MAX11300 DAC output is not linear near 10 Volts output - Page 1
Forum section: electronics / projects

author: AndersJ
author_rank: Frequent Contributor
timestamp: April 20, 2016, 07:03:54 pm
content: The Maxim chip MAX11300 0-10V DAC output seems to be non linear near the end of the range.The output clamps at around 9.930 to 9.950 Volts out, depending on the individual chips.Maxim says they have not had any issues with the DAC output at 10V.This happens on my own PCB, and on the Maxim demo board as well.Has anyone seen this?

author: dmills
author_rank: Super Contributor
timestamp: April 20, 2016, 07:41:42 pm
content: What is your supply voltage and what is the load on the DAC output?

author: Kalvin
author_rank: Super Contributor
timestamp: April 20, 2016, 07:54:37 pm
content: From the datasheethttps://datasheets.maximintegrated.com/en/ds/MAX11300.pdfpage 6 "DAC Electrical Specifications":The integral linearity error is specified for the digital codes 100 ... 3996 to be around +/- 1.0 ... +/- 1.5 bits when the VAVDDIO = +12.0V and VAVSSIO = -2.0.I guess that the linearity error can be whatever if the digital code is less than 100 or more than 3996, and the behaviour you are seeing is within the specifications.Increasing the VAVDDIO from +12.0V to +12.5V and decreasing the VAVSSIO from -2.0V to -2.5V might reduce the linearity error you are seeing, but it would be only a nice bonus and not guaranteed by the datasheet specifications.

author: AndersJ
author_rank: Frequent Contributor
timestamp: April 20, 2016, 08:25:51 pm
content: The power supplies are -2.5 and +12 volts.The output is not loaded.Thanks for the (to me) new perspective.I had not realized that the first and last 100 codes are non documented.It seems those low and high ranges are not mentioned anywhere.I think I could live with reduced linearity near 10,but I don't like that the output clamps about 50 mV below 10.Isn't that why the supply voltage is 12, to allow full swing, up to 10 volts?

author: AndersJ
author_rank: Frequent Contributor
timestamp: May 30, 2016, 06:54:01 pm
content: When I mentioned that their own demo board has the same problemMaxim finally admitted that they do have a problem reaching 10 Volts on the DAC output.If they had said that from day one, I would have saved a lot of time.My message to Maxim, and everyone else:If there is a problem with your product,admit it immediately and do not waist your customers timeand risc your own reputation by trying to hide the problem.

author: JPortici
author_rank: Super Contributor
timestamp: May 30, 2016, 09:08:09 pm
content: Well.. maxim is notorious for strange business practises (like releasing datasheets for many many parts that are too good to be true -on paper-... and you can never get your hand on them because in fact they only exist on paper. or you CAN get a batch of a component but it is discontinued in the moment you need a second batch.)more seasoned engineers will surely have some stories to tell

author: AndersJ
author_rank: Frequent Contributor
timestamp: November 16, 2016, 07:01:56 pm
content: Found another issue.There is a 10-20 mV 1.25 KHz square wave riding on top of the DAC output.Has anyone seen this?