LM2776: Can it use for high current output with multiple parallel ?

Hello aggil,

LM2776 can be paralleled. They need to share the same output capacitor. The more you parallel, the bigger the output capacitor should be.

You also need to be aware that there will be a mismatch between the LM2776 output impedances. Meaning, that if you parallel two of them you will be able to achieve slightly less than 400mA maximum. 

Thank you very much!

Best Regards,

Dorian

Hi Dorian

     Can we use the below schematic that mentioned in LM2662 DS?

Hello Aggil,

The easiest is to refer to the following from the TPS60400 Datasheet, it can be used for your system :

Thank you!

Best Regards,

Dorian

Hi Dorian

  We are designing the circuit to verify. thank you !

Hi Dorian

    Sorry to disturb you again.

   We meet the problem when two LM2776 are parallelled.  The total load current is 40mA, In 16pcs PCB testing, Most of the time the two LM2776 don't work at the same time. One work, another don't switch. And it is irregular. Below picture is the schematic. Pls help to check, thanks

Hello aggil,

As shown in the schematic I sent you previously, I recommend you only use one capacitor at the input and one capacitor at the output.

R1031/R1030, are they 0ohm resistor or 1 Ohm? I would remove it considering the losses you will have. 40ma*1Ohm=40mV loss.

Question is do you achieve target output voltage? 

Because it is normal operation that the two LM2776 are not working at the same time at light loads, 40mA. When paralleling them due to the mismatch in the output impedance of the two LM2776, one LM2776 will regulate the output more than the other and provide a path for the current to flow. As LM2776 are rated 200mA it make sense that one is taking over the other especially at 40mA.

Do you have any further questions?

Thank you very much!

Best Regards,

Dorian

Hi Dorian

  thank you.