TS5A459x leakage current is higher than expected

Douglas Turnbow

Other Parts Discussed in Thread: TS5A4594, TS5A4595

I have a pullup resistor between the NO pin on a TS5A4594 and the IN pin on a TS5A4595.

The in pin on the TS5A4594 is low (disabled)

The voltage drop across the resistor indicates that there is about 2uA of leakage between the two pins on the TS5A459x parts.

I would expect something more like 0.01uA (0.5uA max) based on the datasheets.

Are these parts out of spec or am I missing something?

See attached schematic segment.

U214 is disabled (pin 4 is 0V) so pin "Z" should be high impedance. The datasheet would make me expect 0.5nA max at 25C for IL1.

U213 enable pin leakage (IL2) should be 0.5uA (microamps) max (0.01uA typ) if I look at the +5V section of the datasheet, 0.5nA (nanoamps) if I look at the +3V section of the datasheet.

It looks like between these two nodes they are drawing more than 2uA (4.07-1.98)/1M = 2.09uA

TS5A459xLeakage.pdf

over 8 years ago

0 ShreyasRao over 8 years ago

TI__Guru 58110 points

Hi Douglas ,

I will move this post into the switches forum for now and will take a look soon.

0 Douglas Turnbow over 8 years ago in reply to ShreyasRao

Prodigy 150 points

I've bought a few T55A4594 and TS5A4595 parts to test them outside of my circuit.
I've duplicated the problem both on the T55A4594 part and the TS5A4595 part independent of each other.
This is looking more like a component problem.
Is this the right forum to address this kind of issue?

0 Douglas Turnbow over 8 years ago in reply to Douglas Turnbow

Prodigy 150 points

Wait. I think the problem is that my oscilloscope probe is the 1Mohm type.
I think this is what is causing the problem.

0 ShreyasRao over 8 years ago in reply to Douglas Turnbow

TI__Guru 58110 points

Hi Douglas ,

I would expect 4V at the hi-Z line through the pullup resistor.
The input leakage for the 5V section doesn't seem right at 0.5uA , instead needs to be 0.5nA like the 3V section . will have to update the datasheet . Please let me know changing the probe to 50ohm would help.

0 Douglas Turnbow over 8 years ago in reply to ShreyasRao

Prodigy 150 points

Changing the oscilloscope probe from 1M to 10M helped.
Eliminating the scope and measuring the current directly with a multimeter was best.
I also used an external current-to-voltage converter to measure the current.

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TS5A459x leakage current is higher than expected