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PSoC 4 MCU

JS_4155161
New Contributor
‎Jul 01, 2020 01:52 PM

Why can 7-bit IDAC not reach full scale.

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I have a 7-bit IDAC configured as a source and driving a 10k resistor. The full-scale value should be 127*2.4uA*10k=3.047V. However, it barely generates more than 2V when its value is set to 127. What is the reason for this?

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odissey1
Honored Contributor II
‎Jul 01, 2020 04:07 PM

Re: Why can 7-bit IDAC not reach full scale.

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The IDAC architecture is a current mirror. It needs a headspace approx 0.6-0.7V  from top rail to operate.

/odissey1

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2 Replies
odissey1
Honored Contributor II
‎Jul 01, 2020 04:07 PM

Re: Why can 7-bit IDAC not reach full scale.

Jump to solution

The IDAC architecture is a current mirror. It needs a headspace approx 0.6-0.7V  from top rail to operate.

/odissey1

View solution in original post

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JS_4155161
New Contributor
‎Jul 02, 2020 11:16 AM
In response to odissey1

Re: Why can 7-bit IDAC not reach full scale.

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Great. I found that there is a quantity called compliance voltage in the datasheet, which is basically the headroom required for the idac to operate

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