Pay attention to the following issues when selecting a switching power supply:
1. The best conditions for using LDO When the ripple and noise in the output voltage are required to be particularly small, the input and output voltage difference is not large, and the output current is not more than 100mA, the use of micro-power, low-dropout (LDO) linear regulators is The most suitable, suitable for most portable product applications.
2. When a negative power supply is required, try to use a charge pump. Portable instruments often require a negative power supply. Since the required current is not large, it is easiest to use a charge pump IC to form a voltage inversion circuit. Charge pump IC with LDO linear regulator.
3. Don't pursue high-precision, full-featured power ICs of the latest devices. The accuracy of the power supply IC is generally ±2% to ±4%, and the high accuracy can reach ±0.5% to ±1%. The appropriate accuracy should be selected according to the requirements of the circuit, so that Production costs can be reduced. The price of the device with more complete functions is higher, and the device without the power-off function or the product without a microprocessor (μP) or microcontroller (μC) does not need to choose a device with a power-off function or an output power supply working status signal, which not only Lower cost and smaller size.
4. Don't "big horse-drawn cart" The three main parameters of the power IC are the input voltage VIN, the output voltage Vo and the maximum output current Iomax. Choose according to the working current of the product: it is more appropriate that the maximum working current is 70% to 90% of the maximum output current Iomax of the power supply IC.
