DAC power supply Qs

tiroth · 1st May 2002, 10:19 PM

Consider a current DAC IC which is powered by a dedicated low noise regulator, e.g. LT1762 at 20uV RMS noise from 10-100kHz.

Q1:
Current draw is from 12mA to a max of 17mA, and an additional ~2.7V reference voltage is required for the virtual ground. My first thought is to use a string of LEDs to achieve the reference; any thoughts on this? It seems wasteful to have an IC voltage reference for this task, especially since LEDs are reputed to be "quiet". Only 1mA is required into the DAC.

Q2:
Would it make sense to use a bleeder resistor to help even out the current demands? I'm worried about adding noise to the PSU, but a bleeder resistor sounds like a good idea.

Thanks for any input!

Jocko Homo · 2nd May 2002, 02:01 AM

I use LEDs all the time. Cheap, quiet, and they let you know when you hook it up wrong.

Jocko

tiroth · 3rd May 2002, 03:59 PM

Thanks!

1st May 2002, 10:19 PM	#1
tiroth diyAudio Member Join Date: Dec 2001 Location: Pittsburgh, PA, USA	DAC power supply Qs Consider a current DAC IC which is powered by a dedicated low noise regulator, e.g. LT1762 at 20uV RMS noise from 10-100kHz. Q1: Current draw is from 12mA to a max of 17mA, and an additional ~2.7V reference voltage is required for the virtual ground. My first thought is to use a string of LEDs to achieve the reference; any thoughts on this? It seems wasteful to have an IC voltage reference for this task, especially since LEDs are reputed to be "quiet". Only 1mA is required into the DAC. Q2: Would it make sense to use a bleeder resistor to help even out the current demands? I'm worried about adding noise to the PSU, but a bleeder resistor sounds like a good idea. Thanks for any input!

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2nd May 2002, 02:01 AM	#2
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	I use LEDs all the time. Cheap, quiet, and they let you know when you hook it up wrong. Jocko

3rd May 2002, 03:59 PM	#3
tiroth diyAudio Member Join Date: Dec 2001 Location: Pittsburgh, PA, USA	Thanks!