APPLICATION INFORMATION

DEMAGNETIZATION OF INDUCTIVE LOADS

An internal zener diode, limiting the voltage

across the Power MOS to between 45 and 55V

inductive loads without external clamping devices.

The maximum energy that can be absorbed from

an inductive load is specified as 200mJ (at

°C).

To define the maximum switching frequency three

points have to be considered:

1) The total power dissipation is the sum of the

On State Power and of the Demagnetization

Energy multiplied by the frequency.

2)

The total energy W dissipated in the device

during a demagnetization cycle (figg. 2, 3) is:

W

L

log







1

+









Where:

L = inductive load;

Vs = supply voltage;

3)

In normal conditions the operating Junction

temperature should remain below 125

°C.

Figure 2: Inductive Load Equivalent Circuit

Figure 3: Demagnetization Cycle Waveforms

-25

0

25

50

75

100

125

Tj (

°C)

0.6

0.8

1.0

1.2

1.4

1.6

1.8

α

D93IN018

α=

RDSON (Tj)

RDSON (Tj=25

°C)

Temperature

TDE1897R - TDE1898R

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