TDA7338D013TR

TDA7338 STEREO DECODER 1 FEATURES Figure 1. Package ■ INTEGRATED 19KHz SC NOTCH FILTERFOR PILOT CANCELLATION ■ ON CHIP FILTER FOR PILOT DETECTOR AND PLL ■ ADJUSTMENT FREE VOLTAGE CONTROLLED OSCILLATOR ■ AUTOMATIC PILOT DEPENDENT MONO/ STEREO SWITCHING Table 1. Order Codes Part Number NOISE BLANKING WITH PROGRAMMABLE THRESHOLD ■ HIGH CUT CONTROL AND STEREO BLEND INTEGRATED HIGH PASS FILTER FOR INTERFERENCE DETECTOR ■ LEVEL INPUT FOR ADDITIONAL SPIKE DETECTION ON FIELDSTRENGHT SIGNAL ■ VERY HIGH SUPPRESSION OF HARMONIC AND INTERFERENCE SIGNALS e t e ol d t c u SO20 SO20 in Tape & Reel t e l o DESCRIPTION The TDA7338 is a new concept of monolithic integrated stereo decoder with noise blanking for FM car radio applications. With the used BICMOS technique, the 19KHz Notch Filter, the PLL Filter and Phase Filter is realized on the chip with a Switched Capacitor concept. Avoiding the use of multipliers and non linear circuits a very high performance in terms of noise suppression and total harmonic distortion is ) (s o r P r P e TDA7338D013TR 2 u d o Package TDA7338D ■ Figure 2. reached.Block Diagram ) s ( ct SO20 s b O s b O April 2005 Rev. 9 1/12 TDA7338 Table 2. Absolute Maximum Ratings Symbol Parameter Value Unit 10.5 V 20 mA VCC DC Supply Voltage ICC Suply Current Tstg Storage Temperature -55 to 150 °C Tamb Operating AmbientTemperature -40 to 85 °C Value Unit 200 °C/W Table 3. Thermal Data Symbol Parameter Rth j-pins Thermal resistance junction-pins u d o Figure 3. Block Diagram and Test Circuit 40.2K r P e t e l o 1µF 70K PILOT IND. MONO 20 19 VR 18 VSB 17 LEVEL CONTROL O SC PHASE DETECTOR & PHASE FILTER PLL 2 VCO 12 IN R 40.2K 20K 11 AMP OUT R HIGH CUT CONTROL 19KHz SC NOTCH 20K NOISE BLANKER 10 OUT L AMP 40.2K IN L PEAK DETECTOR AMP 140KHz LPF 120KHz LPF PULSE FORMER TRIGGER THRESHOLD 4 REFERENCE CREF 4.7µF 6 1 LEVEL PROG CSB456F11 7 TBLANK 470pF VCO OFF 2/12 13 9 DIVIDERS VCO HCR 14 s ( t c 25KHz LPF 1nF HCL o r P DEMODULATOR o s b 15 du PILOT DETECTOR e t e l )- VHCC 16 AMP 80KHz LPF s b O 1nF MPX MPX IN ) s ( ct 8 3 PEAK GND 5 VS 47nF MUTE D95AU364C TDA7338 3 ELECTRICAL CHARACTERISTCS Table 4. (VCC = 9V; modulation frequency: 1KHz; de-emphasis time: T = 50µs; nominal MPX input voltage: VMPX = 1.5VPP; m 100% (75KHz deviation, fmod = 1KHz); RIN = 40.2kΩ, ROUT = 40.2kΩ; Tamb = 27°C; CREF = 4.7µF; unless otherwise specified) Symbol Parameter Test Condition Min. Typ. Max. Unit VCC Supply Voltage 7.5 9 10.2 V ICC Supply Current 5 10 15 mA VIN MPX Input Level (peak to peak) fm = 1KHz 1.5 V A.F. Output Voltage (mono) pin 10 and 11VIN = 0.5VRMS MONO; 1.5 V VORMS SVRR Supply Voltage Ripple Rejection VRIPPLE = 200mV; f = 1KHz VL/VR Difference of Output Voltage Levels pin 10 and 11- mono -0.8 Vo/Vi Gain V10/V20 8.5 RO Output Resistance pin 10 and 11 VO DC Output Voltage pin 10 and 11 α Channel Separation VR - VSB = -50mVDC Total Harmonic Distortion S+N -------------N Signal plus noise to noise ratio f = 20Hz to 16KHz; S = 2Vrms αM Muting Attenuation V7 and V8 < 0.6V VDC Mute DC Steps at pins 10, 11 Mute at pin 8 s ( t c u d o 9.5 Pr 4.5 30 45 s b O dB 0.8 4.2 e t e ol ) s ( ct 55 10 THD )- 40 0.02 10.5 50 4.8 dB dB Ω V