Hi,
I’m evaluating the partial power-down currents specified in the TI datasheet for an SN74AVCH4T245. My test results don’t correlate with my literal interpretation of the datasheet.
The partial power-down leakage current is specified as -2uA maximum. In evaluating the current of the powered-down supply with VI at VCC and VI at GND for the power-down supply across the industrial temp range (the 4 corners - if you will), there is only one of the 4 conditions where I observe values below the -2uA limit. For all other conditions the current is “negligible” which fails the -2uA maximum limit.
I would like to know if my observations are correct. If they are correct, a brief physical explanation of the reason would be appreciated. If they are incorrect a detailed description of the test setup conditions would be appreciated:
Observations
VCCA powered-down (0V), VCCB at 3.6V (results are the same with VCCB powered-down and VCCA at 3.6V). Voltages on DIR and OE appear to be don’t care:
-40C: ICCA with A inputs at 3.6V is in the -85nA range (fails -2uA max)
-40C: ICCA with A inputs at GND is in the -75nA range (fails -2uA max)
85C: ICCA with A inputs at 3.6V is in the -4uA range (passes -2uA max)
85C: ICCA with A inputs at GND is in the -80nA range (fails -2uA max)
(Room temps are ~-150nA at 3.6V and ~-70nA at GND)
Thanks,
Mike