ICs for FM/AM Tuner AN7280S FM Front-end IC for Car Radio ■ Overview Unit : mm 5.4±0.3 7.7±0.3 0.15 0.65 0.3 12.6±0.3 0.4±0.25 0.1±0.1 1.27 ■ Features • High sensitivity, high S/N ratio • Good IM characteristics at strong input • Available for two loop AGC (keyed AGC) • Pre IF amp. gain variable • PIN diode driver (ADX) built-in 20 19 18 17 16 15 14 13 12 11 1 2 3 4 5 6 7 8 9 10 1.5±0.2 0.4 The AN7280S is an FM front-end IC designed for DTS except RF amp. of car radio. It features built-in local oscillation frequency buffer output, PIN diode driver for antenna damping and SSC (search stop control). 20-Lead SOP Package (SOP020-P-0300B) ■ Block Diagram GND 20 19 18 17 16 15 14 13 12 11 IF Amp. ADX Mixer VREG Buffer AGC Amp. Buffer SSC OSC 1 Det. 2 3 4 5 6 7 8 GND 9 10 VCC ICs for FM/AM Tuner AN7280S ■ Absolute Maximum Ratings (Ta=25˚C) Symbol Rating Supply Voltage Parameter VCC 9.2 Unit V Supply Current ICC 50 mA Power Dissipation PD 460 mW Operating Ambient Temperature Topr –40 ~ + 85 ˚C Storage Temperature Tstg –55 ~ + 150 ˚C ■ Recommended Operating Range (Ta=25˚C) Parameter Symbol Range Operating Supply Voltage Range VCC 6.8V ~ 9.2V ■ Electrical Characteristics (Ta=25˚C) Parameter Symbol S/N Ratio NOUT Local Oscillation Level VOSC min. Condition VCC= 8V, Vin=17dBµNo modulation However, S= output at 400Hz, 30%modulation VCC= 8V, fOSC= 108.7MHz Measured by Pin4, No signal input VCC= 8V, Vin= 51dBµ IF Output Level VOUT AGC Level (L) VAGC (L) VCC= 8V, Vin= 67dBµ AGC Level (H) VAGC (H) VCC= 8V, Vin= 53dBµ typ. max. 22 30 219 384 41 6 Unit dB 435 mV 58 82 mV 0.05 0.5 V 6.5 V ■ Characteristics Curve Level · Diagram Input/Output Characteristics Frequency Change 50 40 20 0 30 24.5 10 –20 13.5 0 0.01µF IFT IN IF–Amp. Mix. 080 MS3 IF OUT Vin (dBµV) 8.5 10 VCC=8V fin=1kHz Mod.=22.5kHz IF : AN7256 15 16.0 (min.) 20 AFOUT (dB) Level (dB) fm=1kHz IF : AN7256 400Hz HPF ON VCC=8V fin=98MHz Mod.=22.5kHz 43.5 (max.) –40 –60 5 Practical Sensitivity (S/N=30dB) Limiting Sensitivity 0 –5 –10 Residual Noise –15 330Ω –80 0 20 40 Vin (dBµV) 60 80 88 90 92 94 96 98 100 102 104 106 108 fin (MHz) ICs for FM/AM Tuner AN7280S Amp. Gain Adjustment with AGC AGC ON Level IF-Amp. Gain Adjustment 110 IF Amp. 13 f=10.7MHz Input Output 330Ω VCC= 8V fin = 18MHz Radj. is Piny external resistance (AGC Start Point Variable) 110 40 VCC = 8V fin = 98MHz No Adjustment Pin7 = HIGH 100 20 90 AGC ON Level (dBµV) 30 Vin (dBµV) Gain (dB) 100 Radj.= 0Ω 80 27dB 70 90 Pin9 = High 80 70 60 Radj.= ∞ 10 Pin9 = Low 60 50 0 0 1k 0 ∞ 10K 50 0 1 1.4 1.8 2.2 Pin7 Vcont Pin13 Adjusting Resistance (Ω) in 4 0 ∞ 10K Pin6 Adjusting Resistance (Ω) Supply Voltage Dependence Supply Voltage Change 1k (V) Supply Voltage Dependence No Input No Input 35 11 30 10 60 AGC ON Level 50 Vref Itot 3 15 20 Practical Sensitivity 10 Limiting Sensitivity 0 4 20 6 7 8 9 1 5 0 12 4 2 4 6 10 SSC ON Level 6 5 6 7 8 10 100 6 95 4 90 2 85 30 20 Practical Sensitivity (S/N=30dB) 10 0 –60 –40 –20 Limiting Sensitivity 0 20 40 Ta (˚C) 60 80 100 0 Vin (dBµV) 40 Total Gain (dB) Vin (dBµV) AGC ON Level (max. Gain) 0dB= 43.5dB –2 –6 65 –8 60 0 20 40 60 Ta (˚C) 0 80 100 Pin7=HIGH Pin6=GND Pin9=OPEN 75 70 –40 –20 12 Pin7=1V Pin6=GND Pin9=OPEN 80 –4 –10 11 105 60 50 10 AGC Start Point Temperature Characteristics Mixer+IF–Amp. VCC= 8V 8 9 VCC (V) Total Gain Temperature Characteristics IC for IF/DET is normal temperature 2 1 VCC (V) Temperature Characteristics 70 8 3 7 5 0 4 8 2 VCC (V) 80 Vt 10 0 10 5 9 55 Pin7=HIGH Pin6=OPEN Pin9=5V Pin7=HIGH Pin6=OPEN