LP2985: question on the slew rate requirement on ON/OFF pin

Sandburg HU

Part Number: LP2985

Hello,

The datasheet calls out 40mv/us slew rate on the ON/OFF pin. What's the symptom when failing this requirement? If the ON/OFF pin ramps too slow, would it cause LDO no output or output bouncing but will eventually up? And what's the cause? Thank you.

Sandburg

over 7 years ago

0 kai klaas69 over 7 years ago

Guru 140200 points

Hi Sandburg,

do you plan to violate this recommendation?

Kai

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

TI__Guru 55940 points

Hi Sandburg,

The ON/OFF pin of LP2985 was designed, tested, and characterized to accept a digital input signal. The ON/OFF rail enables the internal circuitry including the reference in a specific order in order to ensure a proper startup. A slower slew rate will impact the startup sequence and as such the output may never come out of dropout, regulate at a different voltage, or not come up at all. It is very important to follow the datasheet requirement and have a slew rate of 40 mV/us or greater in order to ensure proper operation.

Very Respectfully,
Ryan

0 Sandburg HU over 7 years ago in reply to kai klaas69

Prodigy 70 points

Not exactly. I'm weighing options for a design concept.

0 Sandburg HU over 7 years ago in reply to Ryan Eslinger

Prodigy 70 points

Thanks Ryan.

Power management

Power management forum

LP2985: question on the slew rate requirement on ON/OFF pin