dB 0.3 % 91 dB 100 dB 0 4 mV CARRIER AND HARMONIC SUPPRESSION AT THE OUTPUT α19 Pilot Signal f = 19KHz α38 Subcarrier f = 38KHz α57 Subcarrier f = 57KHz α76 Subcarrier f = 76KHz INTERMODULATION (note 1) e t e l 55 u d o Pr 70 dB 75 dB 62 dB 90 dB α2 fmod = 10KHz; fspur = 1KHz 65 dB α3 fmod = 13KHz; fspur = 1KHz 75 dB 70 dB 75 dB o s b TRAFFIC RADIO (note 2) α57 O Signal f = 57KHz SCA - SUBSIDIARY COMMUNICATIONS AUTHORIZATION (note 3) α67 Signal f = 67KHz ACI - ADJACENT CHANNEL INTERFERENCE (note4) α114 Signal f = 114KHz 95 dB α190 Signal f = 190KHz 84 dB MONO/ STEREO SWITCH VINTH Pilot Threshold Voltage for stereo "ON" 12 VINTH 7 20 28 mVRMS 14 21 mVRMS 0.2 0.5 V Pilot Threshold Voltage for stereo "OFF" VPI Pilot Indicator Saturation Voltage I = 1mA IPI Pilot Indicator Leakage Current V = 9V 10 µA V19 Control Voltage for forced mono α = < 3dB 0.8 V 3/12 TDA7338 Table 4. (VCC = 9V; modulation frequency: 1KHz; de-emphasis time: T = 50µs; nominal MPX input voltage: VMPX = 1.5VPP; m 100% (75KHz deviation, fmod = 1KHz); RIN = 40.2kΩ, ROUT = 40.2kΩ; Tamb = 27°C; CREF = 4.7µF; unless otherwise specified) STEREO BLEND V16-17 Control Voltage for Channel Separation α = 6dB; VR = 3.6V (note 5) V16-17 Control Voltage for Channel Separation -0.31 -0.27 -0.23 V α = 26dB; -85 -55 -30 mV µs HIGH CUT CONTROL τdeemp De-Emphasis Time Constant C13, C14 = 1nF; V15-17 = 50mV 43 50 57 R15-17 High Cut Control Resistance V15 - 17 = 50mV 43 50 57 R15-17 High Cut Control Resistance V15 - 17 = -0.5V (note 5) 115 150 185 fosc Oscillator Frequency with Murata CSB456F11 ∆f/f Capture and Holding Range VCO VVCO VCO OFF Pin 7 e t e ol NOISE INTERFACE DETECTOR (test condition: VSB > VR + 50mV) VTR Trigger Threshold (note 6) VPEAK = 1.3V; PROG = GND Trigger Threshold TS Suppression Pulse Duration Input Offset Current during suppression time VN1 VPEAK (pin 8) VN2 VPEAK (pin 8) VN3 VPEAK (pin 8) e t e ol VPEAK = 1.5V; PROG = GND 260 mV )- 340 mV s b O s ( t c CBLANK = 470pF 50 µs 10 pA VIN = 0mVRMS 0.7 1.0 1.3 V VIN = 50mVRMS; f = 150KHz 1.1 1.5 2 V VIN = 100mVRMS; f = 150KHz 1.7 2.3 2.8 V V O ( signal ) ( at1KHz ) α2 = ------------------------------------------------------------------ ; fs = (2 x 10KHz) - 19KHz V O ( spurious ) ( at1KHz ) V O ( signal ) ( at1KHz ) α3 = ------------------------------------------------------------------ ; fs = (3 x 13KHz) - 38KHz V O ( spurious ) ( at1KHz ) measured with : 91% mono signal; 9% pilot signal; fm=10KHz or 13KHz 2) TRAFFIC RADIO (V.F.) suppression V O ( signal ) ( at1KHz ) α57 ( V.W.F. ) = -------------------------------------------------------------------------------------------V O ( spurious ) ( at1KHz ± 23KHz ) measured with : 91% stereo signal; 9% pilot signal; fm=1KHz; 5% subcarrier (f = 57KHz, fm = 23Hz AM, m = 60%) 4/12 V mV 3.1 NOTES TO THE CHARACTERISTICS 1) INTERMODULATION SUPPRESSION s b O % 250 u d o Pr 0.6 KHz mV VPEAK = 1.5V; PROG = OPEN/VDD IOS Pr KΩ 180 VPEAK = 1.3V; PROG = OPEN/VDD VTR u d o 456 ±1 ) s ( ct KΩ TDA7338 3. SCA (SUBSIDIARY COMMUNICATIONS AUTHORIZATION) V O ( signal ) ( at1KHz ) α67 = ------------------------------------------------------------------ ; fs = (2 x 38KHz) - 67KHz V O ( spurious ) ( at9KHz ) measured with : 81% mono signal; 9% pilot signal; fm=1KHz; 10% SCA - subcarrier (fs = 67KHz, unmodulated) 4. ACI (ADJACENT CHANNEL INTERFERENCE) V O ( signal ) ( at1KHz ) α114 = -----------------------------------------------------------------V O ( spurious ) ( at4KHz ) ; fs = 110KHz - (3 x 38KHz) V O ( signal ) ( at1KHz ) α190 = -----------------------------------------------------------------V O ( spurious ) ( at4KHz ) ; fs = 186KHz - (5 x 38KHz) measured with : 90% mono signal; 9% pilot signal; fm=1KHz; 1% spurious signal (fs = 110KHz or 186KHz, unmodulated) ) s ( ct u d o r P e 5. Control range typ 11% of VR (see figure 5 and figure 6) 6. MEASUREMENT OF TRIGGER THRESHOLDS t e l o All thresholds are measured by using a pulse with TR = 2µs, THIGH = 2µs, and TF = 10µs. The repetition rate must not increase the PEAK voltage. Figure 4. ) (s Vin t c u VTR DC e t e l s b O d o r P D95AU365 4 TR o s FUNCTIONAL DESCRIPTION b O THIGH TF Time 4.1 Signal Path The TDA7338 Stereodecoder contains all necessary functions for processing the MPX signal. Due to the external input resistance (Pin 20) the circuit can be adapted to different MPX input levels. Behind a 80kHz lowpass filter the adjustment free PLL for the pilot Tone is placed. The only external component needed for the PLL is the ceramic resonator for the oscillator which runs at 456kHz. The pilot detector output is designed as an open collector output, therefore an external pullup resistor is needed. To force the decoder to "MONO" Pin 19 has to be clamped to a voltage below 0.8V. The voltage level (signal strength from the IF part) applied to Pin 15 (VHCC) allows to control the time constant of the deemphasis (nom. = 50µs, see fig. 5). If the RF-signal is weak, the corner frequency is reduced down to 1kHz to improve the signal to noise ratio. 5/12 TDA7338 Figure 5. High Cut Control Figure 6. Stereo Blend D95AU367 SEP (dB) D95AU366 fc (KHz) 50 3.18 (=50µs) 40 VR=3.6V VR=3.6V 30 2 20 1 ) s ( ct 10 0 -0.5 -0.4 -0.3 -0.2 -0.1 0 0.0 VHCC-VR(V) -0.40 -0.32 -0.24 -0.16 u d o -0.08 VSB-VR(V) r P e Furthermore the conditions of the stereo separation (see fig.6) can be controlled through the signal applied to Pin 16 (VSB). Both signal levels (VSB and VHCC) are referred to Pin 17 (VR), with the characteristic that the control range is 11% of VR. By modifying the feedback resistor value of the output stages (Pin 9 - 10, Pin 11 - 12) the total gain of the stereodecoder can be modified. t e l o Pin 7 and Pin 8 have an additional function. By pulling them to ground the VCO-OFF (Pin 7) and the MUTE (Pin 8) function are activated. The MUTE signal disconnects the MPX-signal from the circuit, while in combination with VCO-OFF also the output buffers are disconnected from the circuit. In this mode the output buffers can be used for AM-stereo, cassette play back and other purposes. ) (s s b O 4.2 AM Mono Mode By selecting VCO-OFF (Pin 7 to GND) the VCO is switched off and the SB and HCC are disabled. The deemphasis time constant is changed to 40µs (fc = 4KHz). t c u d o r P 4.3 DESCRIPTION OF THE NOISE BLANKER In the normal automotive environment the MPX signal is disturbed by ignition