MAX8678 is an integrated white LED charge pump with an audio loudspeaker amplifier. It has high efficiency, adaptive mode switching, and can drive multiple LEDs with constant current for uniform brightness. Through a single-wire serial-pulse interface, the LED current can be adjusted in the range of 0.1mA-24mA in 31 pseudo-logarithmic steps, and the LED current is accurate and well matched throughout the adjustment range. MAX8678 also integrates a single-channel AB class audio amplifier, which can directly drive an 8Ω loudspeaker and obtain 1.1W RMS continuous output power from a 5V power supply with a THD+N of less than 1%. The gain can be adjusted in the range of -9dB to +18dB in ten 3dB steps through a single-wire serial-pulse interface. MAX8678 also has soft-start, thermal shutdown, open-circuit and short-circuit protection, and is packaged in a 16-pin, 3mm x 3mm Thin QFN package (maximum height of 0.8mm).
The MAX8678 integrates a high‑efficiency charge pump for up to four white LEDs and a mono class‑AB audio amplifier that drives an 8 Ω loudspeaker with up to 1.1 W RMS output. LED current is programmable from 0.1 mA to 24 mA per LED in 31 pseudo‑logarithmic steps via a single‑wire serial‑pulse interface, while the audio gain is adjustable from –9 dB to +18 dB in 3 dB steps.
The device is supplied in a 16‑pin thin QFN package (3 mm × 3 mm) and includes protection features such as soft‑start, thermal shutdown at +160 °C, and over‑current protection. Detailed electrical characteristics, pin descriptions, and typical operating curves are provided for design reference.
| LED current range | 0.1 mA to 24 mA per LED |
|---|---|
| Audio amplifier gain range | -9 dB to +18 dB |
| Supply voltage range (IN) | 2.7 V to 5.5 V |
| Switching frequency | 1 MHz |
| Thermal shutdown temperature | +160 °C |
The LED current can be set from 0.1 mA up to 24 mA per LED in 31 pseudo‑logarithmic steps.
The audio amplifier gain is programmable from –9 dB to +18 dB in ten 3 dB steps.
It is offered in a 16‑pin thin QFN package measuring 3 mm × 3 mm with a maximum height of 0.8 mm.
The device includes soft‑start, thermal shutdown, open‑circuit and short‑circuit protection.