ICs for FM/AM Tuner AN7259S FM-IF Amplifier Circuit for Car Radio ■ Overview Unit : mm and separation control, etc. IF counter output and search output in channel selection signal as electronic tuning and with IF counter output ON/OFF circuit (SSC) • Adjustment of search band width and search output center frequency • Soft muting adjusting function 0.3 5.4±0.3 7.7±0.3 0.15 0.65 0.1±0.1 • 12.6±0.3 0.4±0.25 1.27 ■ Features • Quadrature detection system and fewer external parts • Good linearity of control voltage output used for AGC 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 AN7259S is an FM–IF/DET IC for car radio/car stereo and has each function necessary for electronictuner. 20-Lead SOP Package (SOP020-P-0300A) ■ Block Diagram 20 19 18 17 16 13 3 4 5 6 12 11 FM Det. Mute Amp. Search VCONT. 2 14 Counter SSC FM IF Amp. 1 15 7 8 GND 9 10 VCC ICs for FM/AM Tuner AN7259S ■ Absolute Maximum Ratings (Ta=25˚C) Symbol Rating Supply Voltage Parameter VCC 9.6 Unit V Supply Current ICC 23 mA mW Power Dissipation (Ta = 75˚C) PD 230 Operating Ambient Temperature Topr –30 ~ + 75 ˚C Storage Temperature Tstg –55 ~ + 125 ˚C AN7259S H2 ■ Recommended Operating Range (Ta=25˚C) Parameter Symbol Range Operating Supply Voltage Range VCC 7.3V ~ 9.6V ■ Electrical Characteristics (VCC = 8V, FM 1kHz 30%Modulation, Ta= 25˚C) Parameter Symbol Condition min. typ. max. Unit Limiting Sensitivity Vlim Input at VO = –3dB 26.5 29.5 32.5 Detection Output Level VO Vin = 70dBµ 150 175 210 mVrms dBµ Voffset Vin = 0dBµ, Pin9 –14 voltage –240 0 240 mV Signal Voltage (1) VSIG1 Vin = 0dBµ, Pin2 voltage 0.19 0.52 0.85 V Signal Voltage (2) VSIG2 VSIG4 –VSIG1 2.51 2.92 3.33 V Signal Voltage (3) VSIG3 VSIG5 –VSIG4 1.15 1.45 1.75 V Signal Voltage (4) VSIG4 Vin = 70dBµ, Pin2 voltage 2.92 3.4 3.98 V Signal Voltage (5) VSIG5 Vin = 100dBµ, Pin2 voltage 4.11 4.8 5.56 V BW Band width at Pin4 DC voltage = 2.5V, R = 30kΩ 145 165 185 kHz 15 19 23 mA AFC Offset Voltage Search Signal Band Width Supply Current Itot Vin = 0dBµ THD Mod. = 30%, Vin = 100dBµ 0.1 THD Mod. = 100%, Vin = 100dBµ 0.3 % S/N 63 dB 250 mVrms AMR Mod. = 30%, Vin = 100dBµ Pin16, 10.7MHz Output AM = 30% Mod., FM = 30% Mod. 50 dB Residual Noise Level Vin = 0dBµ –23 dB Control Voltage Adjusting Width Referred to Input IF Counter Output Level % dB 30 Reference Voltage 3.9 V AF Output Impedance 300 Ω ■ Characteristics Curve Output Voltage, AMR –Vin Control Voltage – Vin 20 5 Control Voltage Pin2 10 FM 1kHz, 30% Modulation 0 SD Output Pin4 4 –20 AM 1kHz, 30% Modulation –30 –40 –50 0% Modulation (Noise) –60 Vcont (dB) VO (dB) –10 3 Mute Voltage Pin3 2 1 –70 –80 0 10 20 30 40 50 60 70 80 90 100 110 120 Vin (dBµ) 0 0 10 20 30 40 50 60 70 80 90 100 110 120 Vin (dBµ) ICs for FM/AM Tuner AN7259S Signal Voltage (4) – Ta Signal Voltage (1) –Ta 2.0 4.0 Vin= 0dBµ 10V 9V 8V 7V 3.4 1.2 1.0 0.8 3.2 3.0 2.8 0.6 2.6 0.4 2.4 0.2 2.2 0 –40 –20 0 20 40 60 80 100 10V 9V 8V 7V 3.6 VSIG 4 (V) 1.6 1.4. VSIG 1 (V) 3.8 VCC VCC 1.8 Vin=70dBµ 2.0 –40 120 –20 0 20 4.8 140 4.6 130 4.4 120 BW (kHz) VSIG 5 (V) 150 4.2 4.0 3.8 VCC 3.6 3.2 60 80 100 10V 9V 8V 7V 110 100 90 70 60 R14 – 9 = 60kΩ 50 –40 120 –20 0 20 180 32 170 31 160 Vo (mV) Vlim (dBµ) 190 33 30 29 VCC 26 25 24 20 40 60 80 100 FM 1kHz 30% Modulation IF T Damp R=1kΩ 120 VCC 10V 9V 8V 7V 150 140 120 110 100 –40 120 –20 0 20 40 60 80 100 Ta (˚C) Ta (˚C) Supply Voltage Itot – Ta Reference Voltage Vref –Ta Vin= 0dBµ VCC VCC 22 4.0 Vref (V) 21 20 19 120 10V 9V 8V 7V 4.1 10V 9V 8V 7V 23 Itot (mA) 100 130 10V 9V 8V 7V 27 0 80 Output Voltage – Ta FM 1kHz 30% Modulation –20 60 200 34 25 –40 40 Ta (˚C) Limiting Sensitivity – Ta 28 120 VCC Ta (˚C) 35 100 80 10V 9V 8V 7V 3.4 40 80 Search Band Width – Ta Signal Voltage (5) – Ta 5.0 20 60 Ta (˚C) Ta (˚C) Vin=100dBµ 3.0 –40 –20 0 40 3.9 3.8 18 17 3.7 16 15 –40 –20 0 20 40 Ta (˚C) 60 80 100 120 –40 –20 0 20 40 Ta (˚C) 60 80 100 120 ICs for FM/AM Tuner AN7259S ■ Application Circuit IF COUNTER OUT SSC REF 330Ω 1.2kΩ 20 200kΩ 0.022µF 0.022µF FROM F.E. 19 18 17 0.22µF 200kΩ 16 + 15 820Ω 15pF 200kΩ 14 13 7 8 12 11 9 10 3 0.022µF 10kB + 4 5 6 + 0.022µF 2 2.2µF 1 22kΩ AN7259S 30kB 100kΩ 0.22µF VCC + 7.5kΩ VCONT. OUT 0.022µF AF OUT SEARCH 1000pF ■ Pin Descriptions • Control Signal Output Block The AN7259S has linear level