CSD87503Q3E: Do Mosfets have ON (and Linear Region) Leakage

Peter Baxter

Intellectual 390 points

Part Number: CSD87503Q3E

Tool/software:

Hi John Wallace,

A general MOSFET question please.

MOSFETs leak when OFF - predominantly due to the body diode.

But do MOSFETS also add leakage - when they are turned on?

Naturally when ON, there is RDs(on) of say 100 milli-ohm. At the low currenst I am discussing, there will be very little voltage drop between Drain and Source. This might prevent/reduce leakage. But then, there might be leakage regardless.

My application is using MOSFETS as switches. Two common Source N-ch MOSFETS create a bipolar switch (the standard method). Think of the application as a current measure or current source/sink. I am using the MOSFETS to switch in the SENSE resistors (1R-1A, 10R-100mA, 100R-10mA, 1k-1mA, 10k-100uA, 100k-10uA, 1M-1uA and 10M-100nA).

Simulations of a method to handle the OFF leaked look promising. So its just knowing whether there is ON leakage?

Thanks

Peter Baxter

3 months ago

0 John Wallace1 3 months ago

TI__Mastermind 38330 points

Hello Peter,

Thanks for the inquiry. When the FET is on, there should be no leakage from drain-to-source. Applying a voltage at the drain will cause current to flow in the channel. However, I think the gate-to-source leakage current will add to the source current and may cause a small amount of error. TI only does the leakage measurements as specified in the datasheet and we don't do have any leakage data with the FET on. I hope this helps. Let me know if I can be of further assistance.

Best Regards,

John Wallace

TI FET Applications

0 Peter Baxter 3 months ago in reply to John Wallace1

Intellectual 390 points

Thanks for that information.

I'll consider Analog switches (DG412) for the low ranges - rather than discrete MOSFET switching.

My maximum switched current is 2 amps. Is there a series of TI MOSFETS you'd suggest that consider for this Analog Switch type application?

Regards,

Peter Baxter

+1 John Wallace1 3 months ago in reply to Peter Baxter

TI__Mastermind 38330 points

Hi Peter,

There are a number of FETs that can work. Are you looking for a single FET or a dual common source device like the CSD87503Q3E? TI has some other dual common source devices as well as dual common drain and dual independent FETs. The link below is a sorted table of dual common source and dual common drain FETs. For single FETs, our FemtoFET products are small, high performance FETs. You can find them on the MOSFET landing page.

https://www.ti.com/power-management/mosfets/products.html#267=12%3B30&1143=Dual%20Common%20Source%3BDual%20Common%20Drain%3BDual&1241=N-channel&

https://www.ti.com/power-management/mosfets/overview.html

Thanks,

John

Power management

Power management forum

CSD87503Q3E: Do Mosfets have ON (and Linear Region) Leakage