T4258NFN [ATMEL]
Audio Single Chip Receiver, AM/FM, BICMOS, PDSO44, SSOP-44;
| 型号： | T4258NFN |
| 厂家： | 
ATMEL |
| 描述： | Audio Single Chip Receiver, AM/FM, BICMOS, PDSO44, SSOP-44 信息通信管理 光电二极管 |
| 文件： | 总38页 (文件大小：443K) |
| 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 (AM and FM)
• Automatic Alignment Possible
• Pin Compatible with U4255BM
AM/FM
Receiver IC
• World Tuner, US Weatherboard, J-band
Electrostatic sensitive device.
Observe precautions for handling.
T4258N
Description
The T4258N 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. 4566B–AUDR–02/04
Figure 1. Block Diagram
V3
IF1OUT MX2IN
IF1FMI
IF1AMI
33
MX2OB
MX1OA MX1OB
IF1REF
39
MX2OA
24
IF2IN V3P
44
43
38
29
28
27
30
26
23
AM
AM
OPLPF
Dem.
32
FM
41
IFAGCL
IFAGCH
AGC
MX1AMA
MX1AMB
36
35
AM
3
7
V3
AMAGC
AMVREG
AMPLPF
AGC
IF2OUT
FILADJ
6
8
Noise-
blanker
20
37
Automatic
Adjustment
AGC
MX1FMA
MX1FMB
GNDMX
1
FM
Multi-
path
MULTIP
MPX
2
4
40
11
Divider
2...10
OSCOUT
Offset
FM
Dem.
Soft
Mute
16
Adj.
Chan.
Stop
Divider
OSC
GNDOSC
OSCE
15
14
13
V3
Dev.
Ana.
Bandgap
Bus
INT
OSCB
22
10
21
INT
34
SMUTE
31
19
DATA METER
12 25 42
5
17 18
EN
9
DEV
V57
VS
GND
MX2LO ADJAC
FMAGC
CLK
2
T4258N
4566B–AUDR–02/04
T4258N
Pin Configuration
Figure 2. Pinning SSO44
1
2
3
4
5
6
44 MX1OB
43 MX1OA
MX1FMA
MX1FMB
MX1AMB
GNDMX
FMAGC
42
VS
41 MX1AMA
40 MULTIP
IF1REF
AMVREG
39
38 IF1FMI
AMAGC
AMPLPF
7
8
FILADJ
37
36
9
METER
IFAGCL
35
34
ADJAC 10
IFAGCH
SMUTE
MPX
V57
11
12
13
33 IF1AMI
OSCB
32
31
OPLPF
DEV
OSCE 14
GNDOSC
15
16
17
30 IF1OUT
V3
29
28
OSCOUT
EN
IF2IN
CLK 18
27 V3P
26
DATA 19
MX2IN
GND
IF2OUT 20
25
24
23
MX2OA
MX2OB
21
22
INT
MX2LO
3
4566B–AUDR–02/04
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
2
3
4
5
6
7
AM preamplifier AGC
AM AGC LP filter
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
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
2nd 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
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
IF1OUT
DEV
OPLPF
IF1AMI
SMUTE
IFAGCH
IFAGCL
FILADJ
IF1FMI
IF1REF
MULTIP
1st IF FM amplifier input
1st IF & MX1OUT reference, MX1AM A, MX1AM B
Multipath detection output
4
T4258N
4566B–AUDR–02/04
T4258N
Pin Description (Continued)
Pin
41
42
43
44
Symbol
MX1AMA
VS
Function
1st mixer AM input A
Supply voltage
1st mixer output A
1st mixer output B
MX1OA
MX1OB
Functional
Description
The T4258N 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 imple-
mented 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 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 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 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 ampli-
fier 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
4566B–AUDR–02/04
Table 1. Operating Mode
AM/FM/Weather Channel
Bit 93
Bit 92
Bit 63
Bit 62
Standby
FM
0
0
1
1
0
1
0
1
X
0
1
1
X
0
1
0
AM
Weather band
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 2. Test Mode
Mode
Bit 9
Normal operation
Test mode
0
1
VCO/Local Oscillator
Prescaler
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 frequency has a range of 70 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)
AGC off (default)
AGC on
Bit 30
0
1
Table 4. Local Oscillator Gain
Local Oscillator (VCO)
Low Gain
Bit 52
0
1
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 5 on
page 7.