meter output (control voltage on Pin2) whose dynamic range is about 60dB wider for change of the input. This control voltage is adjustable by the resistor R4 of Pin1. The adjustable range at R4= 0.8kΩ ~ 10kΩ is more than 30dB in conversion of the input. The polarity of the output voltage from Pin3 is reverse to that of the voltage to be output from Pin2. This output from Pin3 requires insertion of a capacitor (C5 = 4.7µF) since it is used for soft muting. The search output (right sketch) to be used for channel selection is obtainable on Pin4. The band width of this search output is adjustable. (Refer to Detection Block.) The search stop sensitivity is externally adjustable because the L level value varies with the input signal level. 200Ω 10kΩ 1 2 R4 10kB ~ 20kB 3 4 Search output R5 C4 C5 0.022µF C6 0.22 20kΩ µF R6 4.7 1.8 µF kΩ Control voltage output Search output Control voltage • Soft Mute Pin7 is the AF output pin, and the emitter follower output of≈300Ω in output impedance is obtainable on this pin. Pin6 is the soft mute adjusting pin to adjust the attenuation at the non-input mode. Soft mute here denotes muting by the level signal output from Pin3, and the soft mute response varies with the time constant of this voltage output. The r2 and C12 are related to the weak input S/N and the soft mute ON time, and with increase of the C12 value, the weak input S/N is proportionately improved, but the speed of response accordingly becomes lower. The r1, on the other hand, is related to the soft mute OFF time. Each value specified in the right sketch denotes a recommended value. 200Ω Increase of R4 30dB Input Frequency VCC 200Ω 2kΩ r1 r2 36kΩ GND 3 5 6 7 8 VREF + C12 VR R13 4.7µF To VCC C13 Soft mute adj. AF OUT ICs for FM/AM Tuner AN7259S • Detection Block VCC 43kΩ 21kΩ Pin11 and Pin12 constitutes a phase-shifting circuit of the QUAD detector by external circuit.The R7 is a coil damp resistor, and it exerts influences on the noise, THD, and output level. Its recommended value is 1.2kΩ ~ 1.8kΩ. Pin9 is the AFC voltage output pin,and according to the value of R10, the band width of the Pin4 search output can be adjusted. Pin13 is the center frequency adjusting pin of the Pin4 search output, and makes it possible to adjust the center frequency of the search output independently of the coil. VCC 9 C7 10 11 C9 12 13 14 VREF 15pF VR R8 200kΩ R7 820Ω 1.2 R10 kΩ C8 0.2µA C11 30kΩ R10 R9 VCC *An Example of Coil Adjusting Method In case of channel selection by IF counter output Adjust the coil so that the V (9, 14) at Vin= 0dBµbecomes equal to V (9, 14) at Vin= 100dBµ. In case of channel selection by search output Same as above. Thereafter,adjust the center frequency of the search output by the Pin13 VR. V (9, 14) ··· DC voltage between Pin9 and Pin14 Vin ··· Level of IF input Pin20 • Reference Voltage (VREF) + – The reference voltage (3.9V) is output from Pin14. Remember to bypass it by an external capacitor since this line is used as the power supply line to the limiter. Limiter VREF 8 14 19 • IF Counter Output SSC Pin16 is the IF counter output pin, and the output of about 300mVP– P is obtainable on this pin. Because of its high gain, the IF counter output line is separated on the pattern from the Pin20 (IF input) line in order to avoid oscillation trouble. Pin15 is the SSC pin to stop the IF counter, and according to the V SSC level, the IF counter operation changes as shown in the table below. The H level must be 4.2V or higher, and the L level must be 1V or lower. SSC is used for prevention of the bad influences of the IF counter output on the other blocks in the receiving mode. VSSC H L IF counter ON STOP VREF 20kΩ 15 200kΩ R2 200kΩ R3 16 C3 IF counter output 200pF SSC IN (from microcomputer) • IF Input Block Pin20 is the IF input pin, and the input impedance is set between this pin and Pin17 by R1. Usually a resistor of 330Ω is used as R1 to secure optimum matching with CF. Pin17 and Pin18 are the internal DC feedback pins, and the high frequency components are bypassed through C1 and C2. Pin19 is the GND pin dedicated to the limiter, and each GND of CF, C2 and C1 must be set close to Pin19. Externally short the GND of Pin19 with the GND of Pin8. 30kΩ 17 30kΩ 18 19 20 CF C2 C1 0.022µF 0.022µF R1 330Ω IF in