LM4917 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – Ground-Referenced, 95mW Stereo Headphone Amplifier

November 2004
LM4917
Ground-Referenced, 95mW Stereo Headphone Amplifier
General Description
The LM4917 is a stereo, output capacitor-less headphone
amplifier capable of delivering 95mW of continuous average
power into a 16Ω load with less than 1% THD+N from a
single 3V power supply.
The LM4917 provides high quality audio reproduction with
minimal external components. A ground referenced output
eliminates the output coupling capacitors typically required
by single-ended loads, reducing component count, cost and
board space consumption. This makes the LM4917 ideal for
mobile phones and other portable equipment where board
space is at a premium. Eliminating the output coupling ca-
pacitors also improves low frequency response.
The LM4917 operates from a single 1.4V to 3.6V power
supply, features low 0.02% THD+N and 70dB PSRR. Inde-
pendent right/left channel low-power shutdown controls pro-
vide power saving flexibility for mono/stereo applications.
Superior click and pop suppression eliminates audible tran-
sients during start up and shutdown. Short circuit and ther-
mal overload protection protects the device during fault con-
ditions.
Key Specifications
j Improved PSRR at 1kHz
j Power Output at V_DD = 3V,
R_L = 16Ω, THD % 1%
j Shutdown Current
70dB (typ)
95mW (typ)
0.01µA (typ)
Features
n Ground referenced outputs
n High PSRR
n Available in space-saving TSSOP package
n Ultra low current shutdown mode
n Improved pop & click circuitry eliminates noises during
turn-on and turn-off transitions
n 1.4 – 3.6V operation
n No output coupling capacitors, snubber networks,
bootstrap capacitors
n Shutdown either channel independently
Applications
n Notebook PCs
n Desktop PCs
n Mobile Phone
n PDAs
n Portable electronic devices
Block Diagram
200893B8
FIGURE 1. Circuit Block Diagram
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© 2004 National Semiconductor Corporation DS200893
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