ACPL-331J-000E Datasheet, PDF(20/22 Page) AVAGO TECHNOLOGIES LIMITED – 1.5 Amp Output Current IGBT Gate Driver Optocoupler

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ACPL-331J-000E Datasheet, PDF (20/22 Pages) AVAGO TECHNOLOGIES LIMITED – 1.5 Amp Output Current IGBT Gate Driver Optocoupler

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Under Voltage Lockout

The ACPL-331J Under Voltage Lockout (UVLO) feature is

designed to prevent the application of insufficient gate

voltage to the IGBT by forcing the ACPL-331J output

low during power-up. IGBTs typically require gate

voltages of 15 V to achieve their rated VCE(ON) voltage.

At gate voltages below 13 V typically, the VCE(ON) voltage

increases dramatically, 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 (VCC2) is applied.

Once VCC2 exceeds VUVLO+ (the positive-going UVLO

threshold), the UVLO clamp is released to allow the

device output to turn on in response to input signals. As

VCC2 is increased from 0 V (at some level below VUVLO+),

first the DESAT protection circuitry becomes active. As

VCC2 is further increased (above VUVLO+), 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 feature work together

to provide seamless protection regardless of supply

voltage (VCC2).

Active Miller Clamp

A Miller clamp allows the control of the Miller current

during a high dV/dt situation and can eliminate the use

of a negative supply voltage in most of the applications.

During turn-off, the gate voltage is monitored and the

clamp output is activated when gate voltage goes below

2V (relative to VEE). The clamp voltage is VOL+2.5V typ

for a Miller current up to 1100mA. The clamp is disabled

when the LED input is triggered again.

Other Recommended Components

The application circuit in Figure 33 includes an output

pull-down resistor, a DESAT pin protection resistor, a

FAULT pin capacitor, and a FAULT pin pullup resistor and

Active Miller Clamp connection.

Output Pull-Down Resistor

During the output high transition, the output voltage

rapidly rises to within 3 diode drops of VCC2. If the output

current then drops to zero due to a capacitive load, the

output voltage will slowly rise from roughly VCC2-3(VBE)

to VCC2 within a period of several microseconds. To limit

the output voltage to VCC2-3(VBE), a pull-down resistor,

RPULL-DOWN between the output and VEE is recommend-

ed to sink a static current of several 650 Î¼A while the

output is high. Pull-down resistor values are dependent

on the amount of positive supply and can be adjusted

according to the formula, Rpull-down = [VCC2-3 * (VBE)] /

650 Î¼A.

1 VS

2 VCC1

3 FAULT

4 VS

5 CATHODE

6 ANODE

7 ANODE

8 CATHODE

VE 16

VLED 15

DESAT 14

VCC2 13

VEE 12

VOUT 11

VCLAMP 10

VEE 9

VCC

RPULL-DOWN

Figure 35. Output pull-down resistor.

DESAT Pin Protection Resistor

The freewheeling of flyback diodes connected across

the IGBTs can have large instantaneous forward voltage

transients which greatly exceed the nominal forward

voltage of the diode. This may result in a large negative

voltage spike on the DESAT pin which will draw substan-

tial current out of the driver if protection is not used. To

limit this current to levels that will not damage the driver

IC, a 100 ohm resistor should be inserted in series with

the DESAT diode. The added resistance will not alter the

DESAT threshold or the DESAT blanking time.