LED Driver has integrated Class D audio amplifier.
May 16, 2008 -
Integrating negative charge pump with fully differential Class D audio amplifier and 2 low-noise, LDO current regulators, Model MAX8821 drives 6 white LEDs with 1% accurate current matching. It employs negative architecture that eliminates high-side, in-line switch resistance loss in 1x mode, delaying 1x to 1.5x mode transitions during battery discharge. Available in 4 x 4 x 0.8 mm, 28-pin TQFN package, unit utilizes independent adaptive-mode switching for each LED to extend battery life.
Highly Integrated WLED Driver with Class D Amplifier Provides Excellent Noise Immunity and Ultra-High Efficiency
WLED Driver Combines Negative Charge Pump, Class D Audio Amp, and Two LDOs
o The MAX8821 is the first negative-charge-pump, white-LED driver to integrate a Class D audio amplifier and two low-noise, low-dropout (LDO) current regulators.
o This highly integrated device saves PCB space and reduces BOM costs.
o These benefits are enabled by the MAX8821's unique integration of a highly efficient negative charge pump, a Class D audio amplifier, and two low-noise LDO regulators.
o The MAX8821 is ideal for handheld devices in which battery life is precious and PCB space is limited.
SUNNYVALE, CA-March 10, 2008-Maxim Integrated Products (Pink Sheets: MXIM) introduces the MAX8821-the only white-LED (WLED) driver to combine a highly efficient, negative charge pump with a fully differential, bridged audio amplifier and two low-noise, low-dropout (LDO) current regulators. To maximize efficiency, this LED driver features a negative architecture that completely eliminates high-side, in-line switch resistance loss in 1x mode, delaying 1x to 1.5x mode transitions during battery discharge. The MAX8821 utilizes independent adaptive-mode switching for each LED to further extend battery life, even with large LED forward-voltage (VF) mismatching. Moreover, the audio amplifier accepts differential input signals, offering excellent noise immunity to improve audio reproduction. This superior performance and integration make the MAX8821 ideal for use in cell phones, smartphones, PDAs, and portable media players in which every milliamp-hour of battery life is precious and PCB space is limited.
This innovative device drives six WLEDs with 1% accurate current matching. To maximize flexibility, the MAX8821 supports I²C dimming control with 32 pseudo-logarithmic dimming levels. Additionally, this WLED driver achieves low, 70µA quiescent current, and features an on-chip, TA derating function that reduces the current above +40°C to prevent the LEDs from burning out. The integrated, dual LDO regulators deliver over 200mA of current output with low, 45µV noise and high, 70dB PSRR for sensitive circuitry.
The MAX8821's Class D audio amplifier delivers 2W to the speaker differentially by the use of a bridge-tied load (BTL) output stage. This provides up to four times more output power than a conventional, single-ended output stage and eliminates the need for an output-coupling capacitor. At 1kHz, the MAX8821's amplifier achieves a high 65dB PSRR. Through an I2C interface, the gain is adjustable from -3dB to +24dB in ten 3dB steps. Integrated click-and-pop suppression circuitry ensures rich, clean sound quality.
The MAX8821 is available in a tiny, 4mm x 4mm x 0.8mm, 28-pin TQFN package and is fully specified over the -40°C to +85°C extended temperature range. Prices start at $2.55 (1000-up, FOB USA).
Maxim Integrated Products, a two billion dollar company, designs and manufactures ICs for analog and mixed-signal applications. The company's broad portfolio of 27 product categories is among the industry's deepest, with over 5400 products.
Customer Service: 1-800-998-8800 Company Information: Name: Maxim Integrated Products Address: 120 San Gabriel Dr. City: Sunnyvale State: CA ZIP: 94086 Country: USA Phone: 408-737-7600 FAX: 408-737-7194 http://www.maxim-ic.com
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