CN1904790A - Output adjustable voltage stabilizing power circuit - Google Patents

Abstract

An output adjustable voltage stabilized power supply circuit, including an adjustment circuit and a voltage divider circuit, the adjustment circuit has an adjustment terminal, an input terminal and an output terminal, the input terminal receives an input voltage, and a load is connected to the output terminal R, the voltage provided to the load R is the output voltage, the voltage divider circuit includes resistors R1, R4, the resistors R1, R4 are connected in series, one end of the resistor R1 is connected to one end of R4, the other end is grounded, and the resistor The other end of R4 is connected to the output terminal 23. On the output terminal 23, the output voltage of the load R is divided by the voltage divider circuit and then fed back to the adjustment terminal. The voltage divider circuit also includes two resistors R2, R3, one end of the resistors R2, R3 is connected to the node between the resistors R1, R4, and the other end receives a set of control signals to control whether the resistors R2, R3 are grounded to participate in voltage division.

Description

Output adjustable regulated power supply circuit

【Technical field】

The invention relates to an output adjustable voltage stabilizing power supply circuit on a computer mainboard.

【Background technique】

In motherboard design, the design of the power supply circuit is very important, it will directly affect the quality of the entire motherboard. In order to meet more demands, it is necessary to constantly optimize the existing motherboard power supply circuit or develop a new power supply circuit.

Please refer to FIG. 1, which is an existing linear regulated power supply 1, including an adjustment chip 10, which has an adjustment terminal 11, an input terminal 12 and an output terminal 13, and the input terminal 12 is connected to an input voltage Vin' such as 3.3V; a load R' is connected to the output terminal 13, and the other end of the load R' is grounded; resistors R1' and R2' are connected in parallel with the load R' between the output terminal 13 and the ground, and the resistance R1 ′, R2 ′ are connected in series, and the node between the resistors R1 ′, R2 ′ is connected to the adjustment terminal 11 , and the voltage of this node is used as the reference voltage Vref′ of the load R′. Wherein, an appropriate reference voltage Vref' can be provided to the load R' by adjusting the resistance values of the resistors R1', R2', or any one of the resistors R1' or R2'. The relationship between the voltage Vout' provided to the load R' through the voltage division of the resistors R1' and R2' and the reference voltage Vref' is shown in the formula:

Vout′＝Vref′*(1+R1′/R2′)

When the input terminal 12 of the adjustment circuit 10 receives an input voltage Vin' of 3.3V, the adjustment terminal 11 provides a reference voltage Vref' to the output terminal 13, so that the voltage of the output terminal 13 is stabilized at a certain voltage The value is like 2.5V.

The linear regulated power supply circuit in Figure 1 above has a fixed output voltage of 2.5V within a certain input voltage range, and when the output voltage is required to be adjustable, such as adjusting the output voltage from 2.5V to 2.6V, 2.7V , 2.8V above circuit can not be realized.

【Content of invention】

The main purpose of the present invention is to provide an output adjustable voltage stabilized power supply circuit.

An output adjustable voltage stabilized power supply circuit, including an adjustment circuit and a voltage divider circuit, the adjustment circuit has an adjustment terminal, an input terminal and an output terminal, the input terminal receives an input voltage, and a load is connected to the output terminal R, the voltage provided to the load R is the output voltage, the voltage divider circuit includes resistors R1, R4, the resistors R1, R4 are connected in series, one end of the resistor R1 is connected to one end of R4, the other end is grounded, and the resistor The other end of R4 is connected to the output terminal. On the output terminal, the output voltage of the load R is divided by the voltage divider circuit and then fed back to the adjustment terminal. The voltage divider circuit also includes two resistors R2 and R3, One end of the resistors R2, R3 is connected to the node between the resistors R1, R4, and the other end receives a set of control signals to control whether the resistors R2, R3 are grounded to participate in voltage division.

The output adjustable voltage stabilized power supply circuit of the present invention can generate four output voltages with fixed voltage increments according to the state of the received control signal, which more flexibly meets the needs of the circuit for different working voltages.

【Description of drawings】

The present invention will be further described below in conjunction with the embodiments with reference to the accompanying drawings.

Fig. 1 is a circuit diagram of an existing regulated power supply circuit.

Fig. 2 is a circuit diagram of an output adjustable voltage stabilized power supply in a preferred embodiment of the present invention.

