TPS563201: TPS563201

Hossam Moghrabi

Part Number: TPS563201

Tool/software:

Hello,

I plan to use TPS563201 but need to use big polymer capacitors along with ceramic caps... but i read that it is unstable beyond just 68uF caps.

for me I intend to use 5x10u 0805 ceramics + 2 or 3 470u polymer caps + 10uF elec cap + 4.7uH inductor (can choose anything suitable).

for your kind help to figure out how can this work fine.

regards,

Hossam

4 months ago

0 Shipeng Cheng 4 months ago

TI__Expert 8770 points

Hi Hossam,

Could I know what's your purpose of using polymer cap? Usually using only ceramics can get a good transient response. Thanks.

Regards,

Shipeng

0 Hossam Moghrabi 4 months ago in reply to Shipeng Cheng

Prodigy 210 points

i want to eliminate ripple and noise by a lot + high capacitance to tackle whatever load changes or needs. i tested this previously with other designs and i liked it.

if tps563201 can work with this please tell me how as they are available very cheaply from lcsc. if there is another part number which can work please inform me...i guess continuous current mode allows very high capacitance values right?

0 Shipeng Cheng 4 months ago in reply to Hossam Moghrabi

TI__Expert 8770 points

Hi Hossam,

You can see the application report below, you need to measure the loop to adjust output capacitors and feedback network to get a stable loop.

https://www.ti.com/lit/an/slvae93/slvae93.pdf

0 Hossam Moghrabi 4 months ago in reply to Shipeng Cheng

Prodigy 210 points

i don't have the capabilities or tools to do any bode analysis. not all caps i use have esr data shown accurately.

can you help with this? even approximation is good enough for me.

like, what could go wrong if i use the caps i mentioned above?

0 Shipeng Cheng 4 months ago in reply to Hossam Moghrabi

TI__Expert 8770 points

Hi Hossam,

A high ESR capacitor can cause higher crossover frequency and lower phase margin. Usually unstable is caused by no phase margin, so you can try to remove the Cff, or even add a capacitor in parallel with lower divided resistor to get a enough phase margin.

0 Hossam Moghrabi 4 months ago in reply to Shipeng Cheng

Prodigy 210 points

my caps are ceramics with low esr, 1210 + 0805 sizes. Plus, 470u polymer with about 7-8 mOhm esr. I put one small 10uF elec. with 3 ohms esr to act as a damper.

what possible combination i can use with this?>

0 Shipeng Cheng 4 months ago in reply to Hossam Moghrabi

TI__Expert 8770 points

Hi,

What is your input and output voltage, I need to run a simulation for you. Thanks.

0 Hossam Moghrabi 4 months ago in reply to Shipeng Cheng

Prodigy 210 points

input voltage is 15 and output is 5v and 3.3v. 5v is at 2 amps but 3.3v max 1 amp.

another design i have input 5v and output 3.3v at 3 amps.

regards

0 Shipeng Cheng 4 months ago in reply to Hossam Moghrabi

TI__Expert 8770 points

Hi Hossam,

In my simulation, you can use upper resistor 33.2k and lower resistor 10k and Cff 1nF to get a result at crossover: 10.1k, phase margin 54°. Thanks.

0 Hossam Moghrabi 4 months ago in reply to Shipeng Cheng

Prodigy 210 points

hello,

what do you mean by upper and lower resistor? you mean the feedback resistors to set output voltage? i have no problems with that... but rather the usage of bulk output caps.

actually i asked a similar question here https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1369098/tps564247-tps563231drlr-tps564247drlr-selection-of-capacitors-and-total-output-ripple

as these 2 parts are more interested to me than this thread. please check it and report to me if using bulk caps are ok...

0 Shipeng Cheng 4 months ago in reply to Hossam Moghrabi

TI__Expert 8770 points

Hi Hossam,

Yes, I mean feedback resistors.

Regards,

Shipeng

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TPS563201: TPS563201