AS3542 Stereo Audio Codec with System Power Management Unit0 pages

AS3542

Data Sheet, Strictly Confidential

U l t r a L o w P o w e r St e r e o A ud i o C o d e c w i t h S y s t e m P M U

1 General Description

2 Key Features

The AS3542 is an ultra low power stereo audio codec
and is designed for Portable Digital Audio Applications.

Audio

It allows CD quality playback with up to 96dBA SNR and
recording in FM quality. With one microphone (including
pre-amplifier and supply for an electret microphone) and
one line input, it allows connecting a variety of audio
inputs. The different audio signals can be mixed via a 6channel mixer and fed to either a headphone output for
16 /32 headsets or a line output. The audio outputs
have also an auto fading implemented which performs
the fade-in, fade-out as well as the transition between
specific volume levels automatically with an selectable
timing.

Audio power consumption:

Further the device offers advanced power management
functions. All necessary ICs and peripherals in a Digital
Audio Player are supplied by the AS3542. It features 2
DCDC converters for core and memory/periphery supply
as well as 4 LDOs. Both DCDC converter feature DVM
(dynamic voltage management) with an selectable timing for the voltage stepping. The different regulated supply voltages are programmable via the serial control
interface.
The step-up converter for the backlight can operate up
to 15V (with an external transistor even higher) in voltage and current control mode. An internal voltage protection is limiting the output voltage in the case of
external component failures. An automatic dimming
function allows a logarithmic on/off of the backlight with
selectable timing.
AS3542 also contains a Li-Ion battery charger with constant current, constant voltage and trickle charging. The
maximum charging current is 460mA. An integrated battery switch is separating the battery during charging or
whenever an external power supply is present. With this
switch it is also possible to operate with no or deeply discharged batteries.
The AS3542 has an on-chip, phase locked loop (PLL)
which generates the needed internal CODEC master
clock. I2S Frame and shift-clock have to be applied from
the processor for playback and recording.
The single supply voltage may vary from 2.7V to 5.5V.

- 5mW: 95dB DAC to Headphone @ 1.8V, 32Ω

Sigma Delta Converters
DAC
- 96dB SNR ('A' weighted) @ 1.8V
ADC
- 85dB SNR ('A' weighted) @ 1.8V
Sampling Frequency
- DAC: 8-48kHz
- ADC: 8-24kHz

High Efficiency Headphone Amplifier
volume control via serial interface
32 steps @1.5dB and MUTE
2x12mW @16Ω driver capability@ 1.8V supply
THD -74dB @16Ω; 1.8V
2x40mW @16Ω driver capability@ 2.9V supply
THD -77dB @16Ω; 2.9V
headphone and over-current detection

Line Output
volume control via serial interface
32 steps @1.5dB and MUTE
0.6Vp @10kΩ

Microphone Input
3 gain pre-setting (30dB/36dB/42dB) and AGC
32 gain steps @1.5dB and MUTE
supply for electret microphone
microphone detection
remote control by switch

Line Input
volume control via serial interface
32 steps @1.5dB and MUTE
stereo or 2x mono

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Revision 1.10

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