Maxim launched WLED driver MAX8821, integrated negative charge pump, D class audio amplifier and two LDO

Maxim introduces a white LED (WLED) driver integrated with a high efficiency negative charge pump, a fully differential bridge audio amplifier and a 2 low noise low dropout (LDO) current regulator (MAX8821). To maximize efficiency, the LED driver uses a negative pressure architecture that completely eliminates the internal high side switch resistance loss in the 1x mode and the 1x to 1.5x mode conversion delay during battery power supply. The MAX8821 provides an independent adaptive mode switch for each LED, which can be adjusted adaptively even when the LED forward voltage drop (VF) occurs in a large mismatch, thus further prolonging the battery life. In addition, the audio amplifier receives differential input signals, providing excellent noise suppression to improve the performance of audio reproduction. Excellent performance and high integration makes MAX8821 ideal for cellular phones, smart phones, PDA and portable media players, such as the battery life of each Ma is very important, and PCB space limited applications.

The innovative device can drive 6 WLED current matching of 1%. In order to improve the flexibility, MAX8821 supports the adoption of 32 pseudo logarithmic brightness levels through the I2C interface to control brightness. In addition, the WLED driver has a low quiescent current of 70 A, provides on-chip TA derating function, can reduce the current over +40 DEG C, prevent burn out LED. The integrated dual LDO regulator is capable of output greater than 200mA current, providing 45 V low noise and 60dB low PSRR for sensitive circuits.

MAX8821 class D audio amplifier using the bridge load (BTL) output stage, the speaker can provide 2W differential output. The output power of the device is 4 times higher than that of the traditional single ended output stage amplifier, and the output coupling capacitance is omitted. In addition, the PSRR gain of the device at 1kHz up to 65dB and provides flexible 3dB step size, -3dB to +24dB gain setting. The integration of the click / Pop beep suppression circuit in order to obtain excellent, clean sound quality guarantee.

MAX8821 offers a miniature, 4mm x x 0.8mm, 28 pin TQFN package that operates over a full -40 to +85 C expansion temperature range. Chip starts at $2.55 (1000 chips, us FOB).

Source: International Electronic Business