ICs for FM/AM Tuner AN7243S FM Front-end Circuit for Car Radio ■ Overview Unit : mm 0.3 10.1±0.3 1.5±0.2 temper- ature characteristics to RF amp. 14 13 12 11 10 9 8 0.15 0.65 0.4±0.25 1.24 0.1±0.1 ■ Features • High sensitivity · High S/N ratio • Good IM characteristics at strong input • Timing for AGC input level is variable. • Built-in pre-IF-Amp. having negative (positive) 1 2 3 4 5 6 7 1.27 The AN7243S is an FM front-end IC designed for DTS except RF amp. of car radio. It is built-in local oscillation frequency buffer output and PIN diode (ADX) driver for antenna damping. 4.2±0.3 6.5±0.3 14-Lead SOP Package (SOP014-P-0225) ■ Block Diagram GND 14 13 12 ADX Driver 11 10 9 8 Mix. IF-Amp. Buffer OSC 1 AGC & Det. Buffer 2 3 VCC 4 5 6 7 ICs for FM/AM Tuner AN7243S ■ Absolute Maximum Ratings (Ta=25˚C) Symbol Rating Supply Voltage Parameter VCC 9.6 Unit V Supply Current ICC 50 mA mW Power Dissipation PD 380 Operating Ambient Temperature Topr –40 ~ + 80 ˚C Storage Temperature Tstg –55 ~ + 125 ˚C ■ Recommended Operating Range (Ta=25˚C) Parameter Symbol Range Operating Supply Voltage Range VCC 6.5V ~ 9.6V ■ Electrical Characteristics (VCC = 8V, fin = 98MHz, 400Hz 30%Modulation, S1 : Open, Ta= 25˚C) Parameter Symbol S/N Ratio NOUT Local Oscillation Output Level VOSC Condition min. typ. max. Vin =17dBµ no conversion However, S= output at 400Hz 30%conversion fOSC =108.7MHz Measured by Pin4, No signal 22 30 160 250 330 Unit dB mV IF Output Level VOUT No modulation, Vin = 53dBµ 41 58 82 mV AGC Maximum Sensitivity SAGC Input level at VAGC = 3V 60 65 70 dBµ 0.02 0.5 V AGC Level (L) VAGC(L) Vin = 72dBµ AGC Level (H) VAGC(H) Vin = 58dBµ At S1ON, difference between input level at VAGC = 3V and AGC maximum sensitivity AGC Sensitivity Variable Range ADX Drive Current IX(max.) Vin = 72dBµ ADX Leak Current IX(leak) Vin = 63dBµ 6 6.6 V 18 dB 20 mA 1 µA ■ Characteristics Curve IF – Amp. Input/Output Characteristics Itot – VCC AGC Start Point Variable Axis 10 25 120 8 20 10 100 6 IAGC (V) IF OUT (dBµ) Itot (mA) 6.6V 15 0.01µF 5 IF IN 60 0 0 2 4 6 VCC (V) 8 10 12 40 60 AN7243S 0.01µF 80 IF IN (MHz) AGC Adj. R = ∞ AGC Adj. R = 0 4 80 2 IF OUT 330Ω 100 120 0 0 10 60 70 80 90 Vin (dBµ) 100 110 ICs for FM/AM Tuner AN7243S AGC Adj. R – AGC ON Level AGC Freq. Characteristics IADX – VADX 8 120 fOSC =108.7MHz 85 7 110 90 80 5 VADX (V) AGC ON LEVEL (dBµ) AGC Start Point (dBµ) 6 100 75 4 3 2 50Ω +75Ω AN7243S 70 103 60 88 92 96 100 104 0 108 10 100 0 ∞ 1000 5 10 15 20 25 30 35 IADX (mA) VAGC (H) Supply Voltage Characteristics OSC OUT – fOSC IF Amp. Saturation Level 16 130 AN7243S 3 14 400 OSC OUT C 12 110 Saturation Level (mVrms) 2 0.01µF SG VAGC (H) (V) VCC =8V Input 115dBµV from SG to Pin2 Pin3 OPEN C =3pF 120 C =10pF 10 8 6 300 200 4 100 100 2 90 50 0 AGC Adj R (Ω) Input Frequency fin (MHz) OSCOUT (dBµ) 1 AGC Adj. R 65 0 60 70 80 90 100 110 120 130 4 6 8 10 12 14 2 4 6 8 10 12 VCC (V) VCC (V) AGC ON Level Temperature Characteristics AGC ON Level VCC Dependence fOSC (MHz) 14 Mixer + IF Amp. Total Gain Temperature Characteristics 100 4 VCC =8V Total Gain =0dB at Ta =25˚C 3 90 90 2 85 AGC ON LEVEL R Adj = ∞ 0 –1 –2 70 R Adj = 0Ω 60 –4 75 70 AGC ON LEVEL –3 AGC ON LEVEL R Adj = ∞ 80 80 Vin (dBµ) Vin (dBµ) DTotal G (dB) 1 65 AGC ON LEVEL R Adj = 0Ω 60 –5 –6 –60 –40 –20 0 20 40 T (˚C) 60 80 100 50 –60 –40 –20 0 20 40 T (˚C) 60 80 100 2 4 6 8 10 VCC (V) 12 14 16 ICs for FM/AM Tuner AN7243S OSC Buff OUT VCC Dependence Input/Output Characteristics Example Limiting Sensitivity, Usable Sensitivity VCC Dependence IF : AN7257S (0.2061V) 0 –10 