Details, datasheet, quote on part number: NTE789
DescriptionNTE789, Integrated Circuit Stereo Multiplex Decoder
CompanyNTE Electronics, Inc.
DatasheetDownload NTE789 datasheet
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Features, Applications

Description: The NTE789, a monolithic silicon integrated circuit, is a stereo multiplex decoder intended for FM multiplex systems. This stereo multiplex decoder requires only one low­inductance tuning coil (requires only one adjustment for complete alignment), provides automatic stereo switching, energizes a stereo indicator lamp, and operates from a wide range of voltage supplies. Figure 1 shows the block diagram for the NTE789. The input signal form the detector is amplified by a low­distortion preamplifier and simultaneously applied to both signal, generated by a local voltage­controlled oscillator (VCO), is counted down by two frequency dividers a 38kHz signal and to two 19­kHz pilot­tone supplied by the FM detector is compared to the locally generated 19­kHz signal in a synchronous detector. The resultant signal controls the voltage controlled oscillator (VC)) so that it produces an output signal to phase­lock the stereo decoder with the pilot tone. A second sychronous detector compares the locally generated 19­kHz signal with the 19­kHz pilot tone. If the pilot tone exceeds and externally adjustable threshold voltage, a Schmitt trigger circuit is energized. The signal from the Schmitt trigger lights the stereo indicator, enables the 38­kHz synchronous detector, and automatically switches the NTE789 form monaural to stereo operation. The output signal from the 38­kHz detector and the composite signal from the preamplifier are applied to a matrixing circuit from which emerge the resultant left and right channel audio signals. These signals are applied to their respective left and right post amplifiers for amplification to a level sufficient to drive most audio amplifiers. The NTE789 utilizes the 16­lead quad­in­line plastic package and operates over the ambient temperature range to +85°C. Features: D Requires the use of only one low­inductance tuning coil D Automatic stereo switching D Directly drives a stereo indicator lamp 100mA D Includes driver for stereo­lamp indicator D Operates from a wide range of power supplies: to 16 volts D Requires only one adjustment for alignment D Switching from monaural to stereo and stereo to monaural produces no audible thumps D Low distortion: under 0.5% D Separate dc input permits stereo defeat or enable D High signal output: directly drives audio amplifiers D Excellent SCA (storecast) rejection: 55dB typ. D High audio channel separation: 40dB typ.

Absolute Maximum Ratings: (TA = +25°C unless otherwise specified) DC Supply Voltage. 16V Current Pin12. 100mA Input Signal Voltage (Composite)(Note 1). 400mV Operating Ambient Temperature Range. to +85°C Storage Ambient Temperature Range. to +150°C Lead Temperature (During Soldering, 1/32" (0.79mm) from case,10s max.). +265°C Note 1. For stereo operation, a minimum input signal voltage (composite) 40mV is required. Electrical Characteristics: (TA = 12 unless otherwise specified) Parameter Static Characteristics

Total Current Pin10,Pin11) DC Voltage Pin1 Pin6 (Indicator Lamp OFF) Pin9 and Pin10 Pin12 (Indicator Lamp OFF) Voltage Differential ­ Pin1) Current at Pin12 (In actual use external circuit resistance (e.g. lamp should limit Pin12 to the maximum rated value of 100mA) Itotal ­ V1 VIN (at = 16V Lamp OFF mA

Input Impedance Channel Separatiom + R Reference) Channel Balance (Monaural) Monaural Gain Stereo/Monaural Gain Ratio Indicator Lamp ­ Turn­ON Voltage Capture Range (Deviation from 76kHz center frequency) Distortion (75µs De­emphasis) 2nd Harmonic 3rd, 4th, and 5th Harmonic 19kHz Rejection 38kHz Rejection SCA (Storecast) Rejection Stereo Defeat Voltage (V4) Stereo Enable Voltage (V4) Zin VIN = 180mV, Note 3 VIN = 180mV VIN = 180mV VIN = 180mV, Note 3 19kHz pilot­tone Pin1 19kHz pilot­tone voltage mV %

Note 2. For improved pilot sensitivity and overload characteristics, replace the.039µF capacitor between Pin7 and Pin8 with a Series L­C Network = 0.015µF). Under these conditions, Indicator Lamp Sensitivity: "ON" = 3.3mV, "OFF" = 2.0mV. Note 3. For stereo operation, test conditions require a composite stereo input signal (modulated at 1kHz) including 19kHz (18mV) pilot­tone signal.

Composite FM 1 Detected Signal Input Bypass 2 GND 3 GND 4 GND 5 RC Network 6 19kHz Pilot Lamp 7 Sensitivity Network 8

Indicator Input 16 76kHz Network Capacitor Input 15 76kHz Network 14 Phase Lock Filter Loop Network 13 GND 12 Lamp Drive Circuit 11 VCC 10 Right Ch Output 9 Left Ch Output


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