ATMEL ATR4258

Features
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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.
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. 4838A–AUDR–10/04
Figure 1. Block Diagram
IF1FMI
MX1OA
MX1OB
43
44
IF1AMI
IF1REF
38
39
V3
MX2OB
IF1OUT MX2IN
33
30
29
26
MX2OA
24
23
IF2IN V3P
28
27
AM
AM
Dem.
OPLPF
32
FM
41
AGC
MX1AMA
MX1AMB
AMAGC
AMVREG
AMPLPF
V3
7
6
8
35
AGC
1
IFAGCH
20
Automatic
FILADJ
Adjustment 37
FM
MX1FMB
MultiMULTIP
path 40
2
GNDMX
IFAGCL
IF2OUT
Noiseblanker
AGC
MX1FMA
36
AM
3
4
Divider
2...10
OSCOUT
16
Offset
Adj.
Chan.
FM
Dem.
Stop
Soft
Mute
MPX
11
Divider
GNDOSC
OSCE
OSCB
15
14
13
V3
OSC
Bandgap
12
25 42
Bus
5
17 18
19
V57
VS
EN
DATA
GND
FMAGC
CLK
2
Dev.
Ana.
INT
9
METER
22
MX2LO
10
ADJAC
21
INT
34
SMUTE
31
DEV
ATR4258
4838A–AUDR–10/04
ATR4258
Pin Configuration
Figure 2. Pinning SSO44
MX1FMA
1
44
MX1OB
MX1FMB
2
43
MX1OA
MX1AMB
3
42
VS
GNDMX
4
41
MX1AMA
FMAGC
5
40
MULTIP
AMVREG
6
39
IF1REF
AMAGC
7
38
IF1FMI
AMPLPF
8
37
FILADJ
METER
9
36
IFAGCL
ADJAC 10
35
IFAGCH
MPX 11
34
SMUTE
V57 12
33
IF1AMI
OSCB 13
32
OPLPF
OSCE 14
31
DEV
GNDOSC 15
30
IF1OUT
OSCOUT 16
29
V3
EN 17
28
IF2IN
CLK 18
27
V3P
DATA 19
26
MX2IN
IF2OUT 20
25
GND
INT 21
24
MX2OA
MX2LO 22
23
MX2OB
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4838A–AUDR–10/04
Pin Description
4
Pin
Symbol
Function
1
MX1FMA
1st mixer FM input A
2
MX1FMB
1st mixer FM input B
3
MX1AMB
1st mixer AM input B
4
GNDMX
Ground 1st mixer, preamplifier AGC
5
FMAGC
FM preamplifier AGC
6
AMVREG
7
AMAGC
AM preamplifier AGC
8
AMPLPF
AM AGC LP filter
AM control voltage
9
METER
Field strength output
10
ADJAC
Adjacent channel detection output
11
MPX
Multiplex signal
12
V57
5.7 V reference voltage
13
OSCB
Oscillator basis
14
OSCE
Oscillator emitter
15
GNDOSC
Oscillator ground
16
OSCOUT
Oscillator output
17
EN
3-wire bus enable
18
CLK
3-wire bus clock
19
DATA
3-wire bus data
20
IF2OUT
2nd IF amplifier output
21
INT
Interrupt, stop signal
22
MX2LO
10.25 MHz input for 2nd mixer
23
MX2OB
2nd mixer output B
24
MX2OA
2nd mixer output A
25
GND
26
MX2IN
Ground
2nd mixer input
27
V3P
3 V reference for AMPIN, AMIFAGC, Control, IF2IN
28
IF2IN
2nd IF amplifier input
29
V3
30
IF1OUT
3 V reference for IF1OUT, MX2IN
1st IF amplifier output
31
DEV
32
OPLPF
Operating point LPF
Deviation detect output, test output
33
IF1AMI
1st IF AM amplifier input
34
SMUTE
Soft MUTE control input
35
IFAGCH
IF AGC LP filter high time
36
IFAGCL
IF AGC LP filter low time constant
37
FILADJ
Filter adjust
38
IF1FMI
1st IF FM amplifier input
39
IF1REF
1st IF & MX1OUT reference, MX1AM A, MX1AM B
40
MULTIP
Multipath detection output
41
MX1AMA
42
VS
43
MX1OA
1st mixer output A
44
MX1OB
1st mixer output B
1st mixer AM input A
Supply voltage
ATR4258
4838A–AUDR–10/04
ATR4258
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.
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 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 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.
5
4838A–AUDR–10/04
Table 1. Operating Mode
Test Mode
AM/FM/Weather Channel
Bit 93
Bit 92
Bit 63
Bit 62
Standby
0
0
X
X
FM
0
1
0
0
AM
1
0
1
1
Weather band
1
1
1
0
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 2. Test Mode
VCO/Local Oscillator
Prescaler
Mode
Bit 9
Normal operation
0
Test mode
1
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 3. Local Oscillator AGC
Local Oscillator (VCO)
Bit 30
AGC off (default)
0
AGC on
1
Table 4. Local Oscillator Gain
Local Oscillator (VCO)
Bit 52
Low Gain
0
High Gain
1
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 5 on
page 7.
