HCPL-314J Datasheet, PDF (11/16 Pages) Agilent(Hewlett-Packard) – 0.4 Amp Output Current IGBT Gate Drive Optocoupler

11
Applications Information
Eliminating Negative IGBT
Gate Drive
To keep the IGBT firmly off,
the HCPL-314J has a very low
maximum V_OL specification of
1.0 V. Minimizing Rg and
the lead inductance from the
HCPL-314J to the IGBT gate and
emitter (possibly by mounting the
HCPL-314J 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-314J input as this can
result in unwanted coupling of
transient signals into the input of
HCPL-314J and degrade
performance. (If the IGBT
drain must be routed near the
HCPL-314J 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-314J.) An external
clamp diode may be connected
between pins 14 & 15 and pins 9
& 10 (as shown in Figure 19) for
the protection of HCPL-314J in
the case of IGBTs switching
inductive load.
+5 V
1
CONTROL
270 Ω
INPUT
2
74XX
OPEN
COLLECTOR
3
GND 1
+5 V
6
270 Ω
CONTROL
INPUT
7
74XX
OPEN
COLLECTOR
8
GND 1
HCPL-314J
16
0.1 µF
15
14
FLOATING
SUPPLY
V_CC = 18 V
+
–
Rg
V_OL
11
0.1 µF
10
9
V_CC = 18 V
+
–
Rg
Figure 19. Recommended LED Drive and Application Circuit for HCPL-314J.
+ HVDC
3-PHASE
AC
- HVDC