Product category: Analogue and Mixed Signal ICs
News Release from: National Semiconductor | Subject: LM4670 and LM4671
Edited by the Electronicstalk Editorial Team on 17 March 2005
Audio amplifiers promise flexible design
Two new high-efficiency Class D audio amplifiers are housed in tiny micro SMD packages and feature externally configurable gain for space savings and flexibility in design.
National Semiconductor has added two new high-efficiency Class D audio amplifiers to its expansive Boomer portfolio These new audio amplifiers are housed in tiny micro SMD packages and feature externally configurable gain for space savings and flexibility in design
This article was originally published on Electronicstalk on 5 Jan 2001 at 8.00am (UK)
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These two parts are ideal for applications such as cellular phones, PDAs and other portable electronic devices.
"National continues to flex its analogue muscles with its new Class D audio amplifiers", said Mike Polacek, Vice President of National Semiconductor's Audio group.
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"With features such as small footprint, high power, high efficiency and flexible gain settings, National's LM4670 and LM4671 give customers the performance required for portable applications that continually expand in feature and power requirements".
National Semiconductor's LM4670 is a 3W and the LM4671 is a 2.5W fully integrated single-supply, high-efficiency switching audio amplifier.
They feature innovative modulation schemes that eliminate the output filter used with typical switching amplifiers.
Eliminating the output filter reduces external component count, simplifies circuit design and reduces board area.
The LM4670 processes analogue inputs with a delta-sigma modulation technique that lowers output noise and total harmonic distortion (THD).
Due to its high output power, the LM4670 is optimised for ultra high-power push-to-talk, push-to-talk over cellular (PoC) and hands-free use.
The LM4671 processes analogue inputs with a pulse width modulation technique that results in lower output noise, making it well suited for earpiece/receiver applications as well as normal high-power ringer and hands-free operation.
Operating on a single 5V supply, the LM4670 and LM4671 are capable of driving a 4ohm speaker load at a continuous average output of 2.3W with less than 1% total harmonic distortion plus noise (THD+N).
Flexible power supply requirements of these parts allow operation from 2.4 to 5.5V.
The LM4670 and LM4671 have high efficiency with speaker loads compared with typical Class AB amplifiers.
With a 3.6V supply driving an 8ohm speaker, the amplifier's efficiency is 88% at 600mW output power.
Additionally, the LM4670 and LM4671 feature a low power consumption shutdown mode.
Shutdown may be enabled by driving the shutdown pin to a logic low level.
Gain is externally configurable to allow the user to sum multiple inputs while optimising the gain for each source.
Available now in 9-bump micro SMD packages, the LM4670 and LM4671 are priced at $0.48 in 1000-unit quantities.
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