6
T4258N
4566B–AUDR–02/04
T4258N
Table 5. Local Oscillator Prescaler (VCO/Buffer Divider)
Prescaler VCO
Prescaler Buffer
Bit 12
Bit 11
Bit 10
1
1.5
1.5
2
1
3
X
0
0
0
0
1
1
0
1
1
0
1
1.5
2
1
X
X
3
3
Note:
The U4256 FMOSCIN (pin 19) input frequency is limited to 160 MHz.
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 out-
puts 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
100 dBµV
Bit 65
Bit 64
0
0
1
1
0
1
0
1
97 dBµV
94 dBµV
91 dBµV
Figure 3. FM RF-AGC Bit 92
VS
Pin 42
Pin 5
C111
R115
PIN Diode
AGC
B92
7
4566B–AUDR–02/04
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
91 dBµV
Bit 65
Bit 64
0
0
1
1
0
1
0
1
94 dBµV
97 dBµV
100 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 8. (The AM prescaler is only active in AM mode).
Table 8. Divide Factor of the AM Prescaler
Divider (AM Prescaler)
Divide by 2
Bit 93
Bit 92
Bit 84
Bit 83
Bit 82
Bit 81
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
1
1
1
1
X
0
0
1
1
0
0
1
1
X
0
1
0
1
0
1
0
1
X
Divide by 3
Divide by 4
Divide by 5
Divide by 6
Divide by 7
Divide by 8
Divide by 9
Divide by 10
8
T4258N
4566B–AUDR–02/04
T4258N
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 Ωand
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
19 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
21 dB
23 dB
25 dB
27 dB
28 dB
29 dB
30 dB
Table 10. Temperature Coefficient Setting of FM IF Amplifier
Temperature Coefficient (TC) of the IF Amplifier
Bit 66
TKmin (TK 1)
TKmax (TK 2)
0
1
AM 1st IF Amplifier
2nd Mixer
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.
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.
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
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.
9
4566B–AUDR–02/04
Table 12. FM Bandwidth Mixer 2
Bit 61
Bit 60
FM Bandwidth Mixer 2
150 kHz
0
0
1
1
0
1
0
1
200 kHz
250 kHz
450 kHz
Note:
The bandwidth is also dependant on the values of the application circuit.
2nd IF Amplifier
In AM and WB mode, the input of the second IF amplifier is pin 28, is externally con-
nected 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 con-
nected 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
2
nd 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
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 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 14. 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.
10
T4258N
4566B–AUDR–02/04
T4258N
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
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.
Figure 4. Automatic IF Center Frequency Adjustment
Automatic
Center
frequency
FM-Demod
Pin 22
frequency
adjustment
10.25 MHz
Center
FM-
band filter
frequency
Bit 56...59
Bit 14...17
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. Addition-
ally, the center frequency of the band filter can be adjusted separately by means of
bit 14 to bit 17.
11
4566B–AUDR–02/04
Table 16. 2nd IF Center Frequency
Bit 59
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
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
Table 17. 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
12
T4258N
4566B–AUDR–02/04
T4258N
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
IF Bandwidth FM
IF Bandwidth WB
Bit 3
0
Bit 2
0
Bit 1
0
Bit 0
0
220
...
195
...
...
0
...
0
...
1
...
1
200
...
160
...
...
0
...
1
...
1
...
0
165
...
120
...
...
1
...
0
...
0
...
1
130
...
80
...
...
1
...
1
...
0
...
1
80
70
60
35
–
1
1
1
0
–
1
1
1
1
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 com-
pensate 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 (Pin 11)
B92
AM
AGC
Center freq.
+
IFAGCH (Pin 35)
V3P
(Pin 27)
Bit 53
Automatic
frequency
adjustment
13
4566B–AUDR–02/04
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
17 dB
21 dB
23 dB
0
0
1
1
0
1
0
1
Table 20. Demodulator Fine Adjustment
Demodulator Fine Adjustment
Fine tuning ON
Bit 53
0
1
Fine tuning OFF
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 the MPX output in this case. If the
input level falls below an adjustable threshold continuously, the output of the FM demod-
ulator 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 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
21).
