The LM4949 is a fully integrated audio subsystem designed
for stereo cell phone applications. The LM4949 combines a
2.5W stereo Class D amplifier plus a separate 190mW stereo
headphone amplifier, volume control, and input mixer into a
single device. The filterless class D amplifiers deliver 1.19W/
channel into an 8Ω load with <1% THD+N from a 5V supply.
The headphone amplifier features National’s Output Capacitor-
less (OCL) architecture that eliminates the output coupling
capacitors required by traditional headphone amplifiers. Additionally,
the headphone amplifiers can be configured with
capacitively coupled (CC)loads, or used to drive an external
headphone amplifier. When configured for an external amplifier,
the VDD/2 output (VOC) controls the external amplifier’s
shutdown input.