1FEATURES

2? Noise cancellation for uplink and downlink

without DSP-type artifacts, distortions or

delays

? Adapting AGC on ambient noise level &

downlink signal strength for earpiece

? Downlink adjustable noise-reducing high pass

filter

? E2S Class D Amplifier with ALC

? Ground Referenced Headphone Outputs with

Advanced Click Pop Suppression

? Micro-power shutdown

APPLICATIONS

? Mobile Phones

? Portable Electronic Devices

DESCRIPTION

The LM49155 is a fully integrated audio subsystem designed for portable handheld applications such as cellular

phones. The LM49155 combines a Noise Suppression microphone amplifier, a 1.35W mono class D amplifier

with ALC, class AB earpiece driver with AGC, a high efficiency, stereo, ground referenced headphone amplifier

with click pop suppression and I2C modes select and volume control.

The LM49155 features analog fully differential input, and differential output microphone amplifier designed to

reduce background acoustic noise, while delivering superb speech clarity in voice communication applications.

Downlink SNR enhancement with an advanced acoustic AGC technology to adjust output levels.

The LM49155 speaker amplifier features National’s unique output limiter that provides both a no-clip feature and

speaker protection. The E2S class D amplifier features a patented, ultra low EMI PWM architecture that

significantly reduces RF emissions while preserving audio quality and efficiency. The headphone drivers feature

National’s ground referenced architecture that creates a ground-referenced output from a single, low-voltage

supply.

The LM49155 is available in an ultra-small 36-bump micro SMD package (3.434mm x 3.459mm x 0.6mm).