TI Charge Pump with I²C Interface Drives Seven White LEDs

Texas Instruments Inc. (TI) introduced a high-efficiency, constant-frequency charge pump dc-dc converter that uses dual-mode conversion to maximize efficiency over the input voltage range. The 3mm x 3mm device provides a fully programmable current with I²C interface for applications, such as cellular phones, PDAs and multi-display handheld devices.

TI’s TPS60250 drives up to five white LEDs for a main display and up to two white LEDs for a sub-display with regulated constant current for uniform intensity. By utilizing adaptive charge pump modes and very low-dropout current regulators, the TPS60250 is said to achieve high efficiency over the full one-cell lithium-battery input voltage range. Four enable inputs, available through I²C, are used for simple on/off controls for the independent displays. To lower operating current when using one sub-display LED, the device provides completely separate operation in sub-display LEDs.

Among the device’s features are: 3 to 6V input voltage range; 1x and 1.5x charge pump; fully programmable current with I²C; 64 dimming steps with 25mA maximum (sub and main display banks); 4 dimming steps with 80mA maximum (DM5 for auxiliary application); 2% current matching for sub-LEDs at light load condition (each 100 µA); 750kHz charge pump frequency; continuous 230mA maximum output current; auto-switching between 1x and 1.5x mode for maximum efficiency; built-in soft start and current limit; open lamp detection; and 16-pin, 3mm x 3mm QFN.

The TPS60250 is shipping in volume production with a suggested resale price starting at $1.40 in 1,000-unit quantities.