ATR4255 [ATMEL]
AM/FM RECEIVER IC; AM / FM接收器IC
| 型号： | ATR4255 |
| 厂家： | 
ATMEL |
| 描述： | AM/FM RECEIVER IC |
| 文件： | 总32页 (文件大小：377K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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 for AM and FM
• Automatic Alignment Possible
• Lead-free Package
AM/FM
Receiver IC
ATR4255
Electrostatic sensitive device.
Observe precautions for handling.
Description
The ATR4255 is a highly integrated AM/FM front-end circuit manufactured using
Atmel’s advanced BICMOS technology. It represents a complete, automatically adjust-
able 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. 4837A–AUDR–10/04
Figure 1. Block Diagram
IF1FMI
IF1AMI
V3
MX2OB
MX1OA
IF2IN
28
AMPLPF
MX1OB IF1REF
IF1OUT MX2IN
MX2OA
V3P
27
IF2OUT
20
30 29
23 24
39
43 44
33
26
8
38
7
6
AMAGC
AM
AGC
AMVREG
FM
AM
dem.
OPLPF
32
41
3
MX1AMA
MX1AMB
AM
V3
AGC
IFAGCL
36
35
IFAGCCH
4
GNDMX
FM
2
1
MX1FMB
MX1FMA
Automatic
adjustment
AGC
FILADJ
37
11
Multi-
path
16
15
OSCOUT
Divider
Adj.
chan
.
Soft
mute
FM
dem.
MPX
Stop
GNDOSC
OSCE
14
13
OSC
OSCB
V3
Dev.
ana.
Bandgap
Bus
INT
17 18 19
5
12 25 42
GND
9
22
10
21
INT
40
34
31
SMUTE DEV
EN
DATA FMAGC
METER
MX2LO
ADJAC
MULTIP
CLK
V57
VS
Pin Configuration
Figure 2. Pinning SSO44
2
ATR4255
4837A–AUDR–10/04
ATR4255
Pin Description
Pin
Symbol
Function
1
MX1FMA
MX1FMB
MX1AMB
GNDMX
FMAGC
AMVREG
AMAGC
AMPLPF
METER
ADJAC
MPX
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
2
3
4
5
6
7
8
9
Field strength output
Adjacent channel detection output
Multiplex signal
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
V57
5.7 V reference voltage
Oscillator basis
OSCB
OSCE
Oscillator emitter
GNDOSC
OSCOUT
EN
Oscillator ground
Oscillator output
3-wire bus enable
CLK
3-wire bus clock
DATA
3-wire bus data
IF2OUT
INT
2nd IF amplifier output
Interrupt, stop signal
10.25 MHz input for 2nd mixer
2nd mixer output B
MX2LO
MX2OB
MX2OA
GND
2
nd mixer output A
Ground
2nd mixer input
MX2IN
V3P
3 V reference for AMPIN, AMIFAGC, Control, IF2IN
2nd IF amplifier input
IF2IN
V3
3 V reference for IF1OUT, MX2IN
1st IF amplifier output
IF1OUT
DEV
Deviation detect output, test output
OPLPF
IF1AMI
SMUTE
IFAGCH
IFAGCL
FILADJ
IF1FMI
IF1REF
MULTIP
MX1AMA
VS
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 and MX1OUT reference, MX1AM A, MX1AM B
Multipath detection output
1st mixer AM input A
Supply voltage
1st mixer output A
1st mixer output B
MX1OA
MX1OB
3
4837A–AUDR–10/04
Functional Description
The ATR4255 implements an AM up/down-conversion reception path from the RF input
signal to the AM-demodulated audio frequency output signal, and for FM reception a
double-conversion reception path from the RF input signal to the FM-demodulated mul-
tiplex 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 soft-
mute 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 17. The meaning of the control bits is mentioned in the following
sections.
Reception Mode
The IC can be operated in four different modes. Mode AM, FM, WB, Standby are
selected by means of bit 92 and bit 93 according to Table 1.
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 acti-
vated. 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, pin 24 and pin 28. The output of the
2
nd IF amplifier is fed to the integrated bandfilter and FM demodulator. The output of the
FM demodulator is available at MPX output pin 11.
WB mode is similar to FM mode but the input of the 2nd IF amplifier is fixed to pin 28, the
range of the bandwidth control of the integrated band filter 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.
Table 1. Operating Mode
AM/FM/Weather Channel
Bit 93
Bit 92
Standby
FM
0
0
1
1
0
1
0
1
AM
Weather band
4
ATR4255
4837A–AUDR–10/04
ATR4255
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 application.
