LM4991 Datasheet, PDF (1/15 Pages) National Semiconductor (TI) – 3W Audio Power Amplifier with Shutdown Mode

May 2003
LM4991
3W Audio Power Amplifier with Shutdown Mode
General Description
The LM4991 is a mono bridged audio power amplifier ca-
pable of delivering 3W of continuous average power into a
3Ω load with less than 10% THD when powered by a 5V
power supply (Note 1). To conserve power in portable appli-
cations, the LM4991’s micropower shutdown mode (I_SD =
0.1µA, typ) is activated when V_DD is applied to the SHUT-
DOWN pin.
Boomer audio power amplifiers are designed specifically to
provide high power, high fidelity audio output. They require
few external components and operate on low supply volt-
ages from 2.2V to 5.5V. Since the LM4991 does not require
output coupling capacitors, bootstrap capacitors, or snubber
networks, it is ideally suited for low-power portable systems
that require minimum volume and weight.
Additional LM4991 features include thermal shutdown pro-
tection, unity-gain stability, and external gain set.
Note 1: An LM4991LD that has been properly mounted to a circuit board will
deliver 3W into 3Ω (at 10% THD). The other package options for the LM4991
will deliver 1.5W into 8Ω (at 10% THD). See the Application Information
sections for further information concerning the LM4991LD and LM4991M.
Key Specifications
n Improved PSRR at 217kHz and 1kHz
64dB (typ)
n P_O at V_DD = 5.0V, 10% THD, 1kHz
n LM4991LD (only), 3Ω, 4Ω
3W (typ), 2.5W (typ)
n All packages, 8Ω load
1.5W (typ)
n Shutdown current
0.1µA (typ)
Features
n Available in space-saving LLP and MA packages
n Ultra low current shutdown mode
n Can drive capacitive loads up to 500pF
n Improved pop & click circuitry reduces noises during
turn-on and turn-off transitions
n 2.2 - 5.5V operation
n No output coupling capacitors, snubber networks,
bootstrap capacitors or gain-setting resistors required
n Unity-gain stable
Applications
n Wireless and cellular handsets
n PDA’s
n Portable computers
n Desktop computers
Connection Diagrams
Small Outline Package
LLP Package
20074002
Top View
Order Number LM4991MA
See NS Package Number M08A
20074039
Top View
Order Number LM4991LD
See NS Package Number LDC08A
Boomer^® is a registered trademark of National Semiconductor Corporation.
© 2003 National Semiconductor Corporation DS200740
www.national.com