LM4938 Datasheet, PDF (1/26 Pages) National Semiconductor (TI) – Stereo 2W Audio Power Amplifiers with DC Volume Control and Selectable Gain

February 2005
LM4938
Stereo 2W Audio Power Amplifiers
with DC Volume Control and Selectable Gain
General Description
The LM4938 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) with less than
1.0% THD or 2.2W into 3Ω (Note 2) with less than 1.0%
THD.
Boomer^® audio integrated circuits were designed specifically
to provide high quality audio while requiring a minimum
amount of external components. The LM4938 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 LM4938 features an externally controlled, low-power
consumption shutdown mode, and both a power amplifier
and headphone mute for maximum system flexibility and
performance.
Note 1: When properly mounted to the circuit board, LM4938MH will deliver
2W into 4Ω. See Application Information section Exposed-DAP package
PCB Mounting Considerations for more information.
Note 2: An LM4938MH 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
n into 4Ω
n into 8Ω
n Single-ended mode - THD+N at 92mW into
32Ω
n Shutdown current
2.2W (typ)
2.0W (typ)
1.3W (typ)
1.0%(typ)
0.5µA (typ)
Features
n Improved click and pop circuitry virtually eliminates
noise during turn on/off transitions
n DC Volume Control Interface
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
n Unity gain stable
Applications
n Flat Panel Displays
n Portable and Desktop Computers
n Multimedia Monitors
n Portable Radios, PDAs, and Portable TVs
Block Diagram
20095601
FIGURE 1. LM4938 Block Diagram
Boomer^® is a registered trademark of NationalSemiconductor Corporation.
© 2005 National Semiconductor Corporation DS200956
www.national.com