When the input of the ADCV0831 is driven by an op-amp operating at a supply voltage greater than 5V, it is a good idea to protect

the input of the ADCV0831 from exceeding the supply voltage. Two diodes can be added to the input one to supply and one to

the ground pin.

Note: Diodes are IN914

This circuit utilizes the LM385 reference to detect the power supply voltage level. When the supply voltage is 3V, the LSB = 3/256

= 11.7mV. Since the LM385 reference sets the input to 1.2V. The output code is 102. As the supply voltage decreases, the LSB

decreases and the output code increases. When the supply voltage reaches 2.7V, the LSB = 10.5 mV. The input voltage is still

at 1.2V, and the output code is 114. If the supply voltage increases, the LSB increases and the output code decreases. When the

supply voltage reaches 3.3V, the LSB = 12.9mV and the output code is 93.

Protecting the input

DS100104-64

Power Supply Level Detection

DS100104-65

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