ACPL-H342 View Datasheet(PDF) - Avago Technologies
Part Name
Description
MFG CO.
'ACPL-H342' PDF : 19 Pages View PDF
Selecting the Gate Resistor (Rg)
Step 1: Calculate Rg minimum from the IOL peak specification. The IGBT and Rg in Figure 33 can be analyzed as a simple
RC circuit with a voltage supplied by ACPL-H342/K342.
Rg ≥
VCC VEE VOL
IOLPEAK
=
18V
0V
2.5A
2.3V
= 6.28Ω ≈ 7Ω
The VOL value of 2.3V in the previous equation is the VOL at the peak current of 2.5A (see Figure 7).
Step 1: Check the ACPL-H342/K342 power dissipation and increase Rg if necessary. The ACPL-H342/K342 total power dis-
sipation (PT) is equal to the sum of the emitter power (PE) and the output power (PO).
PT = PE + PO
PE = IF • VF • Duty Cycle
PO = PO(BIAS) + PO(SWITCHING)
= ICC • (VCC-VEE) + ESW(Rg;Qg) • f
Using IF(worst case) = 16mA, Rg = 7Ω, Max Duty Cycle = 80%, Qg = 500nC, f = 25kHz and TA max = 85°C:
PE = 16mA • 1.95V • 0.8 = 25mW
PO = 2.5mA • 18V + 4µJ • 25 kHz
= 45mW + 100mW
= 145mW < 500mW (PO(MAX) @ 85°C)
The value of 2.5mA for ICC in the previous equation is the maximum ICC over the entire operating temperature range.
Since PO is less than PO(MAX), Rg = 7Ω is alright for the power dissipation.
8
7
Qg = 100nc
Qg = 500nc
6
Qg = 1000nc
5
4
3
2
1
0
0
10
20
30
40
50
Rg - GATE RESISTANCE - Ω
Figure 36. Energy Dissipated in the ACPL-H342/K342 for each IGBT switching cycle.
16
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