6
ATR4258
4838A–AUDR–10/04
ATR4258
Table 5. Local Oscillator Prescaler (VCO/Buffer Divider)
Prescaler VCO
Prescaler Buffer
Bit 12
Bit 11
Bit 10
1
1
X
0
0
1.5
3
0
0
1
1.5
1.5
1
0
1
2
2
X
1
0
3
3
X
1
1
Note:
FM RF-AGC
The U4256 FMOSCIN (pin 19) input frequency is limited to 160 MHz.
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 3) 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 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 6. FM-AGC Threshold
FM-AGC Threshold
Bit 65
Bit 64
100 dBµV
0
0
97 dBµV
0
1
94 dBµV
1
0
91 dBµV
1
1
Figure 3. FM RF-AGC Bit 92
VS
Pin 42
C111
R115
Pin 5
PIN Diode
AGC
B92
7
4838A–AUDR–10/04
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 7. AM-AGC Threshold
AM-AGC Threshold
Bit 65
Bit 64
91 dBµV
0
0
94 dBµV
0
1
97 dBµV
1
0
100 dBµV
1
1
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.
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 8. (The AM prescaler is only active in AM mode).
Table 8. Divide Factor of the AM Prescaler
8
Divider (AM Prescaler)
Bit 93
Bit 92
Bit 84
Bit 83
Bit 82
Bit 81
Divide by 2
1
0
0
0
0
0
Divide by 3
1
0
0
0
0
1
Divide by 4
1
0
0
0
1
0
Divide by 5
1
0
0
0
1
1
Divide by 6
1
0
0
1
0
0
Divide by 7
1
0
0
1
0
1
Divide by 8
1
0
0
1
1
0
Divide by 9
1
0
0
1
1
1
Divide by 10
1
0
1
X
X
X
ATR4258
4838A–AUDR–10/04
ATR4258
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 Ω and
fits to external ceramic filters.
Two different temperature coefficients of the FM IF amplifier can be selected by bit 66.
Table 9. Gain of the FM IF Amplifier
Gain FM IF
Bit 91
Bit 90
Bit 89
19 dB
0
0
0
21 dB
0
0
1
23 dB
0
1
0
25 dB
0
1
1
27 dB
1
0
0
28 dB
1
0
1
29 dB
1
1
0
30 dB
1
1
1
Table 10. Temperature Coefficient Setting of FM IF Amplifier
Temperature Coefficient (TC) of the IF Amplifier
Bit 66
TKmin (TK 1)
0
TKmax (TK 2)
1
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.
2nd Mixer
The 2nd mixer is used in AM, FM and WB mode. The mixer input has 330 Ω 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.
Table 11. 2nd Mixer Output Resistance in FM Mode
Bit 61
Bit 60
Output Resistance (Bit 54 = 0)
Output Resistance (Bit 54 = 1)
0
0
3.3 kΩ
~100 kΩ
0
1
0.63 kΩ
0.78 kΩ
1
0
0.47 kΩ
0.55 kΩ
1
1
0.29 kΩ
0.32 kΩ
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.
9
4838A–AUDR–10/04
Table 12. FM Bandwidth Mixer 2
Bit 61
Bit 60
FM Bandwidth Mixer 2
0
0
150 kHz
0
1
200 kHz
1
0
250 kHz
1
1
450 kHz
Note:
2nd IF Amplifier
The bandwidth is also dependant on the values of the application circuit.
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.
Table 13. 2nd IF Filter in FM Mode
2nd IF Filter
Bit 54
Internal filter
0
External and internal filter
1
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.
IF-AGC
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 14. IF-AGC Time Constant
Mode
Bit 92
Bit 88
IF AGC Time Constant
FM/WB
1
X
IFAGCL (fast)
AM reception
0
0
IFAGCH (slow)
AM search
0
1
IFAGCL (fast)
In FM/WB mode, the output signal of the FM demodulator is applied to pin 35 via a
series resistor of about 95 kΩ. 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.
10
ATR4258
4838A–AUDR–10/04
ATR4258
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 15. Pin 20 Output Setting
Pin 20
nd
2
Bit 55
IF output
0
Multipath field strength
Automatic IF Center
Frequency Adjustment
1
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. Automatic IF Center Frequency Adjustment
Pin 22
10.25 MHz
Automatic
frequency
adjustment
Bit 56...59
Center
frequency
Center
frequency
Bit 14...17
FM-Demod
FMband filter
Pin 37
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.
11
4838A–AUDR–10/04
Table 16. 2nd IF Center Frequency
IF Center
Bit 59
Bit 58
Bit 57
Bit 56
450.00 kHz
0
0
0
0
456.25 kHz
0
0
0
1
462.50 kHz
0
0
1
0
468.75 kHz
0
0
1
1
475.00 kHz
0
1
0
0
481.25 kHz
0
1
0
1
487.50 kHz
0
1
1
0
493.75 kHz
0
1
1
1
450.00 kHz
1
0
0
0
443.75 kHz
1
0
0
1
437.50 kHz
1
0
1
0
431.25 kHz
1
0
1
1
425.00 kHz
1
1
0
0
418.75 kHz
1
1
0
1
412.50 kHz
1
1
1
0
406.25 kHz
1
1
1
1
Table 17. FM Band Filter Center Frequency Correction
12
IF Correction
Bit 17
Bit 16
Bit 15
Bit 14
-0 kHz
0
0
0
0
-6.25 kHz
0
0
0
1
-12.50 kHz
0
0
1
0
-18.75 kHz
0
0
1
1
-25.00 kHz
0
1
0
0
-31.25 kHz
0
1
0
1
-37.50 kHz
0
1
1
0
-43.75 kHz
0
1
1
1
+0 kHz (default)
1
0
0
0
+6.25 kHz
1
0
0
1
+12.50 kHz
1
0
1
0
+18.75 kHz
1
0
1
1
+25.00 kHz
1
1
0
0
+31.25 kHz
1
1
0
1
+37.50 kHz
1
1
1
0
+43.75 kHz
1
1
1
1
ATR4258
4838A–AUDR–10/04
ATR4258
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 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 18. Bandwidth of the Integrated Band Filter
FM Demodulator
IF Bandwidth FM
IF Bandwidth WB
Bit 3
Bit 2
Bit 1
Bit 0
220
195
0
0
0
0
...
