SM8135B
White LED Driver IC
OVERVIEW
The SM8135B is a charge pump type white LED driver. It can drive 1 to 4 backlight white LED connected in
parallel, making it ideal for portable devices with small LCD. The charge pump switches between
×
1 bypass
mode,
×
1.5 and
×
2 boost mode in response to LED drive current requirements. The boost switching occurs in
response to the drive current of all the connected LED and thus supports variations in LED forward-bias volt-
age drop (VF). Besides, the detection of switching is repeated in approx. 1sec-cycle by mode reset action, the
SM8135B can respond to temporary variation of supply voltage. These ingenuities on switching detection can
prolong the battery life to the fullest extent. Each LED drive current is controlled by a 4-channel LED drive
current control circuit. The LED drive current per channel is setup by external resistor.
FEATURES
I
PINOUT
(Top view)
GND
NC
DIN3
DIN4
DIN2
DIN1
VOUT
C2P
C2M
PGND
C1P
C1M
ISET
EN
GND
VIN
I
I
I
I
I
I
I
I
I
I
A
3.0 ± 0.08
0.3 ± 0.1
0.5
I
1.8
C 0.3
0.22 ± 0.05
I
I
3 = 1.5 ± 0.05
I
Battery life extension by automatic charge pump
switch between
×
1,
×
1.5 and
×
2 according to the
detection of the LED drive current
Controlling 1 to 4 lights of white LED connected
in parallel
Set up LED drive current value by external resistor
(120k
Ω
: 20mA/ch)
1-wire input controlling
ON/OFF and brightness control by signal control-
ling of EN pin
Soft start circuit built-in
Thermal shut down circuit built-in
Input voltage range
No-load current (I
OUT
= 0mA): 2.7 to 4.6V
Load current (I
OUT
= 80mA): 3.0 to 4.6V
Maximum output voltage: 4.9V (typ)
Maximum output current: 80mA (typ)
Quiescent current
Not-switching (×1 mode): 0.3mA (typ)
Switching (×1.5 mode): 1.5mA (typ)
Switching (
×
2 mode): 1.5mA (typ)
Standby current: 0.01
µ
A (typ)
Operating frequency (boost mode): 1MHz (typ)
LED drive current accuracy between channel
(REST = 120k
Ω
): ± 5% (max)
Package: 16-pin QFN
PACKAGE DIMENSIONS
(Unit: mm)
TOP VIEW
3.0 ± 0.08
B
BOTTOM VIEW
1.8
0.02 S A B
0.1 ± 0.05
S
0.2 S
φ
0.05 M
S A B
APPLICATIONS
I
I
I
I
I
I
I
I
0.2 ± 0.05
Cellular phone
PDA
Portable games
Handy terminal
Digital still camera
Digital video camera
LCD panel back light
White LED driving
0.05 S
0.5
ORDERING INFORMATION
Device
SM8135BB
Package
16-pin QFN
0.7 ± 0.05
SEIKO NPC CORPORATION —1