SGM3122 Datasheet, PDF (1/17 Pages) SG Micro Corp – PWM Brightness Control

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
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