ADS1292: Internal Reference Settle time

user4793539

Part Number: ADS1292

ads1292 data sheet shows vcap1 settle time need 0.5s. When Initialize the ads1292 PDB_REFBUF = 1 with no delay, then write certain registers.

We test 10 pieces of PCBA and found 1 PCBA VREFP= VREFN = -2.5V, It should be VREFP= 0, VREFN = -2.5V。

Sometimes the pcba VREFP is not correct, but sometimes it proper functioning. We don't know what happened.

We think settle time only affect the voltage accuracy, Does the settle time affect the VREFP value?

over 6 years ago

0 user4793539 over 6 years ago

Intellectual 580 points

The ads1292 works in internal reference mode.

0 Ryan Andrews over 6 years ago in reply to user4793539

TI__Guru 67626 points

Hello User,

Thank you for your post!

The internal reference voltage should be either 2.42 V or 4.033 V with respect to AVSS. If VREFP = VREFN = AVSS, then there could be a problem with the internal reference buffer. Make sure that you are following the Power Up Sequence correctly as outlined in the datasheet. In addition, please try following the steps outlined in these FAQ posts on our BIOFAQ page:

The actual settling time of the internal reference after power-up will depend on the RC time constant formed by the internal resistor R1 (see Figure 31) and the value of the VCAP1 bypass capacitor.

Best regards,

Data converters

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ADS1292: Internal Reference Settle time