LT1054: LT1054 5VIN to -12V

Red Yen

Part Number: LT1054
Other Parts Discussed in Thread: TPS63700

Hi Support team

in case, i would like to convert from 5V to -12V

May just calculate the value of R1 and R2? Do I need to go to the ground when OSC is not in use?

0 Jasper Li over 4 years ago

Hi Red,

the expert supporting this device is out of office. the reply for your question will be delayed.

0 Red Yen over 4 years ago in reply to Jasper Li

Hi Jasper,

may I have your kindly update for this request?

0 Jasper Li over 4 years ago in reply to Red Yen

Hi Red,

Brigitte is back to office, and i just re-assigned the post to her.

0 Brigitte over 4 years ago

Hello Red,

Sorry for the late response as I was out of the office during Christmas season.

In the configuration you show above, the most negative output voltage of the LT1054 from VIN = 5V is VOUT = -5V (+ some voltage drop).

So you cannot regulate to -12V with the above configuration. You need then an input voltage of at least 13V for full output load.

If you only have 5V input voltage available, you need to use a voltage tripler to get to around 13.5V and then you can invert it with LT1054.

Maybe you might have a look at TPS63700 for -12V from 5V input voltage.

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