SGM3122
White LED Charge Pump Current
Source with PWM Brightness Control
GENERAL DESCRIPTION
The SGM3122 is a charge pump with PWM brightness
control for white LED supplies in LCD display backlight
applications. The supply voltage ranges from 2.7V to
5.5V, it is ideally suited for all applications powered by a
single Li-ion battery cell or three to four NiCd, NiMH, or
alkaline battery cells.
The device provides a constant current for each LED,
and the initial current value can be set by an external
resistor. High efficiency is achieved by utilizing a 1×/1.5×
fractional conversion technique in combination with very
low dropout current sources.
The SGM3122 is capable of driving up to four channels of
LEDs at 30mA per channel from a 2.7V to 5.5V input.
Additionally, the current controlled charge pump ensures
low input current ripple and EMI. A low external part
count (two 0.47µF flying capacitors and two small 1µF
capacitors at VIN and VOUT) makes this part ideally
suited for small, battery-powered applications.
The SGM3122 is available in a Green TQFN-3×3-16L
package, and is rated over the -40°C to +85°C
temperature range.
FEATURES
Input Voltage Range: 2.7V to 5.5V
Drives up to 4 LEDs at 30mA Each
LED Brightness Control Through PWM Control
Signal
High Efficiency by Fractional Conversion with 1×
and 1.5× Modes
Switching Frequency: 1MHz
Regulated Output Current with 0.5% Matching
Internal Soft-Start Limits Inrush Current
Low Input Ripple and Low EMI
Over-Current and Over-Temperature Protected
Under-Voltage Lockout with Hysteresis
Available in Green TQFN-3×3-16L Package
APPLICATIONS
Cellular Phones
Smart Phones
Digital Cameras
Handheld PCs
Camcorders
PDAs
Keypad Backlight
SG Micro Corp
www.sg-micro.com
REV. A. 2
SGM3122
White LED Charge Pump Current
Source with PWM Brightness Control
PACKAGE/ORDERING INFORMATION
ORDER NUMBER
SGM3122YTQ16G/TR
PACKAGE
DESCRIPTION
TQFN-3×3-16L
SPECIFIED
TEMPERATURE
RANGE
-40°C to +85°C
PACKAGE
OPTION
Tape and Reel, 3000
MARKING
INFORMATION
3122TQ
ABSOLUTE MAXIMUM RATINGS
Supply Voltage………………….……………….……-0.3V to 6.0V
Voltage at EN1, EN2, VOUT, ISET…………..….……-0.3V to V
IN
Output Current at VOUT………….…………...……………300mA
Storage Temperature Range…………………....-65℃ to +150℃
Maximum Junction Temperature……….…...………………160℃
Operating Temperature Range...…........….……. -40℃ to +85℃
Lead Temperature (Soldering 10 sec)
……………………………………………………….…………260℃
ESD Susceptibility
HBM……………………………………...……………………4000V
MM………………………………………………………………400V
NOTE:
Stresses beyond those listed under “Absolute Maximum
Ratings” may cause permanent damage to the device. These
are stress ratings only, and functional operation of the device at
these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
CAUTION
This integrated circuit can be damaged by ESD if you don’t pay
attention to ESD protection. SGMICRO recommends that all
integrated circuits be handled with appropriate precautions.
Failure to observe proper handling and installation procedures
can cause damage. ESD damage can range from subtle
performance degradation to complete device failure. Precision
integrated circuits may be more susceptible to damage because
very small parametric changes could cause the device not to
meet its published specifications.
SGMICRO reserves the right to make any change in circuit
design, specification or other related things if necessary without
notice at any time. Please contact SGMICRO sales office to get
the latest datasheet.
SG Micro Corp
www.sg-micro.com
2
SGM3122
PIN CONFIGURATION
(TOP VIEW)
C2-
12
VIN 13
GND 14
EN1 15
EN2 16
1
2
C1-
11
White LED Charge Pump Current
Source with PWM Brightness Control
C1+ C2+
10
9
8 VOUT
GND
7 PGND
6
5
D1
D2
3
D4
4
D3
ISET NC
TQFN-3×3-16L
PIN DESCRIPTION
PIN
1
2
3-6
7
8
9
10
11
12
13
14
15
NAME
ISET
NC
D1 - D4
PGND
VOUT
C2+
C1+
C1-
C2-
VIN
GND
EN1
I/O
I
-
I
-
O
-
-
-
-
I
-
I
FUNCTION
Connect a resistor between this pin and GND to set the maximum current through the
LEDs.
No internal connection.
Current sink input. Connect the cathode of the white LEDs to these inputs.
Power ground.
Connect the output capacitor and the anode of the LEDs to this pin.
Connect to the flying capacitor C2.
Connect to the flying capacitor C1.
Connect to the flying capacitor C1.
Connect to the flying capacitor C2.
Supply voltage input.
Analog ground.
Enable input. A logic high enables the converter, logic low forces the device into
shutdown mode reducing the supply current to less than 1μA if EN2 is tied to GND.