For normal operation, bit 9 has to be set to 0. Bit 18 to bit 30 are deactivated in normal
operation mode.
Table 2. Test Mode
Mode
Bit 9
Normal operation
Testmode
0
1
VCO
An oscillator circuit is implemented to build a VCO as proposed in the application sche-
matic. 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 signal is provided at the buffered output pin 16 to be fed to the PLL circuit.
FM RF-AGC
The FM RF-AGC circuit includes a wideband 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 3. The in-band AGC threshold referred 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 3. FM-AGC Threshold
FM-AGC Threshold
104 dBµV
Bit 65
Bit 64
0
0
1
1
0
1
0
1
101 dBµV
98 dBµV
92 dBµV
Figure 3. FM RF-AGC Bit 92
VS
Pin 42
Pin 5
C111
R115
PIN Diode
AGC
B92
5
4837A–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 62 and bit 63. 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. AM-AGC Threshold
AM-AGC Threshold
99 dBµV
Bit 63
Bit 62
0
0
1
1
0
1
0
1
102 dBµV
104 dBµV
105 dBµV
FM 1st Mixer
AM 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.
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 5.
Table 5. Divide Factor of the AM Prescaler
Divider AM Prescaler
Divide by 10
Divide by 6
Bit 93
Bit 92
Bit 84
Bit 83
Bit 82
Bit 81
1
1
1
1
1
0
0
0
0
0
x
x
x
x
x
0
0
0
1
1
0
0
1
0
0
0
1
0
0
1
Divide by 7
Divide by 8
Divide by 4
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.
6
ATR4255
4837A–AUDR–10/04
ATR4255
Table 6. Gain of the FM IF Amplifier
Gain FM IF
20 dB
Bit 91
Bit 90
Bit 89
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
22 dB
24 dB
26 dB
28 dB
29 dB
30 dB
31 dB
Table 7. Temperature Coefficient Setting of FM IF Amplifier
Temperature Coefficient (TC) of the IF Amplifier
Bit 66
TKmin
TKmax
0
1
AM 1st IF Amplifier
2nd Mixer
In AM mode, the gain of the 1st IF amplifier is controlled by the IF-AGC to extend the
control range of the IF-AGC.
The 2nd mixer is used in AM, FM and WB mode. The mixer input has 330 Ω input resis-
tance 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.
Table 8. 2nd Mixer Output Resistance in FM Mode
Bit 61
Bit 60
Output Resistance (Bit 54 = 0)
Output Resistance (Bit 54 = 1)
0
0
1
1
0
1
0
1
3.3 kΩ
0.63 kΩ
0.47 kΩ
0.29 kΩ
~100 kΩ
0.78 kΩ
0.55 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.
Table 9. FM Bandwidth Mixer 2
Bit 61
Bit 60
FM BW Mixer 2
150 kHz
0
0
1
0
1
0
1
200 kHz
250 kHz
1
450 kHz
Note:
The bandwidth is also depending from the values of the application circuit.
7
4837A–AUDR–10/04
2nd IF Amplifier
In AM and WB mode, the input of the second IF amplifier is pin 28, which is externally
connected to the 2nd mixer tank through the AM ceramic filter to achieve channel selec-
tivity. 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 10. 2nd IF Filter in FM Mode
2nd IF Filter
Internal filter
Bit 54
0
1
External and internal filter
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 bandfilter 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 mode
and in AM search mode. The long time constant (IFAGCH) is used for AM reception.
Table 11. IF-AGC Time Constant
Mode
FM/WB
Bit 92
Bit 88
IF AGC Time Constant
IFAGCL (fast)
1
0
0
X
0
1
AM reception
AM search
IFAGCH (slow)
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 demodula-
tor is used for the FM demodulator fine adjustment, for muting and as a reference for the
deviation sensor.
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 12. Pin 20 Output Setting
Pin 20
Bit 55
2
nd IF output
0
1
Multipath field strength
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.
8
ATR4255
4837A–AUDR–10/04
ATR4255
Figure 4. Automatic IF Center Frequency Adjustment
Automatic
frequency
adjustment
center
FM demod
Pin 22
freq.
10.25 MHz
center
freq.
FM
bandfilter
+
Bits 56 to 59
Bits14 to 17
Pin 37
center
freq.
Adj. channel
sensor
+
Bits 5, 6
For fine tuning, the center frequency of all these integrated active filters (band filter,
demodulator and adjacent channel sensor) 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 if bit 4 is set to 1. If bit 4 is set to 0, the
default setting is used.