Table 21. 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
14
T4258N
4566B–AUDR–02/04
T4258N
Table 22. Maximum Soft Mute
Maximum Value of Soft Mute
Bit 67
30 dB
26 dB
0
1
Figure 6. Soft Mute
+
FS (Pin9)
Pin 34
Bit 67
Gain FM-Demodulator
Bit 68..70
Pin 29
V3
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 23. MPX Output Mute
MPX Output
MPX out, pin 11 normal operation
Mute ON
Bit 7
0
1
Table 24. MPX Output Bandwidth
Bandwidth MPX Low-pass Filter
Bit 79
90 kHz
0
1
180 kHz
Receiving Condition
Analyzer
The T4258N implements several sensors that provide information about the receiving
condition of the selected station.
15
4566B–AUDR–02/04
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/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
Bit 21
Bit 20
Bit 19
Bit 18
0.0 dB
0.5 dB
1.0 dB
...
0
0
0
0
0
0
0
1
0
0
1
0
...
1
...
1
...
1
...
1
7.5 dB
Field Strength Selection 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
FM field strength (wide band)
Bit 80
Bit 13
0
0
1
1
0
1
0
1
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)
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 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 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
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
16
T4258N
4566B–AUDR–02/04
T4258N
Table 28. 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 29. 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)
Note:
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
4566B–AUDR–02/04
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 con-
necting 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)
Normal mode
Bit 6
0
1
Connection to ground
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
+
Pin 40
4k
18
T4258N
4566B–AUDR–02/04
T4258N
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 84
(see Table 32), the MPX signal may be muted and this situation (MPINT) can be signal-
ized 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
Active
Bit 8
0
1
Not active
Table 32. Sensitivity of the MNC
Sensitivity MNC (Threshold)
Bit 84
Bit 83
Bit 82
Bit 81
Off
0
0
0
0
0
0
0
1
Low
...
(-33 dB)
...
...
0
...
0
...
1
...
1
...
0
...
1
...
1
...
1
Normal (-14 dB)
...
...
1
...
1
...
1
...
1
High (-9 dB)
Note:
Valid in FM or WB mode (bit 92 = 1)
The Multipath interupt can also be switched on/off by bit 4.
Table 33. Multipath Interrupt (MPINT)
MPINT (Pin 21)
Off
Bit 4
0
1
On (MPINT active)
19
4566B–AUDR–02/04
AM Noise Blanker
The AM Noise Blanker of the T4258N 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
On
0
1
Table 35. Sensitivity of AM Noise Blanker
AM Noise Blanker Sensitivity
Bit 87
Bit 86
Bit 85
Low
.....
0
...
0
0
...
1
0
...
1
Normal
...
...
1
...
1
...
1
High
3-wire Bus Description
The register settings of the T4258N 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 avail-
able (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 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 the T4258N are compatible to the
addressing used in the U4256BM. That means both the T4258N and U4256BM can
be operated on the same 3-wire bus as shown in the application circuit (Figure 20 on
page 36).
20
T4258N
4566B–AUDR–02/04
T4258N
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
21
4566B–AUDR–02/04
Data Transfer
Table 36. Control Registers
A24_100
MSB
BYTE 3
LSB
MSB
BYTE 2
LSB
MSB
BYTE 1
LSB
BW/
MPX/
LPF/
Demodulator
AM/FM/WB
Gain FM
IF amplifier
AM OSC divider/multipath
sensitivity
Field
strength
ADDR.
0
Search
Width of window
Time window stop signal
1
0
B93
B92
B91
B90
B89
LSB
B88
B87
B86
B85
B84
B83
B82
B81
B80
B79
B78
B77
B76
B75
B74
B73
LSB
A24_101
MSB
BYTE 3
MSB
BYTE 2
LSB
MSB
BYTE 1
1st
Mixer
+
AGC
AM/
FM
IF1
AGC threshold ampl.
Soft
Gain
local
OSC
WB-
Demod-gain
Start soft mute
threshhold
IFOUT IF2IN Dem.
Pin 20 Pin 28 Contr.
ADDR.
mute Tk-FM IF
depth
BW 2nd mixer
Int. IF2 reference shift
AM/FM
AM/
FM
1
0
1
B72
B71
B70
B69
B68
B67
B66
B65
B64
B63
B62
B61
B60
LSB
B59
B58
B57
B56
B55
B54
B53
B52
A24_111
MSB
BYTE 3
LSB
MSB
BYTE 2
MSB
BYTE 1
Fieldst.
