Hysteresis with AD594/595

Thread Starter

DC_Kid

Joined Feb 25, 2008
794
quick question about setting hysteresis on the ad594. in the datasheet (http://www.analog.com/static/imported-files/data_sheets/AD594_595.pdf) they show a resistor from Vout to pin 3. i understand its 200nA per degree C, but in their setpoint controller uses basis comparator to bring Vout high if the setpoint is exceeded. so i have a couple of questions:

1. how does hysteresis work if the injection current is only present when Vout goes high?
2. how to determine resistor value for a specific hysteresis? would it not be better to use a voltage ref IC and resistor to feed the hysteresis injection pin?
 

Thread Starter

DC_Kid

Joined Feb 25, 2008
794
nevermind. i see that hysteresis is amp feedback + setpoint voltage on the amp input. and i found hysteresis formula from ad597 datasheet.
 
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