Author Topic: Constant power load monitoring  (Read 143 times)

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Offline thephantom1492

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  • Country: ca
Constant power load monitoring
« on: July 17, 2021, 10:06:31 pm »
Hi there,

I need to monitor the power of a constant power load (smps based 9W light) over a wide range of voltage (8-16V) to detect a partially failed light.
I can not use a microcontroller because of reasons out of my control. I wish I could...

Currently, I found the analog multiplier circuit using opamp, but from what I understood it is unstable with varying temperature, so not great...

The other mean I found is to cheat and go with an "idealised" linear slope instead of the real current curve for the comparison, which give precision issue...

Is there another good way to do it cheaply and reliably with parts available at jlcpcb?

My requirement is:
- 9W load
- 8-16V input, noisy as heck
- detect at 80% of 9W
- handle 0-60°C
- trip time in 10ms
- output 12V when in fault

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