LM1112

LM1112 NSC | Alldatasheet

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a NX = | LM1112A/LM1112B/LM1112C =| Dolby® B-Type Noise Reduction Processor = | General Description Features = | The LM1112 is a monolithic integrated circuit specifically ™ Very high signal/noise ratio, 74 dB encode bar designed to realize the Dolby B-type noise reduction sys- (CCIR/ARM) tem. = Wide supply voltage range, 6V to 20V It is a replacement for the LM1111 and the Signetics NE- ™ Very close matching to standard Dolby characteristics 645/648 but with improved performance figures. ®@ Audible switch-on transients greatly reduced m Improved temperature performance @ Reduced number of precision external components @ Improved transient stability 1m Input protection diodes Available only to licensees of Dolby Laboratories Licensing Corporation, San Francisco, from whom licensing and application information must be obtained. Dolby and the double-D symbol are registered trademarks of Dolby Laboratories Licensing Corporation. Schematic Diagram [s] (] [3] a | & 1a & 1a an a % a HE CEY FAD - _ roa} 7) [4 QT ad TT ap ; | a a a ee Pe Q Q Q Q|Q Q 26 6 sige! ile | 7 [8] fo} Oe) bs} fe] Del bs] TUH/TE76-1 1-118

c Absolute Maximum Ratings = if Milltary/Aerospace specified devices are required, Storage Temperature Range ~65°Cto +1500 | Please contact the National Semiconductor Sales Lead Temperature (Soldering, 10 sec.) 2crc | > Office/Distributors for availability and specifications. Fr Supply Voltage 24v = Operating Temperature Range =20°C to +70°C = Electrical Characteristics vg = 12v, Ta = 25°C. 0 dB refers to Dolby level which is 580 mVrms at pin 3. iJ ramete | conatuone | _ttttan [| __atetag | _taitae & Parameter Senaent win [tye [wax [win [typ [wax | in | Typ [Wax | | = SupplyVoltageRange [| [fo | 6 [fa | 6 TT ao] vv SupplyGurent [|e [ao] | | | | ms |? Voltage Gain - (Pin 5-3) oentz Pins 6 and 12 24.5 4B (Pins-6) [rittzPin6Open | [var | |v | | 7] [a mon Vuseee [mele [ee [-el eae oT Reduction Out) Distortion [ak ods | [o03 for [fos [or [| os | on | % [row +1008 | [oz | fee} | joa] |» Signal Handing [teHe, 09% Distorion| [||| [| | J [vs=ev | fos TUT CPs TT os | [very |e [ass] | [tes] | [ass] | a vs=rev Tf to Pt TT 9 Ta wer ee TP er at Pin 7 (Note 1) Connected a Oe Pd (CCIR/ARM) NR In 71.5 | 74 m | 74 zo | 74 dB [ps=te TP Tl J To NR Out [ps=tokK | fo To J To | A (CCIR/ARM) peewee ER La [an baal a [oa onl oe 10 kHz, 0 dB 12 dB InputResistance [Pins | 45 | 65 | eo | 45 | o5 [ ao | 45 | 65 | 80 | ko [ring df 43 | 56 | oo [4s | 56 | 69 [4s | 56 | 60 | ko OutputResistance [Ping | 18 | 24 | 30 [ 18 | 24 | 30 | 18 | 24 | 90 | ko [rng To fs | co fs | 80 fs | 8 | fring To Pas [0 as PO 0 [as | | | PSRR jr=rzonz | | ao TTP wo TT ao Ta fe er re | Pin3 ka Pin 7 OS OS GO OO 1 Note 1: Gaussian noise, measured over a period of 50 ms with a CCIR filler and an average responding meter. | 1-119

=| Typical Performance Characteristics a Signal/Noise Ratio vs Source Impedance o Encode Mode (CCIR/ARM) Gain vs Frequency (NR OFF) x a a 3 = eof EE) ef

