MC33153

http://onsemi.com

8

−60

10

1.0

80

5.0

10

Drive Output Open

f, INPUT FREQUENCY (kHz)

Figure 28. Supply Current versus

Supply Voltage

Figure 29. Supply Current versus Temperature

Output High

Figure 30. Supply Current versus Input Frequency

Output Low

= 5.0 nF

= 2.0 nF

= 1.0 nF

8.0

6.0

4.0

2.0

0

20

40

60

80

100

120

140

20

−20

0

−40

10

15

8.0

6.0

4.0

2.0

0

1000

10

100

60

40

20

0

OPERATING DESCRIPTION

GATE DRIVE

Controlling Switching Times

The most important design aspect of an IGBT gate drive

is optimization of the switching characteristics. The

switching characteristics are especially important in motor

control applications in which PWM transistors are used in a

bridge configuration. In these applications, the gate drive

circuit components should be selected to optimize turn−on,

turn−off and off−state impedance. A single resistor may be

used to control both turn−on and turn−off as shown in

Figure 31. However, the resistor value selected must be a

compromise in turn−on abruptness and turn−off losses.

Using a single resistor is normally suitable only for very low

frequency PWM. An optimized gate drive output stage is

shown in Figure 32. This circuit allows turn−on and turn−off

provides control over the IGBT turn−on speed. In motor

control circuits, the resistor sets the turn−on di/dt that

controls how fast the free−wheel diode is cleared. The

interaction of the IGBT and free−wheeling diode determines

the turn−on dv/dt. Excessive turn−on dv/dt is a common

controls the turn−off speed and ensures that the IGBT

remains off under commutation stresses. Turn−off is critical

to obtain low switching losses. While IGBTs exhibit a fixed

minimum loss due to minority carrier recombination, a slow

gate drive will dominate the turn−off losses. This is

particularly true for fast IGBTs. It is also possible to turn−off

an IGBT too fast. Excessive turn−off speed will result in

large overshoot voltages. Normally, the turn−off resistor is

a small fraction of the turn−on resistor.

The MC33153 contains a bipolar totem pole output stage

that is capable of sourcing 1.0 amp and sinking 2.0 amps

peak. This output also contains a pull down resistor to ensure

MC33153.

In a PWM inverter, IGBTs are used in a half−bridge

configuration. Thus, at least one device is always off. While