I have reviewed both the datasheet for the TPS26600 and the App Report SLVA934A on how to handle the FLTn and IMON outputs during input reverse polarity. But I don't think things are clear concerning the final note on the SLVA934A report, where it says
"The proposed fix either with a blocking diode or with a current limiting resistor is not required
for devices with date code value ≥ 2013. It is only required for devices with date code value
< 2013.
Date code of the device can be found on packaging label of the device."
The date code (I think) on my parts is 37TG4 where the G4 is smaller and underlined. From my reading of date code decoding, this is 2023, 7th month, and lot code T or TG4. This is a very recent part.
I have FLTn pulled up to 3.3V with a 100k. It currently feeds nowhere from there, but when my design is complete it will feed a GPIO of a microcontroller. I do not have the recommended 100k series resistor.
I have the IMON signal tied to RTN through a 21.5k resistor. And the output from there is feeding to an ADC input of a microcontroller. I do not have the recommended 100k series resistor.
As specified in the datasheet, I do not have the RTN net tied anywhere to the system ground. It is its own connected island.
If I apply -12V to the input, I see -0.8V on the IMON net, and 8mA flowing from the external power supply. If I apply -15V to the input, I see -0.88V and 19mA flowing from the external power supply. I'm nervous to test higher negative voltages at risk of ruining something; my design needs to survive -34V when done. From the statement in the App Note, I would not have expected to need the recommended series resistors.
What am I missing or misunderstanding?