...
...
...
...
...
200
160
0
0
1
1
...
...
...
...
...
...
165
120
0
1
1
0
...
...
...
...
...
...
130
80
1
0
0
1
...
...
...
...
...
...
80
35
1
1
0
1
70
–
1
1
1
0
60
–
1
1
1
1
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 5. FM Demodulator Automatic Fine Tuning
MPX (Pin 11)
FM Demod
Center freq.
AM
AGC
B92
IFAGCH (Pin 35)
+
Bit 53
V3P
(Pin 27)
Automatic
frequency
adjustment
13
4838A–AUDR–10/04
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 19. Demodulator Gain in Weather Band Mode
Demodulator Gain in Weather Band Mode Relative to FM Mode
Bit 72
Bit 71
14 dB
0
0
17 dB
0
1
21 dB
1
0
23 dB
1
1
Table 20. Demodulator Fine Adjustment
Soft Mute
Demodulator Fine Adjustment
Bit 53
Fine tuning ON
0
Fine tuning OFF
1
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 21. Soft Mute Threshold
14
Relative Soft Mute Threshold
Bit 70
Bit 69
Bit 68
Soft mute OFF
0
0
0
-18 dB
0
0
1
-15 dB
0
1
0
-12 dB
0
1
1
-9 dB
1
0
0
-6 dB
1
0
1
-3 dB
1
1
0
0 dB
1
1
1
ATR4258
4838A–AUDR–10/04
ATR4258
Table 22. Maximum Soft Mute
Maximum Value of Soft Mute
Bit 67
30 dB
0
26 dB
1
Figure 6. Soft Mute
+
FS (pin 9)
Bit 67
Pin 34
Gain FM demodulator
Bits 68 to 70
Pin 29
MPX Output
V3
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 23. MPX Output Mute
MPX Output
Bit 7
MPX out, pin 11 normal operation
0
Mute ON
1
Table 24. MPX Output Bandwidth
Receiving Condition
Analyzer
Bandwidth MPX Low-pass Filter
Bit 79
90 kHz
0
180 kHz
1
The ATR4258 implements several sensors that provide information about the receiving
condition of the selected station.
15
4838A–AUDR–10/04
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 25. Field Strength Offset
Offset Field Strength
Field Strength Selection
Bit 21
Bit 20
Bit 19
Bit 18
0.0 dB
0
0
0
0
0.5 dB
0
0
0
1
1.0 dB
0
0
1
0
...
...
...
...
...
7.5 dB
1
1
1
1
Bit 80 and bit 13 allows the switches between narrow-band field strength and wide-band
field strength information.
Table 26. Field Strength (Combined)
Field Strength (Pin 9) Narrow-band/Wide-band
Search Stop Detector
Bit 80
Bit 13
FM field strength (wide band)
0
0
Multipath field strength and FM field strength (wide band)
0
1
AM AGC field strength (narrow band)
1
0
Multipath field strength and AM AGC field strength (narrow band)
1
1
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 29 on page 17. The frequency of 10.25 MHz at pin 22 is used
as a time reference.
Table 27. Search Stop Detector Measurement Time
Time Window for Stop Signal
Bit 78
Bit 77
Bit 76
Bit 75
Bit 74
Bit 73
1 × 3.1969 ms
0
0
0
0
0
1
1
1
1
1
1
1
.....
63 × 3.1969 ms
16
ATR4258
4838A–AUDR–10/04
ATR4258
Table 28. Search Stop Window
Search Stop Window
Bit 87
Bit 86
Bit 85
±0.5 kHz
0
0
0
±1.1 kHz
0
0
1
±2.3 kHz
0
1
0
±4.8 kHz
0
1
1
±10 kHz
1
0
0
±20 kHz
1
0
1
±40 kHz
1
1
0
±80 kHz
1
1
1
Table 29. Signals Available at Digital Output Pin 21
Note:
Bit 88
Bit 92
INT (Pin 21)
0
0 (AM)
1
0
1 (FM/WB)
NOT MPINT
1
0 (AM)
NOT STOP
1
1 (FM/WB)
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.
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 7). The output voltage at pin 31 is proportional to the frequency deviation in
FM/WB or the modulation depth in AM respectively.
Figure 7. Deviation Sensor
+
MPX
4k
Pin 31
25k
17
4838A–AUDR–10/04
Adjacent Channel
Sensor
The adjacent channel sensor is active in FM mode only and measures the field strength
outside the reception band.
