ADS8910B: SDO pin is not operate.

TAKAHIRO NAKAYAMA

Part Number: ADS8910B

The CONVST, CS, and SCLK pins are operating as recommended, but the SDO pin is not.

After power-up, the RVS pin remains low.

In the datasheet page 25; 7.4.1 RST State
"In RST state, all configuration registers are reset to their default values, the RVS pin remains low"

Is the SDO pin not operating because the RST state not exit?

[Electrical Parameter]
　・RVDD = +5.3V
　・DVDD = +2.5V

Thanks

Taka

over 4 years ago

0 Keith Nicholas over 4 years ago

TI__Mastermind 36170 points

Hello Taka,

If the RST pin is not pulled high, or floating, the device will stay in reset. Can you confirm that RST pin is pulled up to DVDD=2.5V?

You are correct, with /CS high, the RVS pin should show conversion activity. If the pin does not change state after a CONVST, then the device is either in RESET or there is some other problem.

The supply voltages look correct. Do you have bypass capacitors on the power supply pins, RVDD, DVDD, as well as the internal LDO, DECAP? Excessive power supply noise could be causing the device to misbehave. Also, do you have the thermal pad connected to GND?

If you can provide a schematic showing the circuit around the ADS8910, I will take a look to see if there is anything missing.

Regards,
Keith Nicholas
Precision ADC Applications

0 TAKAHIRO NAKAYAMA over 4 years ago in reply to Keith Nicholas

Prodigy 20 points

Hello Keith,

Thanks for the response.

The problem has been resolved.
It did not operate because "DECAP" 13pin and 14pin were not shorted.

This understood that 3V from LDO was not connected to the internal circuit ADC.

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ADS8910B: SDO pin is not operate.