LTC3892 for high power buck

Hi Trampas,

Driving high Qg MOSFETs are normal, in high power applications.

Please use the PowerCad design tool to estimate the power loss distribution, including the internal LDO.

External bias to supply the EXTVCC is recommended if your MOSFETs have high gate charge (Qg).

Thanks,

Ding

What Qg is considered "high gate charge"?

On Tue, May 29, 2018 at 12:50 PM, Ding.Li <

Please calculate the gate driver loss:

Pdrv=N*Qg*Vdrv*fsw, where N is the MOSFET count, Vdrv is the driver voltage and fsw is the switching frequency.

Gate drive current thru internal LDO: Idrv=Pdrv/Vdrv

Internal LDO loss: Pldo=(Vin-Vdrv)* Idrv

Thanks,

Thanks!

My numbers came out to be 47mA per side, @36VDC input this is well beyond

the internal LDO.  From the documentation there appears to be one LDO per

side but only one pin for the DRVcc decoupling cap.

Either way I have too much gate capacitance and will address and look at

adding an external VCC.

Thanks

Trampas

On Tue, May 29, 2018 at 1:33 PM, Ding.Li <

This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

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