Thanks for the link on the TI document. I agree that in this particular circumstance it is probably not a latchup condition.
In one specific case I came across recently I never dug deep enough to check if it was a proper latchup or not but it certainly looked like it as it pulled the 5V line low. The case was with a TI PCF8574 which was hooked up to the same 5V line as a PIC processor, the PIC processor started to communicate with the PCF8574 on the I2C bus at some 1.8V and then the TI PCF8574 went bonkers, pulling the 5V line to some 2.5V. If I replaced the TI part with an NXP PCF8574 everything was just fine (the design had used the NXP parts for many years without a problem but as soon as the TI parts were used the problem started to pop up intermittently). It was also fine if I let the processor wait until the voltage had reached some 4.85V with a POR ic. I didn't dig further into problem after I added the POR ic to the circuit. Instead of using the TI PCF8574s I made SOIC to DIP adapters and continued to use the NXP PCF8574, but I still use the POR ic as a precaution if NXP change their design in the future and also as a good measure. /Martin -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/2e45e2ec-9750-4187-8ecf-f680c5be82ff%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
