Ordering number : ENN*7931 LA1845NV Monolithic Linear IC Single-Chip Home Stereo IC The LA1845NV is designed for use in mini systems and is a single-chip tuner IC that provides electronic tuning functions using SD/IF-count technique. It incorporates a pilot canceler and an adjustment-free MUX VCO circuit, thus allows additional parts to be reduced. Functions • AM : RF amplifier, mixer, oscillator, IF amplifier, detector, AGC, SD, oscillator buffer, IF buffer, stereo IF output, AGC time constant switch • FM IF : IF amplifier, quadrature detector, S-meter, SD (signal detection), S-curve detection, IF buffer output • MPX : PLL stereo decoder, stereo display, forced monaural, VCO stop, audio muting, adjacent channel interference rejection function, pilot canceler Features • Integrated MPX VCO (ceramic resonators are no longer required.) • Built-in adjacent channel interference rejection function (114kHz, 190kHz) • Supports both SD and IF-count techniques • Both FM SD sensitivity and bandwidth can be set • Pilot canceler built in. Maximum Ratings at Ta = 25°C Parameter Symbol Maximum Power Supply Voltage VCC max Allowable Power Consumption Pd max Conditions Ratings Unit 6 V Ta = 80°C with board 360 114.3mm×76.1mm×1.6mm material : mW Glass epoxy resin Operating Temperature Topr -20 to +80 °C Storage Temperature Tstg -40 to +125 °C Operating Conditions at Ta = 25°C Parameter Symbol Recommended Supply Voltage VCC Operating Supply Voltage Range VCC op Conditions Ta = 80°C Ratings Unit 5 V 4.3 to 5.5 V 91004 JO IM No.7931-1/10 LA1845NV Electrical Characteristics • Operating Characteristics at VCC = 8V, in the specified test circuit. FM Mono Characteristics at fc = 10.7MHz, Vi = 100dBµ, fm = 1kHz, Modulation = 75kHz Parameter Conditions Ratings min typ Unit max Current Drain With no input signal Demodulator Output 100dBµ, 100% modulation, fm = 1kHz 20 30 40 mA 230 360 460 mVrms Total Harmonic Distortion 100dBµ, 100% modulation, fm = 1kHz 0.35 1.5 % Signal-to-Noise Ratio 100dBµ, 100% modulation, fm = 1kHz 73 80 dB AM Rejection Ratio 100dBµ, AM = 30% modulation, fm = 1kHz 47 65 dB 3dB Sensitivity 100dBµ, 100% modulation, fm = 1kHz Output reference, 32 -3dB input SD Sensitivity 0% modulation IF Counter Buffer Output 100dBµ Mute Attenuation 100dBµ, 100% modulation, fm = 1kHz 40 dBµ 38 47 56 dBµ 200 275 400 mVrms 76 dB FM Stereo Characteristics at fc = 10.7MHz, Vi = 100dBµ, L+R = 90%, Pilot = 10%, fm = 1kHz Parameter Conditions Ratings min typ Unit max Separation L+R = 90%, Pilot = 10%, fm = 1kHz 30 42 Stereo On Level Pilot input 1.5 3.5 5.5 % Total Harmonic Distortion Pilot input 0.45 1.5 % Adjacent Channel Rejection Ratio 1 fs = 113kHz, VS = 90%, Pilot = 10% ; The left-right modulation, demodulated output Adjacent Channel Rejection Ratio 2 fs = 189kHz, VS = 90%, Pilot = 10% ; The left-right modulation, demodulated output Carrier Leak L+R = 90%, Pilot = 10% reference, Pilot = 10% output 38 dB 36 dB 41 dB 44 dB AM Characteristics at fc = 1000kHz, Vi = 80dBµ, fm = 1kHz, Modulation = 30% Parameter Conditions Ratings min 13 typ Unit max Current Drain With no input signal 27 39 mA Detector Output 1 23dBµ, 30% modulation, fm = 1kHz 40 80 160 mVrms Detector Output 2 80dBµ, 30% modulation, fm = 1kHz 90 160 230 mVrms Signal-to-Noise Ratio 1 23dBµ, 30% modulation, fm = 1kHz 17 23 Signal-to-Noise Ratio 2 80dBµ, 30% modulation, fm = 1kHz 46 Total Harmonic Distortion 1 80dBµ, 30% modulation, fm = 1kHz 0.4 1.1 % Total Harmonic Distortion 2 107dBµ, 30% modulation, fm = 1kHz 0.5 1.3 % dB 52 dB SD Sensitivity 0% modulation 11 20 29 dBµ Local Oscillator Buffer Output With no input signal 100 140 200 mVrms IF Counter Buffer Output 23dBµ 140 285 400 mVrms No.7931-2/10 LA1845NV Package Dimensions unit : mm 3175B Pin Description Pin No. 1 Pin function FM IF input Pin voltage Equivalent circuit Notes Vreg Input impedance ri = 330Ω 1 3 2 AM mixer output VCC Connect the mixer coil between this pin and VCC 2 3 REG 4 AM IF input 2.1 3 Vreg Vreg = 2.1V Input impedance ri = 2kΩ 4 5 GND 6 Tu-LED 7 ST-LED/AF-IF 0V VCC 6 output 8 FM detector Active low VCC 7 Open collector The 600BEAS-10471 (Toko Mfg. Co., Ltd.) is recommended for detector coil. 9 VCC Continued on next page. No.7931-3/10 LA1845NV Continued from preceding page. Pin No. 10 Pin function AM/FM IF counter Pin voltage Equivalent circuit Notes 0V V10≤0.5V : Reception state 1.4V≤V10≤2.2V : Muting on V10≥3.5V : IF counter output and muting on output, output control switch, mute switch 11 Phase comparator 10 VCC-1.0 The device operates in AM mode when a current of 11 low-pass filter over 200µA flows from pin. 12. (AM/FM switching) 12 Pilot detector low- VCC-1.0 The device is forced to monaural when a current of 12 pass filter (Forced over 50µA flows from this pin. mono) (VCO stop) The VCO is stopped when a current of over 200µA flows from this pin. The limit values for the resistor are the same as those for pin 11. 13 L outputs 14 R outputs 3.2V Output impedance ro = 3.3kΩ 13 ( 15 Pilot canceler Vreg 14 ) 15 output 3 16 Decoder input Vreg Inverting input pin RNF RNF = 20kΩ 16 17 PLL input Vreg Input impedance ri = 20kΩ 17 18 FM demodulator output Vreg+0.7 18 Output impedance ro = 2.3kΩ The channel separation can be adjusted with an external capacitor connected between this pin and ground. Continued on next page. No.7931-4/10 LA1845NV Continued from preceding page. Pin No. Pin function 19 AM detector output Pin voltage Equivalent circuit Notes 0V (FM) Output impedance ro = 3.3kΩ 1.5V (AM) 19 20 S meter, 0.2V (FM) The resistance of the built-in resistor R is 13.9kΩ. AM AGC 0.9V (AM) The SD response during seek operation is determined with the external capacitor connected to 20 this pin. R 21 AM RF input Vreg Must be used at the same potential as pin 22. 21 22 AFC Vreg The FM SD bandwidth can be adjusted with the external resistor connected between this pin and pin 3 (Vreg). 22 23 OSC VCC Connect the oscillator coil between this pin and pin 23 9 (VCC). Note : Impedance of the secondary oscillator coil must be 5kΩ or higher. 24 Oscillator buffer VCC-1.4 The FM SD sensitivity can be adjusted with an output, FM SD sensitivity adjustment external resistor connected to this pin. Output impedance R = 200Ω R 24 Note : Resistance of the external resistor connected to the pin 24 must be 3.3kΩ or higher. No.7931-5/10 LA1845NV Equivalent Circuit Block Diagram No.7931-6/10 75Ω FM-IN (10.7MHz) 2 1 0.047µF 23 24 39pF 20pF 0.047µF 33µF 300Ω 6.8kΩ 1000pF 5.6kΩ OSC BUFF 3 4 21 3.3µF 39MH 50Ω 0.047µF HW6215 22 HW50425 AM-IN (1MHz) 5 20 19 0.01µF 1000pF 50kΩ V-SD 6 7 8 17 10kΩ 20kΩ Detector coil Discriminator 600BEAS-10471 50kΩ 20kΩ 10µF 4.7µF 18 AM IF 1000pF V-ST ST-LED LA1845NV TU-LED 22µF 0.047µF 9 1000pF AM/FM IF-BUFF 16 65kΩ 0.1µF SEEK AM 12 13 1µF 3kΩ 0.015µF 0.47µF 11 14 NORMAL 20pF 10 15 0.0047µF FM LPF ROUT LOUT VCC 5.0V Top view MONO 1µF LPF 0dB 0.015µF A A LA1845NV Test Circuit No.7931-7/10 LA1845NV No.7931-8/10 LA1845NV No.7931-9/10 LA1845NV PS No.7931-10/10