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LTC7001 high side MOSFET driver thermal losses

LTC7001 high side MOSFET driver thermal losses

(OP)
Can anyone help me figure out how to go about calculating the thermal losses of an LTC7001 high side MOSFET driver? I looked through the data sheet and it does not provide any simple means for me to calculate the thermal losses. I am assuming that there would be switching, conduction, and diode drop power losses, but I am not sure how I go about calculating it. I would also imagine it would depend on what circuit the device is used in.

Any help would be appreciated. Thanks

RE: LTC7001 high side MOSFET driver thermal losses

Thermal loss is calculated the same way, regardless of the circuit it's in...

You have power loss due to the DCR characteristic when fully on, you have additional loss during the switching period as the FET is not fully turned on and will present a higher resistance (you need to know how much time you spend turning the FET on/off, it's not instantaneous), etc., but those will be the two highest losses. The datasheet provides you with those values, along with the thermal efficiency of the die-to-case and case-to-air interfaces. Plug and chug numbers.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: LTC7001 high side MOSFET driver thermal losses

(OP)
I am trying to find a way to calculate the heat dissipated by the device in watts during operation.

The device is being used in the configuration as shown in figure 5 of the data sheet on page 12. (See URL)

https://www.analog.com/media/en/technical-document... (btw P/N is LTC7004 not LTC7001).

My guess is that the power dissipated would depend on the frequency the driver is switching at, and the type of MOSFET that it is driving.

RE: LTC7001 high side MOSFET driver thermal losses

Correct... frequency matters, since a FET can only switch on/off within a minimum amount of time. As I mentioned above, the more times you switch, the more time you spend in that mid-range on/off area (which has a higher loss).

Dan - Owner
http://www.Hi-TecDesigns.com

RE: LTC7001 high side MOSFET driver thermal losses

Quote:

My guess is that the power dissipated would depend on the frequency the driver is switching at, and the type of MOSFET that it is driving.

And, the capacitive load the MOSFET is driving, since there's some coupling from the source to the gate of the MOSFET.

TTFN (ta ta for now)
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RE: LTC7001 high side MOSFET driver thermal losses

I would think it would be pretty quick to get an estimate. Pull-up the LT Spice Macromodel for this device. Spruce-up the LT Spice model with some of your application details. Take all the 'goes-in', subtract all the 'goes-outs', and what you have left is heat related.

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