Datasheet TLE6280GP

9

2007-07-19

Estimation of power dissipation within the driver IC

The power dissipation within the driver IC is strongly dependent upon the use of the driver

and the external components. Nevertheless, a rough estimation of the worst case power dis-

sipation is possible.

Worst case calculation is:

With:

= Power dissipation in the driver IC

= Switching frequency

n

= number of switched Mosfets

const

= constant considering some leakage current in the driver and the power dissipa-

tion caused by the charge pump (nominally = 2)

= Voltage at Vs

= Power dissipation in the external gate resistors

This value can be reduced dramatically by the use of external gate resistors.

Recommended start up procedure

To assure the driver to be active and functional, a special initialization procedure is required

enabled, after 10

µs or later, positive-going transition signals at all ILx pins are required in or-

der to ensure proper start-up of the output driver. This procedure assures a proper wake up

the device and allowes to fill the bootstrap capacitors. Not filling the bootstrap capacitors

might lead to low Gate-Source voltages mainly in highside and can cause a short circuit de-

tection when the highside switches are activated. Not changing the ILx input signal after

enabling the device may cause the lowside outputs to stay in off conditions.