tps7b7701-q1: Device Ron in Power Switch Mode

Rakesh

Guru** 105361 points

Part Number: TPS7B7701-Q1

What is the device Ron in Power Switch Mode?

Thanks,

Rakesh

over 7 years ago

0 kai klaas69 over 7 years ago

Guru 140200 points

Hi Rakesh,

you can estimate it from figure 7 of datasheet: 620mV / 210mA = 2.95R

Kai

0 Ryan Eslinger over 7 years ago in reply to kai klaas69

TI__Guru 55940 points

Hi Rakesh,

LDOs specify the voltage drop across the LDO rather than Ron; however, since dropout is linear with respect to output current, Ohm's Law can be used to calculate Ron. As kai klaas69 mentions, you can use figure 7 of the datasheet to estimate Ron.

Very Respectfully,
Ryan

0 Rakesh over 7 years ago in reply to kai klaas69

TI__Guru** 105361 points

Thank you Kai.

0 Rakesh over 7 years ago in reply to Ryan Eslinger

TI__Guru** 105361 points

Hi Ryan,
Thank you..
Datasheet (Features section) mentions that the device can be operated in "Power Switch Mode by Tying FB to GND". I was under impression that since it is not LDO mode, the GATE will be fully driven for lowest Ron. So, there is no change in GATE control or GATE drive strength b/n LDO mode and Power Switch Mode right?

Best Regards,
Rakesh

0 Ryan Eslinger over 7 years ago in reply to Rakesh

TI__Guru 55940 points

Hi Rakesh,

Correct, there is no difference between what the datasheet is calling "Power Switch Mode" and dropout. By tying FB to GND you are forcing dropout. This rails the internal error amp which in turn drives the pass FET as hard as possible.

Very Respectfully,
Ryan

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tps7b7701-q1: Device Ron in Power Switch Mode