The question is essentially a continuation of this old thread :
I am using the attached circuit to driver 6 relays with a ULN2003 driven by a PCF8574.
The problem is that, at power on, the relays a left in a random state, most times they momentarily switch ON and then OFF.
The problem of random initial state could be solved with pull-up resistors at the output of the PCF8574. However, in this case, the initial state is always ON (till software switches output to OFF) while the requirement is for the initial state to be OFF.
On the other hand using pull-down resistors at the output of PCF8574 instead, is not an option since the PCF8574 would then be unable to drive the outputs high due its the low driving current capabilities.
Replacing the ULN2003 with an PNP darligton array equivalent would be a solution, (they stay OFF till the base is driven low). Is there a PNP equivalent of ULN2003?
Any other ideas would be mostly welcome!
Thanks for your support.