LT3518 Full-Featured LED Driver with 2.3A Switch Current FEATURES DESCRIPTION
The LT®3518 is a current mode DC/DC converter with an internal 2.3A, 45V switch specifically designed to drive LEDs. The LT3518 operates as a LED driver in boost, buck mode and buck-boost mode. It combines a traditional voltage loop and a unique current loop to operate as a constant-current source or constant-voltage source. Programmable switching frequency allows optimization of the external components for efficiency or component size. The switching frequency of the LT3518 can be synchronized to an external clock signal. The LED current is externally programmable with a 100mV sense resistor. The external PWM input provides 3000:1 LED dimming. The CTRL pin provides further 10:1 dimming ratio. The LT3518 is available in the tiny footprint 16-lead QFN (4mm Ч 4mm) and the 16-pin TSSOP package. The LT3518 provides a complete solution for both constant-voltage and constant-current applications.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. True Color PWM is a trademark of Linear Technology Corporation. Patent Pending. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 7199560, 7321203, 7746300. 3000:1 True Color PWMTM Dimming Ratio 2.3A, 45V Internal Switch 100mV High Side Current Sense Open LED Protection Adjustable Frequency: 250kHz to 2.5MHz Wide Input Voltage Range: Operation from 3V to 30V Transient Protection to 40V Operates in Boost, Buck Mode and Buck-Boost Mode Gate Driver for PMOS LED Disconnect Constant-Current and Constant-Voltage Regulation CTRL Pin Provides 10:1 Analog Dimming Low Shutdown Current: <1A Available in (4mm Ч 4mm) 16-Lead QFN and 16-Pin TSSOP Packages APPLICATIONS Display Backlighting Automotive and Avionic Lighting Illumination Scanners TYPICAL APPLICATION
1.5A Buck Mode LED Driver
100 CTRL = VREF PVIN 24V 68m 2.2F ISP VIN SHDN LT3518 VREF PWM CTRL PWM FB SS 40 0 16.9k 1MHz 0.1F
3518 TA01a Efficiency
10F M1 90 EFFICIENCY (%) 80 70 60 50 1.5A 15H ISN TG SW VIN 3.3V 2.2F SYNC RT TGEN VREF VC GND 0.1F 20 40 60 80 PWM DUTY CYCLE (%) 100
3518 TA01b 3518fe 1 LT3518 ABSOLUTE MAXIMUM RATINGS
(Note 1) VIN, SHDN, PWM, TGEN (Note 3).40V SW, ISP ISN, TG .45V , TG Pin Below ISP Pin .10V FB, SYNC, SS, CTRL .6V VC, RT, VREF .3V Operating Junction Temperature Range (Notes 2, 4) LT3518E . 40°C to 125°C LT3518I . 40°C to 125°C LT3518H . 40°C to 150°C Storage Temperature Range QFN. 65°C to 150°C TSSOP . 65°C to 150°C Lead Temperature (Soldering, 10 sec) TSSOP . 300°C PIN CONFIGURATION …
