The LM4926 is a ground referenced, ultra low noise, fixed gain, 80mW stereo headphone amplifier from TI. The chip utilizes a new circuit technology that uses a charge pump to generate a negative reference voltage. This allows the outputs to be biased about ground, thereby eliminating output-coupling capacitors typically used with normal single-ended loads. The LM4926 also features an Automatic Standby Mode circuitry (patent pending). When there is no input signal, after about 12 seconds, the LM4926 will enter low current standby mode. When an input signal is applied to either the left or right input pins, the LM4926 will immediately resume full power operation mode. This feature saves power supply current in battery-operated applications.
The LM4926 is a ground‑referenced, fixed‑gain audio power amplifier delivering 80 mW into a 16 Ω load with less than 1 % THD+N from a 3 V supply. It uses a charge‑pump to generate a negative reference, eliminating the need for output‑coupling capacitors, and includes automatic standby, independent channel shutdown, and pop‑and‑click reduction circuitry.
Designed for low‑power mobile applications, the device operates from 1.6 V to 4.2 V, supports independent shutdown of each channel, and is offered in a space‑saving micro‑SMD package. Typical applications include notebook PCs, mobile phones, PDAs, MP3 players, and other portable electronics.
| Internal Fixed Gain | 1.5 V/V (typ) |
|---|---|
| Operating Voltage | 1.6 V to 4.2 V |
| Shutdown Current | 0.01 µA (typ) |
| Power Supply Rejection Ratio (PSRR) | 70 dB at 217 Hz (typ) |
After about 12 seconds without an input, the LM4926 enters a low‑current standby mode and resumes full power instantly when a signal is applied to either channel.
No, the ground‑referenced outputs eliminate the need for output‑coupling or bootstrap capacitors.
The LM4926 has a fixed internal gain of 1.5 V/V.
It operates from 1.6 V up to 4.2 V.