spikes, motors and high frequency switches etc. e t e ol The aim of the noise blanker part is to cancel the influence of the spikes produced by these components. Therefore the output of the stereodecoder is switched off for a time of 40µs (average spike duration). s b O In a first stage the spikes must be detected but to avoid a wrong triggering on high frequency noise a complex trigger control is implemented. Behind the trigger stage a pulse former generates the 40ms "blanking" pulse. This duration of 40µs can be varied by changing the capacitor at pin 7. 4.3.1 Trigger Path The incoming MPX signal is highpass-filtered, amplified and rectified (block RECT-PEAK). The second order highpass-filter has a corner-frequency of 140KHz. The rectifier signal, RECT, is used to generate by peak-rectification a signal called PEAK, which is available at the PEAK pin 8. Also noise with a frequency >100KHz increases the PEAK voltage. The value of the PEAK voltage influences the trigger threshold voltage Vth (block ATC). The higher the noise level the higher the threshold. Both signals, RECT and PEAK+Vth are fed to a comparator (block PEAK-COMP) which outputs a sawtooth-shaped waveform at the TBLANK pin 7. A second comparator (block BLANK-COMP) forms the internal blanking duration of 40µs. The noise blanker is supplied by his own biasing circuit (block BIASMONO) to avoid any cross talk to the signal path (block BIAS-MONO). 6/12 TDA7338 4.3.2 Noise Controlled Threshold Adjustment (ATC) The behaviour of the noise controlled threshold adjustment is shown in fig. 8. It can be influenced lightly by adding a resistor in parallel to the PEAK capacitor at Pin 8 either to GND or VDD. A resistor to GND will decrease the threshold whereas a resistor to VDD will increase it. But it is recommended to choose one of the internal thresholds by use of the PROG pin (see table 5) 4.3.3 Automatic Threshold Control by the Stereoblend voltage (ATC-SB) Besides the noise controlled threshold adjustment there is an additional possibility for influencing the trigger. It is controlled by the difference between Vsb and Vr, similar to the Stereoblend. The reason for implementing such a second control will be explained in the following: The point where the MPX signal starts to become noisy is fixed by the RF part. Therefore also the starting point of the normal noise controlled trigger adjustment is fixed (fig.9). But in some cases the behaviour of the noiseblanker can be improved by increasing the threshold even in a region of higher fieldstrength, for the MPX signal often shows distortion in this range, which leads to an undesired triggering. ) s ( ct Because of the overlap of this range and the range of the stereo/mono transition it can be controlled by Vsb and Vr. This threshold increase is programmable (see fig. 9). u d o 4.3.4 Blend Mode Another possibility to avoid a disturbing triggering on modulation is to use the spikes on the fieldstrength signal (LEVEL pin). But in the range of higher fieldstrength the signal saturates and no more spike detection is possible. For this reason the TDA7338 offers the "BLEND MODE". When "BLEND MODE" is activated a smooth transition