AS2507 AMSCO
Document overview
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Technical content
Preliminary Data Sheet AS2507 1/9 July 1998 Austria Mikro Systeme International AG Single Chip 2-Wire Intercom CMOS Integrated Circuit Key Features /G01 Line/speech circuit and signalling on one 14 pin CMOS chip /G01 Only 2 wires needed for power supply, signalling and speech /G01 Soft clipping to avoid harsh distortion /G01 Fully integrated 2/4 wire conversion /G01 Side tone cancellation /G01 Low noise /G01 Signalling with FSK modem /G01 Low standby power consumption allows parallel operation of up to 25 terminals on a bus pair with central supply /G01 Parallel operation of up to 70 terminals if supplied locally /G01 Controllable via simple µC interface /G01 Very few external components Application Entrance telephone system, intercom and data transmission, alarm systems, toy phone General Description The AS2507 is a CMOS integrated circuit that contains all the functions needed to build a 2- wire intercom network. The device incorporates 2/4-wire conversion (hybrid), soft clipping for high speech quality, FSK modem and a simple interface to a microcontroller. The signalling mode is selectable between FSK modulation and burst mode. The low standby current (typ. 2 mA) allows several devices to listen to the 2-wire line. The speech circuit is designed for compatibility with commonly used handset (150Ω earpiece and electret microphone) with receive gain of -6 dB and transmit gain of 32 dB (relative to line). Package Available in 14 pin DIP and 16 pin SOIC Block Diagram
Preliminary Data Sheet AS2507 2/9 July 1998 Pin description Pin # DIP 14 Pin # SO 16 Symbol Function
77 M 1 M icrophone Input 1
Differential input for the microphone (electret)
66 M 2 M icrophone Input 2
Differential input for the microphone (electret)
22 R I R eceive Input
Input for ac-separated receive signal
44 R O R eceive O utput to Handset
Output for driving a dynamic earpiece with an impedance from 150Ω to 300Ω 14 15 VDD Voltage D rain D rain Positive Power Supply VSS Voltage Source Source Negative Power Supply
88 A G N D A nalogue G round
Signal ground for the internal amplifiers 11 12 OSC1 O scillator Output 1 Output to ceramic resonator 3.58MHz. 12 13 OSC2 O scillator Input 2 Input for ceramic resonator 3.58MHz.
55 P D Power D own Input
Active high, i.e. a high level on this pin will power down the analogue signal path. 10 11 RxD R eceive D ata Output Output of the FSK demodulator 13 14 TxD Transmit D ata Input Input for the FSK modulator
11 T E Transmit Enable
Input for enabling transmit data
Preliminary Data Sheet AS2507 3/9 July 1998 Functional Description The AS2507 is a CMOS integrated circuit that incorporates a speech circuit and a FSK modem. It is intended to be used as line- powered interface on a 2-wire intercom bus. Standby Condition During standby operation (PD=High) only the FSK demodulator is active to provide the companion microcontroller with all signalling information on the 2-wire bus. The low power consumption (typical 2mA) and a high input and output impedance in standby mode allow the parallel operation of many terminals on each bus pair. 2/4-Wire Conversion The AS2507 has a built-in side tone cancellation circuit. The transmit signal is attenuated by 6 dB over the 600Ω resistor (ac impedance) and subtracted from the receive signal at the receive input (RI). This configuration allows the selection of the required ac impedance and yet maintaining a good side tone cancellation. AC Impedance The ac impedance is determined by an external resistor at the TO output (typical 600Ω ). Transmit Path The gain of the transmit path from the microphone inputs (M1/M2) to the transmit output (TO) is set to 32 dB. The soft clip level is set to 0.5V PEAK at TO. In standby the output impedance is 60kΩ . Receive Path The gain of the receive path from the receive input (RI) to the receive output (RO) is set to -6dB. The receive input is internally biased to A GND with a 500kΩ resistor. FSK Modulator Two signalling modes are provided, namely FSK and burst mode. The signalling mode and the signalling can be controlled by a microcontroller using the TE and TXD inputs as follows: TE TXD MODE 0 0 IDLE, no transmission 0 1 TEST, for testing only 1 0 SPACE ("0") 18.645 kHz 1 1 MARK ("1") 22.375 kHz FSK Demodulator Also the demodulator provides two modes for detection as follows: Signal on line RXD IDLE, no transmission 1 SPACE ("0") 18.645 kHz 0 MARK ("1") 22.375 kHz 1 The demodulator consists out of a bandpass filter to attenuate interfering speech signals and a period counter. The RxD output is updated after each valid period or a counter overflow. Transmission Protocol In order to assure a safe data transmission, data framing is recommended. Each frame should consist out of a preamble (e.g. FF hex), a header (e.g. AA hex), data bytes and checksum. Independence of bus polarity Centrally supplied terminals can be connected to the 2-wire bus independent from polarity. In this case a rectifier bridge, known from telephony, is recommended since the DC- supply current will bias the diodes.
