HCPL-315J Datasheet, PDF (14/21 Pages) Agilent(Hewlett-Packard) – 0.5 Amp Output Current IGBT Gate Drive Optocoupler

14
+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-315J
16
0.1 µF
15
14
FLOATING
SUPPLY
V_CC = 18 V
+
–
Rg
11
0.1 µF
10
9
V_CC = 18 V
+
–
Rg
Figure 25b. Recommended LED Drive and Application Circuit (HCPL-315J).
+ HVDC
3-PHASE
AC
- HVDC
Selecting the Gate Resistor
(Rg) to Minimize IGBT
Switching Losses.
Step 1: Calculate Rg Minimum
From the I_OL Peak Specifica-
tion. The IGBT and Rg in Figure
26 can be analyzed as a simple
RC circuit with a voltage supplied
by the HCPL-3150/315J.
Rg ≥ ^{(–V–C}–^C–––I–_O–V_L–^EPE–^EA–-_K–V–^O––^L)–
= ^{(–V–C}–^C–––I–_O–V_L–^EPE–^EA–-_K–¹â€“–^.7––V–)
= ^(–1––⁵–V₀––_.⁺₆––A⁵––V––-–¹â€“^.–⁷––V–)
= 30.5 Ω
The V_OL value of 2 V in the pre-
vious equation is a conservative
value of V_OL at the peak current
of 0.6 A (see Figure 6). At lower
Rg values the voltage supplied by
the HCPL-3150/315J is not an
ideal voltage step. This results in
lower peak currents (more
margin) than predicted by this
analysis. When negative gate
drive is not used V_EE in the
previous equation is equal to zero
volts.
Step 2: Check the HCPL-3150/
315J Power Dissipation and
Increase Rg if Necessary. The
HCPL-3150/315J total power
dissipation (P_T) is equal to the
sum of the emitter power (P_E) and
the output power (P_O):
P_T = P_E + P_O
P_E = I_F ^• V_F ^• Duty Cycle
P_O = P_O(BIAS) + P_{O (SWITCHING)}
= I_CC^•(V_CC - V_EE)
+ E_SW(R_G, Q_G) ^•f
For the circuit in Figure 26 with I_F
(worst case) = 16 mA, Rg =
30.5 Ω, Max Duty Cycle = 80%,
Qg = 500 nC, f = 20 kHz and T_A
max = 90°C:
P_E = 16 mA^•1.8 V ^•0.8 = 23 mW
P_O = 4.25 mA ^•20 V
+ 4.0 µJ^•20 kHz
= 85 mW + 80 mW
= 165 mW
> 154 mW (P_O(MAX) @ 90°C
= 250 mW−20C^•4.8 mW/C)