ACPL-5160 Datasheet, PDF (24/36 Pages) AVAGO TECHNOLOGIES LIMITED – 2.5 Amp Gate Drive Optocoupler with Integrated (VCE) Desaturation Detection and Fault Status Feedback

ACPL-5160 and ACPL-5161
Data Sheet
Figure 62 Timing Diagram
NORMAL
OPERATION
NON-INVERTING
CONFIGURED
INPUTS
V_{IN- 0 V}
5V
V_IN+
INVERTING
CONFIGURED
INPUTS
V_{IN- 5 V}
V_{IN+ 5 V}
V_DESAT
V_OUT
FAULT
RESET
FAULT
CONDITION
RESET
7V
Slow IGBT Gate Discharge during Fault
Condition
When a desaturation fault is detected, a weak pull-down device
in the ACPL-516x output drive stage will turn on to softly turn
off the IGBT. This device slowly discharges the IGBT gate to
prevent fast changes in drain current that could cause
damaging voltage spikes due to lead and wire inductance.
During the slow turn off, the large output pull-down device
remains off until the output voltage falls below V_EE + 2V, at
which time the large pull down device clamps the IGBT gate to
V_EE.
DESAT Fault Detection Blanking Time
The DESAT fault detection circuitry must remain disabled for a
short time period following the turn-on of the IGBT to allow the
collector voltage to fall below the DESAT threshold. This time
period, called the DESAT blanking time, is controlled by the
internal DESAT charge current, the DESAT voltage threshold,
and the external DESAT capacitor. The nominal blanking time is
calculated in terms of external capacitance (C_BLANK), FAULT
threshold voltage (V_DESAT), and DESAT charge current (I_CHG) as
t_BLANK = C_BLANK x V_DESAT / I_CHG. The nominal blanking time with
the recommended 100-pF capacitor is 100 pF × 7V/250 μA =
2.8 μs. The capacitance value can be scaled slightly to adjust
the blanking time, though a value smaller than 100 pF is not
recommended. This nominal blanking time also represents the
longest time it will take for the ACPL-516x to respond to a
DESAT fault condition. If the IGBT is turned on while the
collector and emitter are shorted to the supply rails (switching
into a short), the soft shutdown sequence begins after
approximately 3 μs. If the IGBT collector and emitter are
shorted to the supply rails after the IGBT is already on, the
response time is much quicker due to the parasitic parallel
capacitance of the DESAT diode. The recommended 100-pF
capacitor should provide adequate blanking as well as fault
response times for most applications.
Undervoltage Lockout
The ACPL-516x Undervoltage Lockout (UVLO) feature is
designed to prevent the application of insufficient gate voltage
to the IGBT by forcing the ACPL-516x output low during
power-up. IGBTs typically require gate voltages of 15V to
achieve their rated V_CE(ON) voltage. At gate voltages below 13V
typically, their on-voltage increases dramatically, especially at
higher currents. At very low gate voltages (below 10V), the
IGBT might operate in the linear region and quickly overheat.
The UVLO function causes the output to be clamped whenever
insufficient operating supply (V_CC2) is applied. Once V_CC2
exceeds V_UVLO+ (the positive-going UVLO threshold), the UVLO
clamp is released to allow the device output to turn on in
response to input signals. As V_CC2 is increased from 0V (at some
level below V_UVLO+), first the DESAT protection circuitry
becomes active. As V_CC2 is further increased (above V_UVLO+),
the UVLO clamp is released. Before the time the UVLO clamp is
released, the DESAT protection is already active. Therefore, the
UVLO and DESAT FAULT DETECTION features work together to
provide seamless protection regardless of supply voltage
(V_CC2).
Broadcom
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