LSB
AGC
Local
OSC
Local OSC
ADDR.
Do not change (test mode bits)
Offset field strength (Pin 9)
Band-path filter
(Pin 9) prescaler (VCO-Buffer)
1
1
1
0
0
0
0
0
0
0
0
0
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
Mute Reset
Test
mode
Noise-
blanker
ADDR.
0
MP
B8
(Pin
11)
MP/
ADJ
1
0
0
B9
B7
B6
B5
LSB
B0
A8_101
MSB
BYTE 1
Band-path filter
Band width
ADDR.
MP INT
1
0
1
B4
B3
B2
B1
22
T4258N
4566B–AUDR–02/04
T4258N
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
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.
8.0
Typ.
Max.
10
Unit
Supply voltage range
Ambient temperature
pin 42
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
8.0
8.5
35
10
45
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
65
mA
A
2
VCO (Bit 52 = 0, Bit 30 = 1)
Frequency range
2.1
2.2
2.3
fVCO
70
260
4.0
MHz
V
D
A
C
DC bias voltage
13
16
3.4
3.7
Buffer output voltage
fosc = 120 MHz
250
mVrms
Buffer output
resistance
2.4
16
70
Ω
D
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
23
4566B–AUDR–02/04
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*
Buffer output DC
voltage
2.5
16
3.8
4.1
4.4
V
A
3
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
C
VS - 0.2
30
115
103
dBµV
Out-of-band signal
(110 MHz),
bit 64, 65 = 0
Maximum threshold
level
3.4
1
100
106
dBµV
B
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
C
C
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
C
C
A
B
A
A
Output voltage for
minimum gain
Bit 92 = 1
Maximum control
voltage
No signal
6
6.5
V
Maximum control
voltage
No signal
6
VS - 1.5
0.2
V
Minimum control
voltage
AGC active
Bits 64, 65 = 1
6
0.8
V
Maximum threshold
level
4.8
5
41
97
14
99
102
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
12
2.8
13
dB
V
C
A
D
D
D
D
2.5 kΩ (pin 41)
Input bias DC voltage
2.45
3.1
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
43, 44
12
15
20
mA
A
pins 43, 44
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
24
T4258N
4566B–AUDR–02/04
T4258N
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*
Conversion
conductance
3rd-order intercept
point
1, 2,
43, 44
6.2
7
mS
dBµV
dB
D
6.3
6.4
1, 2
IP3FMmix
NFFMmix
125
10
C
C
Generator resistance
200 Ω
Noise figure (DSB)
43, 44
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
43, 44
12
Vpp
D
D
6.8
7
Output resistance
1st IF FM Amplifier, FM Mode (Bit 92 = 1, Bit 93 = 0)
100
kΩ
7.1
Minimum voltage gain Bits 89, 90, 91 = 0
38, 30
19
21
23
dB
B
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
17
dB
dB
dB
D
D
D
Gain control range
Generator resistance
2.5 kΩ
Noise figure
NFIFAM
8.4
8.5
8.6
9
Input resistance
Input capacitance
Output resistance
2nd Mixer
33
33
30
10
kΩ
pF
Ω
D
D
D
Pin 39 AC-grounded
1
270
330
400
9.1
FM supply current
Bit 92 = 1, Bit 93 = 0
Bit 92 = 0, Bit 93 = 1
23, 24
23, 24
10
7
12
8
16
10
mA
mA
A
A
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
23, 24
100
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
25
4566B–AUDR–02/04
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*
Maximum differential
output voltage
AM/WB
9.7
VS = 8.5 V
23, 24
12
Vpp
D
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
1
LO input bias voltage
2nd IF Amplifier (Bit 55 = 0)
2.8
3.0
3.2
V
10.1
Input resistance
Pin 27 AC-grounded
28
3
kΩ
D
A
AM/WB mode
(Bit 93 = 1)
10.2
Voltage gain
28, 20
42
45
48
dB
Pin 28 1 mVrms
AM/WB mode
(Bit 93 = 1)
10.3
10.4
Gain control range
DC output voltage
47
dB
V
D
A
20
20
20
3.4
3.7
4.0
Unmodulated signal,
82 dBµV at pin 1
(IF AGC active)
Bit 93 = 1
10.5
AC output voltage
Output impedance
150
180
230
mVrms
A
D
10.6
Small signal
70
Ω
11
FM Demodulator Integrated Band-filter, 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
mVrms
B
D
A
Deviation = ±75 kHz,
Stereo roll-off
fmod = 38 kHz
dB
(reference: 1 kHz)
Total harmonic
distortion
Deviation = ±75 kHz,
THDFM
(S/N)FM
0.7
%
f
mod = 1 kHz
Dev. = ±22.5 kHz,
fmod = 1 kHz, 50 µs
Maximum signal-to-
noise ratio
11.4
11
65
dB
C
de-emphase, signal
input at 450 kHz
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
Mute gain
11
11
-28
-24
-26
-22
-24
-20
dB
dB
A
A
Bit 67 = 1,
V (pin 34) = 2 V
12.2
13
AM Demodulator, AM Mode (Bit 92 = 0, Bit 93 = 1)
Modulation depth =
AC output voltage
13.1
11
135
150
170
mVrms
A
30%, fmod = 1 kHz
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
26
T4258N
4566B–AUDR–02/04
T4258N
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
V(pin 35) = const.
