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Features
* * * * * * * * * * * * *
FM Double-conversion System Integrated Second IF Filter with Software-controlled Bandwidth Completely Integrated FM Demodulator Soft Mute and Multipath Noise Cancellation Receiving Condition Analyzer AM Up/Down-conversion System AM Preamplifier with AGC and Stereo Capability 3-wire Bus Controlled Search Stop Signal Generation (AM and FM) Automatic Alignment Possible Pin Compatible with ATR4255 World Tuner, US Weatherboard, J-band Lead-free Package
AM/FM Receiver IC ATR4258
Electrostatic sensitive device. Observe precautions for handling.
1. Description
The ATR4258 is a highly integrated AM/FM front-end circuit manufactured using Atmel's advanced BICMOS technology. It represents a complete, automatically adjustable AM/FM front end, containing a double-conversion system for FM and an up/down-conversion receiver for AM with IF1 = 10.7 MHz and IF2 = 450 kHz. The front end is suitable for digital or analog AF-signal processing. Together with the PLL U4256BM, an automatically aligned high-performance AM/FM tuner can be built. These ICs are dedicated for highly sophisticated car radio applications.
Rev. 4838B-AUDR-05/05
Figure 1-1.
Block Diagram
IF1FMI MX1OA 43 MX1OB 44 IF1REF 38 39 33 AM AM Dem. FM 41 AGC AM 3 7 6 8 AGC V3 Noiseblanker AGC 35 20 Automatic FILADJ Adjustment 37 IFAGCL IFAGCH IF2OUT OPLPF 32 IF1AMI V3 MX2OB IF1OUT MX2IN 30 29 26 23 MX2OA 24 IF2IN V3P 28 27
MX1AMA MX1AMB AMAGC AMVREG AMPLPF
36
MX1FMA MX1FMB
1 2
FM MultiMULTIP path 40 Divider 2...10 Divider Offset Adj. Chan. Stop
GNDMX OSCOUT
4 16 FM Dem. Soft Mute MPX 11
GNDOSC OSCE OSCB
15 14 13 OSC
V3 Bandgap 12 25 42 5 Bus 17 18 19 9 METER 22 MX2LO 10 ADJAC INT 21 INT 34 SMUTE Dev. Ana. 31 DEV
V57 VS EN DATA GND FMAGC CLK
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2. Pin Configuration
Figure 2-1. Pinning SSO44
MX1FMA MX1FMB MX1AMB GNDMX FMAGC AMVREG AMAGC AMPLPF METER
1 2 3 4 5 6 7 8 9
44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23
MX1OB MX1OA VS MX1AMA MULTIP IF1REF IF1FMI FILADJ IFAGCL IFAGCH SMUTE IF1AMI OPLPF DEV IF1OUT V3 IF2IN V3P MX2IN GND MX2OA MX2OB
ADJAC 10 MPX 11 V57 12 OSCB 13 OSCE 14 GNDOSC 15 OSCOUT 16 EN 17 CLK 18 DATA 19 IF2OUT 20 INT 21 MX2LO 22
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3. Pin Description
Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 Symbol MX1FMA MX1FMB MX1AMB GNDMX FMAGC AMVREG AMAGC AMPLPF METER ADJAC MPX V57 OSCB OSCE GNDOSC OSCOUT EN CLK DATA IF2OUT INT MX2LO MX2OB MX2OA GND MX2IN V3P IF2IN V3 IF1OUT DEV OPLPF IF1AMI SMUTE IFAGCH IFAGCL FILADJ IF1FMI IF1REF MULTIP MX1AMA VS MX1OA MX1OB Function 1st mixer FM input A 1st mixer FM input B 1st mixer AM input B Ground 1st mixer, preamplifier AGC FM preamplifier AGC AM control voltage AM preamplifier AGC AM AGC LP filter Field strength output Adjacent channel detection output Multiplex signal 5.7V reference voltage Oscillator basis Oscillator emitter Oscillator ground Oscillator output 3-wire bus enable 3-wire bus clock 3-wire bus data 2nd IF amplifier output Interrupt, stop signal 10.25 MHz input for 2nd mixer 2nd mixer output B 2nd mixer output A Ground 2nd mixer input 3V reference for AMPIN, AMIFAGC, Control, IF2IN 2nd IF amplifier input 3V reference for IF1OUT, MX2IN 1st IF amplifier output Deviation detect output, test output Operating point LPF 1st IF AM amplifier input Soft MUTE control input IF AGC LP filter high time IF AGC LP filter low time constant Filter adjust 1st IF FM amplifier input 1st IF & MX1OUT reference, MX1AM A, MX1AM B Multipath detection output 1st mixer AM input A Supply voltage 1st mixer output A 1st mixer output B
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4. Functional Description
The ATR4258 implements an AM up/down-conversion reception path from the RF input signal to the AM-demodulated audio frequency output signal, and for FM/WB reception a double-conversion reception path from the RF input signal to the FM-demodulated multiplex signal (MPX). A VCO and an LO prescaler for AM are integrated to generate the LO frequency for the 1st mixer. Automatic gain control (AGC) circuits are implemented to control the preamplifier and IF stages in the AM and FM reception path. For improved FM performance, an integrated IF filter with adjustable bandwidth, a softmute feature and an automatic multipath noise cancellation (MNC) circuit are fully integrated. A powerful set of sensors is provided for receiving condition analysis and stop signal generation. Several register bits (bit 0 to bit 93) are used to control circuit operation and to adapt certain circuit parameters to the specific application. The control bits are organized in two 8-bit and three 24-bit registers that can be programmed by the 3-wire bus protocol. The bus protocol and the bit-to-register mapping is described in the section "3-wire Bus Description" on page 20. The meaning of the control bits is mentioned in the following sections. The integrated VCO has a high frequency range. Additionally the VCO has a special VCO divider which allows (in connection with the VCO) the reception of all analog world bands.
4.1
Reception Mode
The IC can be operated in four different modes. Mode AM, FM, WB, and Standby are selected by means of bit 92 and bit 93 according to Table 4-1 on page 6. Additionally to the operating modes, the signal paths can be set separately. Bit 62 selects the first mixer and AGC, bit 63 selects the 1st amplifier stage. The recommended settings of bit 62 and bit 63 are included in Table 4-1 on page 6. In AM mode the AM mixer, the AM RF-AGC and the 1st IF AM amplifier at pin 33 are activated. The input of the 2nd IF amplifier is connected to pin 28 and the output of the 2nd IF amplifier is fed to the AM demodulator. The output of the AM demodulator is available at MPX output pin 11. In FM mode the FM mixer, the FM RF-AGC and the 1st IF FM amplifier at pin 38 are activated. The bandwidth of the output tank at pin 23, pin 24 is increased and the input of the 2nd IF amplifier can be switched between pin 23 and pin 24 and pin 28. The output of the 2nd IF amplifier is fed to the integrated band filter and FM demodulator. The output of the FM demodulator is available at MPX output pin 11. The WB mode is similar to the FM mode, but to reduce the bandwidth the AM IF amplifier with the AM filter (bit 63 = 1) can be used. In WB mode the range of the integrated filter bandwidth control is shifted to lower bandwidth and the gain of the FM demodulator is increased. In standby mode the mixers, IF amplifiers and AGC circuits are deactivated to reduce current consumption.
