TPS717xx delay en

Jamie Maxwell

I am using the TPS71707 to power a microcontroller and I want to delay the turnon rather than ramping with the input rail. The easiest way would be with a resistor/capacitor ramp on the EN pin.

No hysteresis is mentioned in the datasheet for this pin. Is there any internal protection on this pin so that it will cleanly enable with a slow rising input (order of ms)? I want to avoid the regulator output chattering as the capacitor voltage slowly rises above the threshold.

Jamie

over 10 years ago

0 Ryan Eslinger over 10 years ago

TI__Guru 55940 points

Hi Jamie,

In general adding an RC delay should work; however, it would be recommended that you build a prototype to ensure that it will work for your specific application. If you are looking for a more precise timing you could consider adding a Supervisor IC. This would also provide a nice clean edge for enable.

www.ti.com/.../supervisor-reset-ic-products.page

Very Respectfully,
Ryan

0 Jamie Maxwell over 10 years ago in reply to Ryan Eslinger

Expert 1530 points

Do we know anything about the internal circuit for the enable pin? In this case we're trying to reduce components rather than add them.

0 Ryan Eslinger over 10 years ago in reply to Jamie Maxwell

TI__Guru 55940 points

Hi Jamie,

There is not hysteresis on this pin.

Very Respectfully,

Ryan

0 Jamie Maxwell over 10 years ago in reply to Ryan Eslinger

Expert 1530 points

Thanks Ryan for checking into this promptly.

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TPS717xx delay en