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| TELEFUNKEN Semiconductors U4275B FM-Receiving Condition Analyser and Multipath Noise Cancellation Description The U4275B is a bipolar integrated receiving conditions analyser as well as multipath noise cancellation circuit. It is designed for high performance car radio applications. Features D Preparation of the fieldstrength signal D Detection of multipath and common channel interferences D Evaluation of the receiving conditions by microcomputer D D D D D Interrupt output for abruptly occuring interferences Suitable for analogue as well as digital processing Mute function controllable by microcomputer Multipath noise cancellation Only a few external components necessary Block diagram FIL19 20 CRIN 14 Oscillator Common channel detector Filter Interference interrupt 9 INT FIL26 19 CCHFIL 17 12 Reset Address logic 1 FSIN AVFS 3 Multipath detector Analogue multiplex 11 13 15 ADDR0 ADDR1 OE ANAOUT 2 BFSOUT Buffer MNC control Multipath Noise Cancellation (Gain 1.5) 18 4 5 6 8 Bandgap 7 VS 10 94 8644 16 GND1 MUTE MPFIL GND2 VREF MPXIN MPXOUT Rev. A1: 14.03.1995 Preliminary Information 1 U4275B Pin description Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Symbol FSIN BFSOUT AVFS MPXIN GND2 MPXOUT VS VREF INT MUTE ANAOUT ADDR0 ADDR1 CRIN OE GND1 CCFIL MPFIL FIL26 FIL19 Function Fieldstrength input Buffered fieldstrength output Average of fieldstrength signal Multiplex input signal Analogue ground Multiplex output signal Supply voltage Reference voltage Interrupt output External mute input Analogue multiplex output Address 0 for analogue multiplexer Address 1 for analogue multiplexer Ceramic resonator input (456 kHz) Output enable for ANAOUT Ground Filter for common channel detection Filter for multipath detection Filter for 26 kHz detection Filter for 19 kHz-Pilot detection TELEFUNKEN Semiconductors FSIN 1 BFSOUT 2 AVFS 3 MPXIN 4 GND2 5 MPXOUT 6 VS 7 20 FIL19 19 FIL26 18 MPFIL 17 CCFIL 16 GND1 15 OE 14 CRIN 13 ADDR1 12 ADDR0 11 ANAOUT 94 8830 VREF 8 INT 9 MUTE 10 FSIN / BFSOUT VS 40 mA FSIN 94 8647 AVFS BFSOUT AVFS 40 mA 94 8648 All information about reception conditions is derived from the fieldstrength voltage. The fieldstrength voltage at FSIN is initially buffered so as not to impair the characteristics of the IF IC and is available at BFSOUT. The fieldstrength signal at buffer output BFSOUT is averaged over time and applied to input AVFS via an RC low-pass filter with a large time constant. 2 Preliminary Information Rev. A1: 14.03.1995 TELEFUNKEN Semiconductors MPXIN / MPXOUT VS 50 kW MPXIN U4275B The function unit MNC can be controlled externally via this pin. Blanking occurs when the voltage at the MUTE pin falls below 1 V. A voltage in the range VS/2 > 1 V defines the switching threshold as from which multipath interference is signalled at pin INT. CRIN 50 kW VS 94 8649 VS 60 kW MPXOUT 60 kW VS CRIN 40 kW 200 mA 94 8652 94 8650 The MPX signal is fed directly from the FM demodulator to input MPXIN and is available amplified by a factor of 1.5 at MPXOUT. The MPX signal is blanked out in the event of multipath interference or when MUTE is activated externally in the circuit part MNC (Multipath Noise Canceller). In all other cases, the MPX signal passes through the IC unchanged. The internal one-pin oscillator is connected to CRIN with a 456 kHz ceramic resonator. The 456 kHz reference frequency is used for calibrating the filters and generating pulses at INT. ANAOUT +5V GND2 GND2 is the reference potential for the MPX signal. GND2 should be connected directly with the ground terminal of the IF FM demodulator to ensure a high signal-to-noise ratio of the MPX signal. ANAOUT 60 mA 94 8653 MUTE Analyzer output. DC values are available at this pin that characterize the respective reception situation. The output voltage is limited to max. 5 V. ANAOUT is a multiplex output, i.e. the value for the fieldstrength, level of multipath interference or level of common channel interference is applied to this output depending on addressing. ANAOUT can be switched to the high-impedance state by means of OE. MUTE 94 8651 Rev. A1: 14.03.1995 Preliminary Information 3 U4275B INT +5V 25 kW INT TELEFUNKEN Semiconductors The controller element detects