SUPPLY NON INVERTING PIN OF PRECISION OP AMP

reza jadidi

Prodigy 250 points

Other Parts Discussed in Thread: OPA388

In topic precision op amp amplifier i have a circuite insert below.

(and attach TINA FILE)

I want use a reference voltage equal =.5V on non inverting pin of u1 OPA388 OP AMP.

for this reference can use resistor voltage divider and other method.

please guide about methods for supply non inverting pin of op amp..

USE RESISTOR DIVIDER OR BUFFER THIS RESISTOR DIVIDER WITH PROPER OP AMP UNITY GAIN?

SINCERELY

over 5 years ago

0 reza jadidi over 5 years ago

Prodigy 250 points

opa354-6244.TSC

0 Rohit Bhat over 5 years ago in reply to reza jadidi

TI__Genius 15975 points

Hi Reza,

The answer to your supply method to the non-inverting pin of the op-amp really depends on the supply source you are using.

If you simply use a resistive divider, there is a chance of any power supply ripple to just couple at the op-amp output because the PSRR of your op-amp is set by the resistive divider (which is 6-dB for mid-supplies). This is true when you are using switchers for regulating power supply from a higher voltage to a lower voltage suitable for the op-amp. I would only suggest using resistive divider if you are confident that your supplies are devoid of any power supply ripples. You would still need to add a bypass cap of 0.1uF or similar at the resistive divider in-order to BW limit the resistive divider noise.

Otherwise, buffering the resistive divider with unity gain op-amp is preferred.

Best Regards,
Rohit