LM4851 Datasheet, PDF (1/22 Pages) National Semiconductor (TI) – Integrated Audio Amplifier System

December 2002
LM4851
Integrated Audio Amplifier System
General Description
The LM4851 is an audio power amplifier system capable of
delivering 1.1W (typ) of continuous average power into a
mono 8Ω bridged-tied load (BTL) with 1% THD+N and
115mW (typ) per channel of continuous average power into
stereo 32Ω BTL loads with 0.5% THD+N, using a 5V power
supply.
The LM4851 features a 32 step digital volume control and
eight distinct output modes. The digital volume control and
output modes are programmed through a three-wire SPI
serial control interface, that allows flexibility in routing and
mixing audio channels. The LM4851 has 3 inputs: one pair
for a two-channel stereo signal and the third for a single-
channel mono input.
The LM4851 is designed for cellular phone, PDA, and other
portable handheld applications. It delivers high quality output
power from a surface-mount package and requires only five
external components.
The industry leading micro SMD package utilizes only 2mm
x 2.3mm of PCB space, making the LM4851 the most space
efficient audio sub system available today.
Key Specifications
n THD+N at 1kHz, 1.5W into 4Ω BTL (LQ)
n THD+N at 1kHz, 1.1W into 8Ω BTL
n THD+N at 1kHz, 115mW into 32Ω BTL
n Single Supply Operation
1% (typ)
1% (typ)
0.5% (typ)
2.6 to 5.0V
Features
n Mono 1.1W (typ) and stereo 115mW (typ) output
n SPI programmable 32 step digital volume control
(-40.5dB to +6dB)
n Eight distinct SPI programmable output modes
n micro-SMD and LLP surface mount packaging
n “Click and pop” suppression circuitry
n Thermal shutdown protection
n Low shutdown current (0.1µA, typ)
Applications
n Mobile phones
n PDAs
Typical Application
FIGURE 1. Typical Audio Amplifier Application Circuit
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