Figure 8. Adjacent Channel Sensor
Pin 9 (Meter)
IF
+
SMeter
Pin 10 (ADJAC)
30 µA
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 30. Multipath and Adjacent Channel Reset
MPINT and Adjacent Channel (Pin 10 and Pin 40)
Multipath Sensor
Bit 6
Normal mode
0
Connection to ground
1
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 9. Multipath Sensor
+
Pin 40
4k
18
ATR4258
4838A–AUDR–10/04
ATR4258
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 32), the MPX signal may be muted and this situation (MPINT) can be signalized at pin 21 (INT) according to Table 29 on page 17. Muting of the MPX signal during
multipath disturbances can be activated be setting bit 8.
Table 31. Multipath Noise Canceller
Multipath Noise Canceller
Bit 8
Active
0
Not active
1
Table 32. Sensitivity of the MNC
Note:
Sensitivity MNC (Threshold)
Bit 84
Bit 83
Bit 82
Bit 81
Off
0
0
0
0
Low
0
0
0
1
...
...
...
...
...
(-33 dB)
0
0
1
1
...
...
...
...
...
Normal (-14 dB)
0
1
1
1
...
...
...
...
...
High (-9 dB)
1
1
1
1
Valid in FM or WB mode (bit 92 = 1)
The Multipath interrupt can also be switched on/off by bit 4.
Table 33. Multipath Interrupt (MPINT)
MPINT (Pin 21)
Bit 4
Off
0
On (MPINT active)
1
19
4838A–AUDR–10/04
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 34. AM Noise Blanker Activation
AM Noise Blanker
Bit 5
Off
0
On
1
Table 35. Sensitivity of AM Noise Blanker
AM Noise Blanker Sensitivity
3-wire Bus Description
Bit 87
Bit 86
Bit 85
Low
0
0
0
.....
...
...
...
Normal
0
1
1
...
...
...
...
High
1
1
1
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 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 20 on
page 36).
20
ATR4258
4838A–AUDR–10/04
ATR4258
Figure 10. Pulse Diagram
8-bit command
EN
DATA
LSB
BYTE 1
MSB
BYTE 1
MSB LSB
CLK
24-bit command
EN
DATA
LSB
BYTE 2
MSB LSB
BYTE 3
MSB
CLK
Figure 11. Bus Timing
tR
tF
Enable
tHEN
tS
tR
tF
Data
tHDA
tS
tF
tR
Clock
tH
tL
21
4838A–AUDR–10/04
Data Transfer
Table 36. Control Registers
A24_100
MSB
BYTE 3
Demodulator
AM/FM/WB
ADDR.
1
0
LSB
Gain FM
IF amplifier
MSB
BYTE 2
LSB
AM OSC
divider/multipath
sensitivity
Search Width of window
MSB
BYTE 1
BW/
Field
MPX/
strength
LPF/
LSB
Time window stop signal
0
B93
B92
B91
B90
B89
B88
B87 B86 B85 B84 B83 B82 B81
B80
B79
B78 B77 B76 B75 B74 B73
A24_101
MSB
BYTE 3
LSB MSB
BYTE 2
LSB MSB
BYTE 1
LSB
st
1
IF1 Mixer
Soft
AGC
+
WBStart soft mute
Tkampl.
mute
threshold
Demod-gain
threshhold
FM IF
AM/ AGC
AM/FM
depth
AM/
FM
FM
ADDR.
1
0
BW 2nd
mixer
Int. IF2 reference shift
Gain
IFOUT IF2IN Dem.
local
pin 20 pin 28 Contr.
OSC
1
B72
B71
B70 B69 B68
B67
B66
B65 B64
B63
B62
B61
B60
B59
B58 B57 B56
LSB
MSB
B55
B54
B53
B52
A24_111
MSB
BYTE 3
AGC
Local
OSC
ADDR.
1
1
1
0
B30
LSB MSB
BYTE 2
Do not change (test mode bits)
0
0
0
0
0
B29 B28 B27 B26 B25
0
B24
0
Offset field strength (Pin 9)
BYTE 1
Band-path filter
LSB
Fieldst.
(pin 9)
Local OSC
prescaler
(VCO buffer)
B13
B12 B11 B10
0
B23 B22
B21
B20
B19
B18
B17
B16
B15 B14
A8_100
MSB
BYTE 1
ADDR.
1
0
LSB
Reset
NoiseTest
Mute
MP/
MP
blanker
mode
(pin 11)
ADJ
0
0
B9
B8
B7
B6
B5
A8_101
MSB
BYTE 1
MP
INT
ADDR.
1
0
1
B4
22
LSB
Band-path filter
Band width
B3
B2
B1
B0
ATR4258
4838A–AUDR–10/04
ATR4258
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
Symbol
Value
Unit
Supply voltage, pin 42
VS
10
V
Power dissipation
Ptot
1000
mW
Tj
150
°C
Ambient temperature range
Tamb
-40 to +85
°C
Storage temperature range
Tstg
-50 to +150
°C
Symbol
Value
Unit
RthJA
60
K/W
Junction temperature
Thermal Resistance
Parameters
Junction ambient, soldered to PCB
Operating Range
All voltages are referred to GND (pin 25)
Parameters
Symbol
Min.
Typ.
Max.
Unit
VS
8.0
8.5
10
V
Tamb
-40
+85
°C
Supply voltage range, pin 42
Ambient temperature
Electrical Characteristics
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C
No.
