Serial-Input, Constant-Current Latched

LED Drivers with Open LED Detection

A6279

6

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

A6278, n = 7

A6279, n = 15

CLOCK

OUTPUT

ENABLE

LATCH

ENABLE

CLOCK

OUTPUT

ENABLE

LATCH

ENABLE

CLOCK

OUTPUT

ENABLE

SERIAL

DATA OUT

Don't Care

1

1

2

3

12

3

SDO n

SDO n-1

SDO n-2SDO 0

(A) To enter LED OCD mode, a minimum of one CLOCK pulse is required after LATCH ENABLE is brought back low.

(B) To output the latched error code, OUTPUT ENABLE must be held low a minimum of 3 CLOCK cycles.

(C) When returning to Normal mode, a minimum of three CLOCK pulses is required after OUTPUT ENABLE is brought back high.

Normal Mode Timing Requirements

LED Open Circuit Detection (Test) Mode Timing Requirements

01

n

CLOCK

A6278, n = 7

A6279, n = 15

SERIAL

DATA IN

SDI n

SDI n-1

SDI 0

Don't Care

SDO n

SERIAL

DATA OUT

LATCH

ENABLE

OUTPUT

ENABLE

OUT0

Don't Care

OUT1

OUTn

Don't Care

Don't Care

t

low

t

high

t

t

p(DO)

t

t

W(OE)

t

P(OE)

t

D

t

D(Total)

t

P(OE)

t

D

t

D(Total)

t

SU(OE)