Design principle of mobile power based on MC32P21

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This paper discusses the hardware and software design methods for implementing mobile power using MC32P21 microcontroller.

The mobile power supply is a portable charger that integrates power supply and charging functions. It can be used to charge or standby power to digital devices such as mobile phones. A lithium battery cell or a dry battery is generally used as a power storage unit. A battery that is different from the internal configuration of the product is also called an external battery. Generally equipped with a variety of power adapters, usually with large capacity, multi-purpose, small size, long life and safe and reliable, can be used to power smart phones, tablets, digital cameras, MP3, MP4 and other digital products anytime, anywhere. Or a functional product that stands by for charging.

The mobile power supply can be used by any USB-compliant device through the USB Cable. It has short-circuit, overcharge and over-discharge, constant-current and constant-voltage protection, as well as high-performance power management technology.

The mobile power solution is divided into two technical routes: hardware mobile power and software mobile power, depending on whether it can be programmed. The main problems of the hardware mobile power scheme are: 1. The heat is severe, and the non-synchronous rectification mode is adopted. After the temperature is high, the constant current and the constant are not allowed, and the battery may be damaged, or even the mobile phone being charged may be burnt. 2. Due to process variation, the dispersion of current and voltage parameters is large. When mass production is performed, the defect rate is high and it is difficult to control. 3. Not programmable, functional curing, parameter curing, can not meet the needs of differentiation.

The software mobile power solution is easy to realize synchronous rectification, high efficiency, low heat generation, and flexible function changes, which has become a development trend.

The MC32P21 developed by 晟矽Microelectronics is an 8-bit RISC architecture microcontroller, which is very suitable for mobile power solutions. Its main features are as follows:
● Wide operating voltage range ● 1K program space, 128 bytes RAM, 8-level stack ● 2-channel high-speed PWM output ● 7-channel 12-bit ADC with built-in reference source ● Built-in oscillator with less than 2% deviation ● High anti-interference ability
The hardware block diagram of the mobile power solution developed by MC32P21 is as follows

The system uses MC32P21 single-chip microcomputer as the control core, real-time sampling, sampling data is processed by the single-chip microcomputer to complete the current voltage and current measurement, then the voltage is displayed through the LED light, and the whole system is controlled according to the value of current and voltage. The system main control program flow is as follows: