Other Parts Discussed in Thread: LMZ31530
Hallo,experts,
In the LMZ31520 data sheet page 4 note (3), it is recommended to use a very low-leakage transistor to drive the INH pin (I<300nA).
Is it possible to relax the above leak current recommendation when the VIN voltage is high(12V , 5V,etc)?
I see functional block diagram on page 8 of the LMZ31530 data sheet.
The INH pin of the LMZ31530 is internally set by a resistor bridge between VIN (10KOhms pull-up) and GND (6.65KOhms Pull-down).
I think, the hi-level of INH pin is dependent of VIN value.
For example, if VIN=12V, the INH level will be 4.79V.
If VIN=5V, the INH level will be 2.00V.
If VIN=4.5V, the INH level will be 1.80V.
Even if the IHB pin is driven with a transistor leakage current of 10 μA, the voltage drop at the IHB terminal is 0.1 V (= 10 KOhms pull-up x 10 μA).
The voltage of the IHB pin considering the leakage current of 10 μA of the transistor is as follows.
If VIN=12V, the INH level will be 4.69V.
If VIN=5V, the INH level will be 1.90V.
If VIN=4.5V, the INH level will be 1.70V.
On the other hand,the high level threshold for INH pins is 1.8V.
When VIN is 12V or 5V, it exceeds the high level threshold of INH pin, so I think there is no problem.
Is it possible to relax the above leak current recommendation when the VIN voltage is high(12V , 5V,etc)?
Best regards
ATSU
