repeated lm2776dbvr failure

Angela Brock

Other Parts Discussed in Thread: LM2776, LMP8350

Hi I am running 4 lmp8350 at +-5V from a 5V supply and -5V from the lm2776. One minute it is working appropriately, the next I am getting positive voltage from the negative output. It is either 1.8V or 0.6V. I have replaced them multiple times. When I solder a new one on it works appropriately for awhile. I have (2) 2.2uF caps at Vin and Vout and 1uF flying cap. I have seen another post ()and should note that my Vin Vout caps are to the ground plane not directly to pin 2.

over 9 years ago

0 Angela Brock over 9 years ago

Intellectual 480 points

I just attached a fourth lm2776 to this board and it worked up until I tested the second op amp with inputs. Then it failed, giving a -66mV output. Detaching all op amps raised the voltage to -163mV.

0 Juha Karttunen over 9 years ago in reply to Angela Brock

TI__Intellectual 1120 points

Hi Angela,

It is better to follow layout guide lines described in datasheet.

If you want to share your schematics and layout design, I can take a look at them. Have you measured the output current of the LM2776 in your application?

Regards,

Juha

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repeated lm2776dbvr failure