12
PWM
12.1 PWM introduction
Pulse width modulation (PWM) is an analog control method. The bias of the base of the transistor or the gate of the
MOS tube is modulated according to the change of the corresponding load to realize the change of the conduction
time of the transistor or the MOS tube. So as to realize the change of the output of the switch stable power supply.
This method can keep the output voltage of the power supply constant when the working conditions change, and it is
a very effective technology to control the analog circuit with the digital signal of the microprocessor. It is widely used
in many fields from measurement and communication to power control and conversion.
12.2 PWM main features
• Support 5-channel PWM signal generation
• Three clock sources can be selected (bus clock <bclk>, crystal oscillator clock <xtal>, slow clock <32k>), with
16-bit clock divider
• Double threshold setting, increase pulse flexibility
12.3 PWM function description
12.3.1 Clock and divider
There are three options for each PWM counter clock source, the sources are as follows:
A. bclk - Chip bus clock
B. XTAL - External crystal clock
C. f32k - System RTC clock
Each counter has its own 16-bit frequency divider. The PWM counter will use the divided clock as the counting cycle
unit, and perform one action every time a counting cycle passes .
BL702/704/706 Reference Manual
222/ 375
@2021 Bouffalo Lab
To Next Page
Loading...