【Detailed ways】

Please refer to FIG. 2 , which is a circuit diagram of an output adjustable regulated power supply in a preferred embodiment of the present invention, which includes an adjustment circuit 20, which has an adjustment terminal 21, an input terminal 22 and an output terminal 23, and the input terminal 22 An input voltage Vin is received, a load R is connected to the output terminal 23, and the output voltage Vout on the output terminal 23 is fed back to the adjustment terminal 21. The output adjustable voltage stabilized power supply also includes a voltage divider circuit 30, The voltage divider circuit 30 provides a reference voltage Vref for the output voltage Vout, so as to stabilize the output voltage Vout of the output terminal 23. On the output terminal 23, the output voltage Vout of the load R is divided by the voltage divider circuit for 30 minutes. Feedback to the adjusting end 21 after pressing.

Please refer to FIG. 2 , the adjustment circuit 20 in the present invention is composed of a field effect transistor Q1 and a transistor Q2 . The field effect transistor Q1 may further be an N-channel MOS transistor, or other suitable field effect transistors as required.

In this embodiment, the adjustment circuit 20 includes an N-channel MOS transistor Q1 and a transistor Q2. The drain of the N-channel MOS transistor Q1 is used as the input terminal 22, which is connected to the input voltage Vin, and the input voltage Vin is 3.3V, and its source is used as the output terminal 23, and the output terminal 23 is connected to the resistor R4 and the load R One end of the load R is Vout, and the other end of the load R is grounded. The gate of the MOS transistor Q1 is connected to the collector of the transistor Q2, and the node voltage between them is V, and the node is connected to a driving voltage Vd through a resistor R5, and the driving voltage Vd is 12V, which provides the driving of the MOS transistor Q1 The voltage Vd and the working voltage of the transistor Q2, the adjustment circuit 20 is driven by the driving voltage Vd, so that the output adjustable voltage stabilized power supply circuit can make the input voltage Vin as small as possible while providing a stable output. The voltage divider circuit 30 includes resistors R1, R2, R3, and R4. The resistors R1, R4 are connected in series. One end of the resistor R1 is connected to the other end of R4, and the other end is grounded. One ends of the resistors R2 and R3 are connected to the node between the resistors R1 and R4, the other ends of the resistors R2 and R3 receive a group of control signals 40 and 50, the emitter of the transistor Q2 is grounded, and the base thereof is connected to the The node between the resistors R1 and R4, the voltage at this node is used as the reference voltage Vref of the output adjustable regulated power supply, and the voltage divider circuit 30 provides a reference voltage Vref for the output voltage Vout, so as to realize the stable output terminal 23 The output voltage Vout of the transistor Q2 is used as the adjustment terminal 21 of the adjustment circuit 20 .

The circuit of the present invention can generate four sets of output of fixed voltage increments by receiving four sets of control signals "00", "01", "10" and "11" sent by the IP8203R control chip (not shown) on the computer motherboard Voltage. When receiving four groups of control signals in different states, the output voltage Vout of the circuit of the present invention is calculated as follows by the formula:

At "00", the resistors R2 and R3 are in a grounded state, and the resistors R1, R2, and R3 participate in the voltage division of the voltage dividing circuit 30 in the circuit of Figure 2. The resistors R1, R2, and R3 are connected in parallel, then The output voltage Vout of the output adjustable regulated power supply circuit is:

$\mathrm{<span\; class="notranslate">\; Vout</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Vref</span>}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>$

At "01", the resistor R2 is in the ground state, and the resistor R3 is in the open state, then the resistors R1 and R2 participate in the voltage division of the voltage divider circuit 30 in the circuit of Figure 2, and the output voltage Vout of the output adjustable voltage stabilized power supply circuit for:

$\mathrm{<span\; class="notranslate">\; Vout</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Vref</span>}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

Similarly, at "10", the resistor R2 is in an open circuit state, and the resistor R3 is in a grounded state, then the resistors R1 and R3 participate in the voltage division of the voltage divider circuit 30 in the circuit shown in Figure 2, and the output of the adjustable voltage stabilized power supply circuit is The voltage Vout is:

$\mathrm{<span\; class="notranslate">\; Vout</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Vref</span>}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>$

Similarly, when "11", the resistors R2 and R3 are in an open circuit state, and only the resistor R1 participates in the voltage division of the voltage divider circuit 30, then the output voltage Vout of the output adjustable voltage stabilized power supply circuit is:

$\mathrm{<span\; class="notranslate">\; Vout</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Vref</span>}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>$