Table 13. 2nd IF Center Frequency
IF Center
450.00 kHz
456.25 kHz
461.50 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
Bit 59
Bit 58
Bit 57
Bit 56
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
9
4837A–AUDR–10/04
Table 14. FM Band Filter Center Frequency Correction
IF Correction
-0 kHz
Bit 17
Bit 16
Bit 15
Bit 14
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
-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
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 15) 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 (bit 4 set to 1). 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 15. Bandwidth of the Integrated FM Band Filter
IF Bandwidth
200 kHz
190 kHz
180 kHz
170 kHz
160 kHz
150 kHz
140 kHz
130 kHz
120 kHz
110 kHz
100 kHz
90 kHz
Bit 3
0
Bit 2
0
Bit 1
0
Bit 0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
80 kHz
1
1
0
0
70 kHz
1
1
0
1
60 kHz
1
1
1
0
50 kHz
1
1
1
1
10
ATR4255
4837A–AUDR–10/04
ATR4255
FM Demodulator
For weather band reception, the gain of the FM demodulator is increased and can be
adjusted by means of bit 71, bit 72 in order to increase the output voltage to compen-
sate the low frequency deviation in weather band.
An integrated demodulator fine adjustment allows automatic fine tuning of the demodu-
lator 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
FM demod
MPX
B92
AM
AGC
Center freq.
+
IFAGCH
V3
(10 nF)
Bit 53
Automatic
frequency
adjustment
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 16. Demodulator Gain in Weather Band Mode
Demodulator Gain in Weather Band Mode Relative to FM Mode
Bit 72
Bit 71
12 dB
15 dB
18 dB
21 dB
0
0
1
1
0
1
0
1
Table 17. Demodulator Fine Adjustment
Demodulator Fine Adjustment
Fine tuning ON
Bit 53
0
1
Fine tuning OFF
11
4837A–AUDR–10/04
Soft Mute
The soft mute functionality is implemented to reduce the output level of the FM demodu-
lator at low input signal levels to limit the noise at 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 referred to the input of the FM mixer depends on the gain from FM mixer input
to the field strength sensor.
Table 18. Soft Mute Threshold
Relative Soft Mute Threshold
Bit 70
Bit 69
Bit 68
Soft mute OFF
-18 dB
-15 dB
-12 dB
-9 dB
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
-6 dB
-3 dB
0 dB
Table 19. Maximum Soft Mute
Maximum Value of Soft Mute
Bit 67
28 dB
24 dB
0
1
Figure 6. Soft Mute
+
FS (pin 9)
Bit 67
Pin 34
Pin 29
Gain FM demodulator
Bits 68 to 70
V3
12
ATR4255
4837A–AUDR–10/04
ATR4255
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 bit 1.
The bandwidth of the lowpass filter at the MPX output can be set by means of bit 79 to
90 kHz or 180 kHz.
Table 20. MPX Output Mute
MPX Output
MPX out, pin 11 normal operation
Mute ON
Bit 7
0
1
Table 21. MPX Output Bandwidth
Bandwidth MPX Lowpass Filter
Bit 79
90 kHz
0
1
180 kHz
Receiving Condition
Analyzer
The ATR4255 implements several sensors that provide information about the receiving
condition of the selected station.
Field Strength Sensor
The field strength sensor provides a DC voltage at pin 9 which represents the logarith-
mic 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 band-
width 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 mode and
the AGC field strength is used in AM mode.
Table 22. Field Strength Selection
Field Strength Narrow Band/Wide Band
Fieldstrength at pin 26 (wide band)
Bit 80
0
1
Fieldstrength from IF-AGC (narrow band)
Search Stop Detector
A search stop detector is available in AM and FM/WB mode. A STOP condition is
signaled if the frequency of the ZF 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 ZF signal is measured by counting the
number of periods of the ZF 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 25 on
page 14. The frequency of 10.25 MHz at pin 22 is used as time reference.
13
4837A–AUDR–10/04
Table 23. Search Stop Detector Measurement Time
Time Window for Stop Signal
1 × 3.1969 ms
.....
