FOD8318 Datasheet, PDF (24/31 Pages) Fairchild Semiconductor – 2.5 A Output Current, IGBT Drive Optocoupler with Active Miller Clamp, Desaturation Detection, and Isolated Fault Sensing

Application Information
5 V _{+ 0.1 μF}
3 kΩ ^–
330 pF
FOD8318
1 VIN+
V_E 16
2 V_IN–
V_LED2+ 15
3 V_DD1
DESAT 14
4 GND1
V_DD2 13
5 RESET
V_S 12
6 FAULT
V_O 11
7 V_LED1+
V_CLAMP 10
8 V_LED1-*
V_SS 9
1 μF
1 μF
10 μF
C_BLANK
100 pF _DDESAT
1 kΩ
+–
V_F
+ ^{VDD2 = 15 V}
Q1
–
Rg
Q2
*Pin 8 (V_LED1-) is internally connected to pin 4 (GND1).
+
V_CE
–
3-Phase
Output
+
V_CE
–
Figure 55. Recommended Application Circuit
Functional Description
The functional behavioral of FOD8318 is illustrated by
the detailed internal schematic shown in Figure 56. This
explains the interaction and sequence of internal and
external signals, together with the timing diagrams.
1. Non-Inverting and Inverting Inputs
There are two CMOS/TTL-compatible inputs, V_IN+ and
V_IN-, to control the IGBT in non-inverting and inverting
configurations, respectively. When V_IN- is set to LOW
state, V_IN+ controls the driver output, V_O, in non-inverting
configuration. When V_IN+ is set to HIGH state, V_IN- con-
trols the driver output in inverting configuration.
The relationship between the inputs and output are
illustrated in the Figure 57.
During normal operation, when no fault is detected, the
FAULT output, which is an open-drain configuration, is
latched to HIGH state. This allows the gate driver to be
controlled by the input logic signal.
When a fault is detected, the FAULT output is latched to
LOW state. This condition remains until the input logic is
pulled to LOW and the RESET pin is also pulled LOW for
a period longer than PW_RESET.
V_DD1 ³
V_IN+ ¹
V_IN– ²
6
FAULT
4
GND1
V_LED1– ⁸
5
RESET
Delay
Q
RS
©2010 Fairchild Semiconductor Corporation
FOD8318 Rev. 1.1.2
V_LED+
7 Gate Drive
Optocoupler
250 μA
+
14 _DESAT
– _VDESAT
UVLO Comparator
–
+ _{12 V}
16 _VE
13 _VDD2
12 _VS
Fault Sense
Optocoupler
5 μs Pulse
Generator
15
V_LED2+
Figure 56. Detailed Internal Schematic
24
11 _VO
50x
1x
9 _VSS
+
– _2V
10
V_CLAMP
25x
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