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12Vin to 24Vout (<1W) DCDC modules do not exist with Vout accuracy better then +/-5% ?

We are using 10 ADG1438 multiplexors and feeding them 24V to VDD and -5V to VSS.
Abs Max for VDD is 25V.


The total current draw will be <10mA for all ten of them.
Our power source is 12V…..As such, we are trying to find a 12Vin to 24Vout, <1W DCDC module.

However, every single one I find on the web has a poor load regulation of 10%. This means it could blow up our ADG1438’s.

As such , we are wondering if we are going to need a discrete MC33063A based boost converter. The software engineers prefer a simple DCDC module but it looks like I must tell them that no suitable DCDC modules exist?

ADG1438 datasheet
https://www.analog.com/media/en/technical-documentation/data-sheets/ADG1438_1439.pdf

MC33063A datasheet
https://www.ti.com/lit/ds/symlink/m...https%3A%2F%2Fwww.ti.com%2Fproduct%2FMC33063A
 

crutschow

Well-Known Member
Most Helpful Member
For good reliability I would operate a device at no more than 90% of its Max rating.
Do you have a 24V signal going to the mux?
 

ronsimpson

Well-Known Member
Most Helpful Member
I just looked up TI's MC33063A which has a 2% voltage reference. This is a very old part. I think newer parts are better.
From data sheet. Line regulation = 0.12% Load regulation (10% to 100%) = 0.09%
It is true some parts do not do well on load regulation at zero current. You might need to add a resistor on the output to give it some minimum load.

Multiplexors are not good if there is high frequency noise on the power supply. You might want to add a LC filter on the 24 volt line to clean it up.
 

ChrisP58

Well-Known Member
One way of handling poor regulation from your primary supply is to set it's output a couple of volts high. Then follow it with a low dropout linear regulator.

The LDO post regulator will also give you good noise filtering.
 
Do you have a 24V signal going to the mux?
Thanks, i believe we will be able to keep it below 24V......just

Multiplexors are not good if there is high frequency noise on the power supply. You might want to add a LC filter on the 24 volt line to clean it up.
We have about 5uF of capacitance on the 24V output...but its on virtually no load, so i believe there will be little high frequency ripple voltage on the Vout, if thats what you were referring to.
PQDE6W-Q110-S24
...thanks, but this one cant do our 12vin.
 

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