TPS563210 minimum input voltage

Brian Sala

Other Parts Discussed in Thread: TPS62130A, TPS62133

Hi All,

I need a 12 to 5 volt converter @3A max, for which the TPS563210 is perfect, but I'd like it to keep delivering about 200mA from a 2 cell Li-Ion battery if the mains fails. The datasheet recommends Vin be > Vo/0.65, or >7.7volts. Does anyone know if the 2 cell supply will work? It's close, but does exceed the duty cycle max recommended. The low output current when on battery should help ... but?

Thanks, Brian

over 10 years ago

0 JohnTucker over 10 years ago

TI__Guru**** 191445 points

TPS563210 will continue to operate at duty cycles above 65%. That value of 65% is very conservative. As the duty cycle increases above about 70% you may see some slight lowering of output voltage. Eventually at duty cycle near 80% you will reach the limit imposed by minimum on time. At that point, the output voltage will decrease rapidly as Vin continues to fall. The other consideration is load step transient response. When a load step occurs, the TPS563210 responds by rapidly increasing duty cycle to allow the output current to quickly increase to the new load requirement. if the duty cycle is already near the maximum, the response time is delayed.

0 Chris Glaser over 10 years ago

TI__Guru**** 152110 points

The TPS62130A is generally a more suitable device for portable applications with its small size, lower Iq, and 100% duty cycle mode support.

0 Brian Sala over 10 years ago in reply to JohnTucker

Prodigy 60 points

Thanks John - all makes good sense, and after posting I did search further and found the TPS62133 which runs to 100% DC, so will use that. Now I wonder how they keep the top FET on with 100% DC, but I doubt we will get all the way to 100% so should be good. And thanks for doing the maths with the minimum on time - I was a bit lazy in not doing that myself. Much appreciated.

Brian Sala

0 Brian Sala over 10 years ago in reply to Chris Glaser

Prodigy 60 points

Thanks Chris, I did find the TPS 62133 after posting, so thanks for the confirmation, much appreciated.

Brian Sala

0 JohnTucker over 10 years ago in reply to Brian Sala

TI__Guru**** 191445 points

it probably uses a P channel high side switch. It does not require a BOOT voltage to maintain the switch on like an N channel switch.

0 Brian Sala over 10 years ago in reply to JohnTucker

Prodigy 60 points

Yes John,

There is no bootstrap cap in the circuit, so I agree it's a P-channel FET. Interesting that the datasheet Figs 5 & 6 both 'imply' N-channel FETs. Proof is in Table 8.5 of the datasheet which gives the high side FET Rdson as higher than the low side FET. It's a no contest!

Thanks for your input, Brian

0 JohnTucker over 10 years ago in reply to Brian Sala

TI__Guru**** 191445 points

Yes it is not clear from the datasheet, but that has to be the design,

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TPS563210 minimum input voltage