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AD5422 minimum current load

Question asked by tomdsmet on May 20, 2014
Latest reply on May 21, 2014 by tomdsmet

    We have a design with the AD5422 operating in both current and voltage mode. Current and voltage terminals are not connected. Current mode is using external boost transistor.

 

The voltage mode perfectly matches the specification, whereas we experience issues with the current output: it behaves within specifications for a 500Ohm load, but when using 100ohm we get rather serious errors: (DC measurements)

mA

mA

mA

Set

Meas

Diff

% err

100 Ohm:

4

  1. 3.992

-0.008

-0.2

8

  1. 7.987

-0.013

-0.1625

10

  1. 9.979

-0.021

-0.21

14

  1. 13.918

-0.082

-0.58571

16

  1. 15.845

-0.155

-0.96875

18

  1. 17.755

-0.245

-1.36111

20

  1. 19.695

-0.305

-1.525

500 Ohm:

500

  1. 9.989

20

  1. 19.978

-0.022

-0.0011

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