HCPL3120000E AVAGO TECH, HCPL3120000E Datasheet - Page 17

• Manufacturer Part Number: HCPL3120000E
• Manufacturer: AVAGO TECH

Applications Information
Eliminating Negative IGBT
Gate Drive
to HCPL-3120, HCPL-J312, and
HCNW3120)
To keep the IGBT firmly off, the
HCPL-3120 has a very low
maximum V
0.5 V. The HCPL-3120 realizes
this very low V
DMOS transistor with 1
(typical) on resistance in its pull
down circuit. When the HCPL-
CONTROL
Figure 25. Recommended LED Drive and Application Circuit.
COLLECTOR
INPUT
+5 V
74XXX
OPEN
OL
(Discussion applies
270
specification of
OL
by using a
1
2
3
4
HCPL-3120
3120 is in the low state, the IGBT
gate is shorted to the emitter by
Rg + 1 . Minimizing Rg and the
lead inductance from the HCPL-
3120 to the IGBT gate and
emitter (possibly by mounting the
HCPL-3120 on a small PC board
directly above the IGBT) can
eliminate the need for negative
IGBT gate drive in many applica-
tions as shown in Figure 25. Care
should be taken with such a PC
board design to avoid routing the
8
7
6
5
0.1 µF
+
–
V
CC
Rg
= 18 V
Q1
Q2
IGBT collector or emitter traces
close to the HCPL-3120 input as
this can result in unwanted
coupling of transient signals into
the HCPL-3120 and degrade
performance. (If the IGBT drain
must be routed near the HCPL-
3120 input, then the LED should
be reverse-biased when in the off
state, to prevent the transient
signals coupled from the IGBT
drain from turning on the
HCPL-3120.)
17
3-PHASE
+ HVDC
- HVDC
AC