How to choose power supply IC chip?

We choose power supply IC to meet the requirements of circuit performance and reliability, but also consider its size, required circuit and circuit board, how to extend the battery life and cost and other aspects of the problem. Here to introduce some basic principles of how to choose power IC, for your reference.

1. Booster DC/DC converter is preferred

Using booster DC/DC converters is not only efficient but also can reduce the number of batteries, thus reducing the weight and volume of the entire power supply.

2. The best condition for 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 consumption, low-voltage difference (LDO) linear voltage regulator is the most appropriate.

3, when the negative power supply should be used as far as possible charge pump

Portable instruments often need negative power supply, because the required current is not large, the charge pump IC composition voltage reversal circuit is the simplest, if the noise is small or output voltage stabilizer is required, can be used with LDO linear voltage stabilizer charge pump IC.

4, not necessarily too many functions, applicable

Power supply IC accuracy is generally plus or minus 2% ~ plus or minus 4%, high precision can be up to plus or minus 0.5% ~ plus or minus 1%, according to the requirements of the circuit to choose the appropriate precision, so as to reduce production costs. Full-featured devices cost much more, so devices that do not require power off or products that do not have microprocessors or microcontrollers microns get to choose devices that do not require power off or output power state signals, which not only reduce costs, but can be much smaller.

5, output voltage and current to match, to choose a similar power circuit, play the best efficiency of power IC

The three main parameters of power supply IC are input voltage VIN, output voltage Vo and maximum output current Iomax. According to the working current of the product to choose: it is more appropriate that the maximum working current is the power supply IC maximum output current Iomax 70 ~ 90%.

6. Step-down DC/DC converter is used in circuits with large output current

Most of the working current of portable electronic products is below 300mA, and most of them use 5# nickel-cadmium and nickel-metal hydride batteries. If 1-2 batteries are used and the voltage is increased to 3.3v or 5V and the output current of 500mA or more is required, the battery life is not long or the interval between two charges is too short, which is inconvenient to use. The step-down DC/DC converter is used at this time, and its efficiency is similar to that of the step-up type, but the battery life or charging interval time is much longer.