ACPL-H342 Datasheet, PDF (19/19 Pages) AVAGO TECHNOLOGIES LIMITED – 2.5 Amp Output Current IGBT Gate Drive Optocoupler with Active Miller Clamp, Rail-to-Rail Output Voltage and UVLO in Stretched SO8

LED Input Current Hysteresis
The detector has optical receiver input stage with built in
Schmitt trigger to provide logic compatible waveforms,
eliminating the need for additional wave shaping. The
hysteresis (Figure 12) provides differential mode noise
immunity and minimizes the potential for output signal
chatter.
Under Voltage Lockout
The ACPL-H342 Under Voltage Lockout (UVLO) feature is
designed to prevent the application of insufficient gate
voltage to the IGBT by forcing the ACPL-H342 output low
during power-up. IGBTs typically require gate voltages of
15 V to achieve their rated V_CE(ON) voltage. At gate voltages
below 13 V typically, the V_CE(ON) voltage increases dra-
matically, especially at higher currents. At very low gate
voltages (below 10 V), the IGBT may operate in the linear
region and quickly overheat. The UVLO function causes
the output to be clamped whenever insufficient operating
supply (V_CC) is applied. Once V_CC exceeds V_UVLO+ (the pos-
itive-going UVLO threshold), the UVLO clamp is released
to allow the device output to turn on in response to input
signals.
Thermal Model for ACPL-H342/K342 Stretched SO8
Package Optocoupler
Definitions:
R₁₁: Junction to Ambient Thermal Resistance of LED due
to heating of LED
R₁₂: Junction to Ambient Thermal Resistance of LED due
to heating of Detector (Output IC)
R₂₁: Junction to Ambient Thermal Resistance of Detector
(Output IC) due to heating of LED.
R₂₂: Junction to Ambient Thermal Resistance of Detector
(Output IC) due to heating of Detector (Output IC).
P₁: Power dissipation of LED (W).
P₂: Power dissipation of Detector / Output IC (W).
T₁: Junction temperature of LED (°C).
T₂: Junction temperature of Detector (°C).
T_A: Ambient temperature.
Ambient Temperature: Junction to Ambient Thermal Re­
sistances were measured approximately 1.25cm above
optocoupler at ~23°C in still air
Thermal Resistance
R₁₁
R₁₂, R₂₁
R₂₂
°C/W
145
25, 38
46
This thermal model assumes that an 8-pin single-channel
plastic package optocoupler is soldered into a 7.62 cm x
7.62 cm printed circuit board (PCB) per JEDEC standards.
The temperature at the LED and Detector junctions of the
optocoupler can be calculated using the equations below.
T₁ = (R₁₁ * P₁ + R₁₂ * P₂) + T_A
(1)
T₂ = (R₂₁ * P₁ + R₂₂ * P₂) + T_A
(2)
Using the given thermal resistances and thermal model
formula in this datasheet, we can calculate the junction
temperature for both LED and the output detector. Both
junction temperature should be within the absolute
maxi­mum rating.
For example, given P₁ = 45 mW, P₂ =210 mW, Ta = 85°C:
LED junction temperature,
T₁ = (R₁₁ * P₁ + R₁₂ * P₂) + T_A
= (145 * 0.045 + 25 * 0.210) + 85
= 97°C
Output IC junction temperature,
T₂ = (R₂₁ x P₁ + R₂₂ x P₂) + T_A
= (38 *0.045 + 46 * 0.210) + 85
= 96°C
T₁ and T₂ should be limited to 125°C based on the board
layout and part placement.
Related Application Noted
AN5336 – Gate Drive Optocoupler Basic Design for IGBT/
MOSFET
AN1043 – Common-Mode Noise: Sources and Solutions
AN02-0310EN – Plastics Optocouplers Product ESD and
Moisture Sensitivity
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AV02-2526EN - March 13, 2013