LM4912 Datasheet, PDF (1/14 Pages) National Semiconductor (TI) – Stereo 40mW Low Noise Headphone Amplifier

June 2003
LM4912
Stereo 40mW Low Noise Headphone Amplifier
General Description
The LM4912 is an stereo audio power amplifier capable of
delivering 40mW per channel of continuous average power
into a 16Ω load or 25mW per channel into a 32Ω load at 1%
THD form a 3V power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. Since the LM4912 does not require
bootstrap capacitors or snubber networks, it is optimally
suited for low-power portable systems.
The LM4912 features a low-power consumption shutdown
mode and a power mute mode that allows for faster turn on
time with less than 1mV voltage change at outputs on re-
lease. Additionally, the LM4912 features an internal thermal
shutdown protection mechanism.
The LM4912 is unity gain stable and may be configured with
external gain-setting resistors.
Key Specifications
n PSRR at 217 Hz and 1kHz
65dB (typ)
n Output Power at 1kHz with V_DD = 2.4V, 1% THD+N into
a 16Ω load
25mW (typ)
n Output Power at 1kHz with V_DD = 3V, 1% THD+N into a
16Ω load
40mW (typ)
n Shutdown Current
1.0µA (max)
n Output Voltage change on release from Shutdown
V_DD = 2.4V, R_L = 16Ω
1mV (max)
n Output Noise, 20Hz to 20kHz, A-weighted 10µV (typ)
Features
n External gain-setting capability
n Available in space-saving MSOP package
n Ultra low current shutdown mode
n Mute mode allows fast turn-on (10ms) with less than
1mV change on outputs
n 2.0V - 5.5V operation
n Ultra low noise
n Operation at low supply voltages
Applications
n Portable CD players
n PDAs
n Portable electronics devices
Typical Application
20048180
FIGURE 1. Typical Capacitive Coupled Output Configuration Circuit
Boomer^® is a registered trademark of National Semiconductor Corporation.
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