Parameters
Test Conditions
Pin
Symbol
Min.
Typ.
Max.
Unit
Type*
42
VS
8.0
8.5
10
V
C
1
Power Supply
1.1
Supply voltage
1.2
Supply current
Standby mode
(bit 92 = 0, bit 93 = 0)
42
IStby
35
45
mA
A
1.3
Supply current
Other operation
modes
42
IS
50
65
mA
A
260
MHz
D
4.0
V
A
2
VCO (Bit 52 = 0, Bit 30 = 1)
2.1
Frequency range
2.2
DC bias voltage
2.3
Buffer output voltage
16
250
mVrms
C
2.4
Buffer output
resistance
16
70
Ω
D
2.5
Buffer output DC
voltage
16
3.8
V
A
3
fVCO
13
fosc = 120 MHz
70
3.4
3.7
4.1
4.4
FM RF-AGC
3.1
Saturation voltage
No input signal
5
8.3
V
A
3.2
Saturation voltage
No input signal
5
VS - 0.2
V
B
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
23
4838A–AUDR–10/04
Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C
No.
Parameters
Test Conditions
Pin
3.3
Threshold level
In-band signal
30
3.4
Maximum threshold
level
Out-of-band signal
(110 MHz),
bit 64, 65 = 0
1
4
Symbol
Min.
Typ.
Max.
115
100
103
106
Unit
Type*
dBµV
C
dBµV
B
AM RF-AGC, AM Mode (Bit 92 = 0, Bit 93 = 1)
4.1
Saturation voltage
No input signal
7
8.3
V
C
4.2
Saturation voltage
No input signal
7
VS - 0.2
V
C
4.3
Output voltage for
minimum gain
Bit 92 = 1
7
6.5
V
C
4.4
Output voltage for
minimum gain
Bit 92 = 1
7
V
C
4.5
Maximum control
voltage
No signal
6
V
A
4.6
Maximum control
voltage
No signal
6
VS - 1.5
V
B
4.7
Minimum control
voltage
AGC active
6
0.2
0.8
V
A
4.8
Maximum threshold
level
Bits 64, 65 = 1
41
97
99
102
dBµV
A
43, 44
14
16
20
mA
A
4.1
mS
D
5
Sum of current in
pins 43, 44
Supply current
5.2
Conversion
conductance
5.3
3rd-order input
intercept point
Pin 3 AC-grounded
5.4
Noise figure (SSB)
Generator resistance
2.5 kΩ (pin 41)
5.5
Input bias DC voltage
5.6
Input resistance
5.7
Input capacitance
5.8
Maximum output
voltage
6
7.1
VS 1.7
6.5
7.0
7.5
AM Mixer, AM Mode (Bit 92 = 0, Bit 93 = 1)
5.1
5.9
6.8
3, 41,
43, 44
41
IP3AMmix
132
dBµV
C
43, 44
NFAMmix
12
dB
C
V
A
kΩ
D
pF
D
3, 41
Single-ended, pin 39
AC-grounded
2.45
3, 41
2.8
13
3, 41
Differential
Output resistance
3.1
3
43, 44
12
Vpp
D
43, 44
100
kΩ
D
43, 44
12
mA
A
7
mS
D
FM Mixer (FM Mode (Bit 92 = 1, Bit 93 = 0)
6.1
Supply current
6.2
Conversion
conductance
6.3
3rd-order intercept
point
6.4
Noise figure (DSB)
Sum of current in
pins 43, 44
1, 2,
43, 44
Generator resistance
200 Ω
15
20
1, 2
IP3FMmix
125
dBµV
C
43, 44
NFFMmix
10
dB
C
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
24
ATR4258
4838A–AUDR–10/04
ATR4258
Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C
No.
Parameters
6.5
Input resistance
6.6
Input capacitance
Pin 2 AC-grounded
6.7
Maximum differential
output voltage
VS = 8.5 V
6.8
Output resistance
7
Test Conditions
Pin
Symbol
Min.
Typ.
Max.
Unit
Type*
1, 2
1.6
kΩ
D
1
5
pF
D
43, 44
12
Vpp
D
43, 44
100
kΩ
D
dB
B
st
1 IF FM Amplifier, FM Mode (Bit 92 = 1, Bit 93 = 0)
7.1
Minimum voltage gain
Bits 89, 90, 91 = 0
7.2
Temperature
coefficient of gain
Bit 66 = 0
TKmin
0.039
dB/K
D
7.3
Temperature
coefficient of gain
Bit 66 = 1
TKmax
0.044
dB/K
D
7.4
Input resistance
Pin 39 AC-grounded
38
Ω
D
7.5
Input capacitance
Pin 39 AC-grounded
38
pF
D
Ω
D
16
dB
D
26
dB
D
17
dB
D
kΩ
D
pF
D
7.6
8
Output resistance
Maximum voltage
gain
8.2
Gain control range
8.3
Noise figure
8.4
Input resistance
8.5
Input capacitance
9
19
270
21
330
23
400
5
30
270
330
400
1st IF AM Amplifier, AM Mode (Bit 92 = 0, Bit 93 = 1)
8.1
8.6
38, 30
330 Ω load at pin 30
30, 33
Generator resistance
2.5 kΩ
NFIFAM
33
Pin 39 AC-grounded
Output resistance
10
33
1
30
270
330
400
Ω
D
2nd Mixer
9.1
FM supply current
Bit 92 = 1, Bit 93 = 0
23, 24
10
12
16
mA
A
9.2
AM/WB supply
current
Bit 92 = 0, Bit 93 = 1
23, 24
7
8
10
mA
A
9.3
Conversion
conductance
2
mS
D
9.4
Noise figure (SSB)
9.5
3rd-order input
intercept point
9.6
AM/WB output
resistance
Bit 92 = 0, Bit 93 = 1
23, 24
9.7
Maximum differential
output voltage
AM/WB
VS = 8.5 V
9.8
Maximum differential
output voltage FM
9.9
9.10
26, 23,
24
Generator resistance
330 Ω (pin 26)
23, 24
NFMix2
23
dB
C
26
IP3Mix2
132
dBµV
C
100
kΩ
D
23, 24
12
Vpp
D
23, 24
1
Vpp
D
Input resistance
26
270
400
Ω
D
LO input voltage
22
80
500
mVpp
D
330
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
25
4838A–AUDR–10/04
Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C
No.
