Document
LM4841 Stereo 2W Amplifiers with DC Volume Control,Transient Free Outputs, and Cap-less Headphone Drive
August 2002
LM4841 Stereo 2W Amplifiers with DC Volume Control, Transient Free Outputs, and Cap-less Headphone Drive
General Description
The LM4841 is a monolithic integrated circuit that provides DC volume control and stereo bridged audio power amplifiers capable of producing 2W into 4Ω (Note 1) or 2.2W into 3Ω (Note 2) with less than 1.0% THD. The LM4841 uses advanced, latest generation circuitry to eliminate all traces of clicks and pops when the supply voltages is first applied. The amplifier has a headphoneamplifier-select input pin that is used to switch the amplifiers from bridge to single-ended mode for driving headphones. A new circuit topology eliminates headphone output coupling capacitors (patent pending). Boomer ® audio integrated circuits are designed specifically to provide high quality audio while requiring a minimum amount of external components. The LM4841 incorporates a DC volume control, stereo bridged audio power amplifiers and a selectable gain or bass boost, making it optimally suited for multimedia monitors, portable radios, desktop, and portable computer applications. The LM4841 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, LM4841MH and LM4841LQ will deliver 2W into 4Ω. The LM4841MT will deliver 1.1W into 8Ω. See the Application Information section for LM4841MH usage information. Note 2: An LM4841MH that has been properly mounted to the circuit board and forced-air cooled will deliver 2.2W into 3Ω.
Key Specifications
n PO 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 2.2W (typ) 2.0W (typ) 1.1W (typ) 1.0%(typ) 0.7µA (typ)
Features
n Stereo headphone amplifier mode that eliminates the Output Coupling Capacitors (patent pending) n Acoustically Enhanced DC Volume Control Taper n System Beep Detect n Stereo switchable bridged/single-ended power amplifiers n Selectable internal/external gain and bass boost n Advanced “click and pop” suppression circuitry 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
20028002
Top View Order Number LM4841MT or LM4841MH See NS Package Number MTC28 for TSSOP and MXA28A for Exposed-DAP TSSOP
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© 2002 National Semiconductor Corporation
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LM4841
Connection Diagrams
(Continued) LLP Package
20028097
Top View Order Number LM4841LQ See NS Package Number LQA028AA for Exposed-DAP LLP
Block Diagram
20028001
FIGURE 1. LM4841 Block Diagram
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LM4841
Absolute Maxim.