White LED Charge Pump with Mono Class D Audio Amp and Dual LDO

Industry's First LED Charge Pump with Integrated Audio Amplifier and 2 LDOs Providing Space Savings and Highest Efficiency


The MAX8821 integrates a charge pump for white LEDs, an audio loudspeaker amplifier, and two low-noise LDOs controlled by an I²C control interface. The high-efficiency, adaptive-mode inverting charge pump drives up to six LEDs with constant current for uniform brightness. The LED current is controlled by an I²C interface and adjusts from 0.1mA to 25.6mA per LED into 32 pseudo-logarithmic steps. Independent voltages for each LED maximize efficiency even with large LED forward voltage (VF) mismatch. An internal temperature derating function reduces the current above +40°C to protect the LEDs.

The high-efficiency mono Class D audio amplifier delivers up to 2W into a 4Ω speaker from a 5V input supply. The amplifier features proprietary filterless Active Emissions Limiting (AEL) technology. AEL prevents high-frequency emissions resulting from conventional Class D free-wheeling behavior in the presence of an inductive load. The amplifier offers two modulation schemes: a fixed-frequency mode (FFM) and a spread-spectrum mode (SSM) that reduce EMI-radiated emissions due to the modulation frequency. The amplifier also has robust output protection and high power-supply rejection ratio (PSRR). Click-and-pop suppression is active during power-up/down, enable/disable, and for all mode changes. The amplifier's gain is adjustable through an I²C interface, from -3dB to +24dB in 10 3dB steps. Differential inputs improve common-mode noise rejection.

The LDOs in the MAX8821 are designed for low-noise operation. Each LDO output voltage can be individually programmed by the I²C interface. Both LDO1 and LDO2 have a high 70dB PSRR rating.

The MAX8821 includes soft-start, thermal shutdown, open-circuit, and short-circuit protections, and is available in a compact 28-pin, Thin QFN, 4mm x 4mm package (0.8mm max height).
MAX8821: Typical Operating Circuit MAX8821: Typical Operating Circuit Enlarge+

Key Features

  • White LED Inverting Charge Pump
    • Independent Adaptive Current Regulators for Each LED
    • 6 Low-Dropout Current Regulators
    • Flexible I²C Dimming Control for Each LED
    • Ramp-Up/Down, Current Control for Each LED
    • Low 70µA (typ) Quiescent Current
    • TA Derating Function Protects LEDs
  • Mono 2W Class D Loudspeaker Amplifier
    • 85% Efficiency (RL = 8Ω, POUT = 600mW)
    • Low 0.05% THD+N at 1kHz
    • High 65dB PSRR at 1kHz
    • Fully Differential Inputs
    • -3dB to +24dB Gain Settings in 3dB Steps
    • Integrated Click-and-Pop Suppression
    • Low Quiescent Current
  • Dual Low-Noise LDO
    • 45µVRMS Output Noise, 70dB PSRR
    • Flexible I²C-Controlled Output Voltages
    • 200mA and 300mA Output Current Drive


  • Cell Phones and Smartphones
  • MP3 Players, GPS Devices
  • PDAs, Digital Cameras, Camcorders
Part Number Battery Input Regulation Topology Max. No. of LEDs LED Channels LED Configuration ILED per Channel
Dimming Ratio Dimming Control POUT
LED String Volt.
Oper. Freq.
Package/Pins Budgetary
max max min max max max See Notes
MAX8821  1-Cell Li+ Charge Pump 6 4 Parallel 0.025 256 I2C Serial 0.6 2.7 5.5 0.12 5.5 1000
$2.88 @1k
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Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX8821EVKIT: Evaluation Kit for the MAX8821

Quality and Environmental Data

Request Reliability Report for: MAX8821 
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