IX2204

R03

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7

3

Functional Description

3.1 Input

The INA and INB inputs are TTL compatible and must

be referenced to GND.

3.2 Mode

The MODE input determines how the desaturation

protection and Under-Voltage Lock Out (UVLO)

protection circuitry controls the OUTHA, OUTLA,

OUTHB and OUTLB outputs. For parallel-mode IGBT

drive, MODE should be connected to GND (see 4.1).

For driving IGBTs that require higher gate drive

current than the IX2204 can provide, the IX2204 can

be used to control external drive transistors. In this

stacked configuration, the external drive transistors

constitute an inverting stage, and MODE should be

connected to VHA for proper desaturation protection

and UVLO operation (see 4.3).

3.3 Desaturation Protection

The desaturation protection circuit ensures the

protection of an external IGBT in the event of an

over-current situation. When the voltage at DESAT

exceeds 1.4V (typically) and MODE is connected to

GND, OUTLA and OUTLB are driven low in a two-step

process. First OUTLA, OUTHA, OUTLB and OUTHB

are all turned off (high impedance). Then after a

OUTLB are turned on (driven low), which quickly turns

off the IGBT. This two-step action avoids both

dangerous over-voltages across the IGBT and

reverse-bias SOA problems, especially during a short

circuit turn-off. The time that all the outputs are in

tristate is set by an internal current source and an

external capacitor (CTRISTATE ) that is connected to

the TRISTATE pin. The tristate time is approximately:

The desaturation circuit is disabled for a fixed blanking

time to avoid detecting a false desaturation event

during IGBT turn-on, thus allowing enough time for

IGBT saturation. This blanking time is set by an

internal current source and an external capacitor,

This blanking time starts when INA transitions from

low to high.

The desaturation two-step turn off is slightly different

when MODE is connected to VHA for stack-mode

IGBT drive. When the DESAT voltage exceeds 1.4V,

OUTHA and OUTLB are turned on, tristating the IGBT.

turned off, and OUTHB is turned on, which in

conjunction with the external drive transistor quickly

turns off the IGBT. When MODE is connected to VHA,

the blanking time starts when INA transitions from

high to low.

The desaturation protection circuit cannot be used

when the IX2204 is used to drive two separate IGBTs

(direct IGBT drive, see 4.2). When driving two

separate IGBTs, the DESAT, TRISTATE, MODE, and

BLANK pins should all be connected to GND.

3.4 Under-Voltage Protection

The Under Voltage Lock Out (UVLO) circuit protects

the IGBT from insufficient gate voltage. The UVLO

circuit monitors the VHA supply voltage. If MODE is

connected to GND and VHA is below the UVLO+

threshold, OUTHA and OUTHB are both turned-off

(high impedance), and both OUTLA and OUTLB are

both turned on (pulled low). If VHA is below the

UVLO+ threshold and MODE is connected to VHA,

OUTHA and OUTHB are both are turned on, and

OUTLA and OUTLB are both turned off.

3.5 Fault Output

The FAULT output is pulled low during a desaturation

event, or when VHA is below UVLO+.

3.6 Outputs

The output stages are able to source 2A, and sink 4A.

Separated sink and source outputs allow independent

gate charge and discharge control. For higher gate

drive applications, the source and sink outputs can be

paralleled to source 4A, and sink 8A.

Table 2: Output States with VHA < UVLO+

Mode

OUTHA

OUTLA

OUTHB

OUTLB

GNDZ

0Z0

VHA

1

Z1Z