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Table 4-1.
Operating Mode
Bit 93 0 0 1 1 Bit 92 0 1 0 1 Bit 63 X 0 1 1 Bit 62 X 0 1 0
AM/FM/Weather Channel Standby FM AM Weather band
4.2
Test Mode
A special test mode is implemented for final production test only. This mode is activated by setting bit 9 = 1. This mode is not intended to be used in customer applications. For normal operation, bit 9 has to be set to 0. Bit 22 to bit 30 are deactivated in normal operation mode.
Table 4-2.
Test Mode
Mode Normal operation Test mode Bit 9 0 1
4.3
VCO/Local Oscillator Prescaler
An oscillator circuit is implemented to build a VCO as proposed in the application schematic. The VCO frequency is used to generate the LO frequency of the 1st mixer stages. The control voltage of the VCO is usually generated by the PLL circuit U4256BM. The VCO frequency has a range of 70 MHZ to 250 MHz to allow the reception of all analog world bands. A main element of the implemented oscillator circuit is a bipolar NPN transistor. The internally biased base is connected to pin 13 and the emitter to pin 14. An AGC circuit (bit 30) can be activated to increase the emitter current until the appropriate oscillation level is reached. The fundamental emitter current can be changed by bit 52.
Table 4-3.
Local Oscillator AGC
Bit 30 0 1
Local Oscillator (VCO) AGC off (default) AGC on
Table 4-4.
Local Oscillator Gain
Bit 52 0 1
Local Oscillator (VCO) Low Gain High Gain
In addition (to the AM prescaler) a special VCO prescaler is implemented for all modes (AM, WB and FM). The divider factor of the prescaler buffer provides the signal of the buffered output (at pin 16) and the prescaler VCO provides the signal of the 1st FM mixer stage and AM prescaler. Examples of VCO prescaler settings are described in section "Application Information" on page 29. The divider factor of the VCO and buffer prescaler can be selected according Table 4-5 on page 7.
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Table 4-5. Local Oscillator Prescaler (VCO/Buffer Divider)
Prescaler Buffer 1 3 1.5 2 3 Bit 12 X 0 1 X X Bit 11 0 0 0 1 1 Bit 10 0 1 1 0 1 Prescaler VCO 1 1.5 1.5 2 3 Note:
The U4256 FMOSCIN (pin 19) input frequency is limited to 160 MHz.
4.4
FM RF-AGC
The FM RF-AGC circuit includes a wide-band level detector at the input pin 1 of the FM mixer and an in-band level detector at the output of the FM IF amplifier (pin 30). The outputs of these level detectors are used to control the current into the pin diode (see Figure 4-1) in order to limit the signal level at the FM mixer input and the following stages. The maximum pin diode current is determined by R115 and the time constant of the AGC control loop can be adjusted by changing the value of C111. The AGC threshold level at the input of the FM mixer can be adjusted by bit 64 and bit 65 according to Table 4-6. The in-band AGC threshold refers to the FM mixer input (pin 1, pin 2) depends on the gain of the FM IF amplifier and can be adjusted by bit 89 to bit 91.
Table 4-6.
FM-AGC Threshold
FM-AGC Threshold 100 dBV 97 dBV 94 dBV 91 dBV Bit 65 0 0 1 1 Bit 64 0 1 0 1
Figure 4-1.
FM RF-AGC Bit 92
VS Pin 42 C111 Pin 5 R115
PIN Diode
AGC
B92
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4.5
AM RF-AGC
The AM RF-AGC controls the current into the AM pin diodes (pin 7) and the source drain voltage of the MOSFET in the AM preamplifier stage (pin 6) to limit the level at the AM mixer input (pin 3, pin 41). This threshold level can be set by bit 64 and bit 65. If the level at the AM mixer input exceeds the selected threshold, the current into the AM pin diodes is increased. If this step is not sufficient, the source drain voltage of the MOSFET is decreased. The time constant of the AGC control loop can be adjusted by changing the value of the capacitor at pin 8.
Table 4-7.
AM-AGC Threshold
AM-AGC Threshold 91 dBV 94 dBV 97 dBV 100 dBV Bit 65 0 0 1 1 Bit 64 0 1 0 1
4.6
FM 1st Mixer
In the 1st FM mixer stage, the FM reception frequency is down converted to the 1st IF frequency. The VCO frequency is used as LO frequency for the mixer.
4.7
AM 1st Mixer
The AM 1st mixer is used for up-conversion of the AM reception frequency to the 1st IF frequency. Therefore, an AM prescaler is implemented to generate the necessary LO frequency from the VCO frequency. The divide factor of the AM prescaler can be selected according to Table 4-8. (The AM prescaler is only active in AM mode).
Table 4-8.
Divide Factor of the AM Prescaler
Bit 93 1 1 1 1 1 1 1 1 1 Bit 92 0 0 0 0 0 0 0 0 0 Bit 84 0 0 0 0 0 0 0 0 1 Bit 83 0 0 0 0 1 1 1 1 X Bit 82 0 0 1 1 0 0 1 1 X Bit 81 0 1 0 1 0 1 0 1 X
Divider (AM Prescaler) Divide by 2 Divide by 3 Divide by 4 Divide by 5 Divide by 6 Divide by 7 Divide by 8 Divide by 9 Divide by 10
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4.8 FM 1st IF Amplifier
A programmable gain amplifier is used in FM (and WB) mode between pin 38 and pin 30 to compensate the loss in the external ceramic band filters. The gain of this amplifier is adjusted by bit 89 to bit 91. The input and the output resistance is 330 and fits to external ceramic filters. Two different temperature coefficients of the FM IF amplifier can be selected by bit 66.
Table 4-9.
Gain of the FM IF Amplifier
Gain FM IF 19 dB 21 dB 23 dB 25 dB 27 dB 28 dB 29 dB 30 dB Bit 91 0 0 0 0 1 1 1 1 Bit 90 0 0 1 1 0 0 1 1 Bit 89 0 1 0 1 0 1 0 1
Table 4-10.
Temperature Coefficient Setting of FM IF Amplifier
Temperature Coefficient (TC) of the IF Amplifier TKmin (TK 1) TKmax (TK 2) Bit 66 0 1
4.9
AM 1st IF Amplifier
In AM and WB mode, the gain of the 1st IF amplifier is controlled by the IF-AGC to extend the control range of the IF-AGC.
