SM8131B
White LED Driver IC
OVERVIEW
The SM8131B is a charge pump DC/DC converter that switches between
×1
and
×
1.5 automatically. The
SM8131B switches between
×
1 and
×
1.5 according to detected LED drive current, so that the battery life can
be prolonged to the fullest extent. Since the connected LED are all detected for the switching, the SM8131B
can respond to the variation of LED forward voltage. 6-channel of LED drive current control circuit is built-in,
the SM8131B can control 1 to 6 lights of white LED, which are connected in parallel. The LED drive current
per channel is set up by external resistor. Besides, by setting up SEL1/SEL2 pins, 6-channel of LED drive cur-
rent control circuit can be divided to 2-groups, and input signal controlling of EN1/EN2 pins allow ON/OFF
and dimming per group.
FEATURES
I
PINOUT
(Top view)
EN2
SEL1
SEL2
VOUT
VIN
15 14 13 12 11
I
I
I
I
I
I
I
I
I
I
I
I
I
0.05
0.05 M
I
I
I
I
I
I
I
I
Cellular phone
PDA
Portable games
Handy terminal
Digital still camera
Digital video camera
LCD back light
White LED driving
ORDERING INFORMATION
Device
SM8131B00B
Package
20-pin QFN
NIPPON PRECISION CIRCUITS INC.—1
+ 0.03
0.02
−
0.02
APPLICATIONS
0.22 ± 0.05
1.00MAX
0.22
I
Battery life extension by automatic charge pump
switch between
×
1 and
×
1.5 according to the
detection of the LED drive current
Controlling 1 to 6 lights of white LED connected
in parallel
Set up LED drive current value by external resistor
(5k
Ω
:5mA/ch, 15k
Ω
:15mA/ch, 20k
Ω
:20mA/ch)
Dividing 6-channel to 2-groups by setting up
SEL1/SEL2 pins (L/L
=
6:0ch, L/H
=
5:1ch,
H/L
=
4:2ch, H/H
=
3:3ch)
2-wire input controlling (1-wire input controlling
when SEL1/SEL2 pins are set to “LOW”)
ON/OFF and brightness control by input signal
controlling of EN1/EN2 pins
Supply voltage range
• No-load current (I
OUT
=
0mA): 2.7 to 4.6V
• Load current (I
OUT
=
120mA): 3.3 to 4.6V
Maximum output voltage: 4.2V (typ)
Maximum output current: 120mA (typ)
Quiescent current
• Not-switching (
×
1 mode): 0.7mA (typ)
• Switching (
×
1.5 mode): 2.0mA (typ)
Standby current (Power save mode): 0.01
µ
A (typ)
Operating frequency (
×
1.5 mode): 750kHz (typ)
LED drive current accuracy (RSET
=
20k
Ω
)
:20mA
±
3%
Input signal frequency for dimming (Duty
=
50
%
)
:150kHz (max)
Package:20-pin QFN
EN1
DIN6
DIN5
DIN4
GND
16
17
18
19
20
1 2 3 4 5
10
9
8
7
6
VREG
C2P
C2M
PGND
C1M
PACKAGE DIMENSIONS
(Unit: mm)
4.20 ± 0.20
4.00 ± 0.10
4.20 ± 0.20
4.00 ± 0.10
20
1
0.50
DIN3
DIN2
DIN1
ISET
C1P
0.60 ± 0.10
SM8131B
BLOCK DIAGRAM
GND
DIN4
DIN5
DIN6
EN1
DIN3
EN2
DIN2
LED current
control
Control
logic
SEL1
DIN1
SEL2
ISET
VOUT mode
controller
VOUT
C1P
1.5 Charge pump
VREG
VIN
C1M
PGND
C2M
C2P
VREG
PIN DESCRIPTION
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Name
DIN3
DIN2
DIN1
ISET
C1P
C1M
PGND
C2M
C2P
VREG
VIN
VOUT
SEL2
SEL1
EN2
EN1
DIN6
DIN5
DIN4
GND
I/O
O
O
O
I
–
–
–
–
–
–
–
O
I
I
Ip
*1
Ip
*1
O
O
O
–
Description
LED drive current control output 3
(
connect to GND when not used)
LED drive current control output 2
(
connect to GND when not used)
LED drive current control output 1
(
connect to GND when not used)
LED drive current setting resistor connection
Charge pump capacitor connection 1P
Charge pump capacitor connection 1M
Charge pump ground connection
Charge pump capacitor connection 2M
Charge pump capacitor connection 2P
LED drive current control voltage monitor
(
Don
'
t connect any lines)
Voltage supply
LED driving voltage output
Group setting data input 2
Group setting data input 1
Group B enable data input (High active)
Group A enable data input (High active)
LED drive current control output 6
(
connect to GND when not used)
LED drive current control output 5
(
connect to GND when not used)
LED drive current control output 4
(
connect to GND when not used)
Ground
*1. Input with built-in pull-down resistor
NIPPON PRECISION CIRCUITS INC.—2
SM8131B
SPECIFICATIONS
Absolute Maximum Ratings
Parameter
VIN voltage range
Input voltage range
Output voltage range
Power dissipation
Operating temperature range
Storage temperature range
Symbol
V
IN
V
EN
, V
SEL
V
DIN1 to 6
V
OUT
P
D
Ta
T
stg
Rating
−
0.3 to 6.5
V
GND
– 0.3 to V
IN
+ 0.3
V
GND
– 0.3 to V
IN
+ 0.3
6.5
1429 (Ta
=
25
°
C)
*1
–30 to 85
−
55 to 125
Unit
V
V
V
V
mW
°
C
°
C
*1.When mounted on a 34
×
40
×
1.6mm glass epoxy board, the power dissipation is related to the operating temperature by
the following equation.
