LabVIEW
24V TO 5 V conversion
@Jason93 wrote:
I know this is a 5 year old topic but would a DC to DC converter work?
I can make the voltage divider easily but after that my circuits knowledges falls apart.
Jason
In one system, we needed to trigger a 9401 module using a 24 V signal. Our engineering team provided me with a "converter," specifically a Wago DC-DC converter 24V to 5V. The goal was to trigger the 9401 with low jitter — meaning the delay from the rising edge of the 24 V signal (coming from an ultrasound sensor) to the 5 V TTL trigger should be no more than 500 µs.
The DC-DC converter's datasheet mentioned something like "20 kHz," and the engineer claimed it was fully suitable and in theory fast enough from a timing point of view. For practical testing, I used a 24 V output from a cRIO module (NI-9472, I believe), generated a 24V pulse train of a few kHz, and tried to capture the input train on the 9401 after the converter. I counted the pulses to check for missed edges and to measure jitter (the cRIO used had a 40 MHz FPGA onboard).
The naive experiment didn’t last long. When the 9472 module started (and then finished) smoking, I opened the DC-DC converter and finally understood what "20 kHz" meant: it was the internal switching frequency of the converter. What a shame for someone with an M.Sc. in Physics!
My pulse train had created a huge resonance with the converter’s internal oscillator, resulting in a high back-voltage that propagated to the 9472. This caused physical damage to the module, and ~200 Euros went straight into the trash bin.
Luckily, both the cRIO and the 9401 survived this "noob" experiment.
Lesson learned:
@Andrey_Dmitriev wrote:Lesson learned:
Sounds like your real problem was it was a switching power supply. If it was a linear regulator, you may have been fine. But that is a large voltage drop for a regulator to handle.
With that said, I would likely use a voltage divider and an op-amp in a voltage follower for this application.
