T4258NFN [ATMEL]

Audio Single Chip Receiver, AM/FM, BICMOS, PDSO44, SSOP-44;
T4258NFN
型号: T4258NFN
厂家: ATMEL    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
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Features  
FM Double-conversion System  
Integrated Second IF Filter with Software-controlled Bandwidth  
Completely Integrated FM Demodulator  
Soft Mute and Multipath Noise Cancellation  
Receiving Condition Analyzer  
AM Up/Down-conversion System  
AM Preamplifier with AGC and Stereo Capability  
3-wire Bus Controlled  
Search Stop Signal Generation (AM and FM)  
Automatic Alignment Possible  
Pin Compatible with 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 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  
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 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 k. 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  
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 k(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  
pF  
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 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  
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 (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  
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  
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  
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 generator is terminated by 50 and connected to the  
antenna input by a 50 series resistor to achieve 75 termination at the antenna input.  
The generator level specified is the output voltage of this 50 generator at 50 load. If  
the application board is replaced by a 75 resistor, the voltage at this resistor is 6 dB  
below the specified voltage level of the 50 generator.  
Figure 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  
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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/  
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Tel: (33) 4-76-58-30-00  
Fax: (33) 4-76-58-34-80  
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Room 1219  
Chinachem Golden Plaza  
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Tel: (852) 2721-9778  
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Tel: (33) 4-42-53-60-00  
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Colorado Springs, CO 80906, USA  
Tel: 1(719) 576-3300  
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1-24-8 Shinkawa  
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Japan  
Tel: (81) 3-3523-3551  
Fax: (81) 3-3523-7581  
Fax: 1(719) 540-1759  
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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  

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