Bit 78
Bit 77
Bit 76
Bit 75
Bit 74
Bit 73
0
0
0
0
0
1
63 × 3.1969 ms
1
1
1
1
1
1
Table 24. Search Stop Window
Search Stop Window
±0.5 kHz
Bit 87
Bit 86
Bit 85
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
±1.1 kHz
±2.3 kHz
±4.8 kHz
±10 kHz
±20 kHz
±40 kHz
±80 kHz
Table 25. Signals Available at Digital Output Pin 21
Bit 88
Bit 92
0 (AM)
INT (Pin 21)
0
0
1
1
1
1 (FM/WB)
0 (AM)
NOT MPINT
NOT STOP
1 (FM/WB)
NOT (STOP AND NOT MPINT)
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 lowpass-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
14
ATR4255
4837A–AUDR–10/04
ATR4255
Adjacent Channel
Sensor
The adjacent channel sensor is active in FM mode only and measures the field strength
outside the reception band. By setting the center frequency of the band filter of the adja-
cent channel sensor below or above the 2nd IF frequency (bit 5, bit 6), it can be
determined whether the disturbance signal is located above or below the reception fre-
quency (see Table 28 on page 16). The bandwidth of the band filter used in the adjacent
channel sensor can be changed by means of bit 10 to 13. If bit 4 = 0 the default band-
width setting is used. The output of the adjacent channel sensor is independent of the
bandwidth setting of the integrated FM band filter.
Figure 8. Adjacent Channel Sensor
IF
intergr. FM bandfilter
+
-
+
4k
log
Pin 10
50k
log
Table 26. Bandwidth of the Adjacent Channel Detector Filter
BW Adjustment
3 kHz
Bit 13
Bit 12
Bit 11
Bit 10
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
16 kHz
32 kHz
50 kHz
65 kHz
80 kHz
95 kHz
110 kHz
50 kHz
65 kHz
80 kHz (default)
95 kHz
110 kHz
130 kHz
145 kHz
160 kHz
15
4837A–AUDR–10/04
Table 27. Center Frequency Adjacent Channel Sensor
Center Frequency
450 kHz
Bit 6
Bit 5
0
0
1
1
0
1
0
1
300 kHz
700 kHz
Filter OFF
Table 28. Output Voltage of Adjacent Channel Sensor for Different Receiving Condi-
tions and Center Frequencies
Adjacent Channel Disturbance
300 kHz
high
450 kHz
low
600 kHz
high
no
below
above
high
high
low
low
high
high
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 repre-
sented 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
+
4 k
Pin 40
A Multipath Noise Canceller (MNC) is implemented to reduce disturbance of the
received signal in multipath reception conditions. If the difference between the momen-
tary and the averaged field strength falls below a threshold adjustable by bit 81 to bit 84
(see Table 30 on page 17), the MPX signal may be muted and this situation (MPINT)
can be signalized at pin 21 (INT) according to Table 25 on page 14. Muting of the MPX
signal during multipath disturbances can be activated be setting bit 8.
Table 29. Multipath Noise Canceller
Multipath Noise Canceller
Active
Bit 8
0
1
Not active
16
ATR4255
4837A–AUDR–10/04
ATR4255
Table 30. Sensitivity of the MNC
Sensitivity MNC (Threshold)
Bit 93
Bit 92
Bit 84
Bit 83
Bit 82
Bit 81
Off
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Low
(-18 dB)
Normal (-12 dB)
High (-9 dB)
3-wire Bus Description
The register settings of ATR4255 are programmed by a 3-wire bus protocol. The bus
protocol consists of separate commands. A defined number of bits is transmitted
sequentially during each command.
One command is used to program all bits of one register. The different registers avail-
able (see Table 31 on page 19) 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 pro-
grammed 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 ATR4255 are compatible to the
addressing used in U4256BM. That means ATR4255 and U4256BM can be operated on
the same 3-wire bus as shown in the application circuit.
17
4837A–AUDR–10/04
Figure 10. 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 11. Bus Timing
tR
tF
Enable
tHEN
tS
tR
tF
Data
tHDA
tS
tR
tF
Clock
tH
tL
18
ATR4255
4837A–AUDR–10/04
ATR4255
Data Transfer
Table 31. Control Registers
A24_100
MSB
BYTE 3
LSB MSB
Gain FM
IF amplifier
BYTE 2
LSB
MSB
Field
strength PX
BYTE 1
Time window stop signal
LSB
AM/FM/
WB
OSC divider/multipath
sensitivity
BWM
ADDR.
Search Width of window
1
0
0
AM FM
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
WB-
Demod-
Gain
Tk-
FM IF
FM BW
nd mixer
MP FM Dem. Not
ADDR.
Start Smute
Smute
B67
FM-AGC AM-AGC
IF2 center frequency
2
FS ext
Adj. used
x
1
0
1
B72 B71 B70 B69 B68
B66 B65 B64 B63 B62 B61 B60 B59 B58 B57 B56 B55 B54 B53 B52
A24_111
MSB
BYTE 3
LSB MSB
used in test mode only
BYTE 2
x
LSB MSB
center frequency of
bandfilter
BYTE 1
LSB
bandwidth adj. channel
sensor
ADDR.