Parameters
9.11
LO input resistance
22
LO input bias voltage
22
9.12
10
Test Conditions
Symbol
Min.
Typ.
Input resistance
Pin 27 AC-grounded
10.2
Voltage gain
AM/WB mode
(Bit 93 = 1)
Pin 28 1 mVrms
10.3
Gain control range
AM/WB mode
(Bit 93 = 1)
10.4
DC output voltage
10.5
AC output voltage
Unmodulated signal,
82 dBµV at pin 1
(IF AGC active)
Bit 93 = 1
10.6
Output impedance
Small signal
1
2.8
3.0
28
3.2
3
28, 20
42
45
48
47
Unit
Type*
kΩ
D
V
A
kΩ
D
dB
A
dB
D
20
3.4
3.7
4.0
V
A
20
150
180
230
mVrms
A
20
Ω
D
70
FM Demodulator Integrated Band-filter, FM Mode (Bit 92 = 1, Bit 93 = 0), BW Setting 2
11.1
AC output voltage
Deviation = ±75 kHz,
fmod = 1 kHz
11
11.2
Stereo roll-off
Deviation = ±75 kHz,
fmod = 38 kHz
(reference: 1 kHz)
11
11.3
Total harmonic
distortion
Deviation = ±75 kHz,
fmod = 1 kHz
11
THDFM
0.4
11.4
Maximum signal-tonoise ratio
Dev. = ±22.5 kHz,
fmod = 1 kHz, 50 µs
de-emphase, signal
input at 450 kHz
11
(S/N)FM
65
12
Max.
2nd IF Amplifier (Bit 55 = 0)
10.1
11
Pin
420
480
nd
IF Filter = 120 kHz
540
mVrms
B
dB
D
%
A
dB
C
-2.0
0.7
Soft Mute, FM Mode (Bit 92 = 1, Bit 93 = 0, Bit 80 = 0)
12.1
Mute gain
Bit 67 = 0,
V (pin 34) = 2 V
11
-28
-26
-24
dB
A
12.2
Mute gain
Bit 67 = 1,
V (pin 34) = 2 V
11
-24
-22
-20
dB
A
135
150
170
mVrms
A
2
%
A
dB
C
V
A
13
AM Demodulator, AM Mode (Bit 92 = 0, Bit 93 = 1)
13.1
AC output voltage
Modulation depth =
30%, fmod = 1 kHz
11
13.2
Total harmonic
distortion
Modulation depth =
80%, fmod = 1 kHz
V(pin 35) = const.
11
THDAM
0.6
13.3
Maximum
signal-to-noise ratio
Modulation depth =
30%, fmod = 1 kHz
74 dBµV at pin 41
11
(S/N)AM
54
Bit 7 = 1
11
14
14.1
MPX Output
DC output voltage
2.1
2.3
2.5
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
26
ATR4258
4838A–AUDR–10/04
ATR4258
Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C
No.
Parameters
Test Conditions
Pin
14.2
Mute gain
Bit 7 = 1,
FM dev. = ±75 kHz,
fmod = 1 kHz
14.3
Output resistance
Small signal
15
Symbol
Min.
Typ.
Max.
Unit
Type*
11
-65
-50
dB
A
11
60
Ω
D
V
A
kΩ
D
V
A
1
kΩ
D
0.2
V
C
V
C
Search Stop Detector, INT Output
15.1
LOW saturation
voltage
21
0
15.2
LOW output
resistance
21
0.3
15.3
HIGH saturation
voltage
21
15.4
HIGH output
resistance
16
4.8
21
5.25
Deviation Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0)
16.1
Offset voltage
FM dev. = ±0 kHz
FM demodulator
adjusted
31
16.2
Output voltage
FM dev. = ±75 kHz,
fmod = 1 kHz
31
17
4.5
0.5
1.7
2.0
2.5
Field Strength Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0, Bit 89 to 91 = 0, Bit 80 = 0, Bit 18 to 21 = 0)
17.1
Output voltage
60 dBµV at pin 33
9
0.8
1.3
1.8
V
A
17.2
Output voltage
Unmodulated signal
100 dBµV at pin 33
9
2.8
3.4
3.9
V
A
Field Strength Sensor, AM Mode (Bit 92 = 0, Bit 93 = 1, Bit 80 = 1, Bit 18 to 21 = 0)
17.3
Output voltage LOW
field strength
60 dBµV at pin 28
9
1.5
1.8
2.1
V
A
17.4
Output voltage HIGH
field strength
94 dBµV at pin 28
9
3.0
3.3
3.6
V
A
0
200
mV
A
1.9
2.4
V
A
18
18.1
18.2
Multipath Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0)
Offset voltage
Unmodulated signal,
60 dBµV at pin 1
40
Output voltage
AM modulation depth
= 60%,
fmod = 20 kHz,
60 dBµV at pin 1
40
1.5
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
27
4838A–AUDR–10/04
Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C
No.