An applied PWM signal reduces the LED current as a function of the duty cycle of the
PWM signal. EN1 and EN2 can be tied together for PWM dimming between 0mA and the
maximum set with ISET. EN1 and EN2 can also be used for digital dimming with 4 steps
from 0mA to the maximum current set with ISET.
Connect with PGND and GND.
16
—
EN2
Power
PAD
I
SG Micro Corp
www.sg-micro.com
3
SGM3122
White LED Charge Pump Current
Source with PWM Brightness Control
ELECTRICAL CHARACTERISTICS
(V
IN
= 3.6V, EN1 = EN2 = V
IN
, T
A
= 25°C, unless otherwise noted.)
PARAMETER
SUPPLY VOULTAGE AND CURRENT
Input Voltage Range
Quiescent Power Supply Current
Shutdown Supply Current
CHARGE PUMP STAGE
Overvoltage Limit
Start-Up Time
Soft-Start Duration
Switching Frequency
Efficiency
Shutdown Temperature
Shutdown Temperature Hysteresis
Input Current Limit
CURRENT SINKS
Recommended Maximum Current per
Current Sink
Current into Each Current Sink
when ISET is Shorted to GND
Current Matching between Any
Two Outputs
Line Regulation
Reference Voltage for Current Set
Recommended ISET Pin Current Range
I
DX
to ISET Current Ratio
Voltage at D
X
to GND
EN1, EN2
EN1,EN2 High Level Input Voltage
EN1,EN2 Low Level Input Voltage
EN1,EN2 Trip Point Hysteresis
EN2 Input Leakage Current
EN1 Input Leakage Current
Under-Voltage Lockout Threshold
Under-Voltage Lockout Hysteresis
Frequency Range at PWM
Recommended ON-Time for PWM Signal
Shutdown Delay Time
V
ISET
I
SET
K
V
SOURCE
EN1 = EN2 = 1, I
SET
= 100μA
I
DX
I
DX
3.2V
≤
V
IN
≤
5.5V
3.0V
≤
V
IN
≤
5.5V ISET shorted to GND
V
DX
= 3.1V, T
A
= 25℃
3V < V
IN
< 5.5V, V
LED
= 3.1V, EN1 = EN2 = 1,
I
SET
= 80μA
EN2 = 0, EN1 = 1
EN2 = 1, EN1 = 0
EN2 = 1, EN1 = 1
EN1 = EN2 = 1, ISET = 80μA
EN2 = 0, EN1 = 1
EN2 = 1, EN1 = 0
EN2 = 1, EN1 = 1
-3
SYMBOL
V
IN
I
Q
I
SD
V
OUT
CONDITIONS
I
LED
= 25mA
V
IN
= 4.2V, 1× mode, EN1 = EN2 = 1 I
SET
= 0μA
V
IN
= 4.2V, 1× mode, EN1 = EN2 = 1 I
SET
= 20μA
I
OUT
= 0mA, 1.5× mode
EN1 = EN2 = GND
LED1 unconnected V
IN
= 4.2V
C
OUT
= 1μF, I
DX
≥
0.9 × I
DX_SET
0.6
V
IN
= 3.7V, I
LED
= 15mA each, V
DX
= 3.1V
Temperature rising
MIN
2.7
100
200
2
0.1
5.3
150
130
1
83
160
20
300
30
45
0.5
0.8
200
400
600
255
200
300
400
3
TYP
MAX UNITS
5.5
V
μA
μA
mA
μA
V
μs
μs
MHz
%
℃
℃
mA
mA
mA
%
%
mV
620
130
280
μA
1
f
η
1.4
580
2
230
mV
V
IH
V
IL
I
IKG
I
IKG
V
(UVLO)
EN1, EN2 = GND or EN1, EN2 = V
IN
= 5.5V
EN1, EN2 = GND or EN1, EN2 = V
IN
= 5.5V
Input voltage falling
1.3
0.3
75
0.1
0.1
2.1
20
0
2.5
0.85
1
1
50
V
V
mV
μA
μA
V
mV
kHz
μs
ms
SG Micro Corp
www.sg-micro.com
4
SGM3122
White LED Charge Pump Current
Source with PWM Brightness Control
TYPICAL APPLICATION
C2
0.47μF
C1
0.47μF
C2-
C1-
C1+
C2+
VOUT
VIN
Li-ion
Battery
+
-
C
IN
1μF
EN1
EN2
ISET
GND
PGND
SGM3122
D4
D3
D2
D1
C
OUT
1μF
RSET
FUNCTIONAL BLOCK DIAGRAM
1µF
VOUT
C1+
0.47µF
D4
C1-
C2+
0.47µF
VIN
Charge
Pump
Current
Sinks
D3
D2
D1
C2-
1µF
Reference
Control
EN1
EN2
R
SET
PGND
GND
ISET
SG Micro Corp
www.sg-micro.com
5
PCB设计
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