Vo (dBµ) Vin (dBµ) –20 OSC Buff OUT 110 30 VCC = 8V fin= 98MHz fm = 1kHz, 30% Mod. 400Hz HPF 30kHz LPF ON Vin (dBµ) 120 –30 20 –40 Usable Sensitivity –50 100 10 –60 90 2 4 6 8 10 12 14 Limiting Sensitivity –70 –10 0 16 20 40 VCC (V) 60 80 100 2 4 Vin (dBµ) IF : AN7257S 40 100 Usable Sensitivity 15 10 SUD1 (dBµ) Vin (dBµ) Vin (dBµ) 30 Usable Sensitivity 10 12 14 16 IM Characteristics (1) 110 20 20 8 VCC (V) Limiting Sensitivity, Usable Sensitivity, Frequency Characteristics Limiting Sensitivity, Usable Sensitivity, Temperature Characteristics 6 10 Limiting Sensitivity 90 fD= 98MHz, CW fUD1= 98MHz + ∆fUD 1kHz, 30% Mod. fUD2= 98MHz + 2∆fUD, CW 100dBµ Measure SUD1 level (Referred to Mix. In) which can obtain S/N= 30dB IF is AN7257S SD = 45dBµ SD = 35dBµ 80 Limiting Sensitivity 5 70 Mixer Sp 0 SUD1 0.01µF AN 7243S SUD2 –60 –40 –20 0 20 40 60 80 100 T (˚C) fD =98MHz, CW fUD1=98MHz±∆fUD 1kHz, 30%Mod. fUD2=98MHz±2∆fUD, CW 400HzHPF, 30kHz LPF ON IFT– CF Matching R 120 110 100 To IFT 330Ω To CF 470Ω Set SUD1 and SUD2 up with the same level, Measure SD level (Referred to Mix. In) which can obtain S/N (30dB). 80 70 60 50 40 50Ω Sp 30 SUD1 SUD2 20 10 Mixer SD (dBµ) 90 1F : 7256S 50Ω→75Ω AN 0.01µF 7243S To 1F ∆fUD = + 400Hz, + 800Hz ∆fUD = – 400Hz, + 800Hz 0 60 70 80 88 92 96 100 fin (MHz) IM Characteristics (2) 130 0 90 100 110 120 130 SUD1, SUD2 (dBµ) 104 108 –5 –4 –3 –2 –1 0 1 ∆fUD (MHz) 2 3 4 5 100pF Pin Diode 18pF VVC VC1 Note) VC1 ~ VC3 TOKO KV1340A–3 ANT. 1000pF 18pF 47kΩ 100kΩ 47kΩ 680Ω 100kΩ 470pF 3SK181 2.2µF 470pF 100kΩ 22Ω 470pF 510Ω 2kΩ 100kΩ VC2 1000pF 20kΩ VC3 5pF 1 14 39pF 3 12 OSC OUT 0.01µF 4 AN7243S 11 IFT 5 10 470Ω 1µF 6 9 AGC Adj. 7 8 Above application circuit and circuit constant indicate only an example. It is not assure the design as mass production set. 39pF 2 13 4pF 330Ω IFT : 7E7137A (MATSUSHITA) VCC (8V) IF OUT 0.01µF ICs for FM/AM Tuner AN7243S ■ Application Circuit ICs for FM/AM Tuner AN7243S ■ Pin Descriptions Pin No. Pin Name 1 Oscillation Emitter Typ. Waveform Description Equivalent Circuit Oscillation transistor's emitter pin 2 108.7MHz 1 2 Oscillation Base 3 VCC Oscillation transistor's base pin 108.7MHz DC 8V Main circuit VCC VCC 4 OSC Output Output oscillation signal to microcomputer through buffer. 108.7MHz 4 ≅70µA 6.6V 5 Output AGC signal according to Mix. output dimensions. AGC Output 5 ≅ 0V 6 AGC-Amp. Gain Adjustment DC 0.8V Adjust AGC-Amp. gain by external resistance. (Refer to P.275 AGC circuit.) 6 7 IF Amp. Output IF signal (10.7MHz) output pin Zout ≅ 330Ω 10.7MHz 8 IF Amp. By-pass DC 3.2V + – 7 IF amp. by-pass control 9 330Ω 8 9 IF Amp. Input 10.7MHz IF signal (10.7MHz) input pin 10 10 10.7MHz Convert RF signal to IF signal and output. Mix. Output 11 10.7MHz Note) Typical waveform frequency is the value when tuning receiving frequency to 98.0MHz. 11 ICs for FM/AM Tuner AN7243S ■ Pin Descriptions (Cont.) Pin No. Pin Name Typ. Waveform Equivalent Circuit Description VCC 7.2V 12 PIN Diode Driver Output Drive PIN diode for input attenuate of RF-Amp. Determine drive current by Pin12 external resistance. 12 .0V 2.2kΩ 13 Mix.Output 14 GND 13 Input signal from RF Amp. RF Main circuit GND Note) Typical waveform frequency is the value when tuning receiving frequency 98.0 MHz. ■ Supplementary Explanation • AGC AGC used at the AN7243S uses mixer output (IFT primary side) signal and controls AGC output. IFT RF Amp. Mixer IF – Amp. AGC Amp. 6 RAdj. (SAGC variable) – AGC Det. 12 + V5, V12 –VIN (RF) 8 VCC= 8V SAGC AGC Voltage (V) 7 6 5 4 Variable V5 3 2 V12 1 0 VIN (RF) (dBµ) 2.2kΩ