Total harmonic
distortion
13.2
11
THDAM
0.6
2
%
A
Modulation depth =
30%, fmod = 1 kHz
74 dBµV at pin 41
Maximum
signal-to-noise ratio
13.3
11
(S/N)AM
54
dB
C
14
MPX Output
14.1
DC output voltage
Bit 7 = 1
11
11
11
2.1
2.3
-65
60
2.5
-50
V
dB
Ω
A
A
D
Bit 7 = 1,
FM dev. = ±75 kHz,
14.2
Mute gain
fmod = 1 kHz
14.3
Output resistance
Small signal
15
Search Stop Detector, INT Output
LOW saturation
voltage
15.1
15.2
15.3
21
21
0
0.5
V
A
D
LOW output
resistance
0.3
kΩ
HIGH saturation
voltage
21
21
4.5
4.8
1
5.25
V
A
D
HIGH output
resistance
kΩ
15.4
16
Deviation Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0)
FM dev. = ±0 kHz
16.1
Offset voltage
FM demodulator
adjusted
31
0.2
2.0
V
V
C
C
FM dev. = ±75 kHz,
16.2
Output voltage
31
1.7
2.5
fmod = 1 kHz
17
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
V
A
A
Unmodulated signal
100 dBµV at pin 33
17.2
17.3
Output voltage
9
2.8
3.4
3.9
Field Strength Sensor, AM Mode (Bit 92 = 0, Bit 93 = 1, Bit 80 = 1, Bit 18 to 21 = 0)
Output voltage LOW
field strength
60 dBµV at pin 28
94 dBµV at pin 28
9
9
1.5
3.0
1.8
3.3
2.1
3.6
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
0
200
2.4
mV
V
A
A
60 dBµV at pin 1
AM modulation depth
= 60%,
18.2
Output voltage
40
1.5
1.9
fmod = 20 kHz,
60 dBµV at pin 1
*) Type means: A =100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter
27
4566B–AUDR–02/04
Electrical Characteristics (Continued)
Test conditions (unless otherwise specified): VS = 8.5 V, Tamb = 25°C
No.
19
Parameters
Test Conditions
Pin
Symbol
Min.
Typ.
Max.
Unit
Type*
Adjacent Channel Sensor, FM Mode (Bit 92 = 1, Bit 93 = 0), Bit 4 = 0 (Default BW Setting)
19.1
Offset voltage
Output voltage
Unmodulated signal
AM mod. 10 %
10
10
200
0.3
1.9
mV
C
19.2
0.6
2.5
f
mod = 100 kHz
AM mod. 60 %
mod = 100 kHz
V
A
19.3
20
1.2
2.7
f
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
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
28
T4258N
4566B–AUDR–02/04
T4258N
Application Information
AM Prescaler (Divider)
Settings
The AM mixer is used for up conversion of the AM reception frequency to the IF fre-
quency. 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) set-
tings 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
fVCO
-----------------------------------
– fIF
frec
=
AM Prescaler
Table 37. AM Prescaler (Divider) Settings and Reception Frequencies
Minimum Reception Frequency Maximum Reception Frequency
Divider (AM Prescaler)
[MHz]
[MHz]
divide by 2
38.4
51.3
divide by 3
20.033
13.85
8.94
30.633
20.3
divide by 4
divide by 5
14.1
divide by 6
5.667
3.329
1.575
0.211
0
9.967
7.014
4.8
divide by 7
divide by 8
divide by 9
3.078
1.7
divide by 10
Note:
Prescaler VCO Divider = 1 in this example.
