DC-DC circuit with low-loss voltage-stabilizing output

Abstract

The utility model discloses a DC-DC circuit with low-loss voltage-stabilizing output, and belongs to the technical field of electronic circuits. The circuit is composed of a fixed DC-DC circuit and a voltage stabilizing circuit. The voltage stabilizing circuit comprises a coupling capacitor C1, rectifier diodes D1 and D2, and a voltage stabilizing diode ZD1. The output end of the ZD1 is connected with the rectifier diode D2 in series and then grounded, the filter capacitor C2 is connected between the output end of the rectifier diode D1 and the ground in parallel and then serves as the auxiliary output end of the low-loss voltage-stabilizing output DC-DC circuit, one end of the C1 is connected with a DC-DC chip SW pin in the fixed DC-DC circuit, and the other end of the C1 is connected with the input end of the voltage-stabilizing circuit. The circuit has the advantages that 1) the loss of charging (discharging) through the ZD1 and the D2 is smaller than that of direct charging (discharging) of the C1 through the D2 of a conventional circuit; and 2) the voltage is reflected to VO plus-ZD1 through the voltage stabilizing characteristic of the main power VO plus, so that a special voltage stabilizing circuit of an auxiliary circuit is omitted.

Description

Technical Field

[0001] The utility model belongs to the technical field of electronic circuits, in particular to a DC-DC circuit with low-loss and voltage-stabilized output. Background Art

[0002] Conventional electronic DC-DC circuits are shown in Figure 1 , Figure 2 , which consists of a fixed DC-DC circuit and a voltage stabilizing circuit. The voltage output of the main circuit is sampled and locked by the DC-DC integrated circuit itself, while the voltage output end of the secondary circuit is coupled through capacitor C1, rectified by the diode to obtain the voltage, and then passed through the corresponding voltage stabilizing circuit to obtain the required negative (positive) voltage value. Figure 1 In the positive half cycle, the main output is a positive voltage VO+, and the secondary output is a negative voltage VO-. In the positive half cycle, the capacitor C1 directly discharges the diode D2. Figure 2 In the circuit, the main output is positive voltage VO1+, and the secondary output voltage is positive voltage VO2+. Since D2 directly charges C1 during the negative half cycle of the voltage output, in either case, the current of the DC-DC circuit is ineffectively lost.

[0003] Conventional electronic DC-DC circuits require a dedicated voltage regulator to be added when the secondary circuit voltage is specified, and this voltage regulator will also cause ineffective current loss. Summary of the invention

[0004] The purpose of the utility model is to provide a low-loss DC-DC circuit with a stable output voltage in view of the shortcomings of the prior art. The utility model is composed of a fixed DC-DC circuit and a voltage-stabilizing circuit, and is characterized in that: the voltage-stabilizing circuit includes a coupling capacitor C1, rectifier diodes D1 and D2, and a voltage-stabilizing diode ZD1;

[0005] The output end of ZD1 is connected in series with the rectifier diode D2 and then grounded. A filter capacitor C2 is connected in parallel between the output end of the rectifier diode D1 and the ground as the auxiliary output end of the low-loss voltage-stabilized output DC-DC circuit. One end of C1 is connected to the SW pin of the DC-DC chip in the fixed DC-DC circuit, and the other end is connected to the input end of the voltage-stabilizing circuit.

[0006] The fixed DC-DC circuit is prior art.

[0007] The working principle of this utility model:

[0008] 1. When positive and negative voltage output (see Figure 3 ):

[0009] In the positive half cycle, D1 is turned off, D2 and ZD1 are turned on, and the current is discharged to C1 through D2 and ZD1. The discharge voltage value is D2+ZD1.

[0010] In the negative half cycle, D1 is turned on, D2 and ZD1 are turned off, and the current charges C1 through D1. The charging value is D1. As a result, the total voltage is D1-(ZD1+D2)=ZD1, that is: (VO-)=-[(VO+)-ZD1]

[0011] 2. When two positive voltage outputs are used (see Figure 4 ): Just reverse the above 1.

