Preliminary Data Sheet AS2504 ® Cordless telephone, answering machine line interface Austria Mikro Systeme International AG Key Features General Description Analogue line interface and speech circuit for a/b terminals on a 28-pin CMOS-IC 2 balanced transmit inputs 3 unbalanced transmit inputs 2 buffered single ended receive outputs (RL>150Ω) 1 auxiliary single ended receive output (RL>10kΩ) Low noise (max. -72dBmp) Soft clipping to avoid harsh distortion Operating range from 15mA to 100mA (down to 5mA with reduced performance) Line loss compensation selectable by pin option Real and complex impedance selectable by external components Side tone adaptation selectable by external components Digital controls input for mode selection Rx volume control AS2504 is a CMOS integrated circuit that incorporates DC and AC line adaptation (DCmask and synthesised AC-impedance of 1000Ω) as well as a speech circuit with softclipping, line loss compensation and Rxvolume control. It shall act as an a/b-line powered or auxiliarily powered device, which is controlled by a CPU. Application Cordless base stations, answering machines, a/b-line or auxiliary powered telephone sets. Package Available in 28 pin SOIC Block Diagram 1/12 August 1998 Preliminary Data Sheet AS2504 Pin description Pin # Symbol 7 LS Function Line Current Sense Input Input for sensing the line current 5 LI Line Input Input used for power extraction and line current sensing 6 RI 13 STB Receive Input Input for ac-separated receive signal Side Tone Balance Input Input for side tone cancellation network 3 CS Current Shunt Control Output N-channel open drain output to control the external high power shunt transistor for synthesising AC- and DC-impedance, modulation of line voltage and shorting the line during make periods of pulse dialling 14 CI Complex Impedance Input Input pin for the capacitor to program a complex impedance 25 MASK MASK Input pin to set circuit into power down mode during e.g. LD-dialling. During MASK=HIGH, CS-pin is internally shorted to ground. 26 LLC Line Loss Compensation Select Pin 45mA-75mA —> VDD 20mA-50mA —> AGND None —> VSS 11 VDD Voltage Drain Drain Positive Power Supply, for external circuitry t.m. 4.0mA@IL=20mA and 4.0mA@IL=20mA 4 VSS Voltage Source Source Negative Power Supply 12 AGND Analogue Ground Special ground for the internal amplifiers 2 M1 Microphone Input 1 Differential input for the microphone (electret) 1 M2 Microphone Input 2 Differential input for the microphone (electret) 28 M3 Microphone Input 3 Differential input for the microphone (electret) 27 M4 Microphone Input 4 Differential input for the microphone (electret) 24 ATI1 Auxiliary Transmit Input 1 RI >= 25kΩ 23 ATI2 Auxiliary Transmit Input 2 RI >= 100kΩ 2/12 August 1998 Preliminary Data Sheet Pin # Symbol 15 ATI3 AS2504 Function Auxiliary Transmit Input 3 RI >= 100kΩ 8 ROH1 Receive Output to Handset 1 Output for driving a dynamic earpiece with an impedance from 150Ω to 300Ω (max. 0.7Vp) 9 ROH2 Receive Output to Handset 2 Output for driving a dynamic earpiece with an impedance from 150Ω to 300Ω (max. 1.4Vp) 10 ARO1 Auxiliary Receive Output 1 RL > 10kΩ (max. 1.4Vp) 16 VOL VOLume Input pin for increasing (= connect to VIN >= VDD-0.3V) or decreasing (= connect to VIN <= VSS+0.3V) the Rx volume. The idle state is between VSS+1.4V < VIN < VDD-1.4V. Max rise time 50ns, max fall time 50ns, min pulse width 1us 22 HSS HandSet or HeadSet / bit Digital input to select the ROH1 or ROH2 signal output path 21 RX0 Receive 0 / bit Digital input to select a signal path 18 AUX0 Auxiliary 0 / bit Digital input to select a signal path 17 AUX1 Auxiliary 1 / bit Digital input to select a signal path 20 TX0 Transmit 0 / bit Digital input to select a signal path 19 TX1 Transmit 1 / bit Digital input to select a signal