ST5088

CompleteCODECand FILTERsystemincluding:
` PCM ANALOG TO DIGITAL AND DIGITAL TO ANALOG CONVERTERS
` POWERFUL ANALOG FRONT END CAPABLE TO INTERFACE DIRECTLY:
   - Microphone Dynamic or Electrete
   - Earpiece down to 100W or up to 150nF
   - Loudspeakerdown to 50 or Buzzer up to 600nF.
` TRANSMIT BAND-PASS FILTER
` ACTIVE RC NOISE FILTER
` RECEIVE LOW-PASS FILTER WITH SIN X/X CORRECTION
` MU-LAW OR A-LAW SELECTABLE COMPANDING CODER AND DECODER
` PRECISIONVOLTAGE REFERENCE
Phones Features:
` DUAL SWITCHABLE MICROPHONE AMPLIFIER
  INPUTS. GAIN PROGRAMMABLE: 15 dB RANGE, 1 dB STEP.
` LOUDSPEAKERAMPLIFIER OUTPUT.
  SWITCHABLE MAXIMUM GAIN: +9dB/+27dB WITH AUTOMATIC DIGITAL ANTICLIPPING SYSTEM. aTTENUATION PROGRAMMABLE: 30dB RANGE, 2dB STEP.
` SEPARATE EARPIECE AMPLIFIER OUTPUT.
  ATTENUATION PROGRAMMABLE: 15 dB RANGE, 1 dB STEP.
` AUXILIARY TAPE RECORDER ANALOG INTERFACE: Tx + Rx COMBINED OUTPUT.
` AUXILIARY SWITCHABLE EXTERNAL RING INPUT (EAIN).
` TRANSIENT SUPRESSION SIGNAL DURING POWERON.
` INTERNAL PROGRAMMABLE SIDETONE
  CIRCUIT. ATTENUATION PROGRAMMABLE: 15 dB RANGE, 1 dB STEP, INDEPENDENT FROM Rx CONTROL.
` INTERNAL RING OR TONE GENERATOR INCLUDING
  DTMF TONES, SINEWAVE OR SQUAREWAVE WAVEFORMS. ATTENUATION PROGRAMMABLE: 27 dB RANGE, 3 dB STEP.
` RINGER CONTROL PROGRAMMABLE INTERNALLY (P) OR EXTERNALLY (pin AT)
` COMPATIBLE WITH HANDS-FREE CIRCUIT TEA7540.
` ON CHIP SWITCHABLE ANTI-ACOUSTIC
  FEED-BACK CIRCUIT (ANTI-LARSEN).
General Features:
` EXTENDED TEMPERATURE RANGE OPERATION (*) 25°C TO +85°C.
` EXTENDEDPOWERSUPPLYRANGE5V±10%.
` 60 mWOPERATING POWER (TYPICAL).
` 1.0 mW STANDBYPOWER (TYPICAL).
` CMOS DIGITAL INTERFACES.
` SINGLE + 5V SUPPLY.
` DIGITAL LOOPBACK TEST MODE.
` PROGRAMMABLE DIGITAL AND CONTROL INTERFACES:
  Digital PCM Interface associated with separate serial Control Interface MICROWIRE™ compatible.
  GCI interface compatible.
(*) Functionality guaranteed in the range 25°C to +85°C; Timing and Electrical Specifications are guaranteed in the range 5°C to +70°C.

ST5088 PIAFE is a combined PCM CODEC/FILTER device optimized for ISDN Terminals and Digital Telephone applications. This device is A-law and Mu-law selectable and offers a number of programmable functions accessed through a serial control channel.

Depending on mode selected, channel control is provided by means of a separate serial channel control MICROWIRE compatible or multiplexed with the PCM voice data channel in a GCI compatible format requiring only 4 digital interface  pins. When separate serial control interface is selected, PCM interface is compatible with Combo I and Combo II families of devices such as ETC5057/54,TS5070/71.

ST5088 PIAFE is built using SGS-THOMSON's advanced HCMOS process.

ST5088 Transmit section of PIAFE consists of an amplifier with switchable high impedance inputs followed by a programmable gain amplifier, an active RC antialiasing pre-filter to provide attenuation of high frequency noise, an 8th order switched capacitor band pass transmit filter and an A-law/Mu-law selectable compandig encoder.

ST5088 Receive section consist of an A-law/Mu-law selectable expanding decoder which reconstructs the analog sampled data signal, a 3400 Hz low pass filter with sin X/X correction followed by two separate programmable attenuation blocks and two power amplifiers: one can be used to drive an earpiece, and the other to drive a 50 loudspeaker loudspeaker or a piezo transducer up to 600nF.

When the loudspeaker section is set up with maximum gain (+27dB) the device provide internally a programmable digital anticlipping system to avoid output distortion.

Programmable functions on PIAFE include a Ring/Tone generator which provides one or two tones and can be directed to earpiece or to loudspeaker(or buzzer).
 
A simple ringer control interface can bypass P control of sweep frequency and ring ON/OFF phases.

A separate programmable gain amplifier allows gain control of the signal injected. Ring/Tone generator provides sinewave or squarewave signal with precise frequencies which may be also directed to the input of the Transmit amplifier for DTMF tone generation.

An auxiliary analog input (EAIN) is also provided to enable for example the output of an external band limited Ring signal to the Loudspeaker. Transmit signal may be fed back into the receive ampifier with a programmable attenuation to provide a sidetone circuitry.

A switchable anti-accoustic feed-back system cancels the larsen effect in speech monitoring application.

Two additional pins are provided for insertion of an external Handfree function in the Loudspeaker receive path.

An output latch controlled by register programming permits external device control.