NAFE73388 GAIN SETTING

[jathishjk]

NAFE73388 GAIN SETTING, Iam not able to set PGA Gain above 1V/V in NAFE73388. Datasheet says it support gain upyo 16V/V. But configuration register setting does not accept settings value for 1V/V and above. Please clarify.

[jathishjk]

The reply provided by NXP Team on how to set the GAIN of above 0.8 is not satisfactory. Datasheet says supported gain is upto 16V/V. But the gain setting value in config register as per datasheet above 0.8 is shown as unused. In the board it is tested and confirmed that above 0.8 gain setting is not working. Kindly give the correct solution.

[jathishjk]

Thank you for the reply. Need some more clarification on configuring a channel for a gain of 16. It will be helpful if you could give the registers value to be set for PGA gain and gaincoefficient register setting for this.    

[ErikaC]

Hello

To help resolve the issue, please provide details about your current configuration: Which channel(s) are you using and in what mode (single-ended or differential)? How is the input signal connected and what is the expected voltage range? What exact values are you writing to the registers for PGA gain adjustment, and could you share the configuration of CH_CONFIG0, CH_CONFIG1, and CH_CONFIG2? 

[jathishjk]

We are using all AI1-AI4channels in differential mode. Voltage range we need to acquire in 0-1V. Please see the portion of the datasheet which shows configuration for gain above 1V/V is unused?  

[ErikaC]

Hello

Thank you for the clarification. If you need to configure gains higher than 1 V/V, this cannot be done using the 16‑bit CH_GAIN field, since its maximum value is 0.8 V/V.

Instead, you must use the 24‑bit calibrated coefficient registers, specifically:
GAIN_COEF0..15 — addresses 0x80h–0x8Fh

Please see section 7.3.6 Gain and offset calibration and Table 30. 24-bit channel-based coefficient and data registers

These registers allow you to apply any effective gain greater than 1 V/V, since they function as 24‑bit multiplicative calibration coefficients.

Hope this helps!

[jathishjk]

The reply provided by NXP Team on how to set the GAIN of above 0.8 is not satisfactory. Datasheet says supported gain is upto 16V/V. But the gain setting value in config register as per datasheet above 0.8 is shown as unused. In the board we tested this and confirmed that above 0.8 gain setting is not working. Kindly give the correct solution.

[Arvind_Srinivasan]

Based on the calibration coefficients also, maximum possible gain is 4 times at 0x FFFFFFFF. So, setting a default gain of max 0.8x with calibration coefficient gain of 4 times leads to a max gain of 3.2x which is still well short of 4x, 8x and 16x claimed in the datasheet of NAFE73388. How to push beyond this max limit of 3.2x