Best Way to Switch Modules

Daniel Luis Martins

Other Parts Discussed in Thread: LM34904, TPS22912C, TPS22929D

Good day gentlemen,

I have a question regarding the switching of the power supply of some modules, such as RFID, BLE, WIFI modules.

I do not use any MOSFET circuit because I think this type of module requires special attention.

Most of the time, the modules have a 3V3 power supply. So, through an LDO with Enable, and from a 5V power supply, I can turn the modules on / off.

However, my question is when we also have a module powered at 5V, my main source is also 5V. What is the best way to do this?

Through an LDO too? Even with some loss? Or maybe through an analog key?

We can consider a current around 300mA for powering these modules.

Thank you for your attention,

Kind regards,

Daniel Martins

over 8 years ago

0 LeonardEllis over 8 years ago

TI__Guru 71526 points

Hi Daniel,

Thanks for the inquiry here on E2E. Not seeing your specific details or block diagram, I'll start out with some suggestions and we can refine the design from here.

First, for the 5V switch, please look at the LM34904: http://www.ti.com/product/lm34904 . Very low-loss, very small package and can handle 500mA.

Next, we have a series of LDOs that are specifically designed for RF applications. For a 5VIN > 3.3VOUT, two possible solutions are the TPS7A4700: http://www.ti.com/product/tps7a47 and the TPS79501: http://www.ti.com/product/tps795 . I have attached Webench designs for these.

INEL_TPS79501_5V-3.3V0.3A.pdf

INEL_TPS7A4700_5V-3.3V0.3A.pdf

Please review and let me know how these would fit into your design. I'm wondering if you have a block diagram, and have selected the RF, as well as other system, ICs? I'd be happy to review this with you.

~Leonard

INEL_TPS79501_5V-3.3V0.3A.pdf

INEL_TPS7A4700_5V-3.3V0.3A.pdf

0 Daniel Luis Martins over 8 years ago in reply to LeonardEllis

Prodigy 230 points

Hi Leonard,

Thank you for your feedback.

As for the LDOs for 3V3, I already use a lot, without problems.

My problem is when I have 5V at the input and I need 5V at the output.

This key that sent me seems to be pretty cool, but does it have some other encapsulation, or some other PN?

Kind regards,

0 Ed Walker over 8 years ago in reply to Daniel Luis Martins

Prodigy 5 points

Hello Daniel,

LM34904 mentioned earlier
www.ti.com/.../LM34904 - 5.3V, 500mA, 360mΩ, Current Limited Power Switch ,
BGA package

The TPS22912C is another great load switch for your need.
www.ti.com/.../TPS22912C
5.5V, 2A, 61mΩ Load Switch With Reverse Current Protection

Its in a BGA package if you can work with that.
Other packages are;

www.ti.com/.../TPS22929D - 5.5V, 1.8A, 115mΩ Load Switch with Quick Output Discharge and Reverse Current Protection
SOT23 package

www.ti.com/.../TPS22953 - 5.7V, 5A, 14mΩ Load Switch with Voltage Monitoring and Reverse Current Protection
WSON package

Would one of these work for you?

0 Daniel Luis Martins over 8 years ago in reply to Ed Walker

Prodigy 230 points

Hi Ed,

Thanks a lot for your reply, and Leonard too.

In fact I did not know this type of component.

I use many IT components, but I always find something new.

I already added the PN TPS22929D in my schematic and I will use a lot.

Thanks a lot guys,

Kind regards,

0 LeonardEllis over 8 years ago in reply to Daniel Luis Martins

TI__Guru 71526 points

You are very welcome Daniel.

And I'm curious, what are the LDOs you are using in this design? And the radios?

~Leonard

Power management

Power management forum

Best Way to Switch Modules