1
1
1
x
1
0
0
0
0
1
0
1
B30 B29 B28 B27 B26 B25
B24 B23 B22 B21 B20 B19 B18 B17 B16 B15 B14 B13 B12 B11 B10
A8_100
MSB
BYTE 1
LSB
Adj.
ADDR.
0
Test MPoff Mute channel
sensor
1
0
0
B9
B8
B7
B6
B5
A8_101
MSB
BYTE 1
Optimize
LSB
ADDR.
Band width
1
0
1
B4
B3 B2 B1 B0
19
4837A–AUDR–10/04
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 refer to GND (pin 25).
Parameters
Symbol
VS
Value
10
Unit
V
Supply voltage, pin 42
Power dissipation
Ptot
1000
mW
°C
Junction temperature
Ambient temperature range
Storage temperature range
Tj
150
Tamb
Tstg
-40 to +85
-50 to +150
°C
°C
Thermal Resistance
Parameters
Symbol
Value
Unit
Junction ambient, soldered to PCB
RthJA
60
K/W
Operating Range
All voltages are referred to GND (pin 25).
Parameters
Symbol
Min.
7.5
Typ.
Max.
10
Unit
Supply voltage range, pin 42
Ambient temperature
VS
8.5
V
Tamb
-40
+85
°C
Electrical Characteristics
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C.
No.
1
Parameters
Test Conditions
Pin
Symbol
Min.
Typ.
Max.
Unit
Type*
Power Supply
Supply voltage
1.1
42
42
VS
7.5
8.5
20
10
25
V
C
A
Standby mode
(bit 92 = 0, bit 93 = 0)
1.2
1.3
Supply current
Supply current
IStby
mA
Other operation
modes
42
IS
50
60
mA
A
2
VCO
2.1
2.2
2.3
Frequency range
DC bias voltage
Buffer output voltage
fVCO
70
2.8
130
160
3.2
MHz
V
D
A
A
13
16
3.0
fosc = 120 MHz
150
250
mVrms
Buffer output
resistance
2.4
2.5
16
16
70
Ω
D
A
Buffer output DC
voltage
2.8
3.0
3.2
V
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
20
ATR4255
4837A–AUDR–10/04
ATR4255
Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C.
No.
3
Parameters
Test Conditions
Pin
Symbol
Min.
Typ.
Max.
Unit
Type*
FM RF-AGC
3.1
3.2
3.3
Saturation voltage
Saturation voltage
Threshold level
No input signal
No input signal
In-band signal
5
5
8.3
V
V
A
B
D
VS - 0.2
30
110
102
dBµV
Out-of-band signal
(110 MHz),
bit 64, 65 = 0
Maximum threshold
level
3.4
1
100
104
dBµV
A
4
AM RF-AGC, AM Mode (Bit 92 = 0, Bit 93 = 1)
4.1
4.2
Saturation voltage
Saturation voltage
No input signal
No input signal
7
7
8.3
V
V
A
B
VS - 0.2
Output voltage for
minimum gain
4.3
4.4
4.5
4.6
4.7
Bit 92 = 1
7
7
6.5
6.8
VS - 1.7
7.0
7.1
7.5
V
V
A
B
A
B
A
A
Output voltage for
minimum gain
Bit 92 = 1
Maximum control
voltage
V(pin 8) = 3 V
V(pin 8) = 3 V
V(pin 8) = 6 V
Bits 62, 63 = 0
6
6.5
V
Maximum control
voltage
6
VS - 1.5
0.2
V
Minimum control
voltage
6
0.7
V
Minimum threshold
level
4.8
5
41
97
14
99
101
dBµV
AM Mixer, AM Mode (Bit 92 = 0, Bit 93 = 1)
Sum of current in
Supply current
5.1
43, 44
16
4.1
132
20
mA
mS
A
D
C
pins 43, 44
Conversion
conductance
3, 41,
43, 44
5.2
5.3
3rd-order input
Pin 3 AC-grounded
intercept point
41
IP3AMmix
NFAMmix
dBµV
Generator resistance
Noise figure (SSB)
5.4
5.5
5.6
5.7
5.8
43, 44
3, 41
14
2.6
2.5
dB
V
C
A
D
D
D
D
2.5 kΩ (pin 41)
Input bias DC voltage
2.4
2.9
3
Single-ended, pin 39
Input resistance
3, 41
kΩ
pF
Vpp
kΩ
AC-grounded
Input capacitance
3, 41
Maximum output
Differential
voltage
43, 44
43, 44
12
5.9
Output resistance
100
6
FM Mixer (FM Mode (Bit 92 = 1, Bit 93 = 0)
Sum of current in
Supply current
6.1
6.2
43, 44
15
17.5
7
20
mA
mS
A
D
pins 43, 44
Conversion
conductance
1, 2,
43, 44
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
21
4837A–AUDR–10/04
Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C.
