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HCPL-3120-560E Datasheet, PDF (20/24 Pages) AVAGO TECHNOLOGIES LIMITED – 2.5 Amp Output Current IGBT Gate Drive Optocoupler | |||
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Thermal Model (Discussion applies to HCPL-3120, HCPL-
J312 and HCNW3120)
The steady state thermal model for the HCPL-3120 is
shown in Figure 28. The thermal resistance values given
in this model can be used to calculate the temperaÂtures
at each node for a given operating condition. As shown
by the model, all heat generated flows through qCA which
raises the case temperature TC accordingly. The value
of qCA depends on the conditions of the board design
and is, therefore, determined by the designer. The value
of qCAâ=â83°C/W was obtained from thermal measureÂ
ments using a 2.5 x 2.5 inch PC board, with small traces
(no ground plane), a single HCPL-3120 soldered into the
center of the board and still air. The absolute maximum
power dissipation derating specificaÂtions assume a
qCAvalue of 83°C/W.
From the thermal mode in Figure 28 the LED and detector
IC junction temperatures can be expressed as:
TJE = PE @(qLC||(qLD + qDC) + qCA)
ââââqLC * qDC
+â PâDâââ¢(âqLâC +âqâDCâ+âqLâD + qCA) + TA
âTâJâDâ=ââPââEâ (ââqâLqCLâ+Cqââ¢DqCâD+CâqLâD + qCA)
+ PD ⢠(qDC||(qLD + qLC) + qCA) + TA
Inserting the values for qLC and qDC shown in Figure 28
gives:
TJE = PE ⢠(256°C/W + qCA)â
â+ PD ⢠(57°C/W + qCA) + TAâ
TJD = PE ⢠(57°C/W + qCA)â
â+ PD ⢠(111°C/W + qCA) + TA
PE Parameter    Description
IF
LED Current
VF
LED On Voltage
Duty Cycle
Maximum LED Duty Cycle
PO Parameter
ICC
VCC
VEE
ESW(Rg,Qg)
f
Description
Supply Current
Positive Supply Voltage
Negative Supply Voltage
Energy Dissipated in the HCPL-3120â
for each IGBT Switching Cycle
(See Figure 27)
Switching Frequency
14
Qg = 100 nC
12
Qg = 500 nC
Qg = 1000 nC
10
VCC = 19 V
8
VEE = -9 V
6
4
2
0
0
10
20
30 40 50
Rg â GATE RESISTANCE â â¦
Figure 27. Energy dissipated in the HCPL-3120 for each IGBT switching
cycle.
HCPL-3120 fig 27
For example, given PE = 45 mW, PO = 250 mW, TA = 70°C
and qCAâ= 83°C/W:
TJE = PE ⢠339°C/W + PD ⢠140°C/W + TAâ
â â= 45 mW ⢠339°C/W + 250 mWâ
ââââ ⢠140°C/W + 70°C = 120°C
TJD = PE ⢠140°C/W + PD ⢠194°C/W + TAâ
â= 45 mW ⢠140°C/W + 250 mW ⢠194°C/W + 70°C = 125°C
TJE and TJD should be limited to 125°C based on the
board layout and part placement (qCA) specific to the ap-
plication.
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