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Hot!Digital current control implementation

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2021/01/28 20:57:28 (permalink)
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Digital current control implementation

Hi. Recently I have designed a digital buck converter using PIC16F1769 with the help of application note TB3103 (Title: Buck converter using the PIC16F753 analog features) from Microchip. It's working fine. Now I have to add current control (not peak current control that is already working as described in application note) so that I can limit output current to the desired value and may be variable current control so that it works as a test bench power supply. My question is how to implement it. I'm using MCC tool in MPLABX to configure the hardware. I don't want to use external circuitry to control the current instead I want to have control over PWM on time so that current control can be implemented along with voltage control within IC.

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    Re: Digital current control implementation 2021/01/29 22:13:31 (permalink)
    the problem is the low value of ISense resistor
    you would need to R/C it again with a much lower cutoff frequency 
    and run it into OP amp and feed it somewhere ADC , or the resistor divider (with diode) ?
    add a 2nd Sense resistor on the input side with a PNP with the collector pulling up on the resistor divider 
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