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LOAD-SWITCH-FET-LOSS-CALC: LOAD-SWITCH

Mykhaylo
Prodigy 20 points
Part Number: LOAD-SWITCH-FET-LOSS-CALC
Other Parts Discussed in Thread: CSD25480F3, CSD25483F4

Tool/software:

Hello

I need your help

I'm designing a pcb board and it needs to have the ability to switch between 2 devices.

General characteristics:
DC voltage
Power - 12v 0.5A
Power - 9V 0.66A
Power - 5v 1.2A
Total power normally works 6 watts

Control through a microcontroller

Logic
if input 0 - device 1 enable Power
device 2 disable Power

if input 1 - device 1 disable Power
device 2 enable Power

Is there anything similar IC in functionality from TI?

  • 0
    TI__Mastermind 33215 points

    Hello Mykhaylo,

    Thanks for the inquiry. I am the applications engineer for TI's FET product line. We only have discrete and power block MOSFET devices. We do not have a standalone FET that would work in your application without additional support. I am going to reassign this to the applications team for power switches. They may have products that will work in your application.

    Best Regards,

    John Wallace

    TI FET

  • 0 in reply to John Wallace1
    Prodigy 20 points
    John Wallace1 said:
    without additional support

    Hi John Wallace

    Thanks for the reply

    I have very little experience with different switches. Since this is a prototype, I'm interested in different options and would build a few pcb and test them. And what do you have?

    can i do support with mcu something like this?

    Logic

    1 0 - device 1

    0 1 - device 2

  • +1 in reply to Mykhaylo
    TI__Mastermind 33215 points

    HI Mykaylo,

    For a discrete implementation, you can use P-channel FETs which are simpler to drive than N-channel FETs. Connect the source of each FET to the input voltage and the drain to the individual loads. A PFET is turned on by pulling the gate to GND and turned off by pulling the gate up to the source. You should be able to drive the gates of the P-channel FETs directly from the MCU using an open collector output pulled up to the input voltage. I'd recommend either the CSD25480F3, -20V PFET in F3 FemtoFET package or the CSD25480F3, -20V PFET in F4 (smaller) FemtoFET package. Please let me know if you have any questions.

    Thanks,

    John

  • 0 in reply to John Wallace1
    Prodigy 20 points

    I started prototyping the PCB and noticed that it was a very small FET(CSD25480F3). will it work normally if the voltage is 12V and the current is 0.5A?

  • 0 in reply to Mykhaylo
    TI__Mastermind 33215 points

    Hi Mykhaylo,

    FemtoFETs are small, chip scale FETs with solderable LGA (land grid array) pads. Both of the recommended FETs have -20V BVDSS and will work with 12V input. Max power dissipation for these LGA devices is about 0.5W. Estimated conduction loss with 1.2A current is 335mW for the CSD25483F4 and 214mW for the CSD25480F3 due to lower on resistance. This is within the capabilities of the packages. Please make sure to follow TI PCB footprint and stencil recommendations to ensure successful assembly onto your PCB. Below is a link to the SMT guidelines for TI FemtoFETs.

    https://www.ti.com/lit/pdf/slra003

    Thanks,

    John