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AD585 internal op amp pin connection

Question asked by springwind on Aug 11, 2018
Latest reply on Aug 11, 2018 by dmercer

Hi,

 

I am designing a sample hold circuit for ADC, and testing AD585.

The datasheet of the AD585 says the PIN1 and the PIN2 are -Vin +Vin (of internal Op amp) for DIP IC,

however the connection diagrams in Fig 6 Fig 7 Fig 8 inconsistent with typical integrator sample hold circuits.

In some traditional articles, the op amp input for sample-hold circuit should be as follows:

1) In non-inverting integrator sample hold circuit

Signal input should be connected to negative input of op amp and

feedback should be connected to positive input of op amp.

2) In inverting integrator sample hold circuit

Signal input should be connected to positive input of op amp and

feedback should be connected to negative input of op amp.

The actual circuit is working fine in Fig 6 diagram connection.

Is this some mistakes of the datasheet, in which the op amp's positive input and

negative input in the IC circuit diagram are reversed?

 

Thank you.

 

Ref:

IEEE JOURNAL OFSOLID-STATE CIRCUITS, VOL. SC-9,NO.6, DECEMBER 1974 381 A Complete Monolithic Sample/Hold Amplifier

Electronic Circuits: Handbook for Design and Application Ulrich Tietze、 Christoph Schenk、 Eberhard Gamm

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