LM48312 Datasheet, PDF (1/20 Pages) National Semiconductor (TI) – 2.6W, Ultra-Low EMI, Filterless, Mono Class D Audio Power Amplifier with E2S

LM48312 
May 13, 2010
2.6W, Ultra-Low EMI, Filterless, Mono Class D Audio Power
Amplifier with E²S
General Description
The LM48312 is a single supply, high efficiency, mono, 2.6W,
filterless switching audio amplifier. The LM48312 features
National’s Enhanced Emissions Suppression (E²S) system,
that features a unique patented ultra low EMI, spread spec-
trum, PWM architecture, that significantly reduces RF emis-
sions while preserving audio quality and efficiency. The E²S
system improves battery life, reduces external component
count, board area consumption, and system cost, simplifying
design.
The LM48312 is designed to meet the demands of portable
multimedia devices. Operating from a single 5V supply, the
device is capable of delivering 2.6W of continuous output
power to a 4Ω load with less than 10% THD+N. Flexible power
supply requirements allow operation from 2.4V to 5.5V. The
LM48312 features both a spread spectrum modulation
scheme, and an advanced, patented edge rate control (ERC)
architecture that significantly reduces emissions, while main-
taining high quality audio reproduction (THD+N = 0.03%) and
high efficiency (η = 88%).
The LM48312 features high efficiency compared to conven-
tional Class AB amplifiers, and other low EMI Class D ampli-
fiers. When driving an 8Ω speaker from a 5V supply, the
device operates with 88% efficiency at P_O = 1W. The
LM48312 features five gain settings, selected through a sin-
gle logic input, further reducing solution size. A low power
shutdown mode reduces supply current consumption to
0.01µA.
Advanced output short circuit protection with auto-recovery
prevents the device from being damaged during fault condi-
tions. Superior click and pop suppression eliminates audible
transients on power-up/down and during shutdown.
Key Specifications
■ Efficiency at 3.6V, 400mW into 8Ω
■ Efficiency at 5V, 1W into 8Ω
■ Quiescent Power Supply Current at 5V
■ Power Output at V_DD = 5V, R_L = 4Ω
THD+N ≤ 10%
THD+N ≤ 1%
■ Power Output at V_DD = 5V, R_L = 8Ω
THD+N ≤ 10%
THD+N ≤ 1%
■ Shutdown current
84% (typ)
88% (typ)
3.1mA
2.6W (typ)
2.1W (typ)
1.6W (typ)
1.3W (typ)
0.01μA (typ)
Features
■ ^{Passes FCC Class B Radiated Emissions with 20 inches}
of cable
■ ^{E2S System Reduces EMI while Preserving Audio Quality}
and Efficiency
■ ^{Output Short Circuit Protection with Auto-Recovery}
■ ^{No output filter required}
■ ^{Improved Audio Quality}
■ ^{Minimum external components}
■ ^{Five Logic Selectable Gain Settings (0, 3, 6, 9, 12dB)}
■ ^{Low Power Shutdown Mode}
■ ^{Click and Pop suppression}
■ ^{Available in space-saving microSMD package}
Applications
■ ^{Mobile phones}
■ ^PDAs
■ ^Laptops
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