between the LEVEL- and the MPX-signal is used to detect the spikes either on LEVEL or on MPX. r P e t e l o s b O In the lower fieldstrength range mainly the LEVEL-signal is used whereas in the higher range mainly the MPX is used. ) (s This switching is controlled also by the normal Stereoblend signal to avoid additional pins. "BLEND MODE OFF" is activated by connecting the LEVEL pin to GND (LEVEL must be also connected to GND if not used). t c u Figure 7. Block Diagram of the Noise Blanker d 80KHz LP e t e ol bs MPX IN O LEVEL o r P 140KHz HP LEFT SIGNAL PATH RECT AMP to OUTPUTS RIGHT BUF PEAK AUTOMATIC THRESHOLD CONTROL BLANK COMP PEAK COMP REF. + + ATC 120KHz HP PEAK+VTH 40µs 2V VS THRESHOLD L/H RECT-PEAK PROG BLEND CONTROL BLEND ON/OFF 0.1V ADDITIONAL THRESHOLD CONTROL on/off + - ADDITIONAL THRESHOLD CONTROL (ATC-SB) 7V VR VSB CPEAK 47nF CBLANK 330pF D95AU368 7/12 TDA7338 Table 5. Programming of the Noiseblanker PIN 1 (PROG) Trigger Threshold Peak Voltage Control By Fieldstrength GND LOW ON OPEN HIGH ON VDD HIGH OFF Figure 8. Trigger Threshold vs. VPEAK VTH ) s ( ct u d o 300mV r P e t e l o 180mV MIN. TRIG. THRESHOLD NOISE ADJUSTED TRIG. THRESHOLD 100mV 60mV 0.9V )- D95AU369 s b O 1.5V VPEAK(V) s ( t c Figure 9. Behaviour of the Field Strength Controlled Threshold Adiustment u d o VPEAK r P e MONO STEREO t e l o ≈3V s b O 2.2V TRIG. THRESHOLD 0.9V NOISE noisy signal 8/12 ATC_SB OFF (PROG=VS) D95AU370 good signal E' TDA7338 Figure 10. Application Diagram 1nF 2) 68K 1) SIGNAL STRENGTH 14 15 47K 13 47K 1) 16 1nF 2) 47K 12 VR IN R 17 PILOT_IND 47K 18 19 TDA7338 100K MONO 68K 470nF 56pF 3) 11 OUT 6 LEVEL (SIGNAL STRENGTH) 9 IN L 47K 33K 20 10 7 8 r P e 4) 680pF 1 100K VCO_OFF (FM ENABLE) 100K 2 4 456KHz 330pF 5 10µF has to be adapted to the signal strength for deemphasis = 50µs not absolutely necessary roll off: to be adjusted to the tuner part let 3 o s b 100nF VS 9V 1) 2) 3) 4) u d o 56pF 3) 10K MPX ) s ( ct 47nF OUT 10K MUTE 10K D95AU371A O ) s ( t c u d o r P e t e l o s b O 9/12 TDA7338 Figure 11. SO20 Mechanical Data & Package Dimensions mm inch DIM. MIN. TYP. MAX. MIN. TYP. MAX. A 2.35 2.65 0.093 0.104 A1 0.10 0.30 0.004 0.012 B 0.33 0.51 0.013 0.200 C 0.23 0.32 0.009 0.013 D (1) 12.60 13.00 0.496 0.512 E 7.40 7.60 0.291 0.299 e 1.27 10.0 10.65 0.394 0.419 h 0.25 0.75 0.010 0.030 L 0.40 1.27 0.016 0.050 0˚ (min.), 8˚ (max.) ddd ) s ( ct u d o 0.050 H k OUTLINE AND MECHANICAL DATA 0.10 0.004 ) (s (1) “D” dimension does not include mold flash, protusions or gate burrs. Mold flash, protusions or gate burrs shall not exceed 0.15mm per side. r P e s b O t e l o SO20 t c u d e t e ol o r P s b O 0016022 D 10/12 TDA7338 5 REVISION HISTORY Table 6. Revision History Date Revision Description of Changes October 2004 8 First Issue in EDOCS April 2005 9 Changed the Style-cheet in compliance to the new “Corporate Technical Pubblications Design Guide. Deleted DIP20 Package ) s ( ct u d o r P e t e l o ) (s s b O t c u d e t e ol o r P s b O 11/12 TDA7338 ) s ( ct u d o r P e t e l o ) (s s b O t c u d e t e ol o r P s b O Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics. 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