4.10
2nd Mixer
The 2nd mixer is used in AM, FM and WB mode. The mixer input has 330 input resistance and can be connected directly to an external ceramic filter. In FM mode, the high output resistance of the second mixer is reduced to increase the bandwidth of the tank at the mixer output. The output resistance can be selected by bit 60 and bit 61. In AM and WB mode bit 61 and bit 62 should be set to 0. 2nd Mixer Output Resistance in FM Mode
Bit 60 0 1 0 1 Output Resistance (Bit 54 = 0) 3.3 k 0.63 k 0.47 k 0.29 k Output Resistance (Bit 54 = 1) ~100 k 0.78 k 0.55 k 0.32 k
Table 4-11.
Bit 61 0 0 1 1
The LO frequency of the 2nd mixer (10.25 MHz) has to be applied at pin 22. This signal is usually generated by the PLL circuit U4256BM.
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Table 4-12.
Bit 61 0 0 1 1 Note:
FM Bandwidth Mixer 2
Bit 60 0 1 0 1 FM Bandwidth Mixer 2 150 kHz 200 kHz 250 kHz 450 kHz
The bandwidth is also dependant on the values of the application circuit.
4.11
2nd IF Amplifier
In AM and WB mode, the input of the second IF amplifier is pin 28, is externally connected to the 2nd mixer tank through the AM ceramic filter to achieve channel selectivity. During normal FM operation (bit 54 = 0), the input of the second IF amplifier is connected to the 2nd mixer output (pin 23, pin 24) and the integrated FM band filter is used for channel selectivity only. It is possible to use an additional external filter between the 2nd mixer tank and pin 28 in FM mode by setting bit 54 to 1. 2nd IF Filter in FM Mode
2nd IF Filter Internal filter External and internal filter Bit 54 0 1
Table 4-13.
4.12
IF-AGC
The IF-AGC controls the level of the 2nd IF signal that is passed to the AM demodulator input or the integrated FM band filter and to the 2nd IF output, pin 20. Two different time constants of the IF-AGC can be selected by the capacitors at pin 35 (IFAGCH) and pin 36 (IFAGCL). The short time constant (IFAGCL) is used in FM/WB mode and in AM search mode. The long time constant (IFAGCH) is used for AM reception.
Table 4-14.
IF-AGC Time Constant
Bit 92 1 0 0 Bit 88 X 0 1 IF AGC Time Constant IFAGCL (fast) IFAGCH (slow) IFAGCL (fast)
Mode FM/WB AM reception AM search
In FM/WB mode, the output signal of the FM demodulator is applied to pin 35 via a series resistor of about 95 k. This low-pass filtered output signal of the FM demodulator is used for the FM demodulator fine adjustment, for muting and as a reference for the deviation sensor.
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4.13 2nd IF Output
The 2nd IF after the gain-controlled 2nd IF amplifier is available at pin 20 (bit 55 = 0). In AM mode, this signal may be used for an external AM stereo decoder. Alternatively, a signal corresponding to the logarithmic field strength after the integrated FM band filter, which is used for multipath detection, can be switched to pin 20 by setting bit 55 = 1.
Table 4-15.
Pin 20 Output Setting
Pin 20 2
nd
Bit 55 0 1
IF output
Multipath field strength
4.14
Automatic IF Center Frequency Adjustment
Integrated active filters are used in the FM band filter, FM demodulator and adjacent channel sensor. The center frequency of these filters is automatically adjusted to the second IF frequency of 450 kHz. The frequency of 10.25 MHz at pin 22 is used as a reference for this alignment. Figure 4-2. Automatic IF Center Frequency Adjustment
Pin 22 10.25 MHz
Automatic frequency adjustment
Center frequency Center frequency Bit 14...17
FM-Demod
Bit 56...59 Pin 37
FMband filter
For fine tuning, the center frequency of all these integrated active filters (band filter and demodulator) can be shifted in steps of 6.25 kHz by means of bit 56 to bit 59. Additionally, the center frequency of the band filter can be adjusted separately by means of bit 14 to bit 17.
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Table 4-16.
2nd IF Center Frequency
Bit 59 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 Bit 58 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 Bit 57 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 Bit 56 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
IF Center 450.00 kHz 456.25 kHz 462.50 kHz 468.75 kHz 475.00 kHz 481.25 kHz 487.50 kHz 493.75 kHz 450.00 kHz 443.75 kHz 437.50 kHz 431.25 kHz 425.00 kHz 418.75 kHz 412.50 kHz 406.25 kHz
Table 4-17.
FM Band Filter Center Frequency Correction
Bit 17 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 Bit 16 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 Bit 15 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 Bit 14 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
IF Correction -0 kHz -6.25 kHz -12.50 kHz -18.75 kHz -25.00 kHz -31.25 kHz -37.50 kHz -43.75 kHz +0 kHz (default) +6.25 kHz +12.50 kHz +18.75 kHz +25.00 kHz +31.25 kHz +37.50 kHz +43.75 kHz
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4.15 Integrated FM Band Filter
For FM reception a band filter with variable bandwidth is integrated in front of the demodulator to provide channel selectivity on the 2nd IF. The bandwidth of this filter can be adjusted by bit 0 to 3 (see Table 4-18) to be suitable for the present receiving condition. In WB mode, the bandwidth of the integrated filter is shifted to lower bandwidth values, while the necessary channel selectivity is achieved by an external ceramic filter. The center frequency of the integrated FM band filter can be adjusted by means of bit 14 to 17. The field strength after the integrated FM band filter that is available at pin 20 (bit 55 = 1) can be used for this purpose.
Table 4-18.
Bandwidth of the Integrated Band Filter
Bit 3 0 ... 0 ... 0 ... 1 ... 1 1 1 1 Bit 2 0 ... 0 ... 1 ... 0 ... 1 1 1 1 Bit 1 0 ... 1 ... 1 ... 0 ... 0 0 1 1 Bit 0 0 ... 1 ... 0 ... 1 ... 0 1 0 1
IF Bandwidth FM (kHz) IF Bandwidth WB (kHz) 220 ... 200 ... 165 ... 130 ... 90 80 70 60 195 ... 160 ... 120 ... 80 ... 45 Not usable Not usable Not usable
4.16
FM Demodulator
For weather band reception, the gain of the FM demodulator is increased and can be adjusted by means of bit 71 and bit 72 in order to increase the output voltage to compensate the low frequency deviation in weather band. An integrated demodulator fine adjustment allows automatic fine tuning of the demodulator center frequency to the average frequency of the received signal. This feature is implemented for use in weather band mode and can be activated by setting bit 53 to 0. Figure 4-3. FM Demodulator Automatic Fine Tuning
FM Demod
MPX (Pin 11) B92 IFAGCH (Pin 35) V3P (Pin 27)
Center freq. + Bit 53
Automatic frequency adjustment
AM AGC
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The center frequency of the FM demodulator can be adjusted by means of bit 56 to 59. At the center frequency, the DC voltage at the MPX output pin 11 is equal to the MPX offset voltage that can be measured at pin 11 while MPX mute is active (bit 7 = 1). This adjustment will affect the center frequency of all integrated filters as mentioned before.
Table 4-19.