Pin9=OPEN –40 –20 0 20 40 60 Ta (˚C) 80 100 SSC ON Level (V) Itot (mA ) Vin (dBµV) 5 25 Vref (V) Local Oscillation Level 100 AGC OUT Vt (V) 110 ICs for FM/AM Tuner AN7280S IF Amp. Output Saturation Level Temperature Characteristics SSC ON Level Temperature Characteristics 5 5 VCC=8V SSC Input Pin 9 3 4 2 Pino Voltage (V) IF Amp. Output Saturation Level (dB) 4 1 0 –1 3 2 –2 –3 1 –4 –5 –40 –20 0 20 40 60 0 80 100 –40 –20 0 20 Ta (˚C) 40 60 80 100 Ta (˚C) ■ Application Circuit VCC 0.01µF KVC–1340 12pF 22Ω 330Ω Produced by MATSUSHITA IFT : ZIF–5EF021B 330Ω 19 18 56pF 3pF KVC–1340 14 Pass Mix Mix Con. OUT OUT IF IN AN7280S 13 To IF 12 11 IF Pass IF Gain Con. OUT Adj AGC Gain 2 Loop Pass OSC C OUT AGC Adj IN GND SSC 3 4 5 6 7 8 9 VCC 10 180kΩ + – 120kΩ VT 15 0.01µF 2 16 0.01µF B 1 RF IN 56pF 0.01µF E 12pF 100kΩ GND PIN D AGC 17 0.001µF 20 0.01µF 0.01µF 0.01µF 4pF 1kΩ C–F 470Ω 100kΩ 100kΩ MA551 3SK1311 100kΩ 18pF KVC–1340 0.001µF 18pF 15pF 0.001µF 82kΩ 820Ω ANT 1µF 5V 5V 0V Control Voltage At Search At Normal 0V ICs for FM/AM Tuner AN7280S ■ Pin Descriptions Pin Name Pin No. Description Equivalent Circuit Vref 1 OSC Emitter Local oscillation transistor emitter pin 2 1 2 OSC Base Local oscillation transistor base pin 3 OSC By-pass Vref by-pass pin for mixer,OSC buffer,OSC section 5V + – 3 Vref 4 OSC Buffer Output Pin for output OSC signal to pre-scaler 4 750Ω VCC .70µA 5 Level Detection Output AGC signal output pin for RF-Amp. secondary gate 6 AGC– Amp. Gain Adjustment Pin for adjusting AGC Amp. gain by external resistance 5 6 5.6kΩ 7 Control Signal Input 8 GND Pin for adjusting AGC-Amp. gain through input of control signal from IF section 1.5kΩ 1.5V Vref 9 SSC Input Pin for adjusting AGC-Amp. gain through input of control signal from microcomputer 70kΩ 39kΩ 10 VCC 9 7 ICs for FM/AM Tuner AN7280S ■ Pin Descriptions (Cont.) 11 Description Pin Name Pin No. IF-Amp. Equivalent Circuit IF-Amp. output pin 240Ω 11 3kΩ ZOUT.300Ω 12 IF-Amp. By-pass IF-Amp. by-pass pin 12 330Ω 14 14 IF-Amp. Input IF-Amp. input pin 13 IF-Amp. Gain Adjustment Pin for adjusting IF-Amp. gain by external resistance 13 12kΩ 15 15 Mix. Output Mixer output pin Mix. By-pass Mixer by-pass pin 340Ω 16 16 2.2kΩ 17 17 2.2kΩ 18 18 Mix. Input Mixer input pin VCC 19 20 ADX Output GND PIN diode driver output pin Determine maximum current to PIN diode by Pin19 external resistance value. Oscillator GND 19 ICs for FM/AM Tuner AN7280S ■ Operational Description • Loop AGC The AN7280S uses 2Loop AGC for AGC circuit. 2Loop AGC controls AGC output by using mixer output (IFT first side) signal and FM–IF control voltage (level meter output), which is a very favorable system for disturbance characteristics, etc. IFT RF–Amp. IF–Amp. Mixer FM–IF To N.C. Control Voltage Output AGC Amp. AGC Det. • AGC start point (Mixer input level at V AGC < 3V) changes in proportion to Pin6 external resistance (following R1) , Pin 7 applied voltage (Determine IF control voltage by R2, R3 resistance division) SSC ON/OFF · Variable width at R 1 28dB (however, V7 ≥3V, V9 = 0V) · Variable width at R7 40dB (however, R1= ∞, V9= 0V) · Variable width at R9 10dB (however, R1= ∞, V7 ≥3V) VREF AGC Output AGC–Adj 3 5 6 Vcont IN SSC IN 7 9 R2 about 4.7V R1 VAGC R3 from microcomputer FM–IF Control voltage • SSC Change AGC start point by microcomputer control signal at seek/reception time. Use at SSC ON ········V9 > 3.5V Use at SSC OFF········V9 < 1.5V * SSC is designed as precondition for switching operation at microcomputer control signal.