path 3/12 August 1998 Preliminary Data Sheet AS2504 Functional Description The DC characteristic is determined by the voltage at LI-pin and a 30Ω resistor between LI- and LS-pin. It can be calculated by the following equation: VLS = VLI + ILine * 30Ω. The t.m. voltage at the LI-pin is 4.5V. The calculation leads to the following DC resistances: 330Ω to 75Ω at line currents from 15mA to 100mA. Modes of operation There are 3 possible modes: Idle Mode: AS2504 is disconnected from the a/b-line (= no line current) and VDD is not supplied by auxiliary power. All internal circuits are powered down. Input of digital control signals is not possible. With a HIGH at the MASK-pin, the speech circuit and other parts of the device, which are not needed for operation, are in power down mode in order to save current. The CS-pin is pulled to Vss to turn the external shunt transistor fully on. This guarantees a low voltage drop (<1V) at the LI-pin during make periods of pulse dialling or flash. Line Power Mode: AS2504 is connected to the a/b-line and VDD is generated by the internal power extraction. The speech circuit is powered up. The line interface circuit is functional (DC-mask and AC-impedance are synthesised). Input of digital control signals is possible. 2/4 wire conversion Aux. Power Mode: AS2504 is disconnected from the a/b-line (= no line current) and VDD is supplied by auxiliary power. The speech circuit is powered up. The line interface circuit is not functional (DC-mask and AC-impedance). Input of digital control signals is possible. AS2504 has a built-in dual Wheatstone bridge with one common ground. This provides a maximum of independence of AC-impedance and side tone from each other. One can adapt side tone without changing the AC-impedance. Start-up in Line Power Mode AC-impedance As soon as AS2504 is supplied with line current, the external Vdd capacitor will be charged up via the LI- and VDD-pin. After the Vdd voltage has reached the operating level of 2V, the line interface circuit and the selected signal path of the speech circuit is switched on. This off-hook status is signalled to the internal logic via the LS-pin (voltage level sensitive). The AC-impedance of AS2504 is set to t.m. 1000Ω. With the external capacitor at CI-pin it can be programmed complex. With an external resistor of approx. 1.5kΩ connected to the LSpin it can be programmed to 600Ω. ZAC(syn) = 33 * 30Ω. Side Tone Start-up in Aux. Power Mode A good sidetone cancellation can be achieved by using the following equation: As soon as AS2504 is supplied with auxiliary power at the VDD-pin, the selected signal path of the speech circuit is switched on. The line interface circuit (DC-mask and AC-impedance) is not functional. This on-hook status is signalled to the internal logic via the LS-pin (voltage level sensitive). ZBAL/ZLINE = 10 Transmit path The gain of the M1/M2 —> LS is set to 37dB. The input is differential with an impedance of 20kΩ. The soft clip circuit limits the output voltage at LS to 2Vp. The attack time is 30µs/6dB and the decay time is 20ms/6dB. DC conditions The normal operating mode is from 15mA to 100mA. An operating mode with reduced performance is from 5mA to 15mA. In the line hold range from 0mA to 5mA the device is in a power down mode and the voltage at LI is reduced to a maximum of 3.5V The gain of the M3/M4 —> LS is set to 43dB. The input is differential with an impedance of 10kΩ. The soft clip circuit limits the output voltage at LS to 2Vp. The attack time is 30µs/6dB and the decay time is 20ms/6dB. 4/12 August 1998 Preliminary Data Sheet AS2504 Rx volume control The gain of the ATI1 —> LS is set to 6dB. The input is unbalanced with an impedance of 25kΩ. There is no softclipping. The gain of the ATI2 —> LS is set to 20dB. The input is unbalanced