Demodulator Gain in Weather Band Mode
Bit 72 0 0 1 1 Bit 71 0 1 0 1
Demodulator Gain in Weather Band Mode Relative to FM Mode 14 dB 17 dB 21 dB 23 dB
Table 4-20.
Demodulator Fine Adjustment
Demodulator Fine Adjustment Fine tuning ON Fine tuning OFF Bit 53 0 1
4.17
Soft Mute
The soft mute functionality is implemented to reduce the output level of the FM demodulator at low input signal levels to limit the noise at the MPX output in this case. If the input level falls below an adjustable threshold continuously, the output of the FM demodulator is continuously muted with decreasing input level until a maximum mute value is reached. The threshold for the start of soft mute and the maximum mute can be adjusted. The signal level for 3 dB mute can be set by means of bit 68 to bit 70 and the maximum value for soft mute can be selected by bit 67. The steepness and the time constant of the soft mute can be adjusted by the resistor and capacitor between pin 34 and pin 29. The field strength signal available at pin 9 is used for soft mute. Therefore, the soft mute threshold that referred to the input of the FM mixer depends on the gain from the FM mixer input to the field strength sensor and on the setting of field strength offset (bit 15 to bit 21).
Table 4-21.
Soft Mute Threshold
Relative Soft Mute Threshold Soft mute OFF -18 dB -15 dB -12 dB -9 dB -6 dB -3 dB 0 dB Bit 70 0 0 0 0 1 1 1 1 Bit 69 0 0 1 1 0 0 1 1 Bit 68 0 1 0 1 0 1 0 1
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Table 4-22. Maximum Soft Mute
Bit 67 0 1 Maximum Value of Soft Mute 30 dB 26 dB
Figure 4-4.
Soft Mute
+ FS (pin 9) Pin 34 Bit 67
Gain FM demodulator Bits 68 to 70 Pin 29 V3
4.18
MPX Output
The output of the AM demodulator (AM mode) or the output of the FM demodulator (FM/WB mode) are available at the MPX output (pin 11). The MPX output signal can be muted by setting bit 7 to 1. The bandwidth of the low-pass filter at the MPX output can be set by means of bit 79 to 90 kHz or 180 kHz.
Table 4-23.
MPX Output Mute
MPX Output MPX out, pin 11 normal operation Mute ON Bit 7 0 1
Table 4-24.
MPX Output Bandwidth
Bandwidth MPX Low-pass Filter 90 kHz 180 kHz Bit 79 0 1
4.19
Receiving Condition Analyzer
The ATR4258 implements several sensors that provide information about the receiving condition of the selected station.
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4.20
Field Strength Sensor
The field strength sensor provides a DC voltage at pin 9 which represents the logarithmic field strength of the signal in the reception band. The field strength information can be retrieved either from a level detector at the input of the 2nd mixer (pin 26) or from the IF-AGC depending on the setting of bit 80. The bandwidth of the field strength detection in the AGC is smaller than by using the level detector because of additional selectivity between the 2nd mixer and the 2nd IF amplifier particularly in AM and WB, but the field strength detection in the AGC is limited to the IF AGC range. Usually the field strength from the level detector is used in FM/WB mode and the AGC field strength is used in AM mode. The field strength output at pin 9 can be adjusted by the bits 18 to 21 in 0.5 dB steps. This offset also has an influence on the soft mute levels.
Table 4-25.
Field Strength Offset
Bit 21 0 0 0 ... 1 Bit 20 0 0 0 ... 1 Bit 19 0 0 1 ... 1 Bit 18 0 1 0 ... 1
Offset Field Strength 0.0 dB 0.5 dB 1.0 dB ... 7.5 dB
4.21
Field Strength Selection
Bit 80 and bit 13 allows the switches between narrow-band field strength and wide-band field strength information.
Table 4-26.
Field Strength (Combined)
Bit 80 0 0 1 1 Bit 13 0 1 0 1
Field Strength (Pin 9) Narrow-band/Wide-band FM field strength (wide band) Multipath field strength and FM field strength (wide band) AM AGC field strength (narrow band) Multipath field strength and AM AGC field strength (narrow band)
4.22
Search Stop Detector
A search stop detector is available in AM and FM/WB mode. A STOP condition is signaled (with a low level at pin 21) if the frequency of the IF signal is within a window around the center frequency of 450 kHz. The width of this search stop window can be set by bit 85 to bit 87 in the range of 0.5 kHz to 80 kHz. The frequency of the IF signal is measured by counting the number of periods of the IF signal during a measurement time which is determined by bit 73 to bit 78. The inverted STOP signal is available at pin 21 according to Table 4-29 on page 17. The frequency of 10.25 MHz at pin 22 is used as a time reference.
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Table 4-27. Search Stop Detector Measurement Time
Bit 78 0 1 Bit 77 0 1 Bit 76 0 1 Bit 75 0 1 Bit 74 0 1 Bit 73 1 1 1 x 3.1969 ms ..... 63 x 3.1969 ms Time Window for Stop Signal
Table 4-28.
Search Stop Window
Search Stop Window 0.5 kHz 1.1 kHz 2.3 kHz 4.8 kHz 10 kHz 20 kHz 40 kHz 80 kHz Bit 87 0 0 0 0 1 1 1 1 Bit 86 0 0 1 1 0 0 1 1 Bit 85 0 1 0 1 0 1 0 1
Table 4-29.
Bit 88 0 0 1 1 Note:
Signals Available at Digital Output Pin 21
Bit 92 0 (AM) 1 (FM/WB) 0 (AM) 1 (FM/WB) INT (Pin 21) 1 NOT MPINT NOT STOP NOT (STOP AND NOT MPINT)
MPINT = Multipath interrupt, Stop and MPINT signal are active low
Pin 35 (IFAGCH) is carried along with pin 36 (IFAGCL) to avoid crackles during a change of the search stop mode to the AM reception mode.
4.23
Deviation Sensor
The deviation sensor is active in AM and FM/WB mode and measures the modulation of the signal. It is implemented as a peak detector of the low-pass-filtered MPX signal (see Figure 4-5). The output voltage at pin 31 is proportional to the frequency deviation in FM/WB or the modulation depth in AM respectively. Figure 4-5. Deviation Sensor
+
MPX
4k
Pin 31
25k
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4.24
Adjacent Channel Sensor
The adjacent channel sensor is active in FM mode only and measures the field strength outside the reception band. Figure 4-6. Adjacent Channel Sensor
IF
SMeter
Pin 9 (Meter) +
Pin 10 (ADJAC)
30 A
4.25
MPINT and ADJAC Reset
Bit 6 allows a resets of the multipath sensor and the adjacent channel sensor by connecting pin 10 and pin 40 internally to ground and so the external capacitors can be discharged very quickly.
Table 4-30.
