Current Sink and Source DACs - Page 1
Forum section: electronics / projects

author: luky315
author_rank: Regular Contributor
timestamp: January 09, 2024, 12:50:30 pm
content: I am using the Cypress PSoC 8-Bit Current Digital to Analog Converter (IDAC8) component for trimming analog circuits and it is working very well. For those not familiar with them: The PSoC Microcontroller uses this (configurable) component to sink AND source a current from 0 to 2mA with 8Bit resolution. They are really great and it is not necessary to know the voltage on the injection node to manipulate the voltage there as long as the impedance is known. So now to my problem: The PSoCs have only 2 or a maximum of 4 IDACs and for a project I need a lot of them, at least 16. So using 8 or 4 PSoCs in parallel and syncronizing them just for the DACs is not really an option, but I haven't found any discrete DACs with similar capabilities (current sink and source). Have I overlooked something? 1V to 4V usable output range (so 5V supply) would be also great, but that can be scaled.

author: David Hess
author_rank: Super Contributor
timestamp: January 09, 2024, 02:58:35 pm
content: There are lots ofcurrent output DACs. And many even operate on a 5 volt supply:https://www.analog.com/en/products/ad7568.htmlhttps://www.analog.com/en/products/ltc2755.html

author: jbb
author_rank: Super Contributor
timestamp: January 09, 2024, 07:46:06 pm
content: A bit out of a lateral move: could a multi-channel LED driver be creatively used? Some of them have current DACs inside.

author: luky315
author_rank: Regular Contributor
timestamp: January 09, 2024, 07:49:39 pm
content: The problem is that i need a DAC capable of sinking AND sourcing current

author: jbb
author_rank: Super Contributor
timestamp: January 09, 2024, 09:03:36 pm
content: Fair.DAC53204 from Texas Instruments supports 5V supplies, has 4 analog outputs (current or voltage) plus internal Non Volatile Memory to store settings. Can apparently be programmed @ manufacture and then operate standalone (no microcontroller).TI have a few more variations on the theme too. Not sure about cost or availability…https://www.ti.com/product/DAC53204

author: PCB.Wiz
author_rank: Super Contributor
timestamp: January 10, 2024, 02:18:47 am
content: Quote from: jbb on January 09, 2024, 09:03:36 pmThat page mentions price, 1ku : $1.710 WQFN16. For a 10 bit DAC. The 12b DAC63204RTER is 1ku : $1.980An alternative is to use a low-cost Quad DAC with a free MCU, like EFM8BB3 - circa 80c/3k, for 4 x 12b V-DAC ( + ADC) and you then add resistors/opamps for analog massage.

author: David Hess
author_rank: Super Contributor
timestamp: January 10, 2024, 02:52:08 am
content: Quote from: luky315 on January 09, 2024, 07:49:39 pmIs that all?Use the DAC's reference to drive another fixed current current source or sink connected in parallel with the DAC's output. Now the output becomes a current with a bipolar output range.

author: luky315
author_rank: Regular Contributor
timestamp: January 10, 2024, 09:05:36 am
content: @jbb Thanks, the DACx3204 (DAC43204 should be good enough) looks great, they can sink and source, I wonder why this is not advertised more clearly...