HCPL-3150 Datasheet, PDF (11/15 Pages) Agilent(Hewlett-Packard) – 0.5 Amp Output Current IGBT Gate Drive Optocoupler

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.
Rg ≥ –(V–^C–^C–––I–_O–V_L–^EP–_EE–_A^-_K–V–^O–^L–)–
= ^{(–V–C}–^C–––I–_O–V_L–^EP–_EE–_A^-_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 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
Power Dissipation and
Increase Rg if Necessary. The
HCPL-3150 total power dissipa-
tion (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)
+5 V
1
270 Ω
2
CONTROL
INPUT
3
74XXX
OPEN
4
COLLECTOR
HCPL-3150
8
0.1 µF
7
6
5
+ ^{VCC = 15 V}
–
Rg
Q1
– ^{VEE = -5 V}
+
Q2
Figure 26. HCPL-3150 Typical Application Circuit with Negative IGBT Gate Drive.
+ HVDC
3-PHASE
AC
- HVDC
P_E
Parameter
I_F
V_F
Duty Cycle
Description
LED Current
LED On Voltage
Maximum LED
Duty Cycle
P_O Parameter
I_CC
V_CC
V_EE
E_SW(Rg,Qg)
f
Description
Supply Current
Positive Supply Voltage
Negative Supply Voltage
Energy Dissipated in the HCPL-3150 for each
IGBT Switching Cycle (See Figure 27)
Switching Frequency
1-207