Multipath and Adjacent Channel Reset
Bit 6
0 1
MPINT and Adjacent Channel (Pin 10 and Pin 40)
Normal mode Connection to ground
4.26
Multipath Sensor
The multipath sensor is active in FM mode only and measures the disturbance due to multipath reception. The multipath sensor detects drops in the field strength after the integrated band filter by calculating the difference between an averaged maximum field strength and the current field strength. The maximum depth of these drops is represented by the voltage of the peak detector at pin 40 (MULTIP). The level of this voltage represents the degree of disturbance in the received signal. Figure 4-7. Multipath Sensor
+
Pin 40 4k
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A Multipath Noise Canceller (MNC) is implemented to reduce disturbance of the received signal in multipath reception conditions. If the difference between the momentary and the averaged field strength falls below a threshold adjustable by bit 81 to 84 (see Table 4-32), the MPX signal may be muted and this situation (MPINT) can be signalized at pin 21 (INT) according to Table 429 on page 17. Muting of the MPX signal during multipath disturbances can be activated be setting bit 8.
Table 4-31.
Multipath Noise Canceller
Multipath Noise Canceller
Active Not active
Bit 8
0 1
Table 4-32.
Sensitivity of the MNC
Bit 84
0 0 ... 0 ... 0 ... 1
Sensitivity MNC (Threshold)
Off Low ... (-33 dB) ... Normal (-14 dB) ... Note: High (-9 dB) Valid in FM or WB mode (bit 92 = 1)
Bit 83
0 0 ... 0 ... 1 ... 1
Bit 82
0 0 ... 1 ... 1 ... 1
Bit 81
0 1 ... 1 ... 1 ... 1
The Multipath interrupt can also be switched on/off by bit 4.
Table 4-33.
Multipath Interrupt (MPINT)
Bit 4
0 1
MPINT (Pin 21)
Off On (MPINT active)
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4.27
AM Noise Blanker
The AM Noise Blanker of the ATR4258 can be activated by bit 5. The noise peak is detected in the field strength of the first IF and if the disturbance exceeds the level defined by the bits 85 to 87, the signal is muted at the second IF.
Table 4-34.
AM Noise Blanker Activation
Bit 5
0 1
AM Noise Blanker
Off On
Table 4-35.
Sensitivity of AM Noise Blanker
Bit 87
0 ... 0 ... 1
AM Noise Blanker Sensitivity
Low ..... Normal ... High
Bit 86
0 ... 1 ... 1
Bit 85
0 ... 1 ... 1
4.28
3-wire Bus Description
The register settings of the ATR4258 are programmed by a 3-wire bus protocol. The bus protocol consists of separate commands. A defined number of bits are transmitted sequentially during each command. One command is used to program all bits of one register. The different registers available (see Table 4-36 on page 22) are addressed by the length of the command (number of transmitted bits) and by three address bits that are unique for each register of a given length. 8-bit registers are programmed by 8-bit commands and 24-bit registers are programmed by 24-bit commands. Each bus command starts with a rising edge on the enable line (EN) and ends with a falling edge on EN. EN has to be kept HIGH during the bus command. The sequence of transmitted bits during one command starts with the LSB of the first byte and ends with the MSB of the last byte of the register addressed. The DATA is evaluated at the rising edges of CLK. The number of LOW to HIGH transitions on CLK during the HIGH period of EN is used to determine the length of the command. The bus protocol and the register addressing of the ATR4258 are compatible to the addressing used in the U4256BM. That means both the ATR4258 and U4256BM can be operated on the same 3-wire bus as shown in the application circuit (Figure 10-9 on page 36).
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ATR4258
Figure 4-8. Pulse Diagram
8-bit command
EN DATA CLK
LSB BYTE 1 MSB
24-bit command
EN DATA CLK
LSB BYTE 1 MSB LSB BYTE 2 MSB LSB BYTE 3 MSB
Figure 4-9.
Bus Timing
tR tF
Enable tS tR Data tHDA tS tR Clock tH tL tF tF tHEN
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4.29
Data Transfer
Control Registers
BYTE 3 Demodulator AM/FM/WB 0 B93 B92 B91 B90 B89 B88 B87 B86 B85 B84 B83 B82 B81 B80 B79 B78 B77 B76 B75 B74 B73 LSB Gain FM IF amplifier MSB BYTE 2 LSB AM OSC divider/multipath sensitivity MSB BW/ Field MPX/ strength LPF/ BYTE 1 Time window stop signal LSB
Table 4-36.
A24_100 MSB ADDR. 1 0
Search Width of window
A24_101 MSB BYTE 3 LSB MSB BYTE 2
st
LSB MSB BW 2nd mixer
BYTE 1
LSB
ADDR.
WBStart soft mute Demod-gain threshhold
1 IF1 AGC Soft Mixer ampl. Tk-FM threshold mute + AGC AM/ IF AM/FM depth AM/ FM FM B67 B66 B65 B64 B63 B62
Int. IF2 reference shift
Gain IFOUT IF2IN Dem. local pin 20 pin 28 Contr. OSC
1
0
1 B72 B71 B70 B69 B68 B61 B60 B59 B58 B57 B56 B55 B54 B53 B52
A24_111 MSB ADDR. 1 1 1 BYTE 3 AGC Local OSC 0 B30 0 LSB MSB Do not change (test mode bits) 0 0 0 0 0 B24 0 0 B21 B20 B19 B18 B17 B16 B15 B14 B13 B12 B11 B10 BYTE 2 LSB MSB Band-path filter BYTE 1 Fieldst. (pin 9) LSB Local OSC prescaler (VCO buffer)
Offset field strength (Pin 9)
B29 B28 B27 B26 B25
B23 B22
A8_100 MSB ADDR. 1 0 0 BYTE 1 LSB Reset NoiseMute Test MP/ MP blanker (pin 11) mode ADJ 0 B9 B8 B7 B6 B5
A8_101 MSB ADDR. 1 0 1 B4 B3 B2 B1 B0 BYTE 1 MP INT Band-path filter Band width LSB
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5. Absolute Maximum Ratings
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. All voltages are referred to GND (pin 25)
Parameters
Supply voltage, pin 42 Power dissipation Junction temperature Ambient temperature range Storage temperature range
Symbol
VS Ptot Tj Tamb Tstg
Value
10 1000 150 -40 to +85 -50 to +150
Unit
V mW C C C
6. Thermal Resistance
Parameters
Junction ambient, soldered to PCB
Symbol
RthJA
Value
60
Unit
K/W
7. Operating Range
All voltages are referred to GND (pin 25)
Parameters
Supply voltage range, pin 42 Ambient temperature
Symbol
VS Tamb
Min.
8.0 -40
Typ.
8.5
Max.
10 +85
Unit
V C
8. Electrical Characteristics
Test conditions (unless otherwise specified): VS = 8.5V, Tamb = 25C
No. 1
1.1 1.2 1.3
Parameters Power Supply
Supply voltage Supply current Supply current Frequency range DC bias voltage Buffer output voltage Buffer output resistance Buffer output DC voltage
Test Conditions
Pin
42
Symbol
VS IStby IS fVCO
Min.
8.0
Typ.
8.5 35 50
Max.