No.
Parameters
Test Conditions
Pin
Symbol
Min.
Typ.
Max.
Unit
Type*
3rd-order intercept
point
6.3
1, 2
IP3FMmix
120
dBµV
C
Generator resistance
200 Ω
6.4
Noise figure (DSB)
43, 44
NFFMmix
10
dB
C
6.5
6.6
Input resistance
1, 2
1
1.6
5
kΩ
D
D
Input capacitance
Pin 2 AC-grounded
VS = 8.5 V
pF
Maximum differential
output vltage
6.7
43, 44
12
Vpp
D
D
6.8
7
Output resistance
43, 44
100
kΩ
1
st IF FM Amplifier, FM Mode (Bit 92 = 1, Bit 93 = 0)
7.1
Minimum voltage gain Bits 89, 90, 91 = 0
38, 30
19
21
23
dB
A
D
Temperature
Bit 66 = 0
7.2
7.3
TKmin
TKmax
0.039
dB/K
coefficient of gain
Temperature
Bit 66 = 1
0.044
dB/K
D
coefficient of gain
7.4
7.5
7.6
8
Input resistance
Input capacitance
Output resistance
Pin 39 AC-grounded
Pin 39 AC-grounded
38
38
30
270
270
330
5
400
400
Ω
pF
Ω
D
D
D
330
1st IF AM Amplifier, AM Mode (Bit 92 = 0, Bit 93 = 1)
Maximum voltage
gain
8.1
8.2
8.3
330 Ω load at pin 30
30, 33
16
26
20
dB
dB
dB
D
D
C
Gain control range
Generator resistance
2.5 kΩ
Noise figure
NFIFAM
8.4
8.5
8.6
9
Input resistance
Input capacitance
Output resistance
33
33
30
10
kΩ
pF
Ω
D
D
D
Pin 39 AC-grounded
1
270
330
400
2
nd Mixer
9.1
FM supply current
Bit 92 = 1, bit 93 = 0
Bit 92 = 0, bit 93 = 1
23, 24
23, 24
10
8
14
10
16
12
mA
mA
A
D
AM/WB supply
current
9.2
9.3
9.4
9.5
9.6
Conversion
conductance
26, 23,
24
2
mS
dB
D
C
C
D
Generator resistance
330 Ω (pin 26)
Noise figure (SSB)
23, 24
26
NFMix2
IP3Mix2
23
3rd-order input
intercept point
132
dBµV
kΩ
AM/WB output
resistance
Bit 92 = 0, bit 93 = 1
VS = 8.5 V
23, 24
100
12
Maximum differential
output voltage
AM/WB
9.7
23, 24
Vpp
D
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
22
ATR4255
4837A–AUDR–10/04
ATR4255
Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C.
No.
Parameters
Test Conditions
Pin
Symbol
Min.
Typ.
Max.