the absolute value of occuring multipath interference. This information is stored in a capacitor which must be connected externally to MPFIL. The capacitor voltage can be interrogated by the system controller via ANAOUT. FIL19 / FIL26 94 8654 Certain types of abruptly occuring interference with reception require a fast reaction by the receiver. INT signals such events to other circuit parts by means of 40-ms-wide pulses (low active). The output voltage is limited to 5 V to permit direct activation of a system controller. A monoblend function can thus be activated on simple receivers. On antenna-diversity receivers, INT can activate switchover between antennas. FIL19 100 kW 100 nA 94 8657 CCFIL FIL26 CCFIL 100 kW 100 nA 94 8655 94 8658 100 kW 100 nA The controller element detects the absolute value of occuring common channel interference. This information is stored in a capacitor which must be connected externally to CGFIL. The capacitor voltage can be selected by the system controller and then available via ANAOUT. In order to differentiate the various types of interference, the amplitudes of a few spectral components of the fieldstrength signal are determined and filtered in FIL19 and FIL26 for further processing. VREF VS 30 k VREF 30 k MPFIL MPFIL 100 kW 94 9669 100 nA 94 8656 IF Mute is activated, the reference voltage VREF will apply to the output MPXOUT. A capacitor of 100 nF should be connected at VREF for filtering. 4 Preliminary Information Rev. A1: 14.03.1995 TELEFUNKEN Semiconductors U4275B ADDR0 / ADDR1 / OE 20 mA ADDR0 94 8659 20 mA 20 mA ADDR1 94 8660 OE 94 8662 The desired output variable at ANAOUT is selected via the address lines ADDR0 and ADDR1 and switched to the output via the enable input OE. The following assignment applies: No 0 OE L ADDR1 L ADDR0 L ANAOUT Internal reference voltage Additional reset of the analog voltages for signal level, multipath, common channel Signal level Multipath Common channel High impedance off-state 1 2 3 4 L L L H L H H X H L H X Rev. A1: 14.03.1995 Preliminary Information 5 U4275B Functional description Interference with FM reception can be triggered by various causes, such as multipath reception, adjacent and insufficient field strength. At the same time, multipath reception is responsible for the most frequently occurring types of interference. In order to suppress this interference systematically, it is first necessary to analyze the received signal so that it is possible to derive the type of interference at any time. The circuit U4275B analyzes the FM reception conditions and makes the data available. This data can be requested by a system controller and evaluated (see figure 1). It is thus possible to introduce measures for optimizing reception - possibly tailored to individual types of interference. Acoustically relevant multipath interference, since it requires a short reaction time, is suppressed directly by the circuit via a Multipath Noise Cancellation (MNC) function. The U4275B can be used both in conventional receivers and in receivers with digital signal processing. Furthermore, it is designed so that it can activate switchover between antennas on antenna-diversity receivers. The integrated circuit can be connected in cascade without much wiring for tuner-diversity receivers. TELEFUNKEN Semiconductors The field strength voltage of the IF amplifier provides all the information about the reception conditions. The following demands are placed on the field strength output of the IF amplifier: (1) A linear characteristic, i.e. the output voltage must be proportional to the logarithm of the IF voltage in the range of RF levels encountered in practice. Deviations from linearity lead to a different evaluation of interference signals of the same intensity of the signal levels are different. (2) The "signal level" output has to react to extremely fast dips in the field strength. Total field strength failures lasting 500 ns and occuring a voltage dip to approx. 