with an impedance of 100kΩ. There is no softclipping. The volume control is available for LS —> ROH1 and LS —> ROH2. It can be decreased by 6dB and increased by 8dB in 2dB steps from the default levels as described in the last paragraph. It remains in the pre-set position as long as VDD does not decrease less than 2.2V Intercom path Line Loss Compensation The gain of the ATI3 —> ROH1 is set to 6dB. The input is unbalanced with an impedance of 100kΩ. There is no softclipping. The line loss compensation is a pin option. When it is activated, the transmit and receive gains for both I/O’s are decreased by 6dB at line currents from 20mA to 50mA when the LLC-pin is connected to AGND and from 45mA to 75mA when the LLC-pin is connected to VDD. The line loss compensation is deactivated when LLC-pin is connected to VSS. The gain of the ATI3 —> ROH2 is set to 12dB. The input is unbalanced with an impedance of 100kΩ. There is no softclipping. The gain of the M1/M2 —> ARO1 is set to 23dB. The input is differential with an impedance of 20kΩ. The soft clip circuit limits the output voltage at ARO1 to 0.4V p. The attack time is 30µs/6dB and the decay time is 20ms/6dB. Digital interface The selection of the available signal paths must be set via the digital control pins. The following modes are possible: The gain of the M3/M4 —> ARO1 is set to 29dB. The input is differential with an impedance of 10kΩ. The soft clip circuit limits the output voltage at ARO1 to 0.4V p. The attack time is 30µs/6dB and the decay time is 20ms/6dB. HSS: bit 0 1 0 1 Receive path The gain of the LS —> ROH2 receive path is set to 9dB. The receive input is the differential signal of RI and STB. The soft clip circuit limits the output voltage at ROH2 to 1.4Vp. It prevents harsh distortion and acoustic shock. There is volume control and LLC for this path. AUX1: bit HSS: bit 1 1 X 0 0 1 1 1 0 X 0 0 X 0 0 0 1 1 5/12 LS —> ROH1 LS —> ROH2 ATI3 —> ROH1 ATI3 —> ROH2 1 0 TX0: bit The gain of the LS —> ARO1 receive path is set to 3dB. The receive input is the differential signal of RI and STB. There is no softclipping, no LLC and no volume control for this path. 0 0 1 1 AUX0: bit The gain of the LS —> ROH1 receive path is set to 3dB. The receive input is the differential signal of RI and STB. The soft clip circuit limits the output voltage at ROH1 to 0.7Vp. It prevents harsh distortion and acoustic shock. There is volume control and LLC for this path. RX0: bit TX1: bit 0 0 1 0 1 HSS: bit 0 1 X X X MUTE M1/M2 —> ARO1 M3/M4 —> ARO1 LS —> ARO1 MUTE M1/M2 —> LS M3/M4 —> LS ATI1 —> LS ATI2 —> LS MUTE August 1998 Preliminary Data Sheet AS2504 Typical Application 6/12 August 1998 Preliminary Data Sheet AS2504 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 <= VDD <= 7V Input Current ± 25mA Input Voltage (LS) -0.3V <= Vin <= 12V Input Voltage (LI, CS) -0.3V <= Vin <= 8V Input Voltage (STB, RI) -2V <= Vin <= VDD+0.3V Digital Input Voltage -0.3V <= Vin <= VDD+0.3V ± 1000V Electrostatic Discharge (HBM 1.5kΩ-100pF) Storage Temperature -65°C to +125°C Recommended operating conditions Supply Voltage (generated internally) 4V <= VDD <= 5V Operating Temperature -25°C to +70°C DC characteristics ILine=15mA w/o operation of any additional external circuitry, unless other specified Symbol Parameter Conditions Min IDD Operating Current Speech Mode MASK=H, VDD=2.5V VLI Line Voltage 15mA<=ILINE<=100mA IOL Output Current, Sink CS 4.2 VOL=0.4V Typ Max Units 3 300 5 mA µA 4.5 4.8 V 1 VIL Digital Input Voltage LOW Pins HSS,RX0,TX0, TX1,AUX0,AUX1 VIH Digital Input Voltage HIGH Pins HSS,RX0,TX0, TX1,AUX0,AUX1 7/12 mA VSS 0.2 VDD V 0.8 VDD VDD V August 1998 Preliminary Data Sheet AS2504 Transmit characteristics V ILine=15mA f=800Hz, unless other specified Symbol Parameter Conditions Min Typ Max Units AM1/2TX Transmit