The LM4904 is an audio power amplifier primarily designed for demanding applications in mobile phones and other portable communication device applications. It is capable of delivering 1 watt of continuous average power to an 8Ω BTL load with less than 1% distortion (THD+N) from a 5VDC power supply. The LM4904 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for mobile phone and other low voltage applications where minimal power consumption is a primary requirement. It features a low-power consumption shutdown mode and an internal thermal shutdown protection mechanism.
The LM4904 audio power amplifier is designed for mobile phones, PDAs and other portable communication devices, delivering 1 W continuous average power into an 8 Ω BTL load with less than 1 % THD+N. It operates from a 2.0 V to 5.5 V supply and includes built‑in shutdown and thermal protection.
Key features include a space‑saving 8‑bump micro‑SMD package, no need for output coupling or bootstrap capacitors, unity‑gain stability, and external gain‑setting resistors. Typical performance data show low distortion across a wide frequency range and good power‑supply rejection.
| Typical Output Power (5 V, 1 % THD, 8 Ω) | 1.07 W (typ) |
|---|---|
| Quiescent Power Supply Current (No Load) | 2.7 mA (max) |
| Shutdown Voltage Input High | 1.5 V (min) |
| Output Offset Voltage | 50 mV (max) |
| Power Supply Rejection Ratio (217 Hz) | 55 dB (min) |
The LM4904 delivers about 1.07 W (typ) into an 8 Ω load with 1 % THD.
It operates from 2.0 V to 5.5 V supply voltage.
The shutdown pin must be driven high; the input high threshold is at least 1.5 V.
The device draws up to 2.7 mA (max) with no load.