29
4566B–AUDR–02/04
Local Oscillator and AM Table 38 gives an example for the VCO prescaler divider and AM prescaler divider set-
tings and the reception frequencies.
Prescaler Settings
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
AM
Prescaler
VCO
Minimum Reception Maximum Reception Minimum VCO Maximum VCO
Band
FM
IF [MHz]
+10.7
-10.7
Frequency [MHz]
Frequency [MHz]
Frequency
Frequency
Prescaler
2
1.5
3
87.5
162.4
76
108
162.55
90
196.4
237.4
-
-
WB
227.55
195.9
227.775
237.9
JPN
-10.7
-
LW/MW
16m
2
+10.7
+10.7
+10.7
0.15
17.5
2.3
1.605
17.9
2.5
195.3
221.49
228.8
9
8
8
1
225.6
120m
2
208
211.2
U4256 N- and R-divider
Calculation
AM Mode
fVCO
N = ---------------------------------------------------------------------------------------------
VCO-divider × AM Prescaler × fstep
fVCO
---------------------------------------------------------------------------
– fIF
frec
=
VCO-divider × AM Prescaler
FM/WB Mode
fVCO
N = --------------------------------------------------
VCO-divider × fstep
fVCO
--------------------------------
– fIF
frec
=
VCO-divider
All Modes
fref
R = ----------
fstep
fref = reference oscillator frequency (e.g. 10.25 MHz)
f
f
f
VCO = VCO frequency
rec = reception frequency
step = step frequency (of the PLL)
30
T4258N
4566B–AUDR–02/04
T4258N
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
Integrated band-filter BW setting: 120 kHz (bits 0 to 2 = 0, bit 3 = 1);
1 kHz modulation frequency; 50 µs de-emphasis (THD)
1.0
0.9
0.8
0.7
0.6
1
0.9
0.8
0.7
0.6
+85°C
0.5
0.4
0.3
0.2
0.1
0.0
0.5
0.4
0.3
0.2
0.1
0
-40°C
MPX
THD
-40°C
+85°C
0
10
20
30
40
50
60
70
80
90
100
Frequency Deviation [kHz]
Figure 13. Multipath Sensor
AM modulation frequency 20 kHz; generator level 40 dBµV
5
4
+85°C
3
-40°C
2
1
0
0
10
20
30
40
50
60
70
80
90
100
AM Modulation Depth [%]
31
4566B–AUDR–02/04
Figure 14. Multipath Sensor Frequency Response
Generator level 40 dBµV
5.0
4.5
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]
Figure 15. Deviation Sensor
FM modulation frequency: 1 kHz; BW setting 2nd IF filter = 120 kHz;
demodulator fine tuning (bit 53 = 0)
5
4
+85°C
3
2
-40°C
1
0
10000
30000
50000
70000
90000
Frequency Deviation [Hz]
The center frequency of the integrated band filter has to adjusted
(e.g., IF center frequency = 462.50 kHz).
