TDA7361 LOW VOLTAGE NBFM IF SYSTEM .. . .. OPERATION FROM 1.8V TO 9V LOW DRAIN CURRENT (4mA, Vs = 4V) HIGH SENSITIVITY (-3dB input limiting at 3µV) 8µV INPUT FOR 20dB S/N LOW EXTERNAL FAIR COUNT DIP16 ORDERING NUMBER : TDA7361 DESCRIPTION The TDA7361 is a low-power narrow band FM IF demodulation system operable to less than 2 V supply voltage. The device includes Oscillator, Mixer, Limiting Amplifier, Quadrature Discriminator, Op. Amp. Squelch, Scan Control and Mute Switch. The TDA7361 is designed for use in NBFM dual conversion communication equipments using a 455 KHz ceramic filter like cordless telephones, walkie-talkies, scan receivers, etc. SO16 ORDERING NUMBER : TDA7361D PIN CONNECTION June1993 1/8 TDA7361 Pin FUNCTION No Name 1-2 XTAL OSCILLATOR 3 MIXER OUT 4 SUPPLY VOLTAGE Must be well decoupled with a 100nF ceramic capacitor. 5 IF LIMITER INPUT Input pin of the six stages amplifier with about 50µV limiting sensitivity and 1.8kΩ input impedance. The if output is connected to the external quadrature coil (Pin 8) via an internal 10pF capacitor. 6-7 DECOUPLING 8 QUADRATURE COIL Connections for the Colpitts XTAL Oscillator. The XTAL may be replaced by an inductor (see Figure 5) if the application does not require high stability. The Mixer is double balanced to reduce spurious products. The output impedance is 1.8kW to match the input impedance of a 455kHz ceramic filter. Good quality 100nF ceramic capacitors and a suitable layou are important. A quadrature detector is uded to demodulate the 455kHz FM signal. The Q of the quad coil has direct effect on output level and distorsion (see Figure 6). For proper operation the voltage should be 100mVRMS. 9 AUDIO OUTPUT SIGNAL 10 OPERATIONAL AMPLIFIER INPUT 11 OPERATIONAL AMPLIFIER OUTPUT 12 SQUELCH INPUT The squelch trigger circuit with a low bias on the input (Pin 12) will force Pin 13 high ; and Pin 14 low. 13 SCAN CONTROL Pulling Pin 12 above mute threshold (0.65V) will force Pin 13 to an impedance of about 60kΩ to ground and Pin 14 will be an open circuit. 14 MUTE An hysteresis of about 50mV at Pin 12 will effectively prevent jitter. 15 GND Ground Connection 16 10.7MHz MIXER INPUT BLOCK DIAGRAM 2/8 Function The audio output signal is buffered by an internal emitter follower. Because of the low DC bias, the swing on the operational amplifier output is limited to 500mVRMS. This can be increased by adding a resistor from the operational amplifier input to ground. Input of the Wide-band Mixer. Normally used as 10MHz/455kHz converter, it can be also used with input frequencies up to 60MHz. TDA7361 ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit VS Supply Voltage 9 V VI RF Input Voltage (Pin 16) 1 VRMS V8 Detector Input Voltage 1 VPP - 0.5 to +5 V14 Mute Function Voltage Toper Operating Ambient Temperature Tstg Storage Temperature V 0 to 70 o - 65, + 150 o C C THERMAL DATA Symbol Rth j-amb Parameter Junction-ambient Thermal Resistance Max. SO16 DIP16 200 100 o Unit C/W ELECTRICAL CHARACTERISTICS T amb = 25oC, unless otherwise specified Symbol Parameter Test Conditions VS Supply Voltage Range IS Supply Current Squelch OFF Squelch ON VI Input Quieting Voltage S/N = 20dB Min. Typ. Max. Unit 1.8 4 9 V 3.8 4.7 mA mA 8 µV 3 µV 150 mVRMS 1.5 VDC VI Input Limiting Voltage - 3dB limiting VO Recovered Audio Output VI = 10mV V9 Detector Output Voltage R9 Detector Output Impedance 400 Ω Dtectot Center Frequency Slope 150 mV/kHz 55 dB 1.5 VDC 20 nA 50 mV 50 10 Ω MΩ GV Operational Amplifier Gain V11 Operational Amplifier Output Voltage IB Operational Amplifier Input Bias Current f = 10kHz, GV = V11 /V10 40 Pin 10 VT Trigger Hysteresis Rm Mute Switching Impedance Low High V13 Scan Voltage Pin 12 High (2V) Pin 12 Low (0V) 3.0 0 3.4 0.5 VDC VDC GC Mixer Converter Gain 30 dB RI Input Resistance 3.3 kΩ CI Input Capacitance 2.2 pF 3/8 TDA7361 Figure 2 : Test Circuit Figure 3 : Supply Current versus Supply Voltage 4/8 Figure 4 : FM IF Characteristics TDA7361 Figure 5 : Colpitts XTAL Oscillator Figure 6 : Effect of Quadrature Coil ”Q” on Audio Level and Distortion Figure 7 : Application Information (49MHz cordless receiver) 5/8 TDA7361 SO16 PACKAGE MECHANICAL DATA mm DIM. MIN. TYP. A a1 inch MAX. TYP. 1.75 0.1 MAX. 0.069 0.25 a2 0.004 0.009 1.6 0.063 b 0.35 0.46 0.014 0.018 b1 0.19 0.25 0.007 0.010 C 0.5 0.020 c1 45 (typ.) D 9.8 10 0.386 0.394 E 5.8 6.2 0.228 0.244 e 1.27 0.050 e3 8.89 0.350 F 3.8 4.0 0.150 0.157 L 0.4 1.27 0.016 0.050 M S 6/8 MIN. 0.62 0.024 8 (max.) TDA7361 DIP16 PACKAGE MECHANICAL DATA mm DIM. MIN. a1 0.51 B 0.77 TYP. inch MAX. MIN. TYP. MAX. 0.020 1.65 0.030 0.065 b 0.5 0.020 b1 0.25 0.010 D 20 0.787 E 8.5 0.335 e 2.54 0.100 e3 17.78 0.700 F 7.1 0.280 I 5.1 0.201 L Z 3.3 0.130 1.27 0.050 7/8 TDA7361 Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics 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 SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. 1994 SGS-THOMSON Microelectronics - All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands - Singapore - Spain - Sweden - Switzerland - Taiwan - Thaliand - United Kingdom - U.S.A. 8/8