2 and the capacitor C3 are both connected to the other end of the inductor L1, and the other ends of the capacitors C2 and C3 are grounded. One end of the resistor R1 and the resistor R2 are both connected to the feedback pin FB of the power supply chip, the other end of the resistor R2 is connected to the reference voltage Vdac, and the other end of the resistor R1 is connected to one end of the inductor L1. Figure 4 The resistors R1 and R2 in the circuit can both be a single resistor, and the output voltage of the power supply device can be changed by changing the resistance value of the resistor; the resistors R1 and R2 can also be a resistor unit composed of multiple resistors connected in series.

[0034] The reference voltage can be provided by a voltage-adjustable digital-to-analog converter DAC or a fixed off-chip reference voltage, thereby increasing the flexibility of the adjustable output voltage and reducing the cost.

[0035] By adjusting the parameters of resistors R1, R2 and Vdac, the output voltage can be adjusted arbitrarily, and the constant voltage output chip can realize the function of a power supply chip with adjustable output voltage.

[0036] The following calculation is still based on TI's TPS6208818, a power chip with a fixed output of 1.8V.

[0037] Figure 3 The figure shows the internal block diagram of the power chip. For the convenience of description, some annotations are made on the figure, such as P1, S1, Rup, etc.

[0038] As described in the data sheet of the power chip, the power chip has a fixed output of 1.8V. The internal S1 switch connects the FB pin to the P2 point, which is connected to the internal voltage regulation resistor network. The resistance values ​​of the internal resistor network Rup and Rdown are 5000k ohms and 2500k ohms respectively. The internal reference voltage V REF =0.6V.

[0039] In the absence of external resistor R1, the output voltage of the power chip can only be a fixed output voltage. According to the node current theorem, Vout = V REF +Rup*V REF / Rdown=0.6+5000*0.6 / 2500=1.8V.

[0040] After adding external resistors R1, R2 and Vdac, according to the node current theorem, Vout = (V REF +Rup*V REF / Rdown)+R1*{(V REF / Rdown+[(V REF +Rup*V REF / Rdown)-Vdac] / R2}(Equation 2).

[0041] After simplifying and expanding Equation 2, Vout = (1.8 + 0.6*R1 / 2500 + 1.8*R1 / R2) - Vdac*(R1 / R2) (Equation 3).

[0042] According to equation 3, the appropriate values ​​of resistors R1 and R2 are selected, and the output voltage of the power chip can be adjusted by adjusting the output voltage of Vdac.

[0043] For example, if the resistors R1=1500k and R2=330k are selected, according to equation 3, Vout=(1.8+0.6*1500 / 2500+1.8*1500 / 330)-Vdac*(1500 / 330)=10.342-Vdac*1500 / 330 (equation 4) can be obtained.

[0044] Select 12-bit resolution and the reference voltage is 2.5V Vdac, then Vdac = 2.5*DAC / (2^12-1), and substitute it into equation 4 to get Vout = 10.342-2.5*DAC / (2^12-1)*1500 / 330 = 10.342-0.002775*DAC (Equation 5 DAC = an integer from 0 to 4095).

[0045] From equation 5, we can calculate that when Vout = 0V, DAC = 3727, and when Vout = 3.3V, DAC = 2537. By changing DAC between 3727 and 2537, the output voltage can be adjusted between 0 and 3.3V, which improves the flexibility of the circuit and the compatibility of the power chip and alleviates the pressure of the shortage of power chip supply.

[0046] Application Example 1: TPS6208818 supplies power to a CDR chip that requires a supply voltage between 1.7 and 1.75 V. As shown in the following table, Vdac uses the 2.5 V reference power supply inside the MCU. By adjusting resistors R1 and R2, the output voltage can be adjusted to within the target voltage.

[0047] ICPN Vdac VFB R1(kohm) R2(kohm) Vref Rup(kohm) Rdown(kohm) Vout TPS6208818 2.5 1.8 2010 510 0.6 5000 2500 1.745

[0048] Application Example 2: TPS6208818 is required to output a continuously adjustable voltage between 0 and 3.3 to control the heating or cooling power of TEC. Select resistors R1=1500k, R2=330k, and a 12-bit resolution, 2.5V reference voltage Vdac. Control DAC to change between 3727 and 2537 to achieve continuous adjustment of the output voltage between 0 and 3.3V, with a control accuracy of 2.775mV.

[0049] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A power supply device capable of changing output voltage, comprising a power supply chip, characterized in that: It also includes an external resistor, the feedback pin of the power chip is connected to the external resistor, and the output voltage of the power supply device is adjusted by changing the parameters of the external resistor; The external resistor comprises a first external resistor, one end of the first external resistor is connected to the feedback pin of the power chip, and the other end of the first external resistor is connected to the switch output end of the power chip; It also includes an inductor, a second capacitor, and a third capacitor, wherein the switch output pin of the power chip is connected to one end of the inductor, the second capacitor, the third capacitor, and the first external resistor are all connected to the other end of the inductor, and the other ends of the second capacitor and the third capacitor are grounded; The external resistor also includes a second external resistor, one end of the second external resistor is connected to the feedback pin of the power chip, and the other end is connected to the reference voltage; The output voltage Vout of the power supply device is adjusted to: Vout = V REF + (Rup + R1) * V REF / Rdown or Vout = (V REF +Rup*V REF / Rdown)+R1*{V REF / Rdown+[(V REF +Rup*V REF / Rdown)-Vdac] / R2}; where V REF It represents the internal reference voltage of the power chip. Rup and Rdown are both resistors inside the power chip. R1 is the first external resistor, R2 is the second external resistor, and Vdac represents the reference voltage.

2. The power supply device capable of changing the output voltage according to claim 1, characterized in that: It also includes a resistor and a capacitor, wherein the two ends of the resistor are respectively connected to the power input pin and the power indication pin of the power chip, one end of the capacitor is connected to the power input pin of the power chip, and the other end is grounded.

3. The power supply device capable of changing the output voltage according to claim 2, characterized in that: An analog-to-digital converter is also included, and the reference voltage is provided by the analog-to-digital converter.

4. A method for changing the output voltage of a power supply based on the power supply device capable of changing the output voltage according to any one of claims 1 to 3, characterized in that: An external resistor is connected to the feedback pin of the power chip, and the output voltage of the power supply is adjusted by changing the parameters of the external resistor; The external resistor is a single resistor or a resistor unit composed of a plurality of resistors connected in series, and the output voltage of the power supply is adjusted by changing the resistance value of the resistor or the resistor unit.

5. The method for changing the output voltage of a power supply according to claim 4, characterized in that: The external resistor includes a first external resistor and a second external resistor, and the second external resistor is connected to a reference voltage. The current flowing through the first external resistor is adjusted by adjusting the reference voltage and the resistance value of the second external resistor, and the output voltage of the power supply is adjusted by adjusting the resistance value of the first external resistor.

Images