Preliminary Data Sheet AS2507 4/9 July 1998 Typical 2-Wire Intercom Application
Preliminary Data Sheet AS2507 5/9 July 1998
Electrical characteristics
Electrical charateristics are measured with the Test Circuit application. Typical mean values will not be tested. Absolute maximum ratings Positive Supply Voltage -0.3V <= V DD <= 7V Input Current ± 25mA Analogue Input Voltage -0.3V <= V in <= VDD +0.3V Digital Input Voltage -0.3V <= V in <= VDD +0.3V Electrostatic Discharge (HBM 1.5kΩ -100pF) ± 1000V Storage Temperature -65°C to +125°C Recommended operating conditions Supply Voltage (VDD )5 V ± 1 0 % Oscillator Frequency 3.58 MHz Operating Temperature -10°C to +60°C DC characteristics VDD =5V, f=1kHz, unless other specified Symbol Parameter Conditions Min Typ Max Units IDDS Supply Current Standby Mode PD=High, VDD =2.5V 23 m A IDDO Supply Current Operating Mode PD=Low, VDD =2.5V 56 m A VIL Digital Input Voltage LOW V SS 0.1 VDD V VIH Digital Input Voltage HIGH 0.9 V DD VDD V
Preliminary Data Sheet AS2507 6/9 July 1998 Transmit characteristics VDD =5V, f=1kHz, unless other specified Symbol Parameter Conditions Min Typ Max Units ATX Transmit Gain M1/M2 —> TO VTO =0.25VRMS +30.0 +32.0 +34.0 dB THD Distortion V TO =0.25VRMS 2% VNO Noise Output Voltage TO TAMP =25°C -60 dBmp VAGC1 Soft Clip Level M1/M2 —> TO at TO
0.5 V P
Zout-TO Output Impedance with PD=High at TO PD=High TAMP =25°C 60 kΩ Receive characteristics VDD =5V, f=1kHz, unless other specified Symbol Parameter Conditions Min Typ Max Units ARX Receive Gain RI —> RO VRI=0.25VRMS -8.0 -6.0 -4.0 dB THD Distortion V RI=0.25VRMS 2% VNO Noise Output Voltage RO TAMP =25°C -60 dBmp ST Sidetone V RI=0.25VRMS 24 dB ZIn-RI Input Impedance RI 500 kΩ
Preliminary Data Sheet AS2507 7/9 July 1998 FSK characteristics VDD =5V, f=1kHz, unless other specified Symbol Parameter Conditions Min Typ Max Units fMARK MARK Frequency TE=High TxD=High fOSC =3.579545MHz 22375 Hz fSPACE SPACE Frequency TE=High TxD=Low f OSC =3.579545MHz 18645 Hz fΔMARK Valid input frequency range MARK TE=Low 22375 ±447 Hz fΔSPACE Valid input frequency range SPACE TE=Low 18645 ±372 Hz VRImin Minimum Receive Input Voltage Detection Level TE=Low 100 mVp VTO Tone Output Level TE=High 600 mVp AVB Attenuation at 4kHz Input Bandpass Filter 35 dB Test circuit
Preliminary Data Sheet AS2507 8/9 July 1998 Packaging The device is available in the packages outlined below (not to scale). For exact mechanical package dimensions please see AMSAG packaging information. 14-pin plastic DIP (suffix P) Max. Body Length 20.19mm / 795mil Max. Body Width 7.11mm / 280mil Pitch 2.54mm / 100mil 16-pin plastic SOICw (suffix T) Max. Body Length 10.5mm / 414mil Max. Body Width 7.6mm / 300mil Pitch 1.27mm / 50mil Pin-out DIP14 (suffix P) 1– T E V DD –1 4 2– R I T x D– 1 3 3– T O O S C 2– 1 2 4 – RO OSC1 – 11 5– P D R x D– 1 0 6– M 1 V SS –9 7– M 2 A GND –8 SO16w (suffix T) 1– T E V DD –1 6 2– R I V DD –1 5 3 – TO TxD – 14 4 – RO OSC2 – 13 5– P D O S C 1– 1 2 6 – M1 RxD – 11 7– M 2 V SS –1 0 8– A GND VSS –9 Marking YYWWAAA AS2507 Austria YY year of production WW calendar week of production AAA AMS AG assembly ID
Preliminary Data Sheet AS2507 9/9 July 1998
Ordering information
Number Package Description AS2507 P DIP14 plastic dual inline package - 14 leads (suffix P) AS2507 T SO16w plastic small outline package - 16 leads (suffix T) Devices sold by Austria Mikro Systeme Int. AG are covered by the warranty and patent idemnification provisions appearing in its Term of Sale. Austria Mikro Systeme Int. AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the decribed devices from patent infringement. Austria Mikro Systeme Int. AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with Austria Mikro Systeme Int. AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equiment are specifically not recommended without additional processing by Austria Mikro Systeme Int. AG for each application. Copyright © 1997-98, Austria Mikro Systeme International Int. AG, Schloss Premstaetten, 8141 Unterpremstaetten, Austria- Europe. Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. The information furnished here by Austria Mikro Systeme Int. AG is believed to be correct and accurate. However, Austria Mikro Systeme Int. AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of Austria Mikro Systeme Int. AG rendering of technical or other services. Headquarters Austria Mikro Systeme International Int. AG Schloß Premstätten
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