k113
Newbie level 4
Need Some help with bypass/decoupling capacitor selection
I'm running into an issue when using a Lm3224 DC/DC boost controller.
When I'm running it, I get a 250mV ripple on my 3V Vin power lines which negatively effects the rest of the board.
The controller itself is a PWM style running at 1.25Mhz.
However I'm activating the controller on a PWM signal where I have a duty cycle of 25-90% at 120hz.
The output wave forms look good, and there is no effective slow start on the controller to mitigate this issue.
How do I effectively remove the ripple on the power lines?
I have been given advice to raise the input capacitor to over 100uF, but before I order parts I'm confused on how high I need to go, whether I should go with a single vs multiple caps, ceramic vs tantalum vs electrolytic, low esr/low esl... etc.
My suspicion is the overall ripple is following the 1.25Mhz cycle, but is being smoothed out by the 20uF input capacitor, but isn't completely removing the dip.
Thanks
I'm running into an issue when using a Lm3224 DC/DC boost controller.
When I'm running it, I get a 250mV ripple on my 3V Vin power lines which negatively effects the rest of the board.
The controller itself is a PWM style running at 1.25Mhz.
However I'm activating the controller on a PWM signal where I have a duty cycle of 25-90% at 120hz.
The output wave forms look good, and there is no effective slow start on the controller to mitigate this issue.
How do I effectively remove the ripple on the power lines?
I have been given advice to raise the input capacitor to over 100uF, but before I order parts I'm confused on how high I need to go, whether I should go with a single vs multiple caps, ceramic vs tantalum vs electrolytic, low esr/low esl... etc.
My suspicion is the overall ripple is following the 1.25Mhz cycle, but is being smoothed out by the 20uF input capacitor, but isn't completely removing the dip.
Thanks