LM4830 Datasheet, PDF (1/14 Pages) National Semiconductor (TI) – Two-Way Audio Amplification System with Volume Control

January 1999
LM4830
Two-Way Audio Amplification System
with Volume Control
General Description
The LM4830 is an integrated solution for two-way audio am-
plification. It contains a bridge-connected audio power ampli-
fier capable of delivering 1W of continuous average power to
an 8Ω load with less than 1% THD from a 5V power supply.
It also has the capability of driving 100 mW into a
single-ended 32Ω impedance for headset operation. There
is a 30 dB attenuator in front of a bridged power amplifier
with 6 dB of gain. The attenuation is controlled through 4 bits
of parallel digital control; 15 steps of 2 dB each.
The device also contains a microphone preamp with two se-
lectable inputs. Mic2 is selected when HS is high and A1 is in
single-ended mode. Mic1 is selected when HS is low and A1
is in bridged mode. This configuration is optimum for switch-
ing between an internal system speaker and external head-
set with microphone. The device also incorporates a buffer
used for driving capacitive loads.
The LM4830 also provides a low-current consumption shut-
down mode making it optimally suited for low-power portable
systems. In addition, the device has an internal thermal shut-
down protection mechanism.
Key Specifications
n THD at 1W cont. avg P_O into 8Ω: 1% (max)
n Instantaneous peak output power: 1.4W
n Shutdown current: 0.5 µA (typ)
n Supply voltage range: 2.7V ≤ V _DD ≤ 5.5V
Features
n 4-bit digital control for 30 dB of volume attenuation
n Two selectable microphone inputs
n High performance microphone preamp
n Extra buffer for driving long cables
n No bootstrap capacitors or snubber circuits are
necessary
n Small Outline (SO) packaging
n Thermal shutdown protection circuitry
Applications
n Hands-free phone systems
n Mobile phone accessories
n Desktop conference phones
n Portable computers
n Teleconference computer applications
Connection Diagram
Dual-In-Line and
Small Outline Packages
DS012677-2
Top View
Order Number LM4830M
See NS Package Number M24B for SO
Order Number LM4830N
See NS Package Number N24A for DIP
© 1999 National Semiconductor Corporation DS012677
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