Low-power single-cell power supply boost circuit diagram
In portable electronic devices (typically MP3 players), it is often only powered by one or two batteries. In such a circuit system, when it is necessary to use an integrated circuit or LCD power supply with a working power of 5V is essential. The most suitable method is to use a boost IC.
The RH5RH/5RI series (product of Ricoh, Japan) is a boost-specific fixed output switching regulator IC that can obtain a fixed boost output with only three components of inductor, diode and capacitor. The most excellent feature of this circuit is its low power consumption (4~15uA) and its ability to work even at low input voltages of 0.9V.
The RH5RI and RH5RH series are frequency modulation type (PFM) and pulse width modulation type (PWM) three-terminal step-up switching regulator ICs. It also has two RH5RIxx1 (RH5RHxx1) series of drivers and an external RH5RIxx2 (RH5RHxx2) series of drivers. The former applies to circuits that vary from no load to several mA load; the latter applies to circuits that vary from mA to hundreds of mA.
The RH5RH/5RI series IC features low power consumption and consumes only 4~15uA at no load. The initial operating voltage is only 0.9V and the efficiency is greater than 80%. It is packaged in a small SOT-89 package.
The following figure shows the basic external circuit diagram of RH5RI and RH5RH. It only needs to connect the three external components of inductor L1, diode VD1 and capacitor C1 to work normally.
The recommended value for the inductor is 82~270uH, and the diode is a Schottky diode. The capacitor is preferably a tantalum capacitor. When it is necessary to drive a large load, a circuit in the form of an external drive as shown in the following figure can be used.
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