a8504 Allegro MicroSystems, Inc., a8504 Datasheet - Page 17

• Manufacturer Part Number: a8504
• Description: Wled/rgb Backlight Driver For Medium Size Lcds
• Manufacturer: Allegro MicroSystems, Inc.

A8504
Terminal List Table
Number
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
1
2
3
4
5
6
7
8
9
–
PGND
COMP
PGND
AGND
LGND
Name
FSET
LED1
LED3
LED5
LED7
LED8
LED6
LED4
LED2
SEL1
SEL2
SEL3
PWM
SKIP
ISET
GND
GND
OVP
SW
SW
VIN
EP
Power ground pin.
Reduces boost switching frequency in case of light load to improve frequency. Normally, this pin should be low; when
high, f
Compensation pin; connect external compensation network for boost converter.
Sets boost switching frequency. Connect RFSET from FSET to GND to set frequency. Range for RFSET is 13 to 40 kΩ.
Sets 100% current through LED string. Connect RISET from ISET to GND. Range for RISET is 8.45 to 30 kΩ.
Connect to AGND.
LEDx capable of 45 mA.
Power ground pin for LED current sink.
LEDx capable of 45 mA.
SEL1, SEL2, and SEL3 decide active LED strings.
Connect to AGND.
On/off and on/off LED current control with external PWM. Apply logic level PWM for PWM controlled dimming mode.
When unused, connect to AGND.
Power ground pin.
Connect to this pin to output capacitor +Ve node through a resistor to enable OVP (overvoltage protection). Default OVP
level with 0 Ω resistor is 30 V, and it can be programmed up to 47 V.
DMOS drain node.
Input supply for the IC. Decouple with a 0.1 μF ceramic capacitor.
Circuit ground pin.
Exposed pad. Electrically connected to PGND and LGND; connect to PCB copper plane for heat transfer.
SW
is divided by 4.
WLED/RGB Backlight Driver for Medium Size LCDs
COMP
PGND
FSET
LED1
SKIP
ISET
GND
Pin-out Diagram
1
2
3
4
5
6
7
(Top View)
EP
Description
21
20
19
18
17
16
15
PGND
PWM
GND
SEL3
SEL2
SEL1
LED2
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
17