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TAS2770: SAR ADC measure of VBAT above 14V

Part Number: TAS2770

Hi, E2E Team!

We are using the TAS2770 in one of our client's products, and as part of a Speaker Health communication system, we report VBAT from the amplifier to the host device.

In the system, we use a VBAT voltage of +16V, but when reading registers 0x27 and 0x28, the result is always 0xE0C (~+14V). This has been replicated on different systems and the readings are about the same (0xE0E, 0xE0F, and similar) 

We isolated VBAT net on one system and connected an external power supply to validate the behavior of the SAR ADC in the amplifier. The readings we obtained from the SAR ADC are correct with any value below +14V, however, with any voltage higher than 14V, the result from the SAR ADC conversion is always around +14V (0xE0C, 0xE0F, and similar).

Is this a limitation of the SAR ADC for VBAT?

Is there any configuration required in the TAS2770 to enable the SAR ADC to read voltages up-to +16V?


  -Diego Melendez Lopez