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https://www.digikey.ca/en/products/detail/koa-speer-electronics-inc/PSL2NTEBL500F/1039674
Block Diagram
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Implementation Ideas
“High” voltage & current passthrough should be done with an XT90 connector.
Current measuring can be implemented with a smaller current transformer to be mounted on the PCB
A simple ADC integrated (presumably 2 channel ADC) and possibly voltage divider circuit can be used to measure both current and voltage
This ADC should support I2C and SPI and may be fitted with a signal buffer IC
Fairly standard to be able to find an ADC that can operate at 3.3V
A single “low voltage connector” should be used
This would be some relatively fine pitch connector
Some standard molex thing
Four conductors on this connector
GND (this will be signal ground, but should be presumed as the same potential and non-isolated from the “high voltage passthrough gnd”
5V or 12 V input power (possibly a range that supports each of these and maybe more)
I2C or UART data lines (2 conductors for each of these protocols.
Alternatively, use the 12V and 5V stepped down from the input line to power all board ICs instead of plugging in external power
Powering the ADC
The ADC and buffer (if a buffer is included, just an idea) will ideally consume very miniscule current, on the order of less than 200mA which makes a simple LDO (low dropout regulator) viable
This LDO will take the low voltage input power and use that to power the ADC chip.
LDO has lower efficiency than a buck, but will save board space and will be more convenient to implment.
Because of the negligible total power requirements for the board a low efficiency doesnt matter as much
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