I
I
I
Maximum junction temperature: T
MAX
= 125
°
C
Operating temperature: Ta [
°
C]
Thermal resistance:
θ
J
= 70
°
C/W
P
D
=
(T
MAX
−
Ta)
θ
J
1600
1429
Power dissipation [mW]
1200
1143
857
800
571
400
0
25
35
45
55
65
75
85
Operating temperature [°C]
NIPPON PRECISION CIRCUITS INC.—3
SM8131B
Electrical Characteristics
V
IN
= 3.6V, GND = 0V, Ta = 25
°
C unless otherwise noted
Rating
Parameter
Pin
Symbol
V
IN0
V
IN
Standby current
Quiescent current
Output voltage
Maximum output current
Operating frequency
Internal power-ON reset time
*1
Soft start time
LED drive pin leakage current
LED drive current
LED drive current
setting resistance
*1
Input signal frequency
*1
Input pulse width
*1
VIN
VIN
VOUT
VOUT
C1M
EN
DIN1 to 6
DIN1 to 6
DIN1 to 6
ISET
EN1/2
I
STB
I
DD1
I
DD2
V
OUT
I
OUT
f
OSC
T
POR
T
SS
I
leak1 to 6
I
LED1 to 6
RSET
f
ENIN
T
ENH
T
ENL
Hold time
EN1/2
EN1/2,
SEL1/2
EN1/2
T
CEH
V
IH
V
IL
I
IH
Condition
min
Supply voltage range
VIN
×
1.0 mode, I
OUT
=
0mA
×
1.5 mode, I
OUT
=
120mA
Power-save mode
×
1.0 mode, I
OUT
=
0mA
×
1.5 mode, I
OUT
=
0mA
×
1.5 mode, I
OUT
=
120mA
×
1.5 mode
×
1.5 mode switching frequency
Time from when power is applied
until internal circuits reset
EN startup
→
I
LED
rising edge
Power-save mode, DIN pin
=
4.2V
×1.0
mode, RSET
=
20kΩ
RSET maximum value
EN input pulse duty 50%,
maximum signal input frequency
Minimum EN pulse HIGH-level width
Minimum EN pulse LOW-level width
Time from when EN1
=
EN2
=
LOW
until LED drive circuit shutdown
HIGH-level input voltage range
LOW-level input voltage range
Pull-down pin, EN pin
=
3.6V
2.7
3.3
–
–
–
4.0
–
650
–
–
–
19.4
–
–
3.0
3.0
1.17
1.8
–
–
typ
3.6
3.6
0.01
0.7
2.0
4.2
120
750
0.05
1.3
0.01
20.0
–
–
–
–
1.37
–
–
5.0
max
4.6
4.6
1.00
1.5
4.0
4.4
–
850
1.0
5.0
1.00
20.6
50
150
–
–
1.63
–
0.6
10.0
V
V
µ
A
mA
mA
V
mA
kHz
ms
ms
µA
mA
kΩ
kHz
µs
µs
ms
V
V
µA
Unit
EN1/2
Input voltage
Input current
*1. Design guaranteed value
NIPPON PRECISION CIRCUITS INC.—4
SM8131B
V
OUT
Efficiency
100
90
V
OUT
efficiency [%]
80
70
VF = 3.2V
VF = 3.4V
VF = 3.6V
VF = 3.8V
60
50
3.2
3.4
3.6
3.8
4.0
V
IN
[V]
4.2
4.4
4.6
Efficiency of P
IN
vs. P
OUT
(LED
×
6pcs, I
LED
=
20mA, I
OUT
=
120mA)
100
90
V
OUT
efficiency [%]
80
70
VF = 3.2V
VF = 3.4V
VF = 3.6V
VF = 3.8V
60
50
3.2
3.4
3.6
3.8
4.0
V
IN
[V]
4.2
4.4
4.6
Efficiency of P
IN
vs. P
OUT
(LED
×
3pcs, I
LED
=
15mA, I
OUT
=
45mA)
NIPPON PRECISION CIRCUITS INC.—5
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