12
Applications Information
Eliminating Negative IGBT
Gate Drive
To keep the IGBT firmly off,
the HCPL-J314 has a very low
maximum V
OL
specification of
1.0 V. Minimizing Rg and
the lead inductance from the
HCPL-J314 to the IGBT gate and
emitter (possibly by mounting the
HCPL-J314 on a small PC board
directly above the IGBT) can
eliminate the need for negative
IGBT gate drive in many
applications as shown in
Figure 19. Care should be taken
with such a PC board design to
avoid routing the IGBT collector
or emitter traces close to the
HCPL-J314 input as this can
result in unwanted coupling of
transient signals into the input of
HCPL-J314 and degrade
performance. (If the IGBT
drain must be routed near the
HCPL-J314 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-J314.)
+5 V
1
270
Ω
2
HCPL-J314
8
0.1 µF
7
Rg
Q1
3
6
+
–
V
CC
= 15 V
+ HVDC
CONTROL
INPUT
74XXX
OPEN
COLLECTOR
3-PHASE
AC
4
5
Q2
- HVDC
Figure 19. Recommended LED Drive and Application Circuit for HCPL-J314.
AGILENT [ AGILENT TECHNOLOGIES, LTD. ]
