Hello all,
I have sucessfully designed a DC/DC buck switcher using the LM2679 IC. I could vary the output voltage from 3V to 10V using a potentiometer (the input voltage is 20V). Now, I want to be able to control the output voltage through a microcontroller. I thought I could easily control the output voltage by controlling the FEEDBACK pin with a variable voltage, but this doesn't seem to work.
- I tried connecting a power supply directly to the FEEDBACK pin and vary the voltage. The IC appears to be in shutdown mode.
- I also try connecting the power supply to the voltage divider, but the IC works intermittently. It's quite unstable.
Am I missing something? How do power supply designer design their power supplies?
Regards,
James
I have sucessfully designed a DC/DC buck switcher using the LM2679 IC. I could vary the output voltage from 3V to 10V using a potentiometer (the input voltage is 20V). Now, I want to be able to control the output voltage through a microcontroller. I thought I could easily control the output voltage by controlling the FEEDBACK pin with a variable voltage, but this doesn't seem to work.
- I tried connecting a power supply directly to the FEEDBACK pin and vary the voltage. The IC appears to be in shutdown mode.
- I also try connecting the power supply to the voltage divider, but the IC works intermittently. It's quite unstable.
Am I missing something? How do power supply designer design their power supplies?
Regards,
James