TPS544C20: Is there any limitation of max load capacitor value

Yasushi Fujiwara

Part Number: TPS544C20
Other Parts Discussed in Thread: TPS544B20

Hi Experts,

I want to know whether is limitation of max load capacitor value. The datasheet mentioned about minimum capacitor value but I do not see any limitation for max load capacitor value.

Best Regards,
Fujiwara

over 6 years ago

0 JohnTucker over 6 years ago

TI__Guru**** 191445 points

Fujiwara-san,

There is no explicit limit. You should be able to use any reasonable value. Extremely large values may cause the TPS544C20 to enter current limit during start up (Iss = (Css * Vout / Tss) + Iload). Also extremely high output capacitance may cause low Fco and Low PM. You should not encounter either of these issues for any reasonable output capacitance. How much are you considering?

0 Yasushi Fujiwara over 6 years ago in reply to JohnTucker

TI__Genius 12725 points

Hi John-san,

The output capacitance will be less than 3500uF for TPS544C20 and less than 2200uF for TPS544B20. I think it is reasonable value for both devices.

Best Regards,
Fujiwara

0 Yasushi Fujiwara over 6 years ago in reply to Yasushi Fujiwara

TI__Genius 12725 points

Hi John-san,

I want your comments on this.

Regards,
Fujiwara

0 JohnTucker over 6 years ago in reply to Yasushi Fujiwara

TI__Guru**** 191445 points

Fujiwara-san

Let me discuss this with our team. I will get back to you tomorrow.

0 JohnTucker over 6 years ago in reply to JohnTucker

TI__Guru**** 191445 points

Fujiwara-san,

The output LC corner frequency should be much greater than 3 kHz. So Cout < 1 / (355.3E6 * Lout).
For a typical Lout of 470 nH, Cout should be much less than 6000 uF. So depending on your Lout value 2500 uF or 3500 uF does not seem unreasonable. Make sure to check your slow start time as mentioned above.

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TPS544C20: Is there any limitation of max load capacitor value