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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 a 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 (ENx, where x indicates LED bank A or B). 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 25 mA per LED.

No internal switching signals are used, eliminating troublesome electromagnetic interference (EMI). The TPS7510x is offered in an ultra-small, 9-ball, 0.4-mm ball-pitch wafer chip-scale package (WCSP) and a 2.50-mm × 2.50-mm, 10-pin WSON package, yielding a very compact total solution size ideal for mobile handsets and portable backlighting applications. The device is fully specified over T_J = –40°C to +85°C.