LM4842 Datasheet, PDF (1/31 Pages) National Semiconductor (TI) – Stereo 2W Amplifiers with DC Volume Control Transient Free Outputs, and Cap-less Headphone Drive

September 2002
LM4842
Stereo 2W Amplifiers with DC Volume Control,
Transient Free Outputs, and Cap-less Headphone Drive
General Description
The LM4842 is a monolithic integrated circuit that provides
DC volume control, and stereo bridged audio power amplifi-
ers capable of producing 2W into 4Ω (Note 1) or 2.2W into
3Ω (Note 2) with less than 1.0% THD+N.
Boomer^® audio integrated circuits were designed specifically
to provide high quality audio while requiring a minimum
amount of external components. The LM4842 incorporates a
DC volume control, stereo bridged audio power amplifiers,
new cap-less headphone driver circuit (patent pending), se-
lectable gain or bass boost, and an input mux making it
optimally suited for multimedia monitors, portable radios,
desktop, and portable computer applications.
The LM4842 features an externally controlled, low-power
consumption shutdown mode (Shutdown Low), and both a
power amplifier and headphone mute for maximum system
flexibility and performance.
Note 1: When properly mounted to the circuit board, the LM4842MH will
deliver 2W into 4Ω. The LM4842MT will deliver 1.1W into 8Ω. See the
Application Information section for LM4842MH usage information.
Note 2: An LM4842MH that has been properly mounted to the circuit board
and forced-air cooled will deliver 2.2W into 3Ω.
Key Specifications
n P_O at 1% THD+N
n into 3Ω (MH and LQ)
n into 4Ω (MH and LQ)
n into 8Ω (MT, MH, and LQ)
n Single-ended THD+N at 85mW into 32Ω
n Shutdown current (Shutdown Low)
2.2W(typ)
2.0W(typ)
1.1W(typ)
1.0%(typ)
0.2µA(typ)
Features
n Stereo headphone amplifier mode that eliminates the
Output Coupling Capacitors (patent pending)
n Advanced “click and pop” suppression circuitry
n Acoustically Enhanced DC Volume Control Taper
n 2 Channel Stereo Input MUX
n System Beep Detect
n Stereo switchable bridged/single-ended power amplifiers
n Selectable internal/external gain and bass boost
n Thermal shutdown protection circuitry
Applications
n Portable and Desktop Computers
n Multimedia Monitors
n Portable Radios, PDAs, and Portable TVs
Connection Diagrams
TSSOP Package
20028102
Top View
Order Number LM4842MT
See NS Package Number MTC28 for TSSOP
Order Number LM4842MH
See NS Package Number MXA28A for Exposed-DAP TSSOP
Boomer^® is a registered trademark of NationalSemiconductor Corporation.
© 2002 National Semiconductor Corporation DS200281
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