Features • Output Short Circuit Protection • Thermal Shutdown • Stereo filterless Class D operation • Selectable OCL/CC Headphone Drivers • RF Suppression • I 2C 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 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 I 2C 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 Specification ■  Efficiency VDD = 3.6V, 400mW  into 8Ω 86.5% ■  Efficiency VDD = 5V, 1W into 8Ω 87.4% ■  Quiescent Power Supply Current   @ 3.6V 9.36mA ■  Power Output at VDD = 5V    Speaker:   RL = 4Ω, THD+N ≤ 1%   RL = 8Ω, THD+N ≤ 1%   RL = 4Ω, THD+N ≤ 10% 2W 1.19W 2.5W  Headphone:   RL = 16Ω, THD+N ≤ 1%   RL = 32Ω, THD+N ≤ 1% 153mW 89mW ■  Shutdown Current 0.1μA Applications • Mobile phones • PDAs • Laptops

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Datasheet

Title		Size	Date	Other Language
	LM4949  Stereo Class D Audio Subsystem with OCL Headphone Amplifier	984 Kbytes	13-Mar-07

Featured Application Notes

Title		Size	Date	Other Language
	AN-1567: Application Note 1567 LM4949 Demonstration Board	3533 Kbytes	18-Jul-07	中文

More Application Notes

Title		Size	Date	Other Language
	AN-1496: Application Note 1496 Noise, TDMA Noise, and Suppression Techniques	85 Kbytes	28-Apr-08	中文

Design Tools

Title	Size	Date
Audio Amplifier Digital Control Interface Evaluation Board Software

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM4949TL	CMOS7	0	18406	0	0	1089000	4	309006723
LM4949TLX	CMOS7	0	18406	0	0	1089000	4	309006723

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

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