LM48311 Datasheet, PDF (1/16 Pages) National Semiconductor (TI) – Ultra-Low EMI, Filterless, 2.6W, Mono, Class D Audio Power Amplifier with E2S

LM48311 
June 25, 2009
Ultra-Low EMI, Filterless, 2.6W, Mono, Class D Audio
Power Amplifier with E²S
General Description
The LM48311 is a single supply, high efficiency, mono, 2.6W,
filterless switching audio amplifier. The LM48311 features
National’s Enhanced Emissions Suppression (E²S) system,
that features a unique patent-pending ultra low EMI, spread
spectrum, PWM architecture, that significantly reduces RF
emissions while preserving audio quality and efficiency. The
E²S system improves battery life, reduces external compo-
nent count, board area consumption, system cost, and sim-
plifying design.
The LM48311 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
LM48311 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 LM48311 features high efficiency compared to conven-
tional Class AB amplifiers, and other low EMI Class D ampli-
fiers. When driving and 8Ω speaker from a 5V supply, the
device operates with 88% efficiency at P_O = 1W. The gain of
the LM48311 is internally set to 6dB, further reducing external
component count. A low power shutdown mode reduces sup-
ply 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
85% (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}
■ ^{Internally Configured Gain (6dB)}
■ ^{Low power shutdown mode}
■ ^{Minimum external components}
■ ^{"Click and pop" suppression}
■ ^{Micro-power shutdown}
■ ^{Available in space-saving microSMD package}
Applications
■ ^{Mobile phones}
■ ^PDAs
■ ^Laptops
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