Two methods to reduce standby power consumption of boost switching power supply-EEWORLD

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Usually, the switching transistor of the switching buck converter is connected in series in the circuit, while the switching transistor of the switching boost converter is connected in parallel with the load, and the components connected in series with the load are the inductor and the diode. Therefore, if these two converters are used as backup, when the power supply is in standby mode, the buck converter cuts off the path between the input and output ends due to the switching transistor, and the standby power consumption is very small, and the current consumption is less than 1uA. But the boost converter is not the case. Since the switch tube is cut off but does not cut off the DC path between the input and output ends, the battery will still form a DC loop with the capacitor and voltage detection resistor at the output end through the inductor and the diode, and the current flowing through is about tens of microamperes. In addition, current will also flow through the load, and the current size varies depending on the circuit.
In order to reduce this current loss, the following two methods can be used.
1. Set a switch between the input and output ends
Set a switch on the line between the input and output ends to separate Vin and Vout when in standby mode. The switch can be a mechanical switch such as a relay, or an electronic switch composed of MOSFET.
Recently, manufacturers have produced a boost converter IC with a load cutoff function. When in use, the circuit shown in Figure 1 is used. In standby mode, the P-channel MOSFET Tr2 is turned off to cut off the DC path between the input and output ends. Figure 1 Set a switch between the input and output ends 2. Use a transformer for isolation As shown in Figure 2, an inductor is no longer used between the input and output ends, but a transformer is used instead. In standby mode, the switch tube Tr1 is turned off, the circuit is cut off, and the standby current of the switching power supply can be controlled below 1uA. Figure 2 Use a transformer for isolation

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