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TPS2640: SHD pin and IMON pin operation

Bruno Simard67
Prodigy 240 points
Part Number: TPS2640


Hi, I do have a couple of question with the e-switch TPS26400:

1- Does the SHDN signal when driven can operated with respect to the RTN pin? and or with GND pin

2- Not clear for me what is the difference voltage between the GND pin and the RTN pin when IC operated normally (so not under reverse bias situation)

3- I do see a series resistor of 100Kohms between IMON and TP_IMON (TP5) on the EVM schematic (Figure 3-1) . Can you tell me more about the utility of this resistor please?

4- Finally, what could be the highest resistor suitable between pin IMON and RTN for the current monitoring? Does a 200K can be used in order to get a reliable/repeatable current monitoring value?

Thank you!

Regards

Bruno

  • +1
    TI__Guru* 79181 points

    Hi Bruno,

    1. If you need reverse polarity protection you don't need to connect externally SHDN and GND pin. Your SHNDN signal will be coming from some microcontroller which will refer to system GND which will be shorted to our device GND pin. So logically you will be driving with respect to GND pin. I will recommend connecting resistor in series from driving pin to SHDN pin. 

    2. Normal operation these pin will have negligible voltage difference.

    For 3 and 4 please have a look at this:

    Regards

    Kunal Goel