LMD18400 Datasheet, PDF (18/26 Pages) National Semiconductor (TI) – Quad High Side Driver

LMD18400
SNVS094C – JUNE 1996 – REVISED APRIL 2013
www.ti.com
The total average power dissipation during a full ON/OFF switching cycle of an inductive load will be:
(9)
Due to the common cut-off of all loads forced by thermal shutdown, the thermal time constants of the package
become a concern. Figure 31 provides an indication of the time it takes to heat the die to thermal shutdown with
a step increase in package power dissipation from an initial junction temperature of +25°C. This data was
measured using a PC board layout providing a thermal resistance from junction to ambient of approximately
35°C/W. Less heatsinking will, of course, result in faster thermal shutdown of the power switches.
Figure 31. Approximate time required for the die to reach the 170°C thermal shutdown point from 25°C
for different total package power dissipation levels.
Figure 32. ON/OFF Switching of Multiple Voltage Regulated Circuit Loads
18
Submit Documentation Feedback
Product Folder Links: LMD18400
Copyright © 1996–2013, Texas Instruments Incorporated