IR21141/IR22141SSPbF

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© 2009 International Rectifier

11

HO/LO Status

HOP/LOP

HON/LON

SSDH/SSDL

0

HiZ

0

HiZ

1

1

HiZ

HiZ

SSD

HiZ

HiZ

0

LO/HO

Output follows inputs (in=1->out=1, in=0->out=0)

Output keeps previous status

Logic Table: Output Drivers Status Description

INPUTS

INPUT/OUTPUT

Undervoltage

Yes: V< UV

threshold

No : V> UV

threshold

X: don’t care

OUTPUTS

Operation

Hin

Lin

FLT_CLR

______

SY_FLT

SSD: desat (out)

HOLD: freezing

(in)

_________

FAULT/SD

SD: shutdown (in)

FAULT: diagnostic

(out)

HO

LO

Shutdown

X

X

X

X

0 (SD)

X

X

0

0

Fault Clear

X

†

(FAULT)

No

No

HO

LO

Fault Cleared

1

X

1

††

No

No

HO

LO

1

0

0

1

1

No

No

1

0

0

1

0

1

1

No

No

0

1

Normal

Operation

0

0

0

1

1

No

No

0

0

Anti Shoot

Through

1

1

0

1

1

No

No

0

0

1

0

0

(SSD)

1

No

No

SSD

0

Soft

Shutdown

(entering)

0

1

0

(SSD)

1

No

No

0

SSD

X

X

0

(SSD)

(FAULT)

No

No

0

0

Soft

Shutdown

(finishing)

X

X

0

(SSD)

(FAULT)

No

No

0

0

Freeze

X

X

X

0 (HOLD)

1

No

No

X

X

1

1

No

Yes

0

LO

Undervoltage

X

X

X

1

0 (FAULT)

Yes

X

0

0

†

SY_FLT automatically resets after the SSD event is over, without requiring FLT_CLR to be asserted. To

avoid FLT_CLR conflicting with the SSD sequence of operations, in the event of a SSD during normal

operation it is recommended not to apply FLT_CLR while SY_FLT is active. At power supply start-up

instead, it is recommended to keep FLT_CLR active to prevent spurious diagnostic signals being

generated, as described in section 1.1 Start-Up Sequence and in section 1.4.5 Fault Management at

Start-up.

††

Holding FLT_CLR high all time will not allow the gate driver to latch the FAULT status and migth

compromise power system protection.