Choosing a switching power supply IC should not only consider the requirements and reliability of the circuit performance, but also consider its size, weight, battery life and cost.

Here are some basic principles for switching power supply ic selection:

1. Do not pursue the latest devices with high precision and full function: the accuracy of the switching power supply IC is generally ±2%~±4%, and the high precision can reach ±0.5%～±1%. It is necessary to select the appropriate precision according to the requirements of the circuit. This can reduce production costs. More versatile devices are more expensive, so there is no need to turn off the power function or there is no microprocessor (μP) or microcontroller (μC) in the product, so there is no need to select a device with a power-off function or an output power supply status signal. Not only can the cost be reduced, but the size is smaller.

2, the best conditions for using LDO: When the ripple and noise of the output voltage are required to be particularly small, the input-output voltage difference is not large, and the output current is not more than 100mA. The micro-power, low-dropout (LDO) linear regulator is used. It is the most suitable and suitable for most portable product applications.

3. Don't choose too big, just right: The three main parameters of switching power supply ic are input voltage VIN, output voltage Vo and maximum output current Iomax. According to the working current of the product, it is more suitable that the working current maximum is 70-90% of the maximum output current Iomax of the power IC.

4. When using a negative power supply, try to use a charge pump: a portable power supply often requires a negative power supply. Since the required current is not large, the charge pump IC is the simplest to form a voltage reversal circuit. If the noise is required or the output voltage is required, A charge pump IC with an LDO linear regulator is used.