Author Topic: Why reference control voltage to ground for waveform generator?  (Read 527 times)

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Offline Mp3Topic starter

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Why reference control voltage to ground for waveform generator?
« on: October 13, 2019, 07:21:24 pm »
I am  reading about the ICL8038 waveform generator. The data sheet says you can reference control voltage to +V. Howver it apparently can accept +V, ground or -V.  Is this a quirk of the 8038 specifically?
« Last Edit: October 14, 2019, 11:58:33 pm by Mp3 »
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Offline Kleinstein

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Re: Why reference control voltage to ground for waveform generator?
« Reply #1 on: October 14, 2019, 10:54:09 am »
AFAIR the ICL8038 and similar chips use a current source to set the frequency. This current source seem to start at the positive supply. So the control voltage to set the current is (not optional as in can) relative to the positive supply. If the external circuit want's it relative to GND the choose to have V+ at ground and use a negative supply for the chip.

Other oscillators can have different controls. The XR2206 has the control relative to the negative supply (= GND).
 
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