MIC5014/5015

Micrel

1997

5-145

5

High Side Driver With Load Protection (Figure 12) Al-

though the MIC5014/15 devices are reverse battery pro-

tected, the load and power FET are not, in a typical high side

configuration. In the event of a reverse battery condition, the

internal body diode of the power FET will be forward biased.

This allows the reversed supply access to the load.

Push-Pull Driver With No Cross-Conduction (Figure 13)

As the turn-off time of the MIC5014/15 devices is much faster

than the turn-on time, a simple push-pull driver with no cross

conduction can be made using one MIC5014 and one

MIC5015. The same control signal is applied to both inputs;

the MIC5014 turns on with the positive signal, and the

MIC5015 turns on when it swings low.

This scheme works with no additional components as the

relative time difference between the rise and fall times of the

MIC5014 is large. However, this does mean that there is

Figure 13: Push-Pull Driver

The addition of a Schottky diode between the supply and the

FET eliminates this problem. The MBR2035CT was chosen

as it can withstand 20A continuous and 150A peak,

and should survive the rigors of an automotive environment.

The two diodes are paralleled to reduce switch loss (forward

voltage drop).

Figure 12: High Side Driver WIth Load Protection

considerable deadtime (time when neither driver is turned on).

If this circuit is used to drive an inductive load, catch diodes

must be used on each half to provide an alternate path for the

kickback current that will flow during this deadtime.

This circuit is also a simple half H-bridge which can be driven

with a PWM signal on the input for SMPS or motor drive

applications in which high switching frequencies are not

desired.

MIC5014

Control Input

OFF

ON

1

2

3

4

8

7

6

5

IRF540

12V

NC

Gate

Gnd

Source

Input

V+

NC

NC

10µF

MBR2035CT

MIC5014

Control Input

1

2

3

4

8

7

6

5

IRFZ40

12V

NC

Gate

Gnd

Source

Input

V+

NC

NC

10µF

MIC5015

1

2

3

4

8

7

6

5

NC

Gate

Gnd

Source

Input

V+

NC

NC

12V

IRFZ40