The MAX4409 stereo headphone amplifier combines Maxim’s DirectDrive™ architecture and a common-mode sense input, which allows the amplifier to reject common-mode noise. Conventional headphone amplifiers require a bulky DC-blocking capacitor between the headphone and the amplifier. DirectDrive produces a ground-referenced output from a single supply, eliminating the need for large DC-blocking capacitors, which saves cost, board space, and component height. The common-mode voltage sensing corrects for any difference between SGND of the amplifier and the headphone return. This feature minimizes ground-loop noise when the HP socket is used as a line out connection to other grounded equipment, for example, a PC connected to a home hi-fi system. The MAX4409 draws only 5mA of supply current, delivers up to 80mW per channel into a 16Ω load, and has a low 0.002% THD+N. A high 86dB power-supply rejection ratio allows this device to operate from noisy digital supplies without additional power-supply conditioning. The MAX4409 includes ±8kV ESD protection on the headphone outputs. Comprehensive click-and-pop circuitry eliminates audible clicks and pops on startup and shutdown. A low-power shutdown mode reduces supply current draw to only 6µA. The MAX4409 operates from a single 1.8V to 3.6V supply, has short-circuit and thermal overload protection, and is specified over the extended -40°C to +85°C temperature range. The MAX4409 is available in tiny 20-pin package.
The MAX4409 is a stereo headphone amplifier that uses Maxim’s DirectDrive architecture and a common‑mode sense input to eliminate the need for bulky DC‑blocking capacitors and to suppress ground‑loop noise. It operates from a single 1.8 V to 3.6 V supply, draws only 5 mA in normal mode, and offers a low 0.002 % THD+N.
The device is available in a 14‑pin TSSOP or a 20‑pin thin QFN package, provides +8 kV ESD protection on the outputs, and includes click‑and‑pop suppression circuitry. Typical applications include notebooks, desktop PCs, cellular phones, PDAs, MP3 players, tablet PCs and other portable audio equipment.
| Supply Voltage Range | 1.8 V – 3.6 V |
|---|---|
| Quiescent Supply Current | 5 mA |
| Shutdown Supply Current | 6 µA |
| Total Harmonic Distortion + Noise (THD+N) | 0.002 % (typical) |
| Power‑Supply Rejection Ratio (PSRR) | 86 dB (typical) |
| Common‑Mode Rejection Ratio (CMRR) | 96 dB (typical) |
| ESD Protection on Outputs | +8 kV |
| Operating Temperature Range | ‑40 °C to +85 °C |
| Package Options | 14‑Pin TSSOP, 20‑Pin Thin QFN (4 mm × 4 mm × 0.8 mm) |
The MAX4409 operates from a single supply voltage between 1.8 V and 3.6 V.
The device draws a typical quiescent supply current of 5 mA.
Yes, the headphone outputs are protected with +8 kV ESD rating.