U4255BM-M ATMEL Corporation, U4255BM-M Datasheet

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U4255BM-M

Manufacturer Part Number
U4255BM-M
Description
AM-FM Receiver IC U4255BM-M
Manufacturer
ATMEL Corporation
Datasheet
Features
Electrostatic sensitive device.
Observe precautions for handling.
Description
The U4255BM-M 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.
Pin Configuration
Figure 1. Pinning SSO44
FM Double-conversion System
Integrated Second IF Filter with Software-controlled Bandwidth
Completely Integrated FM Demodulator
Soft Mute and Multipath Noise Cancellation
Receiving Condition Analyzer
AM Up/Down-conversion System
AM Preamplifier with AGC and Stereo Capability
3-wire Bus Controlled
Search Stop Signal Generation for AM and FM
Automatic Alignment Possible
AM/FM
Receiver IC
U4255BM-M
Preliminary
Rev. 4519C–AUDR–07/02
1

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U4255BM-M Summary of contents

Page 1

... Electrostatic sensitive device. Observe precautions for handling. Description The U4255BM 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 ...

Page 2

... SMUTE 35 IFAGCH 36 IFAGCL 37 FILADJ 38 IF1FMI 39 IF1REF 40 MULTIP 41 MX1AMA MX1OA 44 MX1OB U4255BM-M 2 Function st 1 mixer FM input mixer FM input mixer AM input B st Ground 1 mixer, preamplifier AGC FM preamplifier AGC AM control voltage AM preamplifier AGC AM AGC LP filter Field strength output Adjacent channel detection output Multiplex signal 5 ...

Page 3

... ADJAC V57 VS The U4255BM-M implements an AM up/down-conversion reception path from the RF input signal to the AM-demodulated audio frequency output signal, and for FM reception a double-conversion reception path from the RF input signal to the FM-demodulated multiplex signal (MPX). A VCO and an LO prescaler for AM are integrated to generate ...

Page 4

... Test Mode VCO FM RF-AGC U4255BM mode the FM mixer, the FM RF-AGC and the 1 activated. The bandwidth of the output tank at Pin 23, Pin 24 is increased and the input nd of the 2 IF amplifier can be switched between Pin 23, Pin 24 and Pin 28. The output of nd the 2 IF amplifier is fed to the integrated bandfilter and FM demodulator. The output of the FM demodulator is available at MPX output Pin 11 ...

Page 5

... The VCO frequency is used as LO frequency for the mixer. st The AM 1 mixer is used for up-conversion of the AM reception frequency to the 1 frequency. Therefore prescaler is implemented to generate the necessary LO frequency from the VCO frequency. The divide factor of the AM prescaler can be selected according to Table 5. U4255BM-M Bit ...

Page 6

... Amplifier Amplifier nd 2 Mixer U4255BM-M 6 Table 5. Divide Factor of the AM Prescaler Divider AM Prescaler Bit 93 Divide Divide Divide Divide Divide 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 ...

Page 7

... IF after the gain-controlled 2 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 U4255BM Mixer 2 150 kHz 200 kHz ...

Page 8

... Automatic IF Center Frequency Adjustment U4255BM-M 8 Table 12. Pin 20 Output Setting Pin output Multipath field strength 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 ...

Page 9

... Pin 20 (Bit55 = 1) can be used for this purpose. Table 15. Bandwidth of the Integrated FM Band Filter. IF Bandwidth 200 kHz 190 kHz 180 kHz 170 kHz 160 kHz 150 kHz 140 kHz 130 kHz 120 kHz 110 kHz 100 kHz 90 kHz 80 kHz 70 kHz 60 kHz 50 kHz U4255BM-M Bit 17 Bit 16 Bit ...

Page 10

... FM Demodulator U4255BM-M 10 For weather band reception, the gain of the FM demodulator is increased and can be adjusted by means of Bit 71, Bit 72 in order to increase the output voltage to compen- sate the low frequency deviation in weather band. An integrated demodulator fine adjustment allows automatic fine tuning of the demodu- lator center frequency to the average frequency of the received signal ...

