Choosing a Mosfet

Other Hardware General Electronics
1

Hi,

For a project, i will be requiring a P-channel MOSFET to switch a 500mA load. The power source is a
3.7V Lipo battery.

Which one of the following is the most suitable for this application? I am looking for a low power setup.

CSD22202W15:
VDS = -8V
RDS = 14.5mO (VGS = -2.5V)
RDS = 10.2mO (VGS = -4.5V)
VGS = -0.8V
ID (continuous) = -10A

CSD23381F4:
VDS = -12V
RDS = 250mO (VGS = -2.5V)
RDS = 150mO (VGS = -4.5V)
VGS = -0.95V
ID (continuous) = -2.3A

CSD25211W1015:
VDS = -20V
RDS = 36mO (VGS = -2.5V)
RDS = 27mO (VGS = -4.5V)
VGS = -0.8V
ID (continuous) = -3.2A

CSD25402Q3A:
VDS = -20V
RDS = 13.3mO (VGS = -2.5V)
RDS = 7.7mO (VGS = -4.5V)
VGS = -0.9V
ID (continuous) = -15A

Thanks for any guidance

2

Avoid the 0.25 ohm one (CSD23381F4), any of the others will be fine from what I can see.

The threshold voltages and current specs are irrelevant,
go by the Rds(on) specs - both for gate-source voltage
supported and on-resistance. Calculate the voltage drop
and power dissipation (IR, I^2 R) and check they are OK.

The threshold voltages catch a lot of people out, they are
not the voltage for the device being on, but for it being off

Current figures usually are thermal limits anyway, which
you calculate from Rds(on) anyway.

You might want to avoid the 8V one just as its the lowest
Vds spec of the bunch - just in case there are spikes around.

3

Thanks a lot for your detailed response

4

I decided to go with the CSD25211W1015 mosfet http://www.ti.com/lit/ds/symlink/csd25211w1015.pdf

I based my circuit design from previous posts on here. It is attached.

Do i need to make any changes to the circuit? The load is about 500mA.

Thank you

load.png

5

So long as the gate drive goes up to 3.7V or more to switch it
fully off should be fine. ie Arduino can be powered from the LiPo
or from 5V.

6

So long as the gate drive goes up to 3.7V or more to switch it
fully off should be fine. ie Arduino can be powered from the LiPo
or from 5V.

I am making a standalone Arduino circuit using just the chip. Everything in this circuit is powered by the 3.7V lipo battery.

Is this a problem with the Mosfet?

Thanks