How to simply implement a reliable negative power supply with BUCK circuit?

In applications that require very high signal linearity amplification, dual-power op amps need to be used, such as high-precision measuring instruments, meters, etc.; then it is necessary to provide positive and negative power supplies for dual-power op amps.

In applications that require very high signal linearity amplification, dual-power op amps need to be used, such as high-precision measuring instruments, meters, etc.; then it is necessary to provide positive and negative power supplies for dual-power op amps.

Our commonly used buck step-down circuit can get a positive voltage, as shown in Figure 1.


Figure 1: Buck circuit positive voltage output

In fact, the BUCK step-down circuit can convert the negative voltage with the same output capability as the positive voltage without changing the parameters of the components, as shown in Figure 2; its working principle is the same as that of the positive voltage output, and the obtained power quality is also very high .


Figure 2: Negative voltage output of buck step-down circuit

The component models of the above two circuit diagrams are correct and can be used directly.

In addition, the negative voltage charge pump composed of capacitors, diodes and oscillators can also achieve negative voltage. Due to the existence of diodes, a part of the voltage drop will be lost, which is easily affected by the load and has a large ripple. It is not recommended to use.


Figure 3: Negative Voltage Charge Pump

In applications that require very high signal linearity amplification, dual-power op amps need to be used, such as high-precision measuring instruments, meters, etc.; then it is necessary to provide positive and negative power supplies for dual-power op amps.

In applications that require very high signal linearity amplification, dual-power op amps need to be used, such as high-precision measuring instruments, meters, etc.; then it is necessary to provide positive and negative power supplies for dual-power op amps.

Our commonly used buck step-down circuit can get a positive voltage, as shown in Figure 1.


Figure 1: Buck circuit positive voltage output

In fact, the BUCK step-down circuit can convert the negative voltage with the same output capability as the positive voltage without changing the parameters of the components, as shown in Figure 2; its working principle is the same as that of the positive voltage output, and the obtained power quality is also very high .


Figure 2: Negative voltage output of buck step-down circuit

The component models of the above two circuit diagrams are correct and can be used directly.

In addition, the negative voltage charge pump composed of capacitors, diodes and oscillators can also achieve negative voltage. Due to the existence of diodes, a part of the voltage drop will be lost, which is easily affected by the load and has a large ripple. It is not recommended to use.


Figure 3: Negative Voltage Charge Pump

The Links:   LM190E08-TLH2 LTM15C423S