LM49250 Datasheet, PDF (1/36 Pages) National Semiconductor (TI) – Enhanced Emissions Suppression Stereo Class D Audio Sub-System with Ground Referenced Headphone Amplifier and Mono Earpiece

LM49250
www.ti.com
SNAS406C – JANUARY 2008 – REVISED MAY 2013
LM49250
Enhanced Emissions Suppression Stereo Class
D Audio Sub-System with Ground Referenced Headphone Amplifier and Mono Earpiece
Check for Samples: LM49250
FEATURES
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•2 Output Short Circuit Protection
• Thermal Overload Protection
• Stereo Filterless Class D Operation
• Spread Spectrum Modulation
• Ground Referenced Headphone Drivers
• I²C Control Interface
• 32-Step Input Volume Control
• Output Volume Control
• Minimum External Components
• Click and Pop Suppression
• Micro-Power Shutdown
• Available in Space-Saving 36–Bump DSBGA
Package
• Single Supply Operation
• RF Suppression
APPLICATIONS
• Mobile Phones
• Portable Navigation Devices
• Portable Media Players
DESCRIPTION
The LM49250 is a fully integrated audio subsystem
designed for stereo cell phone applications. The
LM49250 combines a 2.4W/Ch stereo class D
speaker amplifiers with a 45mW/Ch stereo ground
referenced headphone amplifier, a class AB earpiece
amplifier, TI 3D enhancement, volume control, and an
input mixer into a single device. The filterless class D
amplifiers deliver 1.2W/Ch into an 8Ω load with <1%
THD+N from a 5V supply.
The LM49250 features a new circuit technology that
utilizes a charge pump to generate a negative supply
voltage. This allows the headphone outputs to be
biased about ground, thereby eliminating the output-
coupling capacitors.
For improved noise immunity, the LM49250 features
fully differential left, right and mono inputs. The three
inputs can be mixed/multiplexed to any output
combination of the loudspeaker, headphone or
earpiece amplifiers. The left and right differential
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 I²C compatible interface.
KEY SPECIFICATIONS
• Power Output at V_DD = 5V Speaker:
– R_L = 4Ω, THD+N ≤ 1%: 1.97W/Ch
– R_L = 4Ω, THD+N ≤ 10%: 2.4W/Ch
– R_L =8Ω, THD+N ≤ 1%: 1.2W/Ch
• Headphone:
– R_L = 16Ω, THD+N ≤ 1%: 41mW/Ch
– R_L = 32Ω, THD+N ≤ 1%: 45mW/Ch
• Earpiece:
– R_L = 16Ω, THD+N ≤ 1%: 170mW
– R_L = 32Ω, THD+N ≤ 1%: 90mW
• Shutdown Current: 0.1μA
• Efficiency at 5V, 1W into 8Ω: 87%
• Efficiency at 3.6V, 500mW into 8Ω: 85%
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PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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