LMG2100R044: LMG2100R044 as high side current switch

Part Number: LMG2100R044
Other Parts Discussed in Thread: LMG2100R026, , LMG3100R044, LMG3100R017

Tool/software:

Hello,

I am trying to use the LMG2100R044/LMG2100R026 as a high side current switch for a high power load. I attached a picture of my design so far.

The LMG2100R044/LMG2100R026 must be positioned between the VIN (28V to 50V) and the load (so high side usage is forced upon me). Expected current is up to 15A.

The purple nets indicate high current conductors and the load is not shown (but it is connected to the SW pin and from there to the board GND).

The idea is to always keep the low side switch open so the AGND/PGND can never be shorted to the VIN.

My questions:

1. I am not sure that the whole design is either correct or optimal (for example: because I can't use the PGND pads which are the main way to conduct heat outside of the IC and the low side superior Rds). It feels that I am trying to use the wrong IC as a current switch.

2. I have no idea what I should connect to the the HB pin, or if I should leave it floating...

Can you help me with this?

Thanks,

Roy

  • Hey Roy,

    The LMG3100R017 or LMG3100R044 may be better for the high side switch application. These are single GaN FETs rather than the half bridges (LMG2100R044/R026). 

    For both LMG3100 or the LMG2100, you'll need an isolated bias supply to supply the high side switch with Vcc voltage. This voltage will be (+5V) with reference to the source of the high side switch.

    If you use the LMG2100, the HB & HS pins will be where you connect the isolated bias supply to. For the LMG2100, you'll just use the Vcc and agnd pins. 

    Best,

    Kyle Wolf

  • Thank you very much!