Hi there,
I'm new to these forums, so I hope I'm posting in the right section. First off, this question is regarding datasheet information only at this point--no testing has been done to confirm/discount the Electrical Characteristics I'll refer to.
As mentioned in the title, I'm trying to understand the source of higher-than-expected supply current specs for two different TI digital ICs (I'm looking at the DIP versions of both if that's relevant). The first is the SN74AHC595, an 8-bit shift register. where the Icc spec is listed as 4uA max at room temperature (and up to 40uA max at wider temp ranges). Note that these numbers do specify the Icc when Vi is either Vcc or GND. Similarly, the SN74HC132--a quad 2-input NAND package--lists an Icc max of 20uA.
In any case, supply currents in the ranges of uAs to 10s of uAs for any of these digital ICs seems high to me. I'd greatly appreciate any insight as to what the main components of this current draw are. Initially my colleagues and I were wondering if the ESD protection circuits could be causing extra current draw, but the likelihood of reverse-biased diodes drawing that much current seems low. Additionally, a TI employee my colleague reached out to confirmed that the diode leakage should be in the pA range.
Thank you in advance!
