AnsweredAssumed Answered

Input protection for AD7740

Question asked by mantoa on Jan 29, 2014
Latest reply on Jan 31, 2014 by MaryMc

Hi,

The circuit I used is an op amp output pin connect to AD7740 input pin.

I need input span -0.15V to +2.5V for AD7740.

But input pin of AD7740 must not be lower than -0.3V.

If the output of op amp series with a resistor than a shottky diode to the GND pin,

it seem can protect AD7740 from input pin to lower than -0.3V.

The shottky diode forward voltage vary with operation temperature. 

I cannot keep the input span -0.15V to +2.5V.

Can you suggest how can I do?

Thank you.

 

 

      OP  --------  R  -------+----------- AD7740

                                      |

                                      |

                                  Diode

                                      |

                                      |

                                  GND

Outcomes