The MAX9709 is a stereo/mono Class D audio power amplifier that provides up to 2 x 25W output power in 8Ω stereo mode and up to 1 x 50W output power in 4Ω mono mode. The product offers high efficiency of up to 87% and combines Class AB amplifier performance with the efficiency advantages of Class D, eliminating the need for a bulky heatsink and conserving power. The MAX9709 operates from a single +10V to +22V supply and drives the load in a BTL configuration. It offers two modulation schemes: fixed-frequency modulation (FFM) mode and spread-spectrum modulation (SSM) mode, which reduces EMI-radiated emissions. The MAX9709 can be synchronized to an external clock from 600kHz to 1.2MHz, and synchronized output allows multiple units to be cascaded in the system. Features include fully differential inputs, comprehensive click-and-pop suppression, and four selectable-gain settings (22dB, 25dB, 29.5dB, and 36dB). A pin-programmable thermal flag provides seven different thermal warning thresholds. Short-circuit and thermal-overload protection prevent the device from being damaged during a fault condition. The MAX9709 is available in 56-pin TQFN (8mm x 8mm x 0.8mm) and 64-pin TQFP (10mm x 10mm x 1.4mm) packages, and is specified over the extended -40°C to +85°C temperature range.
The MAX9709 stereo/mono Class D audio power amplifier delivers up to 2 × 25 W into an 8 Ω load in stereo mode and 1 × 50 W into a 4 Ω load in mono mode, providing Class AB performance with Class D efficiency. It operates from a single +10 V to +22 V supply and includes fully differential inputs, click‑and‑pop suppression, and programmable gain settings.
The device offers two modulation schemes—fixed‑frequency and spread‑spectrum—reduces EMI, and can be synchronized to an external clock from 600 kHz to 1.2 MHz. It is available in 56‑pin TQFN and 64‑pin TQFP packages and is specified over –40 °C to +85 °C temperature range.
| Stereo output power | 2 × 25 W into 8 Ω |
|---|---|
| Mono output power | 1 × 50 W into 4 Ω |
| Efficiency | Up to 87 % |
| Operating temperature range | -40 °C to +85 °C |
| Gain settings | +22 dB, +25 dB, +29.5 dB, +36 dB |
| Power‑supply rejection ratio (PSRR) | 90 dB at 1 kHz |
| THD+N | 0.1 % (typical) |
| Clock synchronization range | 600 kHz to 1.2 MHz |
The MAX9709 can deliver 2 × 25 W into an 8 Ω load in stereo mode.
It operates from a single supply voltage of +10 V to +22 V.
The device achieves up to 87 % efficiency.
Four programmable gain settings are provided: +22 dB, +25 dB, +29.5 dB, and +36 dB.