LM4870 1.1W Audio Power Amplifier with Shutdown Mode
October 1997
LM4870
1.1W Audio Power Amplifier with Shutdown Mode
General Description
The LM4870 is a bridge-connected audio power amplifier ca-
pable of delivering 1.1W of continuous average power to an
8鈩?load with less than 0.5% THD+N over the audio spectrum
from a 5V power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal number of
external components. Since the LM4870 does not require
output coupling capacitors, bootstrap capacitors or snubber
networks, it is optimally suited for low-power portable sys-
tems.
The LM4870 features an externally controlled, low-power
consumption shutdown mode, as well as an internal thermal
shutdown protection mechanism. It also includes two head-
phone control inputs and a headphone sense output for ex-
ternal monitoring. The LM4870 is unity-gain stable and the
gain is set using external resistors.
Key Specifications
n
THD+N at 1W into 8鈩?/div>
n
Output power into 8鈩?at 1kHz
at 10%THD+N
n
Shutdown Current
0.5% (max)
1.5W (typ)
0.6碌A (typ)
Features
n
No output coupling capacitors, bootstrap capacitors, or
snubber circuits are necessary
n
Small Outline (SOIC) power packaging
n
Unity-gain stable
n
External gain configuration capability
Applications
n
Personal computers
n
Desktop computers
n
Low voltage audio system
Typical Application
Connection Diagram
Small Outline Package
DS100094-2
Top View
Order Number LM4870M
See NS Package Number M16A
DS100094-1
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer
廬
is a registered trademark of National Semiconductor Corporation.
漏 1999 National Semiconductor Corporation
DS100094
www.national.com
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