32
T4258N
4566B–AUDR–02/04
T4258N
Figure 16. Deviation Sensor Frequency Response
FM frequency deviation: 22.5 kHz
1.0
0.8
0.6
0.4
0.2
0.0
100
1000
10000
100000
FM Modulation Frequency (Hz)
Figure 17. FM Input Level Sweep
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
10
0
5
4.5
4
-10
-20
-30
-40
-50
-60
-70
3.5
3
2.5
2
1.5
1
0.5
-10
0
10 20
30 40
50
60
70 80
90 100 110 120
Input Level [dBµV]
33
4566B–AUDR–02/04
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
20
4.5
4
Pdes/Pundes
10
0
-10
-20
-30
-40
3.5
3
2.5
2
1.5
-50
1
Adjacent
-60
0.5
0
-70
-300 -250 -200 -150 -100 -50
0
50 100 150 200 250 300
Frequency Offset [kHz]
34
T4258N
4566B–AUDR–02/04
T4258N
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
50
10n
VS
50
10n
10n
VS
50
50
3
50
50
100n
10n
4
47n
5
6
47n
7
P29
8
10n
10n
10n
100n
100n
9
10
11
12
13
14
15
16
17
18
19
20
21
22
10n
200k
P29
1u
100n
P31
10n
50
50
10n
47n
50
50
10n
1k3
V
P29
47n
22n
330
Bus
47n
50
50
100n
Quarz-
50
50
oscillator
10.25 MHz
10n
10n
10k
VS
35
4566B–AUDR–02/04
Figure 20. Application Circuit
36
T4258N
4566B–AUDR–02/04
T4258N
Ordering Information
Extended Type Number
Package
SSO44
SSO44
Remarks
T4258N-ILS
Tube
T4258N-ILQ
Taped and reeled
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
37
4566B–AUDR–02/04
Atmel Corporation
Atmel Operations
2325 Orchard Parkway
San Jose, CA 95131, USA
Tel: 1(408) 441-0311
Fax: 1(408) 487-2600
Memory
RF/Automotive
Theresienstrasse 2
Postfach 3535
74025 Heilbronn, Germany
Tel: (49) 71-31-67-0
Fax: (49) 71-31-67-2340
2325 Orchard Parkway
San Jose, CA 95131, USA
Tel: 1(408) 441-0311
Fax: 1(408) 436-4314
Regional Headquarters
Microcontrollers
2325 Orchard Parkway
San Jose, CA 95131, USA
Tel: 1(408) 441-0311
Fax: 1(408) 436-4314
1150 East Cheyenne Mtn. Blvd.
Colorado Springs, CO 80906, USA
Tel: 1(719) 576-3300
Europe
Atmel Sarl
Route des Arsenaux 41
Case Postale 80
CH-1705 Fribourg
Switzerland
Tel: (41) 26-426-5555
Fax: (41) 26-426-5500
Fax: 1(719) 540-1759
Biometrics/Imaging/Hi-Rel MPU/
High Speed Converters/RF Datacom
Avenue de Rochepleine
La Chantrerie
BP 70602
44306 Nantes Cedex 3, France
Tel: (33) 2-40-18-18-18
Fax: (33) 2-40-18-19-60
BP 123
38521 Saint-Egreve Cedex, France
Tel: (33) 4-76-58-30-00
Fax: (33) 4-76-58-34-80
Asia
Room 1219
Chinachem Golden Plaza
77 Mody Road Tsimshatsui
East Kowloon
Hong Kong
Tel: (852) 2721-9778
Fax: (852) 2722-1369
ASIC/ASSP/Smart Cards
Zone Industrielle
13106 Rousset Cedex, France
Tel: (33) 4-42-53-60-00
Fax: (33) 4-42-53-60-01
1150 East Cheyenne Mtn. Blvd.
Colorado Springs, CO 80906, USA
Tel: 1(719) 576-3300
Japan
9F, Tonetsu Shinkawa Bldg.
1-24-8 Shinkawa
Chuo-ku, Tokyo 104-0033
Japan
Tel: (81) 3-3523-3551
Fax: (81) 3-3523-7581
Fax: 1(719) 540-1759
Scottish Enterprise Technology Park
Maxwell Building
East Kilbride G75 0QR, Scotland
Tel: (44) 1355-803-000
Fax: (44) 1355-242-743
Literature Requests
www.atmel.com/literature
Disclaimer: Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company’s standard
warranty which is detailed in Atmel’s Terms and Conditions located on the Company’s web site. The Company assumes no responsibility for any
errors which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without notice, and
does not make any commitment to update the information contained herein. No licenses to patents or other intellectual property of Atmel are
granted by the Company in connection with the sale of Atmel products, expressly or by implication. Atmel’s products are not authorized for use
as critical components in life support devices or systems.
© Atmel Corporation 2003. All rights reserved.
Atmel® and combinations thereof are the registered trademarks of Atmel Corporation or its subsidiaries.
Other terms and product names may be the trademarks of others.
Printed on recycled paper.
4566B–AUDR–02/04
相关型号：
©2020 ICPDF网 联系我们和版权申明