0 V at the field strength output. Restrictions The field strength voltage becomes increasingly noisy in the range of low RF levels (< 30 dBmV). The noise prevents reliable detection of interference. Therefore, only the average field strength value can be evaluated over a relatively large time constant in this range. The pilot signal component in the receive signal is an important basis for quality assessment. Multipath detection and common channel detection therefore function only in the case of stereo transmitters. MPX in FM - tuner Fieldstrength signal Address MPX out AFleft U4275B Interrupt output ANA out Digital or analogue signal processing AFright System controller 94 8646 Figure 1 Block diagram 6 Preliminary Information Rev. A1: 14.03.1995 TELEFUNKEN Semiconductors Multipath detector Typical multipath interference is characterized by fast, modulation-dependent field strength dips, as shown in figure 2. The multipath detector detects these field strength dips and evaluates them in accordance with the level of anticipated acoustic interference. In the case of acoustically relevant interference, it operates the interrupt output INT and the MNC function as a reaction to the interference. If the acoustic effects of interference can be reduced by monoblend, only pulses will appear at output INT. In the case of stronger interference, interference suppression takes place by means of the Multipath Noise Cancellation (MNC) function. The multipath interference also generates a voltage proportional to the interference level at MPFIL. The capacitor connected there is responsible for storing the information to give the system controller sufficient time to read out the value at ANAOUT. The capacitor at MPFIL is discharged again slowly with a long time constant. The corresponding addressing at ADDR0, ADDR1 and OE to permit a rapid assessment when the station is changed. U4275B signal does not cause the MNC to respond at low RF voltages and - the field strength dip must not be caused by adjacent-channel interference. Blanking will otherwise make the modulation of the adjacent channel audibly. The information for this purpose is derived from the common channel detector. The MNC function can also be activated externally via the MUTE pin (low active). The circuit can therefore also be used as a fast high performance mute stage. Common channel detector The common channel detector evaluates the spectral composition of the field strength signal to distinguish common channel interference from other types of interference. This is a particularly difficult task, since weak multipath interference results in a spectrum of the field strength signal that is similar to that of common channel interference. the pilot signal portion of the field strength signal serves as a reference variable to permit a clear distinction to be made. A voltage proportional to the interference is generated at the filter input CCFIL in the case of common channel interference. The external capacitor is responsible for storing the information to give the system controller sufficient time to read out the value at ANAOUT. The capacitor is discharged again slowly at CCFIL, with a long time constant. The capacitor can also be discharged rapidly via corresponding addressment when stations are changed. The common channel detector is blocked for further 20 ms after the detectors are reset to prevent transitory phenomena in the selective filters from causing an indicating error. Multipath Noise Cancellation (MNC) Extremely strong multipath interference remains audible in spite of the monoblend function. The remaining interference is reduced still further by the MNC circuit if the output MPXOUT is connected to a reference voltage for a few microseconds while the interference is still occuring. In order to eliminate the possibility of malfunctions, activation of the MNC depends on the following conditions: - The average field strength must exceed a certain value so that the noise in the field strength Rev. A1: 14.03.1995 Preliminary Information 7 U4275B TELEFUNKEN Semiconductors 94 8663 Figure 2 8 Preliminary Information Rev. A1: 14.03.1995 TELEFUNKEN Semiconductors U4275B Absolute maximum ratings Reference point Pin 1b, unless otherwise specified Parameters Supply voltage Pin 7 Supply current Pin 7 Ambient temperature range Storage temperature range Junction temperature Electrostatic handling (MIL standard 883 C) Symbol VS IS Tamb Tstg Tj VESD Value 10 t.b.d. - 30 to + 85 t.b.d. t.b.d. 2000 Unit V mA C C C V " Thermal