The TPS7510x linear low dropout (LDO) matching LED current source is optimized for low power keypad and navigation pad LED backlighting applications. The device provides a constant current to up to four unmatched LEDs organized in two banks of two LEDs each in a common-cathode topology. Without an external resistor, the current source defaults to factory-programmable, preset current level with ±0.5% accuracy (typical). An optional external resistor can be used to set initial brightness to user-programmable values with higher accuracy. Brightness can be varied from off to full brightness by inputting a pulse width modulation (PWM) signal on each Enable pin. Each bank has independent enable and brightness control, but current matching is done to all four channels concurrently. The input supply range is ideally suited for single-cell Li-Ion battery supplies and the TPS7510x can provide up to 25mA per LED.
No internal switching signals are used, eliminating troublesome electromagnetic interference (EMI). The TPS7510x is offered in an ultra-small, 9-ball, 0.4mm ball-pitch wafer chip-scale package (WCSP) and a 2,5mm × 2,5mm, 10-pin SON package, yielding a very compact total solution size ideal for mobile handsets and portable backlighting applications. The device is fully specified over TJ = –40°C to +85°C.
Regulated Output Current with 2% LED-to-LED Matching
Drives Up to Four LEDs at 25mA Each in a Common Cathode Topology
28mV Typical Dropout Voltage Extends Usable Supply Range in Li-Ion Battery Applications
Brightness Control Using PWM Signals
Two 2-LED Banks with Independent Enable and PWM Brightness Control per Bank
No Internal Switching Signals—Eliminates EMI
Default LED Current Eliminates External Components
Default values from 3mA to 10mA (in 1mA increments) available using innovative factory EEPROM programming
Optional external resistor can be used for high-accuracy, user-programmable current
Over-Current and Over-Temperature Protection
Available in Wafer Chip-Scale Package or 2,5mm × 2,5mm SON-10