LM27762: OUT- could not startup when it is pre-charged to positive?

Kazuhiko Hirano

Part Number: LM27762
Other Parts Discussed in Thread: LM2776

Hello,

My customer has used a similar type of device as the LM27762 before.
At that time, they experienced a problem that the negative voltage did not start up normally when the negative output was pre-charged to positive during startup.
LM2776 could have the same issue when OUT- is pre-charged to positive at startup?
If yes, to avoid the issue, what kind of workaround is recommended?

Best regards,

K.Hirano

over 3 years ago

+1 Varun John over 3 years ago

TI__Mastermind 21530 points

Hi Hirano,

The OUT- startup of the LM2776 may also be affected by the positive pre-biased voltage. An external Schottky diode can be added to the OUT- pin to discharge a positive voltage on this pin.

For your reference TPS6040x has an integrated Schottky diode to deal with the same problem. You can find more information in section 8.4.1 of the datasheet TPS60400

Best regards,

Varun

0 Kazuhiko Hirano over 3 years ago in reply to Varun John

TI__Genius 14978 points

Varun,

Thank you for your response.

Best regards,

K.Hirano

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LM27762: OUT- could not startup when it is pre-charged to positive?