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LM4949 Stereo Class D Audio Subsystem with OCL Headphone Amplifier
September 2006
LM4949 Stereo Class D Audio Subsystem with OCL Headphone Amplifier
General Description
The LM4949 is a fully integrated audio subsystem designed for stereo cell phone applications. The LM4949 combines a 2.5W stereo Class D amplifier plus a separate 190mW stereo headphone amplifier, volume control, and input mixer into a single device. The filterless class D amplifiers deliver 1.19W/channel into an 8Ω load with < 1% THD+N from a 5V supply. The headphone amplifier features National’s Output Capacitor-less (OCL) architecture that eliminates the output coupling capacitors required by traditional headphone amplifiers. Additionally, the headphone amplifiers can be configured with capacitively coupled (CC)loads, or used to drive an external headphone amplifier. When configured for an external amplifier, the VDD/2 output (VOC) controls the external amplifier’s shutdown input. For improved noise immunity, the LM4949 features fully differential left, right and mono inputs. The three inputs can be mixed/multiplexed to either the speaker or headphone amplifiers. The left and right inputs can be used as separate single-ended inputs, mixing multiple stereo audio sources. The mixer, volume control, and device mode select are controlled through an I2C compatible interface. Output short circuit and thermal shutdown protection prevent the device from being damaged during fault conditions. Superior click and pop suppression eliminates audible transients on power-up/down and during shutdown.
Key Specifications
j Efficiency VDD = 3.6V, 400mW into 8Ω j Efficiency VDD = 5V, 1W into 8Ω j Quiescent Power Supply Current @ 3.6V j Power Output at VDD = 5V
86.5% 87.4% 9.36mA
Speaker: RL = 4Ω, THD+N ≤ 1% RL = 8Ω, THD+N ≤ 1% RL = 4Ω, THD+N ≤ 10% Headphone: RL = 16Ω, THD+N ≤ 1% RL = 32Ω, THD+N ≤ 1%
j Shutdown Current
2W 1.19W 2.5W 153mW 89mW 0.1µA
Features
n n n n n n n n n n n n Output Short Circuit Protection Thermal Shutdown Stereo filterless Class D operation Selectable OCL/CC Headphone Drivers RF Suppression I2C Control Interface 32-step digital volume control Independent Speaker and Headphone Gain Settings Minimum external components Click and Pop suppression Micro-power shutdown Available in space-saving 25 bump µSMD package
Applications
n Mobile phones n PDAs n Laptops
Boomer ® is a registered trademark of National Semiconductor Corporation.
© 2006 National Semiconductor Corporation
DS202001
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LM4949
Typical Application
202001C6
FIGURE 1. Typical Audio Amplifier Application Circuit
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LM4949
Connection Diagrams
TL Package 2.68mm x 2.68mm x 0.6mm
202001C7
Top View Order Number LM4949TL See NS Package Number TLA25JJA LM4949TL Marking
202001C0
Top View XY — 2 digit datecode TT — Die traceability
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LM4949
Absolute Maximum Ratings (Note 2)
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage (Note 1) Storage Temperature Input Voltage Power Dissipation (Note 3) ESD Susceptibility (Note 4) ESD Susceptibility (Note 5) Junction Temperature 6.0V −65˚C to +150˚C −0.3V to VDD +0.3V Internally Limited 2000V 200V 150˚C
Thermal Resistance θJA 35.1˚C/W
Operating Ratings
Temperature Range TMIN ≤ TA ≤ TMAX Supply Voltage (VDD, VDDLS, VDDHP) I2C Voltage (I2CVDD) −40˚C ≤ TA ≤ +85˚C 2.7V ≤ VDD≤ 5.5V 2.4V ≤ I2CVDD≤ 5.5V
Electrical Characteristics VDD = 3.0V (Notes 1, 2) The following specifications apply for AV = 0dB, RL(SP) = 15µH + 8Ω + 15µH, RL(HP) = 32Ω, f = 1kHz unless otherwise specified. Limits apply for TA = 25˚C.
LM4949 Symbol Parameter LS Mode Stereo Mono OCL HP Mode Stereo Mono CC HP Mode Stereo Mono Stereo LS + HP Mode ISD VOS Shutdown Supply Current Output Offset Voltage Speaker (mode 1) OCL HP (mode 1) LS Mode, f = 1 kHz RL = 4Ω, THD+N = 10% RL = 4Ω, THD+N = 1% RL = 8Ω, THD+N = 10% RL = 8Ω, THD+N = 1% OCP HP Mode, f = 1 kHz RL = 16Ω, THD+N = 10% RL = 16Ω, THD+N = 1% RL = 32Ω, THD+N = 10% RL = 32Ω, THD+N = 1% CC HP Mode, f = 1 kHz RL = 16Ω, THD+N = 10% RL = 16Ω, THD+N = 1% RL = 32Ω, THD+N = 10% RL = 32Ω, THD+N = 1% Conditions Typical (Note 6) 6 4.5 5.0 4.3 4.0 3.3 8.6 0.03 8.9 5.6 820 662 515 415 62.5 50 37.5 30.3 63 50 38 30 2 48.9 24.5 Limit (Notes 7, 8) 8.75 Units (Limits) mA (max) mA mA (max) mA mA (max) mA mA µA (max) mV (max) mV (max) mW mW mW mW (min) mW mW mW mW mW mW mW mW (min)
IDD
Supply Current
6.5
5.25
340
POUT
Output Power
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LM4949
Electrical Characteristics VDD = 3.0V (Notes 1, 2) The following specifications apply for AV = 0dB, RL(SP) = 15µH + 8Ω + 15µH, RL(HP) = 32Ω, f = 1kHz unless otherwise specified. Limits apply for TA = 25˚C. (Continued)
LM4949 Symbol Parameter Conditions Differential Mode, f = 1kHz HP Mode, R.