For each group of control signals 40 and 50, the voltage divider circuit 30 will select different resistors R1, R2 and R3 to participate in the voltage division. When the state of the control signals 40 and 50 is confirmed, the resistors R1, R2 and R3 will participate in the voltage division The resistance is also determined. When working, when the resistance of the load R increases instantaneously, the output voltage Vout of the output adjustable voltage stabilized power supply increases instantaneously, and the reference voltage Vref also increases correspondingly after being divided by the resistors participating in the voltage division. The conduction capability of the transistor Q2 is enhanced, and the reduction of the node voltage V between the N-channel MOS transistor Q1 and the crystal Q2 causes the voltage between the gate and the source of the MOS transistor Q1 to decrease, and the N-channel The weakening of the conduction capability of the MOS transistor Q1 causes the voltage drop of the transistor Q1 to rise, thereby causing the output voltage of the N-channel MOS transistor Q1 to drop, thereby adjusting the output voltage Vout that was previously increased to the voltage value when the load R is stable. Conversely, when the resistance of the load R decreases instantaneously, the output adjustable voltage stabilized power supply is fed back to the transistor Q2 after the reference voltage Vref provided by the output adjustable regulated power supply is divided by the resistors involved in the voltage division, and the voltage V increases. , so that the conduction capability of the N-channel MOS transistor Q1 is enhanced, causing the voltage drop of the N-channel MOS transistor Q1 to decrease, thereby leading to an increase in the output voltage of the field effect transistor Q1, thereby stabilizing the output voltage Vout.

Through several calculation formulas of the output voltage of the circuit of the present invention, when the input voltage is 3.3V and the driving voltage is 12V, as long as the appropriate resistance parameters are selected, it can be seen that the circuit of the present invention generates a For the output voltage Vout, the voltage divider circuit 30 receives four sets of control signals to generate four output voltages Vout that change with a fixed voltage increment of 0.1V, as shown in Table 1. If it is necessary to adjust the voltage increment, you can select a suitable resistance parameters.

Table 1 Comparison table of four groups of control signals and output voltage 50 40 Vout 1 1 2.5V 1 0 2.6V 0 1 2.7V 0 0 2.8V

In addition, the adjustment circuit 20 of the present invention may include different numbers of field effect transistors in an appropriate manner, for example, the field effect transistors are connected in parallel and/or in series, etc., and may also include various transistors in an appropriate manner. The configuration may also include an appropriate combination of field effect transistors and transistors, which is not limited here.

Claims (5)

1. An output adjustable voltage stabilized power supply circuit, comprising an adjustment circuit and a voltage divider circuit, the adjustment circuit has an adjustment terminal, an input terminal and an output terminal, the input terminal receives an input voltage, and the output terminal is connected to A load R, the voltage provided to the load R is the output voltage, the voltage divider circuit includes resistors R1, R4, the resistors R1, R4 are connected in series, one end of the resistor R1 is connected to one end of R4, and the other end is grounded , the other end of the resistor R4 is connected to the output terminal, and at the output terminal, the output voltage of the load R is divided by the voltage divider circuit and then fed back to the adjustment terminal, characterized in that: the voltage divider circuit also includes Two resistors R2, R3, one end of the resistors R2, R3 are connected to the node between the resistors R1, R4, and the other end receives a set of control signals to control whether the resistors R2, R3 are grounded to participate in voltage division. 2. The output adjustable voltage stabilized power supply circuit according to claim 1, characterized in that: the adjustment circuit includes a field effect transistor Q1 and a transistor Q2, the drain of the field effect transistor Q1 is used as an input terminal, and its Connect the input voltage, its source serves as the output end, the output end is connected to one end connected to the resistor R4 and the load R, the other end of the load R is grounded, the gate of the field effect transistor Q1 is connected to the collector of the transistor Q2 Connected, its connection node is connected to a driving voltage through a resistor R5, the driving voltage provides the driving voltage of the field effect transistor Q1 and the operating voltage of the transistor Q2, the emitter of the transistor Q2 is grounded, and its base is connected to the R1, R4 The node between, the base of the transistor Q2 serves as the adjustment terminal of the adjustment circuit. 3. The output adjustable voltage stabilized power supply circuit according to claim 2, wherein the field effect transistor Q1 is an N-channel MOS transistor. 4. The output adjustable voltage stabilized power supply circuit according to claim 1, wherein the control signal is sent by a control chip on the motherboard. 5. The output adjustable voltage stabilized power supply circuit according to claim 1, characterized in that: said output adjustable voltage stabilized power supply circuit can generate four output voltages with fixed voltage increments according to the received control signal.

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