M57962K Powerex Power Semiconductors, M57962K Datasheet - Page 5

• Manufacturer Part Number: M57962K
• Description: Hybrid Integrated Circuit
• Manufacturer: Powerex Power Semiconductors

Powerex, Inc., 173 Pavilion Lane, Youngwood, Pennsylvania 15697 [phone]
M57962K
Hybrid IC for IGBT Gate Driver
General Description
The M57962K is a hybrid integrated circuit designed
to provide gate drive for high power IGBT modules.
This circuit has been optimized for use with Powerex
1700V IGBT modules. However, the output charac-
teristics are compatible with most MOS gated power
devices. The M57962K features a compact single-in-
line package design. The upright mounting minimizes
required printed circuit board space to allow efficient
and flexible layout. The M57962K converts logic level
control signals into fully isolated +15V/-8V gate drive
with up to 5A of peak drive current. Control signal
isolation is provided by an integrated high speed opto-
coupler. Short circuit protection is provided by means
of destauration detection.
Short Circuit Protection
Figure 1 shows a block diagram of a typical desatura-
tion detector. In this circuit, a high voltage fast recovery
diode (D1) is connected to the IGBT’s collector to moni-
tor the collector to emitter voltage. When the IGBT is
in the off state, V
With D1 off the (+) input of the comparator is pulled up
to the positive gate drive power supply (V+) which is
normally +15V. When the IGBT turns on, the com-
parators (+) input is pulled down by D1 to the IGBT’s
V
a fixed voltage (V
dition the comparator’s (+) input will be less than V
and it’s output will be low. During a normal off-state
condition the comparator’s (+) input will be larger than
/06
INPUT
CE(sat)
. The (-) input of the comparator is supplied with
Figure 1. Desaturation Detector
AND
DELAY
t trip
TRIP
CE
DRIVE
GATE
is high and D1 is reverse biased.
). During a normal on-state con-
COMPARE
SHUTDOWN
+
R G
V+
G
E
V trip
D1
IGBT
MODULE
C
E
TRIP
V
into a short circuit, the high current will cause the IGBT’s
collector-emitter voltage to rise above V
though the gate of the IGBT is being driven on. This
abnormal presence of high VCE when the IGBT is
supposed to be on is often called desaturation.
Desaturation can be detected by a logical AND of the
driver’s input signal and the comparator output. When
the output of the AND goes high a short circuit is
indicated. The output of the AND can be used to com-
mand the IGBT to shut down in order to protect it from
the short circuit. A delay (t
after the comparator output to allow for the normal
turn on time of the IGBT. The tTRIP delay is set so that
the IGBTs Vce has enough time to fall below V
during normal turn on switching. If t
erroneous desaturation detection will occur. The maxi-
mum allowable t
short circuit withstanding capability. In typical applica-
tions using Powerex IGBT modules the recommended
limit is 10µs.
Operation of the M57962K Desaturation Detector
The Powerex M57962K incorporates short circuit
protection using desaturation detection as described
above. A flow chart for the logical operation of the
short-circuit protection is shown in Figure 2. When a
desaturation is detected the hybrid gate driver performs
a soft shut down of the IGBT and starts a timed (t
1.5ms lock out. The soft turn-off helps to limit the tran-
sient voltage that may be generated while interrupt-
ing the large short circuit current flowing in the IGBT.
During the lock out the driver pulls Pin 8 low to indicate
the fault status.
resume after the lock-out time has expired and the
control input signal returns to its off state.
Adjustment of Trip Time
The M57962K has a default short-circuit detection
time delay (t
prevent erroneous detection of short-circuit conditions
as long as the series gate resistance (R
minimum recommended value for the module being
used. The 2.5µs delay is appropriate for most applica-
tions so adjustment will not be necessary. However, in
some low frequency applications it may be desirable
to use a larger series gate resistor to slow the switch-
ing of the IGBT, reduce noise, and limit turn-off tran-
sient voltages. When RG is increased, the switching
TRIP
and it’s output will be high. If the IGBT turns on
TRIP
TRIP
) of approximately 2.5µs. This will
Normal operation of the driver will
delay is limited by the IGBT’s
TRIP
) must be provided
TRIP
is set too short,
G
) is near the
TRIP
timer
even
TRIP
)