# VCTCXO Trim DAC

**URL:** <https://discourse.myriadrf.org/t/vctcxo-trim-dac/3482>\
**Category:** LimeSDR\
**Created:** [12 October 2018 14:30 UTC](https://discourse.myriadrf.org/t/vctcxo-trim-dac/3482 "2018-10-12T14:30:09Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![mc955](https://avatars.discourse-cdn.com/v4/letter/m/f08c70/32.png) [@mc955](https://discourse.myriadrf.org/u/mc955)\
**Post date:** [12 October 2018 14:30 UTC](https://discourse.myriadrf.org/t/vctcxo-trim-dac/3482/1 "2018-10-12T14:30:09Z")

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I have been trying to trim the VCTCXO on a LimeSDR-Mini by adjusting the DAC voltage, however I have found that the adjustment step is a bit too coarse. Changing the output by one causes the VCTCXO output to shift by 5Hz or so at 30.72MHz.

I was wondering if I was to swap out the DAC for the [DAC7311](http://www.ti.com/lit/ds/symlink/dac5311.pdf), which is the 12-bit version of the existing 8-bit DAC, would that work with LimeSuite?

The datasheet for the DAC says that they are pin and function compatible and the LMS API takes a uint16\_t as the DAC value, so I feel like this should work, I’m just worried that somewhere under the hood only the 8 LSBs are being sent to the DAC, and I can’t find where it is happening in the source.

Thanks.