10 45 65 260
Unit
V mA mA MHz V mVrms
Type*
C A A D A C D A
Standby mode (bit 92 = 0, bit 93 = 0) Other operation modes
42 42
2
2.1 2.2 2.3 2.4 2.5
VCO (Bit 52 = 0, Bit 30 = 1)
70 3.4 3.7 250 70 3.8 4.1 4.4 13 fosc = 120 MHz 16 16 16 4.0
V
3
3.1 3.2 3.3
FM RF-AGC
Saturation voltage Saturation voltage Threshold level No input signal No input signal In-band signal
5 5 30
8.3 VS - 0.2 115
V V dBV
A B C
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
23
4838B-AUDR-05/05
8. Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5V, Tamb = 25C
No.
3.4
Parameters
Maximum threshold level
Test Conditions
Out-of-band signal (110 MHz), bit 64, 65 = 0
Pin
1
Symbol
Min.
100
Typ.
103
Max.
106
Unit
dBV
Type*
B
4
4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8
AM RF-AGC, AM Mode (Bit 92 = 0, Bit 93 = 1)
Saturation voltage Saturation voltage Output voltage for minimum gain Output voltage for minimum gain Maximum control voltage Maximum control voltage Minimum control voltage Maximum threshold level No input signal No input signal Bit 92 = 1 Bit 92 = 1 No signal No signal AGC active Bits 64, 65 = 1 7 7 7 7 6 6 6 41 97 6.5 8.3 VS - 0.2 6.5 6.8 VS - 1.7 7.0 VS - 1.5 0.2 99 0.8 102 7.5 7.1 V V V V V V V dBV C C C C A B A A
5
5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9
AM Mixer, AM Mode (Bit 92 = 0, Bit 93 = 1)
Supply current Conversion conductance 3rd-order input intercept Pin 3 AC-grounded point Noise figure (SSB) Input bias DC voltage Input resistance Input capacitance Maximum output voltage Output resistance Differential Single-ended, pin 39 AC-grounded Generator resistance 2.5 k (pin 41) Sum of current in pins 43, 44 43, 44 3, 41, 43, 44 41 43, 44 3, 41 3, 41 3, 41 43, 44 43, 44 Sum of current in pins 43, 44 12 100 IP3AMmix NFAMmix 2.45 14 16 4.1 132 12 2.8 13 3 3.1 20 mA mS dBV dB V k pF Vpp k A D C C A D D D D
6
6.1 6.2 6.3 6.4 6.5 6.6
FM Mixer (FM Mode (Bit 92 = 1, Bit 93 = 0)
Supply current Conversion conductance 3rd-order intercept point Noise figure (DSB) Input resistance Input capacitance Pin 2 AC-grounded Generator resistance 200 43, 44 1, 2, 43, 44 1, 2 43, 44 1, 2 1 IP3FMmix NFFMmix 12 15 7 125 10 1.6 5 20 mA mS dBV dB k pF A D C C D D
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
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8. Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5V, Tamb = 25C
No.
6.7 6.8
Parameters
Maximum differential output voltage Output resistance
st
Test Conditions
VS = 8.5V
Pin
43, 44 43, 44
Symbol
Min.
12 100 19
Typ.
Max.
Unit
Vpp k
Type*
D D B D D D D D D D D D D D A A D C C D D D D D D A
7
7.1 7.2 7.3 7.4 7.5 7.6
1 IF FM Amplifier, FM Mode (Bit 92 = 1, Bit 93 = 0)
Minimum voltage gain Bits 89, 90, 91 = 0 38, 30 TKmin TKmax 38 38 30 330 load at pin 30 Generator resistance 2.5 k 33 Pin 39 AC-grounded 33 30 Bit 92 = 1, Bit 93 = 0 Bit 92 = 0, Bit 93 = 1 23, 24 23, 24 26, 23, 24 Generator resistance 330 (pin 26) 23, 24 26 Bit 92 = 0, Bit 93 = 1 VS = 8.5V 23, 24 23, 24 23, 24 26 22 22 22 2.8 NFMix2 IP3Mix2 100 12 1 270 80 1 3.0 3.2 330 400 500 270 10 7 30, 33 270 270 21 0.039 0.044 330 5 330 16 26 NFIFAM 10 1 330 12 8 2 23 132 400 16 10 17 400 400 23 dB dB/K dB/K Temperature coefficient Bit 66 = 0 of gain Temperature coefficient Bit 66 = 1 of gain Input resistance Input capacitance Output resistance
st
Pin 39 AC-grounded Pin 39 AC-grounded
pF
dB dB dB k pF
8
8.1 8.2 8.3 8.4 8.5 8.6
1 IF AM Amplifier, AM Mode (Bit 92 = 0, Bit 93 = 1)
Maximum voltage gain Gain control range Noise figure Input resistance Input capacitance Output resistance
mA mA mS dB dBV k Vpp Vpp
9
9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.11 9.12
2
nd
Mixer
FM supply current AM/WB supply current Conversion conductance Noise figure (SSB) 3rd-order input intercept point AM/WB output resistance Maximum differential output voltage AM/WB Maximum differential output voltage FM Input resistance LO input voltage LO input resistance LO input bias voltage
mVpp k V
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
25
4838B-AUDR-05/05
8. Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5V, Tamb = 25C
No. 10
10.1 10.2
Parameters 2
nd
Test Conditions
Pin 27 AC-grounded AM/WB mode (Bit 93 = 1) Pin 28 1 mVrms AM/WB mode (Bit 93 = 1)
Pin
28 28, 20
Symbol
Min.
Typ.
3
Max.
Unit
k
Type*
D A
IF Amplifier (Bit 55 = 0)
Input resistance Voltage gain
42
45
48
dB
10.3 10.4
Gain control range DC output voltage
47 20 3.4 3.7 4.0
dB V
D A
10.5
AC output voltage
Unmodulated signal, 82 dBV at pin 1 (IF AGC active) Bit 93 = 1 Small signal Deviation = 75 kHz, fmod = 1 kHz Deviation = 75 kHz, fmod = 38 kHz (reference: 1 kHz) Deviation = 75 kHz, fmod = 1 kHz Dev. = 22.5 kHz, fmod = 1 kHz, 50 s deemphase, signal input at 450 kHz Bit 67 = 0, V (pin 34) = 2V Bit 67 = 1, V (pin 34) = 2V Modulation depth = 30%, fmod = 1 kHz Modulation depth = 80%, fmod = 1 kHz V(pin 35) = const. Modulation depth = 30%, fmod = 1 kHz 74 dBV at pin 41 Bit 7 = 1 Bit 7 = 1, FM dev. = 75 kHz, fmod = 1 kHz Small signal
20
150
180
230
mVrms
A
10.6
Output impedance
20
70
D
11
11.1
FM Demodulator Integrated Band-filter, FM Mode (Bit 92 = 1, Bit 93 = 0), BW Setting 2nd IF Filter = 120 kHz
AC output voltage 11 420 480 540 mVrms B
11.2
Stereo roll-off Total harmonic distortion Maximum signal-to-noise ratio
11
-2.0
dB
D
11.3
11
THDFM
0.4
0.7
%
A
11.4
11
(S/N)FM
65
dB
C
12
12.1 12.2
Soft Mute, FM Mode (Bit 92 = 1, Bit 93 = 0, Bit 80 = 0)
Mute gain Mute gain 11 11 -28 -24 -26 -22 -24 -20 dB dB A A
13
13.1
AM Demodulator, AM Mode (Bit 92 = 0, Bit 93 = 1)
AC output voltage Total harmonic distortion Maximum signal-to-noise ratio 11 135 150 170 mVrms A
13.2
11
THDAM
0.6
2
%
A
13.3
11
(S/N)AM
54
dB
C
14
14.1 14.2 14.3
MPX Output
DC output voltage Mute gain Output resistance 11 11 11 2.1 2.3 -65 60 2.5 -50 V dB A A D
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
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8. Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5V, Tamb = 25C
No. 15
15.1 15.2 15.3 15.4
Parameters
LOW saturation voltage LOW output resistance HIGH saturation voltage HIGH output resistance
Test Conditions
Pin
21 21 21 21
Symbol
Min.
