GENERAL DEscriptION
The SGM3758 is a high efficiency white LED driver with a 1.2MHz boost converter. With the fixed switchingfrequency and an internal 40V/3A switch FET, the SGM3758 is designed for powering single or parallel LED strings for various size panel backlighting and ideal for smart phone image capture using display device as a flash mode light source, as it is capable of driving up to 200mA current at 30V for 320ms when the strobe signal is active.
The FB feedback voltage is regulated at 200mV typically. The backlight mode default LED current is programmed by an external RSET resistor. During the operation, the LED current can be controlled by applying a PWM signal to the CTRL pin. The feedback voltage depends on the PWM signal duty cycle. For PWM dimming control, there are no audible noises on the output capacitor.
The SGM3758 integrates LED open protection. It prevents the device from damaging due to the overvoltage during LED open conditions.
When the device is in operation and the STROBE pin is pulled up, the SGM3758 will enter flash mode within 100μs. The feedback voltage is regulated to 5× of the backlight mode voltage that is determined by the PWM signal duty cycle. When the STROBE pin is pulled down or the strobe signal remains high for longer than the 320ms timer, the SGM3758 will enter backlight mode within 100μs.
The SGM3758 is available in a Green TDFN-2×2-6L package. It operates over an ambient temperature range of -40℃ to +85℃.
FEATURES
Input Voltage Range: 2.7V to 5.5V
Integrated 40V/3A Switch
Up to 200mA Output Current at 30V
Accumulated 320ms Flash Timer Control
Switching Frequency: 1.2MHz
PWM Dimming Control
PWM Dimming Frequency: 20kHz to 100kHz
Strobe Interface for Image Capture Mode
Up to 87% Efficiency for 7S2P LEDs
Up to 92% Efficiency for 3S20P LEDs
Dimming Stable in 1:500 Range
Feedback Voltage
Backlight Mode: 200mV
Flash Mode: 1000mV
Flash Mode Under-Voltage Lockout
Automatic Soft-Start for Reducing Inrush Current
PFM Mode at Light Load
Protection Features
38V Over-Voltage Protection
LED Open or Short Protection
Thermal Shutdown
-40℃ to +85℃ Operating Temperature Range
Available in a Green TDFN-2×2-6L Package
APPLICATIONS
PDAs, Handheld Computers
Backlight for Media Form Factor LCD Displays with 1-Cell Battery Input