Gain M1/M2 —> LS ZAC(syn)=1000Ω +36.0 +37.5 +39.0 dB AM3/4TX Transmit Gain M3/M4 —> LS ZAC(syn)=1000Ω +42.0 +43.5 +45.0 dB AAT1X Transmit Gain ATI1 —> LS ZAC(syn)=1000Ω +5.0 +6.5 +8.0 dB AAT2X Transmit Gain ATI2 —> LS ZAC(syn)=1000Ω +19.0 +20.5 +22.0 dB ∆ATX Variation with frequency f = 500Hz … 3.4kHz THD Distortion VLS=0.25VRMS VUFC Unwanted Freq. Comp. f = 200Hz … 20kHz VAGC1 Soft Clip Level M1/M2 —> LS at LS 2.0 VP VAGC2 Soft Clip Level M3/M4 —> LS at LS 2.0 VP ASCO Soft Clip Overdrive M1/M2 - M3/M4 20 dB tattack tdecay Attack time Decay time 30 20 µs/6dB ms/6d B ZIN-M1/2 Input Impedance M1/M2 20 kΩ ZIN-M3/4 Input Impedance M3/M4 10 kΩ ZIN-ATI1 Input Impedance ATI1 25 kΩ ZIN-ATI2 Input Impedance ATI2 100 kΩ AMUTE Mute Attenuation M1/2 - M3/4 VINmax Input Voltage Range M1/2 - M3/4 differential VNO Noise Output Voltage LS TAMP=25°C RL Return Loss ∆ZAC/°C Temp. Variation ±0.8 dB 2 % -60 dBm 60 dB ±1 ZAC(syn)=1000Ω -71 18 0.5 8/12 Vp dBmp dB Ω/°C August 1998 Preliminary Data Sheet AS2504 Intercom characteristics ILine=15mA f=800Hz, unless other specified Symbol Parameter Conditions Min Typ Max Units AM1/2IX Intercom Gain M1/M2 —> ARO1 +21.5 +23.0 +24.5 dB AM3/4IX Intercom Gain M3/M4 —> ARO1 +27.2 +28.7 +30.2 dB AAT3IX Intercom Gain ATI3 —> ROH1 +4.5 +6.0 +7.5 dB AAT4IX Intercom Gain ATI3 —> ROH2 +10.5 +12.0 +13.5 dB ZIN-ATI3 Input Impedance ATI3 100 kΩ Receive characteristics ILine=15mA f=800Hz, unless other specified Symbol Parameter Conditions Min Typ Max Units AHRX Receive Gain LS —> ROH1 ZAC(syn)=1000Ω +1.0 +2.5 +4.0 dB AAR1X Receive Gain LS —> ROH2 ZAC(syn)=1000Ω +7.0 +8.5 +10.0 dB AAR1X Receive Gain LS —> ARO1 ZAC(syn)=1000Ω +0.7 +2.2 +3.7 dB ∆ARX Variation with frequency f=500Hz to 3.4kHz AVOL Volume control range THD Distortion ROH1-ROH2 VLS=0.25VRMS 2 % THD Distortion ARO1 VLS=0.25VRMS 3 % VUFC Unwanted Freq. Comp. f = 200 … 20kHz -60 dBm VAGC Soft Clip Level ROH1 0.7 VP VAGC Soft Clip Level ROH2 1.4 VP ASCO Soft Clip Overdrive ROH1/2 10 dB tattack tdecay Attack time Decay time 30 20 µs/6dB ms/6d B VNO Noise Output Voltage ROH1/2 - ARO1 ZIN-RI VINmax Input Imp. RI Input Voltage Range RI ±0.8 dB -6/+8 dBr TAMP=25°C -71 8 ±2 9/12 dBmp kΩ Vp August 1998 Preliminary Data Sheet Symbol Parameter ZIN-STB VINmax Input Imp. STB Input Volt. Range STB ST Sidetone RL Return Loss ∆ZAC/°C Temp. Variation AS2504 Conditions Min Typ 80 ±2 VRI<=0.25VRMS 24 ZAC(syn)=1000Ω 18 Max Units kΩ Vp dB 0.5 dB Ω/°C Test circuit 10/12 August 1998 Preliminary Data Sheet AS2504 Packaging The device is available in the packages outlined below (not to scale). For exact mechanical package dimensions please see AMSAG packaging information. 28-pin plastic SOIC (suffix T) Max. Body Length Max. Body Width Pitch 18.1mm / 713mil 7.6mm / 300mil 1.27mm / 50mil Pin-out 1 2 3 4 5 6 7 8 9 10 11 12 13 14 – – – – – – – – – – – – – – M2 M1 CS VSS LI RI LS ROH1 ROH2 ARO1 VDD AGND STB CI M3 M4 LLC MASK ATI1 ATI2 HSS RX0 TX0 TX1 AUX0 AUX1 VOL ATI3 – – – – – – – – – – – – – – 28 27 26 25 24 23 22 21 20 19 18 17 16 15 Marking YYWWAAA AS2504 Austria YY WW AAA 11/12 year of production calendar week of production AMSAG assembly ID August 1998 Preliminary Data Sheet AS2504 Ordering information Number Package Description AS2504 T SO28 plastic small outline package - 28 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, AustriaEurope. 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 damag es, 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. 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AG is represented by distributors in the following countries. Please contact your nearest regional sales office for the distributor’s address: China, India, Japan, Korea, Singapore, Taiwan Application support Please contact your local sales office or your distributor 12/12 August 1998