Typ.
0 0.3
Max.
0.5 5.25
Unit
V k V k
Type*
A D A D
Search Stop Detector, INT Output
4.5
4.8 1
16
16.1
Deviation Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0)
Offset voltage FM dev. = 0 kHz FM demodulator adjusted FM dev. = 75 kHz, fmod = 1 kHz 60 dBV at pin 33 Unmodulated signal 100 dBV at pin 33 31 0.2 V C
16.2
Output voltage
31
1.7
2.0
2.5
V
C
17
17.1 17.2
Field Strength Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0, Bit 89 to 91 = 0, Bit 80 = 0, Bit 18 to 21 = 0)
Output voltage Output voltage 9 9 0.8 2.8 1.3 3.4 1.8 3.9 V V A A
Field Strength Sensor, AM Mode (Bit 92 = 0, Bit 93 = 1, Bit 80 = 1, Bit 18 to 21 = 0)
17.3 17.4 Output voltage LOW field strength Output voltage HIGH field strength 60 dBV at pin 28 94 dBV at pin 28 9 9 1.5 3.0 1.8 3.3 2.1 3.6 V V A A
18
18.1
Multipath Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0)
Offset voltage Unmodulated signal, 60 dBV at pin 1 AM modulation depth = 60%, fmod = 20 kHz, 60 dBV at pin 1 Unmodulated signal AM mod. 10% fmod = 100 kHz AM mod. 60% fmod = 100 kHz 40 0 200 mV A
18.2
Output voltage
40
1.5
1.9
2.4
V
A
19
19.1 19.2
Adjacent Channel Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0), Bit 4 = 0 (Default BW Setting)
Offset voltage 10 200 0.3 10 1.2 1.9 2.5 0.6 V A mV C
Output voltage 19.3
20
20.1 20.2 20.3 20.4 20.5
3-wire Bus
Input voltage LOW Input voltage HIGH Leakage current Clock frequency Period of CLK HIGH LOW V = 0V, 5V 17, 18, 19 17, 18, 19 17, 18, 19 18 tH tL 250 250 2.7 10 1.0 0.8 V V A MHz ns ns D D D D D
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
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4838B-AUDR-05/05
8. Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5V, Tamb = 25C
No.
20.6 20.7 20.8 20.9 20.10
Parameters
Rise time EN, DATA, CLK Fall time EN, DATA, CLK Set-up time Hold time EN Hold time DATA
Test Conditions
Pin
Symbol
tr tf ts tHEN tHDA
Min.
Typ.
Max.
400 100
Unit
ns ns ns ns ns
Type*
D D D D D A D D D
100 250 0 5.5 5.7 3.0 3.0 3.0 6.0
21
21.1 21.2 21.3 21.4
Internally Generated Reference Voltages
Output voltage Output voltage Output voltage Output voltage 12 29 27 39 V V V V
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
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9. Application Information
9.1 AM Prescaler (Divider) Settings
The AM mixer is used for up conversion of the AM reception frequency to the IF frequency. Therefore an AM prescaler is implemented to generate the necessary LO from the VCO frequency. For the reception of the AM band different prescaler (divider) settings are possible. Table 9-1 gives an example for the AM prescaler (divider) settings and the reception frequencies. e.g., fVCO = 98.2 MHz ... 124 MHz fIF = 10.7 MHz
f VCO f rec = ----------------------------------- - f IF AM Prescaler
Table 9-1.
AM Prescaler (Divider) Settings and Reception Frequencies
Minimum Reception Frequency [MHz]
38.4 20.033 13.85 8.94 5.667 3.329 1.575 0.211 0
Divider (AM Prescaler)
divide by 2 divide by 3 divide by 4 divide by 5 divide by 6 divide by 7 divide by 8 divide by 9 divide by 10 Note:
Maximum Reception Frequency [MHz]
51.3 30.633 20.3 14.1 9.967 7.014 4.8 3.078 1.7
Prescaler VCO Divider = 1 in this example.
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4838B-AUDR-05/05
9.2
Local Oscillator and AM Prescaler Settings
Table 9-2 gives an example for the VCO prescaler divider and AM prescaler divider settings and the reception frequencies. e.g., fVCO = 195.9 MHz ... 237.9 MHz fIF = +10.7 MHz or -10.7 MHz fVCO = (frec + fIF) x VCO Prescaler x AM Prescaler
Table 9-2.
