NE645/646 DOLBY NOISE REDUCTION CIRCUIT handbook
Contents
1. 14 1986 1832. 0 0 NE Oo DESCRIPTION The NE645 646 is a monolithic audio noise reduction circuit designed as a direct replacement device for the NE645B NE646B in Dolby B Type noise reduction systems The NE645 646 is used to reduce the level of background noise introduced during re cording and playback of audio signals on magnetic tape and to improve the noise level in FM broadcast reception This circuit is available only to licensees of Dolby Laboratories Licensing Corpora tion San Francisco California NOTE T M Dolby Laboratories Licensing Corporation ORDERING INFORMATION DESCRIPTION 16 Pin Plastic DIP BLOCK DIAGRAM TEMPERATURE RANGE 16 Pin Plastic DIP 0 to 70 C NE645 646 Dolby Noise Reduction Circuit Product Specification FEATURES e Accurate record mode frequency response e Excellent frequency response tracking with temperature and Vec 0 4 dB typical e Excellent back to back dynamic response DC shift less than 20mV typical e Improved stability of all op amps e High reliability packaging APPLICATIONS e Tape decks e Dolby surround sound system ORDER CODE NE646N PIN CONFIGURATION N Package c input 1 18 V B INPUT 2 15 F CONTROL B oureur 31 14 G OUTPUT REFERENCE 4 A input 5 12 D INPUT a ourput 6 11 c OUTPUT Ex ourPuT 7 10 FILTER we 8 9 GROUND November 14 1986 179 853 0952 86554 Product S
3. pecification Dolby Noise Reduction Circuit NE645 646 ABSOLUTE MAXIMUM RATINGS SYMBOL PARAMETER RATING UNIT Vcc Supply voltage 24 Temperature range TA Operating ambient 0 to 70 TsrG Storage 65 to 150 Lead soidering temperature 10sec max 300 c TsoLo DC ELECTRICAL CHARACTERISTICS Voc 12V f 20Hz to 20kHz All levels referenced to 580MVpms 0dB at Pin 3 Ta 25 C unless otherwise specified NE645 SYMBOL PARAMETER TEST CONDITIONS Min Typ Max Vec Supply Voltage Range 8 20 lec Supply Current Voc 12V Ay Voltage gain Pins 5 3 f 2 1kHz Pins 6 and 2 connected f 1kHz 0 dB at Pin 3 noise Ay Voltage gain Pins 3 7 reduction out Distortion THD 2nd and 3rd a harmonic f 20Hz 10 kHz OdB f 20Hz 10 kHz 10dB j ina uem o mme eme mI s Record mode 67 72 64 72 dB S N Signal to noise ratio Playback mode 77 82 74 82 dB Record mode Frequency response f 1 4kHz at Pin 7 referenced 1 5 dB to encode monitor point 14 6 17 1 dB Pin 3 21 5 24 0 21 0 dB 1 8 dB 15 8 18 3 16 8 15 3 dB 20 8 23 3 21 8 20 3 dB 28 7 30 2 29 7 28 2 dB f 20kHz 0dB dB 20dB dB 30dB dB Back to back frequency Using typical record mode 5 1 0 1 15 0 415 dB response frequency response test points RiN input resistance kQ kQ Rout Out
4. pt for C309 on Pin 1 which is now an The NE645 646 is a direct replacement for excellent performance required in Dolby B optional component in specific applications the NE6458 646B The NE645 646 incorpo and C Type Audio Noise Reduction Systems defined by Dolby Laboratories AM circuit Critical component values are unchanged parameters are guaranteed at 12V Vcc November 14 1986 181 Product Specification Dolby Noise Reduction Circuit NE645 646 DOLBY ENCODER Output for constant level input single tone frequency response N o input Level dB Frequency E P i kHz 15 20 25 30 35 40 0 1 0 1 0 14 0 2 0 2 0 5 0 3 1 1 0 4 0 5 1 8 0 6 0 7 2 1 0 8 s SARE The figures given in this table are the average response of many of Dolby Laboratories professional encoders and are not intended 1o be taken as required consumer equipment performance characteristics Thus no inference should be drawn on the tolerances which licensees must retain in consumer equipment The figures can however be used to plot typical characteristics November 14 1986 182 Product Specification Dolby Noise Reduction Circuit NE645 646 TEST CIRCUIT POWER INTERNAL SUPPLY REFERENCE TC19460S NOTE All resistors standard and are measured in Optional capacitor in specific applications defined by Dolby Laboratories November
5. put resistance Pin 6 19 24 k Pin 3 80 2 Pin 7 80 2 Back to back frequency response shift vs temperature 0 C to 70 C 0 4 0 4 dB vs supply voltage 8 20V 0 4 0 4 dB NOTES 1 See maximum signal handling versus supply voltage characteristics 2 All noise levels are measured CCIR ARM weighted using a 10k source with respect to Dolby level See Dolby Laboratories Bulletin 19 November 14 1986 180 Product Specification Dolby Noise Reduction Circuit NE645 646 TYPICAL PERFORMANCE CHARACTERISTICS THD vs Frequency Record Mode THD vs Frequency Record Mode THD vs Frequency Play Mode TOTAL HARMONIC DISTORTION TOTAL HARMONIC DISTORTION TOTAL HARMONIC DISTORTION 100 K FREQUENCY Hz FREQUENCY Hz DP100708 OP100905 THD vs Frequency Maximum Signal Handling THD vs Output Record Mode Noise Reduction NR Off vs Supply Voltage 10 ee eee gt 20 f z RECORD MODE E p 18 ikuz 4 o o E b E 2 6 5 1 g 91 2 s Z 9 14 i E n i i P B on 10 20 10 0 10 20 8 10 12 14 18 18 OUTPUT dB FREQUENCY Hz Vcc SUPPLY VOLTAGE VOLTS OP10100 OP10110 0P 101208 Supply Current vs Supply Voltage 20 m z z 15 2 o gt i gt a LI 8 m 5 10 12 14 16 18 Voc SUPPLY VOLTAGE VOLTS L OP101308 APPLICATION INFORMATION rates improved design techniques to insure exce
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NE645/646 DOLBY NOISE REDUCTION CIRCUIT handbook