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).