Features • No output filter required for inductive loads • Externally configurable gain • Very fast turn on time: 1.35ms (typ) • Minimum external components • "Click and pop" suppression circuitry • Micro-power shutdown mode • Short circuit protection • Available in space-saving microSMD and LLP packages Description The LM4670 is a fully integrated single-supply high efficiency switching audio amplifier. It features an innovative modulator that eliminates the LC output filter used with typical switching amplifiers. Eliminating the output filter reduces external component count, simplifies circuit design, and reduces board area. The LM4670 processes analog inputs with a delta-sigma modulation technique that lowers output noise and THD when compared to conventional pulse width modulators. The LM4670 is designed to meet the demands of mobile phones and other portable communication devices. Operating on a single 5V supply, it is capable of driving a 4 speaker load at a continuous average output of 2.3W with less than 1% THD+N. Its flexible power supply requirements allow operation from 2.4V to 5.5V. The LM4670 has high efficiency with speaker loads compared to a typical Class AB amplifier. With a 3.6V supply driving an 8 speaker, the IC's efficiency for a 100mW power level is 77%, reaching 88% at 600mW output power. The LM4670 features a low-power consumption shutdown mode. Shutdown may be enabled by driving the Shutdown pin to a logic low (GND). The gain of the LM4670 is externally configurable which allows independent gain control from multiple sources by summing the signals. Key Specification Efficiency at 3.6V, 100mW into 8 speaker 77% (typ) Efficiency at 3.6V, 600mW into 8 speaker 88% (typ) Efficiency at 5V, 1W into 8 speaker 87% (typ) Quiescent current, 3.6V supply 4.8mA (typ) Total shutdown power supply current 0.01µA (typ) Single supply range 2.4V to 5.5V Applications • Mobile phones • PDAs • Portable electronic devices

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Typical Application click for larger image	Connection Diagram *click for larger image *click for larger image
Typical Performance *click for larger image

Datasheet

Title		Size	Date	Other Language
	LM4670 Boomer ® Audio Power Amplifier Series Filterless High Efficiency 3W Switching Audio Amplifier	1191 Kbytes	13-Jul-06

Featured Application Notes

Title		Size	Date	Other Language
	AN-1651: Application Note 1651 Keeping Up with the Expanding Demands of High-Performance Audio	206 Kbytes	10-Jul-07	中文
	AN-1671: Application Note 1671 Gain and Linearity Testing for Precision Operational Amplifiers	417 Kbytes	21-May-08	日本語
	AN-1784: Application Note 1784 LMV1022 / LMV1023 Digital Output PDM Microphone Amplifier Demo Board User's Guide	3786 Kbytes	6-Mar-08

More Application Notes

Title		Size	Date	Other Language
	AN-1614: Application Note 1614 LM48510 Speaker Application Note	214 Kbytes	14-Aug-07	中文
	AN-1497: Application Note 1497 Filterless Class D Amplifiers	524 Kbytes	24-May-06	中文

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM4670ITL	CMOS7	0	18406	0	0	1089000	4	309006723
LM4670ITLX	CMOS7	0	18406	0	0	1089000	4	309006723
LM4670SD	CMOS7	0	18406	0	0	1089000	4	309006723
LM4670SDX	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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