ZXLD1937 Datasheet | Zetex Semiconductors

DESCRIPTION The ZXLD1937 is a PFM inductive boost converter designed for driving 2, 3 or 4 series connected white LEDs from a Li-Ion cell and up to 8 LEDs from a 5V supply. The device operates from an input supply of between 2.5V and 5.5V and provides an adjustable output current of up to 50m A. The ZXLD1937 includes the output switch and peak current sense resistor, and can operate with a maximum output voltage of 28V. Quiescent current is typically 60␮A and a shutdown function is provided to reduce this current to less than 500n A in the 'off' state. Output current can be adjusted by applying a PWM control signal to the 'Enable' pin. Depending upon the control frequency, this will provide either a continuous or a 'chopped' output current. The PWM filter ponents are contained within the chip. The device is assembled in the TSOT23-5 pin package with 1mm maximum height profile. ADVANCED FEATURES - True Analog Dimming via PWM APPLICATIONS - Mobile phones - Digital cameras - PDAs - LCD modules - Portable internet appliances - Palmtop puters FEATURES - - - - - - - - - - 1mm height profile TSOT23-5 pin package Internal PWM filter for flicker free output High efficiency (80% typ) Wide input voltage range: 2.5V to 5.5V Up to 50m A output current Low quiescent current: (60␮A typ) 500n A maximum shutdown current Up to 1MHz switching frequency Low external ponent count Inherently matched LED currents TYPICAL APPLICATION CIRCUIT PIN CONNECTIONS ISSUE 1 - JULY 2004 1 SEMICONDUCTORS .. ORDERING INFORMATION DEVICE ZXLD1937ET5 DEVICE DESCRIPTION Boost converter in TSOT23-5 TEMPERATURE RANGE -40°C to +85°C PART MARK 1937 TAPING OPTIONS TA, TC ZXLD1937ET5TA for 7” reel of 3,000 devices ZXLD1937ET5TC for 13” reel of 10,000 devices ABSOLUTE MAXIMUM RATINGS (Voltages to GND unless otherwise stated) PARAMETER Input voltage LX output voltage Switch output current Power dissipation Operating temperature Storage temperature Junction temperature SYMBOL (V IN ) (V LX ) (I LX...