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LM5134

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SNVS808C – MAY 2012 – REVISED FEBRURARY 2016

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10.3 Power Dissipation

It is important to keep the power consumption of the driver below the maximum power dissipation limit of the

package at the operating temperature. The total power dissipation of the LM5134 is the sum of the gate charge

losses and the losses in the driver due to the internal CMOS stages used to buffer the output as well as the

power losses associated with the quiescent current.

The gate charge losses include the power MOSFET gate charge losses as well as the PILOT FET gate charge

losses and can be calculated as follows:

(2)

Or

SW

where

•

•

•

(3)

use of an external turnoff switch, part of the gate charge losses are dissipated in the external turnoff switch.

Therefore, the actual gate charge losses dissipated in the LM5134 is less than predicted by the above

expressions. However, they are a good conservative design estimate.

The power dissipation associated with the internal circuit operation of the driver can be estimated with the

characterization curves of the LM5134. For a given ambient temperature, the maximum allowable power losses

of the IC can be defined using Equation 4.

where

•

P is the total power dissipation of the driver

(4)