Parameters
19
Adjacent Channel Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0), Bit 4 = 0 (Default BW Setting)
19.1
Pin
Offset voltage
Unmodulated signal
10
Output voltage
AM mod. 10%
fmod = 100 kHz
AM mod. 60%
fmod = 100 kHz
10
19.2
19.3
20
Test Conditions
Symbol
Min.
Typ.
Max.
200
1.2
0.3
0.6
1.9
2.5
Unit
Type*
mV
C
V
A
V
D
V
D
3-wire Bus
20.1
Input voltage LOW
17, 18,
19
20.2
Input voltage HIGH
17, 18,
19
20.3
Leakage current
20.4
Clock frequency
20.5
Period of CLK
HIGH
LOW
tH
tL
20.6
Rise time
EN, DATA, CLK
tr
20.7
Fall time
EN, DATA, CLK
tf
20.8
Set-up time
ts
V = 0 V, 5 V
0.8
2.7
17, 18,
19
10
µA
D
18
1.0
MHz
D
ns
ns
D
400
ns
D
100
ns
D
100
ns
D
250
250
20.9
Hold time EN
tHEN
250
ns
D
20.10
Hold time DATA
tHDA
0
ns
D
V
A
21
Internally Generated Reference Voltages
21.1
Output voltage
12
5.5
5.7
6.0
21.2
Output voltage
29
3.0
V
D
21.3
Output voltage
27
3.0
V
D
21.4
Output voltage
39
3.0
V
D
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
28
ATR4258
4838A–AUDR–10/04
ATR4258
Application Information
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 37 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 = ⎛ ------------------------------------⎞ – fIF
⎝ AM Prescaler⎠
Table 37. AM Prescaler (Divider) Settings and Reception Frequencies
Divider (AM Prescaler)
Note:
Minimum Reception Frequency Maximum Reception Frequency
[MHz]
[MHz]
divide by 2
38.4
51.3
divide by 3
20.033
30.633
divide by 4
13.85
20.3
divide by 5
8.94
14.1
divide by 6
5.667
9.967
divide by 7
3.329
7.014
divide by 8
1.575
4.8
divide by 9
0.211
3.078
divide by 10
0
1.7
Prescaler VCO Divider = 1 in this example.
29
4838A–AUDR–10/04
Local Oscillator and AM
Prescaler Settings
Table 38 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) × VCO Prescaler × AM Prescaler
Table 38. VCO and AM Prescaler (Divider) Settings and Reception Frequencies
Band
Prescaler
VCO
IF [MHz]
FM
2
+10.7
87.5
WB
1.5
-10.7
162.4
Minimum VCO
Frequency
Maximum VCO
Frequency
AM
Prescaler
108
196.4
237.4
-
162.55
227.55
227.775
-
Minimum Reception Maximum Reception
Frequency [MHz]
Frequency [MHz]
JPN
3
-10.7
76
90
195.9
237.9
-
LW/MW
2
+10.7
0.15
1.605
195.3
221.49
9
16m
1
+10.7
17.5
17.9
225.6
228.8
8
120m
2
+10.7
2.3
2.5
208
211.2
8
U4256 N- and R-divider
Calculation
AM Mode
fVCO
N = --------------------------------------------------------------------------------------------VCO-divider × AM Prescaler × f step
fVCO
f rec = ⎛⎝ ----------------------------------------------------------------------------⎞⎠ – f IF
VCO-divider × AM Prescaler
FM/WB Mode
f VCO
N = ------------------------------------------------VCO-divider × f step
fVCO
f rec = ⎛⎝ --------------------------------⎞⎠ – f IF
VCO-divider
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)
30
ATR4258
4838A–AUDR–10/04
ATR4258
Diagrams
The following data was measured with the application board (see Figure 20).
In the measurement setup, a 50 Ω generator is terminated by 50 Ω and connected to the
antenna input by a 50 Ω series resistor to achieve 75 Ω termination at the antenna input.
The generator level specified is the output voltage of this 50 Ω generator at 50 Ω load. If
the application board is replaced by a 75 Ω resistor, the voltage at this resistor is 6 dB
below the specified voltage level of the 50 Ω generator.