resistance Parameters Junction ambient Symbol RthJA Maximum t.b.d. Unit K/W Electrical characteristics Tamb = 25_C, VS = 8.5 V, unless otherwise specified Parameters Supply voltage Supply current Fieldstrength Input voltage Output voltage Test conditions / Pins Pin 7 Pin 7 Pin 1 Pin 2 Symbol VS IS Vi Vout BW V VMPXIN VMPXOUT 0.06 100 75 G VIN 0 3 IIN 1 0.5 1 VS 82 3.5 Min. 8 6 0 50 100 0 Typ. 8.5 8 Max. 10 10 5.0 5000 Unit V mA V mV KHz V VRMS VRMS % kHz dB dB V Rload Cload Bandwidth Pin 2 Input voltage Pin 3 Multipath Noise Cancellation MPX input voltage Pin 4 MPX output voltage RL = 10 kW Pin 6 THD RL = 10 kW Pin 6 VMPXIN = 350 mV Bandwidth RL = 10 kW Pin 6 Noise figure Mute-depth RL = 10 kW Pin 6 Gain RL = 10 kW Pin 6 Address logic Input voltage Pins 12, 13 and 15 low high Input current Pin 12 low high 5 350 525 0.2 mA mA 9 Rev. A1: 14.03.1995 Preliminary Information U4275B Parameters Interrupt output INT Output voltage low high Reference voltage VREF Output voltage Analog multiplex output Output voltage Oscillator Input voltage Mute Input voltage low high Test conditions / Pins RL = Symbol VINT TELEFUNKEN Semiconductors Min. Typ. Max. Unit R Pin 9 0 4.75 Pin 8 VREF VANA VOSC VMUTE 0 3 0.200 50 VS/2 0.3 5.25 V V V RL = 10 kW Pin 11 Pin 14 Pin 10 5.2 V mVRMS 1 VS V Application circuit 560 k 150 nF 560 k 560 k 150 nF 150 nF 94 8645 20 14 Oscillator 456 kHz 19 17 9 Control signal 12 13 Address logic 15 System - controller Reset Common channel detector Filter Interference interrupt Fieldstrength 1 3 47 kW 2 100 nF 10 Mute control FM - tuner 1 mF 560 k 150 nF 18 Buffer MNC control Multipath Noise Multipath detector Analogue multiplex 11 Exception quality Supply voltage 7 Bandgap Cancellation (Gain 1.5) 4 5 6 8 16 100 nF MPX - Decoder & audio MPX MPX 10 Preliminary Information Rev. A1: 14.03.1995 TELEFUNKEN Semiconductors U4275B Package Remarks Taping according to IEC-286-3 Extended type number U4275B-AFL U4275B-AFLG3 SO 20 plastic SO 20 plastic Dimensions in mm Rev. A1: 14.03.1995 Preliminary Information 11 U4275B It is the policy of TEMIC TELEFUNKEN microelectronic GmbH to TELEFUNKEN Semiconductors OZONE DEPLETING SUBSTANCES POLICY STATEMENT 1. Meet all present and future national and international statutory requirements and 2. Regularly and continuously improve the performance of our products, processes, distribution and operating systems with respect to their impact on the health and safety of our employees and the public, as well as their impact on the environment. Of particular concern is the control or elimination of releases into the atmosphere of those substances which are known as ozone depleting substances ( ODSs). The Montreal Protocol ( 1987) and its London Amendments ( 1990) will soon severely restrict the use of ODSs and forbid their use within the next ten years. Various national and international initiatives are pressing for an earlier ban on these substances. TEMIC TELEFUNKEN microelectronic GmbH semiconductor division has been able to use its policy of continuous improvements to eliminate the use of any ODSs listed in the following documents. 1. Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively 2 . Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental Protection Agency ( EPA) in the USA and 3. Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C ( transitional substances ) respectively. TEMIC can certify that our semiconductors are not manufactured with and do not contain ozone depleting substances. We reserve the right to make changes without further notice to improve technical design. Parameters can vary in different applications. All operating parameters must be validated by the customer for each customer application. Should the buyer use TEMIC products for any unintended or unauthorized application the buyer shall indemnify TEMIC against all claims, costs, damages, and expenses arising out of, directly or indirectly, personal damage, injury or death associated with such unintended or unauthorized use. TEMIC TELEFUNKEN microelectronic GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany Telephone: 49 (0)7131 67 2831, Fax Number: 49 (0)7131 67 2423 12 Preliminary Information Rev. A1: 14.03.1995 |
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