Datasheet

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LPC3152_3154 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
Preliminary data sheet Rev. 0.12 — 27 May 2010 43 of 88
NXP Semiconductors
LPC3152/3154
• Controlled power down sequence comprising a raised cosine mute function followed
by a DC ramp down to zero to avoid audible plops or clicks.
• Digital dB-linear volume control in 0.25 dB steps.
• Digital de-emphasis for 32 kHz, 44.1 kHz, 48 kHz, and 96 kHz.
• Selection for the up-sampling filter characteristics (sharp/slow roll-off).
• Support for 2fs and 8fs input signals.
• Soft mute with a raised cosine function.
7.2.2 Class AB headphone amplifier
The class AB headphone amplifier amplifies an analog input signal to levels appropriate
for a headphone output. Its input can be chosen from the Stereo Digital-to-Analog
Converter (SADC) or from the analog bypass from the tuner input (through the Analog
Volume Control (AVC) block). The class AB amplifier offers a solution in cases where high
output levels are required or when the headphone wire is also used as an antenna for
tuner reception.
This module has the following features:
• Stereo headphone amplifier.
• Three outputs: left, right, and a common signal ground output.
• Common signal ground output enables DC coupling of headphone without electrolytic
capacitors.
• 16 Ω and higher output drive capability.
• Individual power down modes for each output.
• Programmable short-circuit current protection for each amplifier.
• Additional input with Analog Volume Control (AVC) directly connected to the tuner
input pins.
7.2.3 Stereo Analog-to-Digital Converter (SADC) for Audio
The Stereo ADC can convert analog audio input signals into digital audio signals as
shown in Figure 12
. The module has three input signals: stereo line-in
(ADC_VINL/ADC_VINR), stereo tuner-in (ADC_TINL/ADC_TINR), and mono microphone
in (ADC_MIC). These signals can be pre-processed by a Low-Noise Amplifier (LNA,
microphone input only), a Programmable Gain Amplifier (PGA), and a
Single-to-Differential Converter (SDC) before they arrive at the input of the actual SADC.