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AN4539

Voltage mode dual buck converter

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The duty cycle on TD2 is constant.

The ADC is configured to have conversions triggered in the middle of the ON time of each

output. The 2 conversions are done with the same ADC injected trigger (this is possible

since the 2 signals are not overlapping). The ADC is programmed in discontinuous injected

mode (1 conversion triggered on CMP3, another on CMP4).

The 2 conversions are done on the same input (PA4): TD1’s low-pass filtered PWM can be

connected to PA4 for monitoring ADC conversions with the debugger. For a real use case, it

is easy to reprogram the ADC to have the conversions done on each buck output voltage.

The FAULT1 input is enabled on PA12 (active low) to demonstrate PWM shut down (see

Section 4 for details). When the fault is triggered (PA12 input connected to GND), TD1

signal only is stopped. The system can be re-armed by pressing the user button.

LEDs are indicating the following:

•

Blue LED: blinks during normal operation;

•

Red LED: blinks when FAULT is triggered;

•

Orange LED: indicates the occurrence and duration of the PWM refresh ISR.

Demo code

The example code is provided in the HRTIM_DualBuck example.