Unit
Type*
Maximum differential
output voltage FM
9.8
23, 24
1
Vpp
D
9.9
9.10
9.11
9.12
10
Input resistance
26
22
22
22
270
80
330
400
500
Ω
mVpp
kΩ
D
D
D
A
LO input voltage
LO input resistance
LO input bias voltage
1
2.8
3.0
3.2
V
2
nd IF Amplifier (Bit 55 = 0)
10.1
Input resistance
Pin 27 AC-grounded
28
3
kΩ
D
A
Maximum voltage
gain
AM/WB mode
(Bit 93 = 1)
10.2
10.3
28, 20
44
47
50
dB
AM/WB mode
(Bit 93 = 1)
Gain control range
44
dB
D
Maximum voltage
gain
FM mode (bit 92 = 1,
bit 93 = 0, bit 54 = 0)
23, 24
20
10.4
10.5
37
dB
V
D
A
DC output voltage
AC output voltage
Output impedance
20
20
20
3.1
3.4
3.7
Unmodulated signal,
82 dBµV at pin 1
(IF AGC active)
10.6
145
175
200
mVrms
A
D
10.7
Small signal
70
Ω
11
FM Demodulator Integrated Bandfilter, FM Mode (Bit 92 = 1, Bit 93 = 0), BW Setting 2nd IF Filter = 120 kHz
Deviation = ±75 kHz,
fmod = 1 kHz
11.1
11.2
11.3
AC output voltage
11
11
11
420
480
-2.0
0.4
540
-1.7
0.7
mVrms
A
A
A
Deviation = ±75 kHz,
fmod = 38 kHz
(reference: 1 kHz)
Stereo roll-off
-2.3
dB
Total harmonic
distortion
Deviation = ±75 kHz,
fmod = 1 kHz
THDFM
(S/N)FM
%
Dev. = ±22.5 kHz,
fmod = 1 kHz, 50 µs
de-emphase, signal
input at 450 kHz
Maximum signal-to-
noise ratio
11.4
11
62
65
dB
A
12
Soft Mute, FM Mode (Bit 92 = 1, Bit 93 = 0, Bit 80 = 0)
Bit 67 = 0,
V (pin 34) = 2 V
12.1
Mute gain
11
11
1
-31
-26
50
-28
-24
53
-26
-22
56
dB
dB
A
A
B
Bit 67 = 1,
V (pin 34) = 2 V
12.2
Mute gain
Bits 89 to 91 = 0,
Bits 68 to 70 = 1
12.3
13
Soft mute threshold
dBµV
AM Demodulator, AM Mode (Bit 92 = 0, Bit 93 = 1)
Modulation depth =
AC output voltage
13.1
11
350
400
0.6
450
2
mVrms
%
A
A
80%, fmod = 1 kHz
Modulation depth =
Total harmonic
13.2
80%, fmod = 1 kHz,
V(pin 35) = const.
11
THDAM
distortion
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
23
4837A–AUDR–10/04
Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C.
No.
Parameters
Test Conditions
Pin
Symbol
Min.
Typ.
Max.
Unit
Type*
Modulation depth =
80%, fmod = 1 kHz,
74 dBµV at pin 41
Maximum
signal-to-noise ratio
13.3
11
(S/N)AM
52
54
dB
A
14
MPX Output
14.1
DC output voltage
Bit 7 = 1
11
11
11
2.15
2.25
-70
60
2.4
-50
V
dB
Ω
A
A
D
Bit 7 = 1,
FM dev. = ±75 kHz,
fmod = 1 kHz
14.2
Mute gain
14.3
Output resistance
Small signal
15
Search Stop Detector, INT Output
LOW saturation
voltage
15.1
15.2
15.3
15.4
21
21
21
21
0
0.3
4.75
1
0.5
5.0
V
A
D
A
D
LOW output
resistance
kΩ
V
HIGH saturation
voltage
4.5
1.7
HIGH output
resistance
kΩ
16
Deviation Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0)
16.1
Offset voltage
FM dev. = ±0 kHz
31
20
150
2.5
mV
V
A
A
FM dev. = ±75 kHz,
fmod = 1 kHz
16.2
Output voltage
31
2.0
17
Field Strength Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0, Bit 89-91 = 0, Bit 80 = 0)
17.1
Offset voltage
No signal
9
0.4
0.75
3.0
1.1
3.3
V
V
A
A
Unmodulated signal
84 dBµV at pin 1
17.2
17.3
Output voltage
9
2.7
Field Strength Sensor, AM Mode (Bit 92 = 0, Bit 93 = 1, Bit 80 = 1)
Output voltage LOW
field strength
63 dBµV at pin 28
94 dBµV at pin 28
9
9
0.7
2.3
0.9
2.5
1.1
2.7
V
V
A
A
Output voltage HIGH
field strength
17.4
18
Multipath Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0)
Unmodulated signal,
Offset voltage
18.1
40
20
200
2.2
mV
V
A
A
60 dBµV at pin 1
AM modulation depth
= 60%,
fmod = 20 kHz,
18.2
Output voltage
40
1.4
1.8
60 dBµV at pin 1
19
Adjacent Channel Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0), Bit 4 = 0 (Default BW Setting)
19.1
Offset voltage
Unmodulated signal
10
100
300
1.0
mV
V
A
A
FM dev. = ±50 kHz,
fmod = 1 kHz
19.2
Output voltage
10
0.6
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
24
ATR4255
4837A–AUDR–10/04
ATR4255
Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C.
No.
Parameters
Test Conditions
Pin
Symbol
Min.
Typ.
Max.
