Document
LM49155
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SNAS492 – JULY 2010
PRODUCT BRIEF
LM49155 Uplink Noise Suppression & Downlink
SNR Enhancement Analog Audio Subsystem
Check for Samples: LM49155
FEATURES
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•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).
Notice: This document is not a full datasheet. For more information regarding this product or to order samples please contact your local National Semiconductor sales office or visit http://www.national.com/support/dir.html
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates.
Table 1. Key Specifications
Uplink Far Field Noise Suppression Electrical FFNSE at f = 1kHz
Downlink SNR Enhancement Earpiece Amplifier
Class D Loudspeaker Amplifier RL = 15μH+8Ω+15μH POUT, THD+N ≤ %, VDD = 5.0V Headphone Amplifier RL = 32Ω POUT, THD+N ≤ %, HPVDD = 1.8V
Near-Field SNR Enhancement Downlink SNRIE
VALUE 34 6 to 18 16 1.35
19
UNIT dB (typ) dB (typ) W (typ) mW (typ)
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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners.
2
PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.
Copyright © 2010, Texas Instruments Incorporated
LM49155
SNAS492 – JULY 2010
Simplified Block Diagram
COMMUNICATIONS PROCESSOR
UPLINK NOISE SUPPRESSION
SNR ENHANCER
MONO VOLUME
STEREO VOLUME
MIXER
AGC EARPIECE AMPLIFIER
ALC
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Typical Application
MIC_BIAS VOLTAGE
Ci1 470 nF
MIC1+
MIC1Ci2 470 nF Ci3 470 nF
MIC2+ MIC2Ci4 470 nF
MIC_GND
Audio Differential
Input
Audio Single-Ended
Inputs
Ci5 68 nF
INM+ INM Ci6 68 nF
INL Ci7 0.22 µF
INR Ci8 0.22 µF
BYPASS CB 2.2 µF
I2CVDD SDA SCL
LM49155
SNAS492 – JULY 2010
2.7V to 5.5V CS1 1 µF
VDD
2.7V to 5.5V CS2 1 µF
LSVDD
PRE-AMP 12 dB to 36 dB
ANALOG UPLINK/ DOWNLINK NOISE CANCELLING PROCESSOR
and SNR ENHANCER
POST-AMP 6 dB/12 dB
4.7 µF CT1 CT2 4.7 µF CT3 4.7 µF
DCAP 4.7 µF
LPF+
CLP1
MICOUT+ MICOUT-
To Uplink Signal Path
CLP2 LPF-
AGC AMP
OUTPUT POWER LIMITER
EPOUT+ EPOUT-
VOLUME -80 dB to +18
dB
-6 dB
VOLUME -80 dB to +18
dB
Mixer and Output Mode
VOLUME -80 dB to +18
dB
BIAS
I2C INTERFACE
AUTOMATIC LEVEL
CONTROL
Class D +12 dB, +18 dB
-18 dB to
0 dB
-18 dB to
0 dB
CHARGE PUMP
LSOUT+
LSOUT-
SET
CSET
RSET
0.1 µF (Optional)
HPL
HPR
1.7V to 2.7V HPVDD
CS3 1 µF
MIC_GND
GND
CPVSS
2.2 µF
CIN
CIP
CPGND
C1 2.2 µF
Figure 1. Typical Application Circuit
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LM49155
SNAS492 – JULY 2010
Connection Diagrams
spacer spacer
TL Package (3.434mm x 3.459mm x 0.6mm)
Top View
6
5
4
3
2
1
A
B
C
D
E
F
Figure 2. Top View (Bump Side Down)
36 Bump micro SMD Marking
XXYY GN7
Bump A1
Figure 3. Top View XX .