LM48310 Datasheet, PDF (1/20 Pages) National Semiconductor (TI) – Ultra-Low EMI, Filterless, 2.6W, Mono, Class D Audio Power Amplifier with E2S

March 4, 2008
LM48310 
Ultra-Low EMI, Filterless, 2.6W, Mono, Class D Audio
Power Amplifier with E²S
General Description
The LM48310 is a single supply, high efficiency, mono, 2.6W,
filterless switching audio amplifier. The LM48310 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 LM48310 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
LM48310 offers two logic selectable modulation schemes,
fixed frequency mode, and an EMI suppressing spread spec-
trum mode. The E²S system includes an advanced, patent-
pending edge rate control (ERC) architecture that further
reduce emissions by minimizing the high frequency compo-
nent of the device output, while maintaining high quality audio
reproduction (THD+N = 0.03%) and high efficiency (η = 88%).
The LM48310 also features a SYNC_IN input and
SYNC_OUT, which allows multiple devices to operate with
the same switching frequency, eliminating beat frequencies
and any other interference caused by clock intermodulation.
The LM48310 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 LM48310 is internally set to 12dB, further reducing exter-
nal component count. 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%
■ Power Output at V_DD = 5V,
R_L = 8Ω, THD+N ≤ 10%
■ Shutdown current
85% (typ)
88% (typ)
3.2mA
2.6W (typ)
1.6W (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}
■ ^{Stereo Class D operation}
■ ^{No output filter required}
■ ^{Internally Configured Gain (12dB)}
■ ^{Synchronizable Oscillator for Multi-Channel operation}
■ ^{Low power shutdown mode}
■ ^{Minimum external components}
■ ^{"Click and pop" suppression}
■ ^{Micro-power shutdown}
■ ^{Available in space-saving LLP package}
Applications
■ ^{Mobile phones}
■ ^PDAs
■ ^Laptops
EMI Graph 20in of Speaker Cable
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