Maxim Announces New Negative-Charge-Pump, WLED Driver

Maxim Integrated Products introduced the MAX8678, which the company claims is the industry’s only white-LED (WLED) driver to combine a highly efficient negative charge pump with a fully differential, bridged audio amplifier. Available in a tiny, 3mm x 3mm x 0.8mm, TQFN package, this single-chip solution is said to be 50% smaller than the standard two-chip solution.

The MAX8678 features a negative architecture that completely eliminates high-side in-line resistance, delaying 1x to 2x mode transition during battery discharge. The independent adaptive-mode switching for each LED further extends battery life, even with large LED forward-voltage (Vf) mismatch. These features make the MAX8678 suitable for use in cell phones, smartphones, PDAs, and other handheld devices in which space and battery life are precious.

The MAX8678 is said to be the only WLED driver to seamlessly integrate a mono, Class AB audio amplifier. This audio amplifier accepts differential input signals and is said to offer excellent noise immunity to improve audio reproduction. It also delivers 1.1W to the speaker differentially through a bridge-tied-load (BTL) output stage. This provides up to four times more output power than a conventional, single-ended output stage, thus eliminating the need for output-coupling capacitors and further minimizing external component count. The amplifier achieves a superb 90dB PSRR at 1kHz. Moreover, it features a flexible, single-wire, serial pulse interface to realize gain settings from -9dB to +18dB in 3dB steps, and it integrates click-and-pop suppression for clean sound quality.

The MAX8678 is fully specified for the extended temperature range (-40° to +85°C). Prices start at $1.65 (2500-up, FOB USA).