1.0
1
0.9
0.9
0.8
0.8
0.7
0.7
+85°C
0.6
0.6
0.5
-40°C
MPX
0.4
0.5
0.4
THD
0.3
THD [%]
MPX Output Voltage [Vrms]
Figure 12. FM Demodulator
0.3
-40°C
0.2
0.2
+85°C
0.1
0.1
0.0
0
10
20
30
40
50
60
70
80
90
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 µs de-emphasis (THD)
Figure 13. Multipath Sensor
Sensor Output Voltage
5
4
+85°C
3
-40°C
2
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 dBµV
31
4838A–AUDR–10/04
Figure 14. Multipath Sensor Frequency Response
Sensor Output Voltage [V]
5.0
4.5
4.0
90% at 25°C
3.5
90% at -40°C
3.0
2.5
60% at 85°C
60% at 25°C
2.0
60% at -40°C
1.5
1.0
0.5
0.0
100
1000
10000
100000
AM Modulation Frequency [Hz]
Note:
Generator level 40 dBµV
Deviation Sensor Output Voltage [V]
Figure 15. Deviation Sensor
5
4
+85°C
3
2
-40°C
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).
32
ATR4258
4838A–AUDR–10/04
ATR4258
Figure 16. Deviation Sensor Frequency Response
Sensor Output Voltage (V)
1.0
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
10
5
4.5
0
4
MPX Output [dB]
-10
3.5
-20
3
-30
2.5
-40
2
-50
1.5
-60
1
-70
0.5
-10
0
10
20
30
40
50
60
70
80
90
100
Fieldstrength Sensor Output Voltage [V]
Figure 17. FM Input Level Sweep
110 120
Input Level [dBµV]
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
33
4838A–AUDR–10/04
20
4.5
Pdes/Pundes
Pdes/Pundes [dB]
10
4
0
3.5
-10
3
-20
2.5
-30
2
-40
1.5
-50
1
Adjacent
-60
-70
-300 -250 -200
-150 -100
-50
0
0.5
50
100
150
200
250
0
300
Frequency Offset [kHz]
Note:
34
Adjacent Channel Output Voltage [V]
Figure 18. Selectivity
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
ATR4258
4838A–AUDR–10/04
ATR4258
Figure 19. Test Circuit
Test Point
50
1
44
2
43
3
42
4
41
5
40
6
39
7
38
8
37
9
36
10
35
10n
VS
50
10n
VS
50
50
10n
100n
10n
47n
50
50
47n
P29
10n
100n
10n
10n
11
12
1µ
50
ATR4258
100n
10n
34
200k
P29
33
100n
13
32
14
31
15
30
16
29
17
28
18
27
19
26
10n
P31
50
47n
50
50
10n
10n
P29
V
22n
330
47n
1k3
Bus
47n
Quarzoscillator
10.25 MHz
100n
10n
10k
20
25
21
24
22
23
50
50
VS
10n
50
50
35
4838A–AUDR–10/04
36
Ant
FM 75 Ω
R307
47
T111
J109
T302
BC848
D302
S391D
4µ7
L301
220n
S391D
D301
10n
C315 C302
R306
470k
220n
100n
C311
BC
858C
2k2
T102
BC858
C316
R105
100
100µH
R308 T301
L303
2m2
2k2
R311
C319
6p8
L302
R103
1k
10n
C117
R115
1k
2µ2
C106
L102
R112 47k
R104
470
68k
F102
R102
390
R313
1µ
C111
C306
12p
C112
10µ
3p9
C102
T101
BFR93A
10p
F201
2
43
C56
D101
S391D
10n
D103 C103
F101
C104
10n
18p
BB804
27p
6p8
C107
1n
C108 C109
1
44
100p
C in F201
BB804
D102
R41
1k2
C113
100n
10n
C209
R29
10
C201
C110
4n7
3
42
4
41
68k
R122
68k
R121
C11
10n
10n
C307
100n
5
40
100n
C308
6
39
R34
27
7
38
9
34
12
33
100n
14
15
30
C152
330p
1n
C134
R131
5k6
BB804
1
20
22p
F131
47p
C131 C132
13
31
220n
C207
220n
C208
32
D131
R151
8k2
470p
C77
6p8
C133
220n
C114
11
100n
10
C116
22µ
C203
10µ
10n
ATR4258
35
C205
X301
C206
1k5
R305
R33
2k
C115
8
470n
37
36
1µ C204
R111
200k
C202
KR201
R304
5k6
3
18
17
28
4
17
18
27
C27
2µ2
C309
DAC3
5
10n
6
8
9
12
Q151
13
10
11
10n
C157
SWO1
SWO3
SWO2
SWO4
7
14
10p
10.25 MHz
C154
10n
10p
22
23
C312
C153
1n
F302
R32
1k
R106
10
100n
21
24
C310
R303
1k
C155
15
10n
C156
20
25
220n
U4256BM
16
19
26
C159
KF302
Application Board Schematic
C158
10n
10n
C151
2
19
16
29
KR202
R152
10
10
R407
METER
ADJAC
MPX
GND
EN
CLK
DATA
IF2OUT
INT
DEV
MULTIP
VS
(+8.5 V to 10.5 V)
Figure 20. Application Circuit
ATR4258
4838A–AUDR–10/04
ATR4258
Ordering Information
Extended Type Number
Package
Remarks
ATR4258-ILSH
SSO44
Tube, lead-free
ATR4258-ILQH
SSO44
Taped and reeled, lead-free
Package Information
9.15
8.65
Package SSO44
Dimensions in mm
18.05
17.80
7.50
7.30
2.35
0.3
0.25
0.10
0.8
16.8
44
0.25
10.50
10.20
23
technical drawings
according to DIN
specifications
1
22
37
4838A–AUDR–10/04
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4838A–AUDR–10/04