Band
FM WB JPN LW/MW 16m 120m
VCO and AM Prescaler (Divider) Settings and Reception Frequencies
Prescaler VCO
2 1.5 3 2 1 2
IF [MHz]
+10.7 -10.7 -10.7 +10.7 +10.7 +10.7
Minimum Reception Maximum Reception Frequency [MHz] Frequency [MHz]
87.5 162.4 76 0.15 17.5 2.3 108 162.55 90 1.605 17.9 2.5
Minimum VCO Frequency
196.4 227.55 195.9 195.3 225.6 208
Maximum VCO Frequency
237.4 227.775 237.9 221.49 228.8 211.2
AM Prescaler
- - - 9 8 8
9.3
9.3.1
U4256 N- and R-divider Calculation
AM Mode
f VCO N = --------------------------------------------------------------------------------------------VCO-divider x AM Prescaler x f step f VCO f rec = --------------------------------------------------------------------------- - f IF VCO-divider x AM Prescaler
9.3.2
FM/WB Mode
f VCO N = ------------------------------------------------VCO-divider x f step f VCO f rec = ------------------------------- - f IF VCO-divider
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9.3.3 All Modes
f ref R = --------f step
fref = reference oscillator frequency (e.g. 10.25 MHz) fVCO = VCO frequency frec = reception frequency fstep = step frequency (of the PLL)
10. Diagrams
The following data was measured with the application board (see Figure 10-9). In the measurement setup, a 50 generator is terminated by 50 and connected to the antenna input by a 50 series resistor to achieve 75 termination at the antenna input. The generator level specified is the output voltage of this 50 generator at 50 load. If the application board is replaced by a 75 resistor, the voltage at this resistor is 6 dB below the specified voltage level of the 50 generator. Figure 10-1. FM Demodulator
1.0 1 0.9 0.8 0.7
+85C
MPX Output Voltage [Vrms]
0.9 0.8 0.7 0.6 0.5
MPX -40C THD -40C
0.5 0.4 0.3 0.2
0.4 0.3 0.2 0.1 0.0 0 10 20 30 40 50 60 70 80 90
+85C
0.1 0 100
Frequency Deviation [kHz]
Note:
Integrated band-filter BW setting: 120 kHz (bits 0 to 2 = 0, bit 3 = 1); 1 kHz modulation frequency; 50 s de-emphasis (THD)
THD [%]
0.6
31
4838B-AUDR-05/05
Figure 10-2. Multipath Sensor
5
Sensor Output Voltage
4
+85C
3
2
-40C
1
0 0 10 20 30 40 50 60 70 80 90 100
AM Modulation Depth [%]
Note:
AM modulation frequency 20 kHz; generator level 40 dBV
Figure 10-3. Multipath Sensor Frequency Response
5.0
Sensor Output Voltage [V]
4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 100 1000 10000 100000
60% at 85C 60% at 25C 60% at -40C 90% at 25C 90% at -40C
AM Modulation Frequency [Hz]
Note:
Generator level 40 dBV
32
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Figure 10-4. Deviation Sensor
Deviation Sensor Output Voltage [V]
5
4
3
+85C
2
-40C
1
0 10000
30000
50000
70000
90000
Frequency Deviation [Hz]
Note:
FM modulation frequency: 1 kHz; BW setting 2nd IF filter = 120 kHz; demodulator fine tuning (bit 53 = 0)
The center frequency of the integrated band filter has to adjusted (e.g., IF center frequency = 462.50 kHz). Figure 10-5. Deviation Sensor Frequency Response
1.0
Sensor Output Voltage (V)
0.8
0.6
0.4
0.2
0.0 100 1000 10000 100000
FM Modulation Frequency (Hz)
Note:
FM frequency deviation: 22.5 kHz
33
4838B-AUDR-05/05
Figure 10-6. FM Input Level Sweep
10 0 -10
5 4.5 4 3.5 3
-20 -30
2.5
-40
2
-50 -60 -70 -10 0 10 20 30 40 50 60 70 80 90 100
1.5 1 0.5
110 120
Input Level [dBV]
Note:
Soft mute threshold bits 68, 69 = 0, bit 70 = 1; soft mute gain bit 67 = 0 gain FM IF amplifier bit 89 to 91 = 1
Figure 10-7. Selectivity
20 10
Pdes/Pundes
4.5 4 3.5 3 2.5 2 1.5 1
Adjacent
Pdes/Pundes [dB]
0 -10 -20 -30 -40 -50 -60 -70 -300 -250 -200
0.5 0 300
-150 -100
-50
0
50
100
150
200
250
Frequency Offset [kHz]
Note:
Integrated bandfilter BW setting: 120 kHz Desired signal level adjusted to 40 dB S/N without undesired signal Undesired signal level adjusted to 26 dB S/N
34
ATR4258
4838B-AUDR-05/05
Adjacent Channel Output Voltage [V]
Fieldstrength Sensor Output Voltage [V]
MPX Output [dB]
ATR4258
Figure 10-8. Test Circuit
Test Point 1 50 50 10n 3 10n 4 5 6 7 8 10n 9 10n 10n 11 12 1 13 50 50 10n 14 15 10n V 16 1k3 Bus 17 18 19 Quarzoscillator 10.25 MHz 20 21 22 29 47n 28 27 47n 26 100n 10n 10k 25 24 VS 10n 23 50 50 50 50 31 10n 30 P29 22n 330 36 100n 41 10n 40 39 47n 38 37 100n P29 47n 50 50 42 100n 10n 2 43 VS 50 50 44 VS
ATR4258
10
35 10n 34 200k 33 100n 32 P29
P31
47n
50 50
35
4838B-AUDR-05/05
Figure 10-9. Application Circuit
36
R407 VS (+8.5 V to 10.5 V) MULTIP 100n DEV R34 27 R33 2k KR202 X301 KF302 R305 1k5 C in F201 C307 C206 C208 220n 220n C310 C205 10 35 34 33 32 31 30 29 28 27 26 25 24 23 220n 1n C207 C312 10n R152 10 C27 22 10n C309 F302 10n 100p 1 C204 C111 44 R41 1k2 43 42 41 40 39 38 1 470n 37 36 R111 200k C202 R32 1k R303 1k R106 10 F201 C209 100n 10n C201 KR201 R304 5k6 C308 10 R29 10 C306 12p C112 10 C113 100n
ATR4258
ATR4258
1 R313 22 390 C133 R102 F131 68k F102 1n C107 BB804 10n 18p R121 68k D131 R131 5k6 20 C134 U4256BM 1n 1 F101 BB804 R122 D101 C102 3p9 S391D 10n D103 C103 68k C159 C158 10n 10n C157 10n MPX ADJAC C115 100n C116 100n Application Board Schematic METER 2 3 C151 R151 8k2 C152 330p 10n DAC3 SWO1 SWO3 SWO2 SWO4 4 5 6 7 8 9 10 10p 27p T101 BFR93A C56 C104 10n 19 18 17 16 15 14 BB804 R104 470 R112 47k C106 L102 22 C155 100n C153 10p Q151 13 12 11 C154 10p 10.25 MHz D102 C110 4n7 470p 6p8 C11 10n C77 EN C156 GND C108 C109 6p8 47p 22p 220n C203 C114 C131 C132 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 INT IF2OUT DATA CLK
L302
C319 6p8
100H
R311
2k2
R105 100
R115 1k
L303 2m2
T102 BC858
T302 BC848
C316
R308 T301
220n
2k2
BC 858C
R306 470k
T111 J109
R307 47
C315
C302
220n
10n
C117
10n
L301
D301
FM 75
47
Ant
S391D
D302 S391D
C311
100n
R103 1k
4838B-AUDR-05/05
ATR4258
11. Ordering Information
Extended Type Number
ATR4258-ILSH ATR4258-ILQH
Package
SSO44 SSO44
Remarks
Tube, lead-free Taped and reeled, lead-free
12. Package Information
Package SSO44
Dimensions in mm
18.05 17.80 9.15 8.65 7.50 7.30
2.35 0.3 0.8 16.8 44 23 0.25 0.10
0.25 10.50 10.20
technical drawings according to DIN specifications
1
22
37
4838B-AUDR-05/05
Atmel Corporation
2325 Orchard Parkway San Jose, CA 95131, USA Tel: 1(408) 441-0311 Fax: 1(408) 487-2600
Atmel Operations
Memory
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4838B-AUDR-05/05

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