ADS8866: Max Current in the device

Christoph Klees

Part Number: ADS8866

Hi,

I want to use the ADS8866 with a reference voltage of 3.3V.

To get a good Resolution the expected voltage is in the range from 0V-3V.

If a fault happens the voltage can reach 5V. I protect the Inputs of the ADS8866 with a series resistor (Figure 51) of 1k so the expected current in the Input Pin will be less than 2mA.

In the datasheet I find a value "Input current to any pin expect supply Pins <10mA". Is this value also valid for the AINP & AINN Pins ?

Kind regards

over 4 years ago

0 Keith Nicholas over 4 years ago

TI__Mastermind 41230 points

Hello Christoph,

Yes, the 10mA maximum limit is also valid for the AINP and AINN pins. I assume you are driving the inputs with an amplifier powered from 5V. With 1k of resistance, you will see less than 1.7mA in this case.

Please note that if an over-voltage does occur, this fault current will flow into the AINx pin and out of the REF pin, possibly disturbing your reference circuit. Again, there will be no damage to the system, but it may take a long time for everything to settle after the transient has been removed.

You may want to take a look at this TI Precision Lab presentation that discusses this topic in more detail.

https://training.ti.com/protecting-low-voltage-adc-from-high-voltage-amp?context=1139747-1140267-1128375-1139109-1137815

Regards,
Keith Nicholas
Precision ADC Applications

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ADS8866: Max Current in the device