[0012] Beneficial effects of the utility model:

[0013] 1) The loss of the utility model circuit for charging (discharging) through ZD1+D2 is smaller than that of the conventional circuit where D2 directly charges (discharges) C1;

[0014] 2) The voltage stabilizing characteristics of the main power VO+ are reflected to VO+-ZD1, eliminating the dedicated voltage stabilizing circuit of the secondary circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of a conventional electronic DC-DC circuit. The main output is a positive voltage and the secondary output is a negative voltage.

[0016] Figure 2 The schematic diagram of the conventional circuit of the existing electronic DC-DC is shown in FIG. 1 , in which the main output is a positive voltage and the secondary output is a positive voltage.

[0017] Figure 3 This is the principle diagram of Example 1, where the main output is a positive voltage and the secondary output is a negative voltage.

[0018] Figure 4 This is the principle diagram of Example 2, where the main output is a positive voltage and the secondary output is a positive voltage. DETAILED DESCRIPTION

[0019] Example 1: When the output voltage is positive or negative (see Figure 3 ). The low-loss regulated output DC-DC circuit consists of a fixed DC-DC circuit part and a voltage regulated circuit part.

[0020] The voltage stabilizing circuit includes coupling capacitor C1, Schottky diodes D1 and D2, and voltage stabilizing diode ZD1. The negative end of voltage stabilizing diode ZD1 is connected to the negative end of D2, and the positive end of voltage stabilizing diode ZD1 is grounded. The positive end of D1 is connected to filter capacitor C2 to become the voltage output end. The negative end of D1 is connected to one end of C1 and the positive end of D2.

[0021] The fixed DC-DC circuit part is the existing technology, in which C3 is the input filter capacitor and C4 is the output filter capacitor. L1 is a power inductor. D3 is a Schottky rectifier diode, one end of which is connected to the SW pin of the DC-DC chip and one end of L1, and the other end is connected to R1 and one end of C3. R1 and R2 are sampling resistors. U1 is a DC-DC integrated chip, SHDN is the enable pin of the DC-DC chip (1 is on, 0 is off), and SW is the power switch node inside the DC-DC chip. FB is the feedback input pin of the DC-DC chip. The output voltage is determined by R1 and R2. VO- represents a negative voltage, and VO+ represents a positive voltage.

[0022] Example 2: When there are two positive voltage outputs (see Figure 4 ). The low-loss regulated output DC-DC circuit consists of a fixed DC-DC circuit part and a voltage regulated circuit part.

[0023] The voltage stabilizing circuit includes coupling capacitor C1, Schottky diodes D1 and D2, and voltage stabilizing diode ZD1. The positive end of voltage stabilizing diode ZD1 is connected to the positive end of D2, and the negative end of voltage stabilizing diode ZD1 is grounded. The negative end of D1 is connected to filter capacitor C2 to become the voltage output end. The positive end of D1 is connected to one end of C1 and the negative end of D2.

[0024] The fixed DC-DC circuit part is the same as that of Embodiment 1. VO1+ and VO2+ both represent positive voltages.

Claims

1. A low-loss, voltage-stabilized output DC-DC circuit, consisting of a fixed DC-DC circuit and a voltage-stabilizing circuit, characterized in that: The voltage stabilizing circuit includes a coupling capacitor C1, rectifier diodes D1 and D2, and a voltage stabilizing diode ZD1; The output end of ZD1 is connected in series with the rectifier diode D2 and then grounded. The output end of the rectifier diode D1 and the ground are connected in parallel with the filter capacitor C2 to serve as the auxiliary output end of the low-loss voltage-stabilized output DC-DC circuit. One end of C1 is connected to the SW pin of the DC-DC chip in the fixed DC-DC circuit, and the other end is connected to the input end of the voltage-stabilizing circuit.

2. The low-loss, voltage-stabilized DC-DC circuit of claim 1, characterized in that D1 and D2 are Schottky diodes.

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