REV. M Page 1 September 1998
AS3502
Key Features
q 13-Bit Linear Sigma Delta Codec with Filters
Exceeding ETSI prETS30085 and G712 .
q Single Rail 3.0 V ~5.5 V Power Supply.
q Typical Power Dissipation of 30 mW at 3 V.
q Two Low Noise Microphone Inputs with Internal
Gain Adjust (+16 / +46 dB).
q 150Ω Push/Pull Earpiece Driver with Internal
Gain Adjust (-12 / +6 dB).
q 50Ω Loudspeaker Amplifier with up to 50 mW
Output Power.
q Push/ Pull Output Driver for Tone Ringer.
q On Chip Electret Microphone Voltage Source.
q Digital Transmit Gain Setting (-38 / +10 dB).
q Digital Receive Gain Setting ( -42 / +6 dB).
q Digital Sidetone Control Function ( 0 / -48 dB).
q Programmable Call Progress Tone/ DTMF /
Ring Tone Generator.
q Analogue and Digital Loopback Modes.
q 16-Bit Linear / 8-Bit A-Law Switchable Serial
PCM Interface with Non Delayed and Delayed
Timing Modes.
q 4-Wire Serial Control Interface.
q Packaged in SOIC-28, TQFP-64.
General Description
AS3502 is a high performance 13-bit linear feature
Codec/Filter with 8 kHz sampling rate specifically
tailored to implement all analogue frontend functions
of battery powered digital terminals. It includes a
programmable analogue interfaces for handset and
handsfree operation with a minimum amount of
external components.
The Codec function of AS3502 uses Sigma-Delta (Σ∆)
modulation conversion techniques with 2nd order
modulators and an over sampling rate of 128 for
excellent signal to noise performance. The AS3502
exceeds all CCITT G712 recommendations and the
European ETSI prETS 300085 recommendations.
Digital gain setting stages for transmit and receive
allow to compensate for transducer tolerances and to
set up a handsfree function under software control. A
programmable tone generator allows to generate
DTMF/Call-Progress Tones and alert sounds required
in digital terminals. All programmable functions of
AS3502 are controlled by a 4-wire serial control port
that easily interfaces to any popular micro controller.
The interface to the digital world is accomplished by a
serial PCM interface that supports 16-bit linear format
or 8-bit A-Law format for both non-delayed and
delayed frame synchronzation modes.
Block Diagramme
MIC1+
EP+
EP-
SPK+
SPK-
SCL SDI SDO
TXD
TXS
SCLK
RXS
RXD
MIC1-
MIC2+
MIC2-
CS
PCM
TX
MCLK
VREF
POR
+
16/46
dB
AGX
F1-F3,
V1-V3
DGX
TRO+TRO-
POR
GND CAP
AGND
AVDD AVSSDVDD
30Kž
- +
dB
-38/+10
Decimation
Filter
Interpolation
Filter
Freq.
Gen. Seq.
Serial Control
+-
VREF
AAF ADC
DAC
DAC
V2
LPF
-12/+6
dB
AGR
+
+
+3dB
VOICE
TONE LOOP
SINE
SQ.
BPF TXComp.
S1, S2
Caden.
CP, CP
Rep.
RP, RO SG
dB
0/-48
Contr.
DC
Lin/A-
PCM
TX
DGR
dB
-42/+6
LPF RXExp.
Lin/A-
+
AS3502
LOOP
Austria Mikro Systeme International AG
13-BIT LINEAR FEATURE CODEC
WITH ANALOGUE FRONTEND