Page 11

... FM mixer depends on the gain from FM mixer input to the field strength sensor. Table 18. Soft Mute Threshold Relative Soft Mute Threshold Soft mute OFF -18 dB - Table 19. Maximum Soft Mute Maximum Value of Soft Mute Figure 6. Soft Mute FS (Pin9) Pin 34 Bit 68..70 Pin 29 U4255BM-M Bit 70 Bit Bit 67 0 ...

Page 12

... Bandwidth MPX Lowpass Filter 90 kHz 180 kHz The U4255BM-M implements several sensors that provide information about the receiv- ing condition of the selected station. 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. ...

Page 13

... The deviation sensor is active in AM and FM/WB mode and measures the modulation of the signal implemented as a peak detector of the lowpass-filtered MPX signal (see Figure 7). The output voltage at Pin 31 is proportional to the frequency deviation in FM/WB or the modulation depth in AM respectively. Figure 7. Deviation Sensor MPX U4255BM-M Bit 78 Bit 77 Bit 76 Bit 75 0 ...

Page 14

... Adjacent Channel Sensor U4255BM-M 14 The adjacent channel sensor is active in FM mode only and measures the field strength outside the reception band. By setting the center frequency of the band filter of the adja- cent channel sensor below or above the 2 determined whether the disturbance signal is located above or below the reception fre- quency (see Table 28) ...

Page 15

... Table 30), the MPX signal may be muted and this situation (MPINT) can be signal- ized at Pin 21 (INT) according to Table 25. Muting of the MPX signal during multipath disturbances can be activated be setting Bit 8. Table 29. Multipath Noise Canceller Multipath Noise Canceller Active Not active U4255BM-M 300 kHz 450 kHz high low high high ...

Page 16

... Normal (-12 dB) High (-9 dB) The register settings of U4255BM-M are programmed by a 3-wire bus protocol. The bus protocol consists of separate commands. A defined number of bits is transmitted sequentially during each command. One command is used to program all bits of one register. The different registers avail- able (see Table 31) 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 ...

Page 17

... Figure 10. Pulse Diagram 8-bit command EN DATA LSB BYTE 1 CLK 24-bit command EN DATA LSB BYTE 1 CLK Figure 11. Bus Timing t R Enable Data Clock 4519C–AUDR–07/02 MSB MSB LSB BYTE HDA U4255BM-M MSB LSB BYTE 3 MSB HEN ...

Page 18

... A8_100 M S BYTE 1 B Adj. Tes MP Mut ADDR. channel t off e sensor A8_101 M S BYTE 1 B Optimi ADDR. Band width U4255BM MSB BYTE 2 B Sear OSC divider/multipath Width of window ch sensitivity B88 MSB BYTE 2 B Smu Tk- FM-AGC AM-AGC B67 B66 MSB BYTE 2 B used in test mode only ...

Page 19

... T stg Symbol R thJA Symbol Min -40 amb = 8 25°C. S amb Pin Symbol Stby VCO 13 = 120 MHz U4255BM-M Value 10 1000 150 -40 to +85 -50 to +150 Value 60 Typ. Max. 8.5 10 +85 Min. Typ. Max. 7.5 8 160 2.8 3.0 3.2 130 150 250 70 2.8 3 ...

Page 20

... Maximum output Differential voltage 5.9 Output resistance 6 FM Mixer (FM Mode (Bit Bit 6.1 Supply current Sum of current in Pins 43, 44 6.2 Conversion conductance *) Type means: A =100% tested 100% correlation tested Characterized on samples Design parameter U4255BM 8 25°C. S amb Pin Symbol Min -0.2 S ...

Page 21

... S amb Pin Symbol 1, 2 IP3 43 8 43, 44 43 23, 24 23, 24 26, 23 IP3 23 8 23, 24 U4255BM-M Min. Typ. Max. 120 FMmix 10 FMmix 1 100 0.039 min 0.044 max 270 330 400 5 270 330 400 IFAM 10 1 270 330 400 ...

