A8508GLWTR-T View Datasheet(PDF) - Allegro MicroSystems

Part Name

Description

MFG CO.

A8508GLWTR-T

Wide Input Voltage Range, High Efficiency 8-Channel Fault Tolerant LED Driver

Allegro MicroSystems 

A8508

Wide Input Voltage Range, High Efficiency

8-Channel Fault Tolerant LED Driver

Pin-out Diagrams

VDD 1

NC 2

FAULT 3

OVP 4

HVGATE 5

VSENSE 6

VIN 7

21 GATE

20 SENP

19 SENN

PAD

18 PGND

17 LED1

16 LED2

15 LED3

ET Package

SENN 1

24 PGND

SENP 2

23 LED1

GATE 3

22 LED2

VDR 4

21 LED3

COMP 5

20 LED4

MODE 6

PAD

19 AGND

EN 7

18 LED5

PWM 8

17 LED6

FSET/SYNC 9

16 LED7

ISET 10

15 LED8

VDD 11

14 VIN

FAULT 12

13 OVP

LP Package

SENN 1

SENP 2

GATE 3

VDR 4

COMP 5

MODE 6

EN 7

PWM 8

FSET/SYNC 9

ISET 10

VDD 11

FAULT 12

24 PGND

23 LED1

22 LED2

21 LED3

20 LED4

19 AGND

18 LED5

17 LED6

16 LED7

15 LED8

14 VIN

13 OVP

LW Package

Terminal List Table

Name

Number

ET

LP, LW

AGND

13

19

COMP

23

5

EN

25

7

¯F¯ ¯A ¯U ¯¯L¯ ¯T¯

3

12

FSET/SYNC 27

9

GATE

21

3

HVGATE

5

n.a.

ISET

28

10

LED1

17

23

LED2

16

22

LED3

15

21

LED4

14

20

LED5

10

18

LED6

8

17

LED7

11

16

LED8

12

15

MODE

24

6

OVP

4

13

PAD

–

–

PGND

18

24

PWM

26

8

SENN

19

1

SENP

20

2

VDD

1

11

VDR

22

4

VIN

7

14

VSENSE

6

n.a.

Function

LED ground.

Output of the error amplifier and compensation node. Connect a compensation network from this pin to ground.

Enable for the A8508.

This pin is used to indicate a fault condition. Connect a pull-up resistor between this pin and the required logic level

voltage. The pin is an open drain type configuration that will be pulled low when a fault occurs.

Frequency/synchronization pin. A resistor RFSET from this pin to ground sets the switching frequency. This pin can also

be used to synchronize two or more converters in the system.

Gate pin for driving external N-channel FET.

Input disconnect switch: gate driver

Connect the RISET resistor between this pin and ground to set the 100% LED current.

Connect the cathode of each LED string to these pins.

This pin is used to determine the mode of operation. MODE high tied to VDD allows parallel operation, and MODE low is

used for single IC operation.

This pin is used to sense an Overvoltage (OVP) condition. Connect the ROVP resistor from VOUT to this pin to adjust

the overvoltage protection.

For QFN and TSSOP packages, this exposed pad provides enhanced thermal dissipation. This pad must be connected

to the ground plane(s) of the PCB with at least 8 vias, directly in the PAD solder pad.

Power ground for the internal gate driver circuit.

PWM dimming pin. Used to control the LED intensity by using pulse width modulation. The typical PWM dimming

frequency is in the range of 100 to 1000 Hz.

Negative sense line for boost switch current sensing.

Positive sense line for boost switch current sensing.

Output of internal LDO regulator. Connect a 0.1 μF decoupling capacitor between this pin and ground.

Output of the gate driver bias voltage regulator. Connect a 0.22 μF capacitor in series with a 7.5 Ω resistor between this

pin and ground.

Input power to the A8508.

Input disconnect switch: current sense

Allegro MicroSystems, Inc.

4

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

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