REF5030A-Q1: Output voltage error

Part Number: REF5030A-Q1

Hello,

We've used REF5030A-Q1 as a 3.0V reference source for the MCU ADC, buffered by opamps. The output voltage however is incorrect, around 2.88V instead of 3.0V.

I've checked with the scope and there is no oscillation, it's pure DC 2.88V. I've seen on the forum that someone else had this problem before, no solution from TI side - what could be the issue? I've double checked the components around, I have 2x2.2uF ceramic load, and 1uF on the TRIM pin. There's almost no current drawn from the chip, only the opamp input and 20k load.

over 2 years ago

0 Trailokya Rai over 2 years ago

TI__Genius 11391 points

Can you please share the schematic. I'd recommend to use 1 ohm ESR with the capacitor.

Regards

Trailokya

0 GS over 2 years ago in reply to Trailokya Rai

Prodigy 30 points

Hello Trailokya,

I believe I described the schematics around the part: 2.2uF + 100nF at the input with 5V, 2x2.2uF + 20k in parallel at the output, 1uF at the TRIM pin. Output goes directly to the opamp buffer (OPA170A).

The datasheet states requirement of 1.5R or less of the output ESR, is adding 1R really a good idea?

Regards,

Grzegorz

0 Trailokya Rai over 2 years ago in reply to GS

TI__Genius 11391 points

Hi Grzegorz

Adding 1 to 1.5 ohm series resistance will stabilize it.

As per your description below is your test circuit -

I see one possible error source- your capacitor on Trim /NR pin. It can alter the output if it is leaking or there is some leakage path at this pin. Can you please float NR pin and conform it.

Regards

Trailokya

0 GS over 2 years ago in reply to Trailokya Rai

Prodigy 30 points

Hello Trailokya,

I removed the cap on the TRIM pin, cleaned the tracks around, no change.

I also removed one output cap and disconnected the output from the buffer input, no change.

I added 1R in series to the remaining 2.2uF at the output, no change.

The voltage at the VOUT pin is still 2.88V.

0 Trailokya Rai over 2 years ago in reply to GS

TI__Genius 11391 points

Hi GS

Based on the information provided by you , I do not have any other suggestion. Please try below things and see if it helps -

Make sure that you are using it in ESD protected area and soldering it with proper reflow.
Try putting new device on your board and check.
Desolder all the things and and force 3 V on trim pin and see if it is taking any current. If yes then double check your layout.

Good luck.

Regards

Trailokya

0 GS over 2 years ago in reply to Trailokya Rai

Prodigy 30 points

Hello Trailokya,

The area is ESD protected, the components were properly soldered. I have a test batch of 10pcs of those assemblies and all of them have the same problem. I assume either the whole batch is faulty or fake and we need to find the alternative IC.

Regards,

Grzegorz

0 Trailokya Rai over 2 years ago in reply to GS

TI__Genius 11391 points

Hello GS:

If you suspect you have faulty devices, please follow the procedure here: https://www.ti.com/support-quality/additional-information/customer-returns.html
If you suspect you have counterfeit devices, please follow the procedure here: https://www.ti.com/support-quality/quality-policies-procedures/anti-counterfeit.html

Regards

Trailokya

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REF5030A-Q1: Output voltage error