LM3550

LM3550 PRODUCT BRIEF www.DataSheet4U.com May 1, 2009 LM3550 PRODUCT BRIEF 5A Flash LED Driver with Automatic Vf and ESR Detection for Mobile Camera Systems General Description LM3550 is a low noise, switched capacitor DC/DC converter designed to operate as a current-limited and adjustable (up to 5.3V) super-capacitor charger. LM3550 features user selectable super-capacitor charge termination voltages and an optimal charge termination mode that maximizes flash energy efficiency by accounting for flash element losses. Additionally, the device provides one adjustable constant-current output (up to 200mA) and one NFET controller ideal for driving one or more high current LEDs either in a high power Flash mode or a low power Torch mode. The LM3550 can be configured to utilize a proprietary supercapacitor charging scheme (Optimal Mode), allowing faster charging times (0 to Target Voltage) and lower current source power dissipation. Optimal Charge mode adapts to changes in the flash LEDs forward voltage as well as the supercapacitor's ESR ensuring that the super-capacitor is charged to the ideal voltage required to sustain constant current flash operation. The LED current and Flash pulse duration of the LM3550 can be programmed via an I2C compatible interface. The Strobe pin allows the Flash to be toggled via a Flash enable signal from a camera module. The EOC pin sinks current when the output voltage reaches 95% of the final value. The ALD/TEMP input pin allows either a light s...