REF3440: REF3440 negative voltage output?

user3830479

Expert 1090 points

Part Number: REF3440

Dear TI:

We need -4.096V reference voltage, Can REF3440 output -4.096V not add amplifier?

I find LT6654 can output -4.096V directly. please give some advice, thanks !

over 6 years ago

0 Marcoo Z over 6 years ago

TI__Mastermind 19570 points

Hi,

Yes it can. If you are following the schematic from LT6654 DS then it works properly. Make sure R1 and R are proerply sized with Vin and VEE respectively to lower power consumption.

-Marcoo

0 user3830479 over 6 years ago in reply to Marcoo Z

Expert 1090 points

Dear Marcoo:

Thanks! Can you help check circuit design as below?

0 Marcoo Z over 6 years ago in reply to user3830479

TI__Mastermind 19570 points

Hi,

I can help you.
What is your expected output load? This will help determine R255

-Marcoo

0 user3830479 over 6 years ago in reply to Marcoo Z

Expert 1090 points

Hi:

We will power supply for DAC reference voltage, output load is belowe 10mA

0 Marcoo Z over 6 years ago in reply to user3830479

TI__Mastermind 19570 points

Hi,

R254 seems fine. I would increase it slightly so there is not much current loss.
R255 needs to be sized properly.
R255 = (-4.096 - (-5V)) / (95uA + Iout)
You need Iout from the DAC datasheet for an accurate voltage. What is the DAC?

-Marcoo

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REF3440: REF3440 negative voltage output?