Page 22

... Soft mute threshold Bits 89- Bits 68- Demodulator, AM Mode (Bit Bit 13.1 AC output voltage Modulation depth = 80%, f 13.2 Total harmonic Modulation depth = distortion 80%, f V(Pin 35) = const. *) Type means: A =100% tested 100% correlation tested Characterized on samples Design parameter U4255BM 8 25°C. S amb Pin Symbol 23 28, 20 23, 24 ...

Page 23

... Type means: A =100% tested 100% correlation tested Characterized on samples Design parameter 4519C–AUDR–07/ 25°C. S amb Pin Symbol = 1 kHz, 11 (S/N) mod kHz kHz kHz kHz U4255BM-M Min. Typ. Max 2.15 2.25 2.4 -70 - 0.5 0.3 4.5 4.75 5 150 1.7 2.0 2.5 0.4 0.75 1.1 2.7 3.0 3.3 0.7 0.9 1 ...

Page 24

... Hold time DATA 21 Internally Generated Reference Voltages 21.1 Output voltage 21.2 Output voltage 21.3 Output voltage 21.4 Output voltage *) Type means: A =100% tested 100% correlation tested Characterized on samples Design parameter U4255BM 8 25°C. S amb Pin Symbol = 1 kHz 10 17, 18, 19 17, 18, ...

Page 25

... Frequency deviation ( kHz ) Figure 13. Multipath Sensor AM modulation frequency 20 kHz; generator level 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 Modulation Depth (%) U4255BM-M 1 0.9 0.8 +85°C 0.7 0.6 -40°C 0.5 MPX 0.4 THD 0.3 -40°C 0.2 +85°C 0 100 +85° ...

Page 26

... U4255BM-M 26 Figure 14. Multipath Sensor Frequency Response Generator level 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 100 AM Modulation Frequency (Hz) Figure 15. Deviation Sensor FM modulation frequency: 1 kHz; BW setting 20000 90% at +85°C 90% at +25°C 90% at -40°C 60% at +85°C 60% at +25°C 60% at -40°C ...

Page 27

... FM modulation frequency (Hz) Figure 17. FM Input Level Sweep Soft mute threshold Bits 68 Bit soft mute gain Bit gain FM IF amplifier Bit Bits 90 -10 -20 -30 -40 -50 -60 -70 -20 0 U4255BM-M 1000 10000 100000 Signal Sensor output Noise 100 Input level (dBµV) 5 4 ...

Page 28

... U4255BM-M 28 Figure 18. Selectivity Integrated bandfilter BW setting: 120 kHz desired signal level adjusted S/N without undesired signal undesired signal level adjusted S -10 -20 -30 -40 -50 -60 -70 -250 -200 -150 -100 Frequency offset ( kHz ) 4.5 4 Pdes/Pundes 3.5 3 2.5 2 1.5 Adjacent 1 0 100 150 200 250 4519C– ...

Page 29

... P41 11 12 6p8 100n 13 47p 14 22p Bus 18 19 Pin19 20 10n 10k 21 22 10n U4255BM-M Test Point 270 2k2 P41 10n 40 39 100n 38 P29 37 100n 36 100n 35 100n 34 200k P29 33 100n 32 P31 31 30 P29 22n 29 10k 220n ...

Page 30

... Figure 20. Application Circuit U4255BM-M 30 4519C–AUDR–07/02 ...

Page 31

... Extended Type Number U4255BM-MFN U4255BM-MFNG3 Package Information Package SSO44 Dimensions in mm 0.3 0 4519C–AUDR–07/02 Package Remarks SSO44 Tube SSO44 Taped and reeled 18.05 17.80 2.35 0.25 0.10 16 U4255BM-M 9.15 8.65 7.50 7.30 0.25 10.50 10.20 technical drawings according to DIN specifications 31 ...

Page 32

... Atmel Corporation 2002. 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 ...

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