Unit
Type*
Desired
FM dev. = ±75 kHz,
fmod = 1 kHz
undesired:
19.3
Output voltage
unmodulated
RF level
10
1.0
1.2
1.6
V
A
undesired/desired:
+30 dB frequency
offset = -150 kHz
20
3-wire Bus
17, 18,
19
20.1
Input voltage LOW
0.8
V
V
D
D
17, 18,
19
20.2
Input voltage HIGH
2.7
17, 18,
19
20.3
20.4
Leakage current
Clock frequency
V = 0 V, 5 V
10
µA
D
D
18
1.0
MHz
Period of CLK
HIGH
LOW
20.5
tH
tL
250
250
ns
ns
D
Rise time
EN, DATA, CLK
20.6
20.7
tr
tf
400
100
ns
ns
D
D
Fall time
EN, DATA, CLK
20.8
20.9
Set-up time
ts
100
250
0
ns
ns
ns
D
D
D
Hold time EN
tHEN
tHDA
20.10 Hold time DATA
21
Internally Generated Reference Voltages
Output voltage
21.1
21.2
21.3
21.4
12
29
27
39
5.5
5.7
3.0
3.0
3.0
6.0
V
V
V
V
A
D
D
D
Output voltage
Output voltage
Output voltage
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
25
4837A–AUDR–10/04
Diagrams
The following data was measured with the application board (see Figure 20).
In the measurement setup, a 50-Ωgenerator is terminated by 50 Ωand connected to the
antenna input by a 50-Ωseries resistor to achieve 75-Ωtermination 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.
Figure 12. FM Demodulator
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
+85°C
-40°C
MPX
THD
-40°C
80
+85°C
60
0
10
20
30
40
50
70
90
100
Frequency Deviation (kHz)
Note:
Integrated bandfilter 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
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
+85°C
-40°C
+25°C
0.0
0
20
40
60
80
100
AM Modulation Depth (%)
Note:
AM modulation frequency 20 kHz; generator level 40 dBµV.
26
ATR4255
4837A–AUDR–10/04
ATR4255
Figure 14. Multipath Sensor Frequency Response
5.0
4.5
90% at +85°C
90% at +25°C
90% at -40°C
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
60% at +85°C
60% at +25°C
60% at -40°C
100
1000
10000
100000
AM Modulation Frequency (Hz)
Note:
Generator level 40 dBµV.
Figure 15. Deviation Sensor
5
4
3
2
1
+85°C
-40°C
0
0
20000
40000
60000
80000
100000
Frequency Deviation (Hz)
Note:
FM modulation frequency: 1 kHz; BW setting 2nd IF filter = 120 kHz.
Figure 16. Deviation Sensor Frequency Response
1.0
0.5
0.0
100
1000
10000
100000
FM Modulation Frequency (Hz)
Note:
FM frequency deviation: 22.5 kHz.
27
4837A–AUDR–10/04
Figure 17. FM Input Level Sweep
10
5
0
4.5
4
Signal
-10
-20
-30
-40
-50
-60
-70
3.5
3
Sensor output
2.5
2
Noise
1.5
1
-20
0
20
40
60
80
100
120
Input Level (dBµV)
Note:
Soft mute threshold bits 68 and 69 = 0, bit 70 = 1; soft mute gain bit 67 = 1,
gain FM IF amplifier bit 89 = 1, bits 90 and 91 = 0.
Figure 18. Selectivity
20
10
4.5
4
Pdes/Pundes
0
3.5
3
-10
-20
-30
-40
-50
-60
-70
2.5
2
1.5
1
Adjacent
0.5
0
-250 -200
-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.
28
ATR4255
4837A–AUDR–10/04
ATR4255
Figure 19. Test Circuit
Test Point
1
2
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
330
VS
VS
4n7
270
2k2
3
VS
1k
100
4
P41
10n
5
600
6
100n
7
100p
P29
8
100n
10n
100n
100n
9
10
15p
2n2
10
11
12
13
14
15
16
17
18
19
20
21
22
10n
100n
200k
P41
P29
6p8
47p
100n
100n
P31
10k
5k6
22p
V
1n
P29
22n
10k
220n
10k
Bus
220n
U4256BM
Pin15
Pin1
Pin19
10n
10k
2k2
82p
VS
10n
29
4837A–AUDR–10/04
Figure 20. Application Circuit
30
ATR4255
4837A–AUDR–10/04
ATR4255
Ordering Information
Extended Type Number
Package
SSO44
SSO44
Remarks
ATR4255-ILSH
Tube, lead-free
ATR4255-ILQH
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
0.8
0.25
0.10
0.25
10.50
10.20
16.8
44
23
technical drawings
according to DIN
specifications
1
22
31
4837A–AUDR–10/04
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