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| . 4 Sa 28) S 8 re OS Og SR < 5 ST a A LR SPER oe eS = 2 oot SC ST ew Scot coos § oN eal Ce I ns “HHH eh Senin eseetiieeeeet mm aE 0 CCC Cn 01 1 10 100 1000 Source Impedance (2) Frequency (KHz) ‘TL/H/7876-2 Total Harmonic Distortion — 0 dB Level Total Harmonic Distortion — + 10 dB Level ey SE ee ee a | CT ggh COT oa ee a Ty Ce pt} AH be eth i a 06 a Fs : j a co oT 03 Ea A of eas eee aT TY A oe IA a eo PA 2 ene a Coo Dat See i ee ott th) ger Ot 1 10 100 0.1 1 10 100 Frequency (KHz) Frequency (KHz) TUH/T876-3 Back to Back Response Error vs Frequency and — Back to Back Response vs Frequency and Supply Voltage (Standard Dolby Encoder) Temperature (Encoder Temperature 25°C) ee a | | nom rN EI Hit a FH sofa on ober is" Hof tat a atl it Ni A i a — a | oe oe 8-10] fo B -10) at i 1 So a Oe 1g uy q poe ee 8 tH & 20 [ee a oS eee a | — ae 80 2 a 2B a a ot tl Bee ee 8 gh are rel) Ht

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[TI YS ie [I ee EC r) " 40] La eretpanl ty all aoe eh s' tH Bo Se ee Rae a oo CE ot . M1 10-20 100 Frequency (KHz) Frequency (KHz) TUH/T070~4 1-120

Typical Performance Characteristics (Continued) = 30 = CHEE eee q°CP PT ; wh A | & ao Leer eC = Perro E ut Ew & 8 wrdeeter sy |i Tt tt TTT Werte yy = Hy ACP ee 5 a FA ia. = Cee Ae Ft 10 SEREEECEHCE ARE 6 8 1 12 14 16 «18 «20 6 8 10 120«14 16 18 20 Supply Voltage (V) ‘Supply Voltage (V) ‘TL/H/7876-5 TRANSIENT RESPONSE TO ABRUPT LEVEL CHANGE (Measured at pin 7) (a) Encode (f = 5 kHz) (b) Encoded and Decoded (f = 5 kHz) Ria] at [-— oa | i | al | | Hs hasinanp—_—-—| Pitt tet yt Wo ern mr a] Se | eee: i Va 0 Att eee Li ts | Pit Tivi i Py) Lili tit tt 100m TRANSIENT RESPONSE TO ABRUPT FREQUENCY CHANGE (Measured at pin 7) a (a) Encode (—20 dB) (b) Encoded and Decoded (—20 dB) [Es [ie | Lee | | are [ttt té | {| en aa ee =| i B 2] Pee ll Uteaitatatitiid | *) enn sult Me) A A alt a HH Lit Litt tit Pitt tet tit 100 mS/ DIV 100 mS/ DV 1-121

S| ELECTRICAL NOISE REDUCTION SWITCH 2. Supply current may be significantly increased by high pin = | _ In place of the normal mechanical noise reduction on/off 14 forced voltages. Values for V and R should thus be = | __ switch, the circuit below is often used to permit electrical NR chosen such that pin 14 voltage is 3V-4V. =| control. When using this circuit, the following points should 3. When electrical NR switching is used, signal level is | be noted: slightly affected by the minimum value of the internal vari- =| __ 1. Signal boost is reduced by increasing DC voltage on Pin able impedance. (At 10 kHz-10 dB, a residual boost of = 14 (see curve). A voltage of approximately 3V is adequate approximately 0.4 dB remains.) This is not the case for = to achieve NR OFF. mechanical NR switching. a N aa een = f = pots Y B-TYPE WTEGRATED CIRCUIT i 3 | wee LLL a Ln Jaen R303 180K R304, Noise Ri 5% 270K Switch our_® oo r iba v iN 5% other Dolby Processors TUH/7876-10 Note 1: Where not otherwise specitied, component tolerances are +10%. Signai Boost vs Pin 14 Control Voltage Supply Current vs Pin 14 Control Voltage (Encode, 10 kHz) (Vg = 12V) (Encode, 10 kHz) : TT Mex Boom _| at =3 aan ad Cer i eee eee eee ol ee Ae a PH TT ea Pr eee eee, eee aE LTT TTT Tavtute sont it ot ALT rrr) CA reir er TOC eer eS Se a ee o 2 4 6 8 10 o 2 4 6 8 10 12 Pin 14 Voltage (V) Pin 14 Vottage (V) TUH/7876-11 1-122

Test Circuit (Encode) = reer SE SE ETE ep | Dolby B-Type Integrated Circuit I 5 * National LM1112N | = « eternal ok) [=> E [2 | aN | =< pers f 1 = NN ps | |e N N woe Pa i et, ew HIE cm [gt gt a a, SE, | = C308 c209 3 0K. n302 03 R901 2 303 ry 30s : “ Pe ome s a 6301, 6208 390K. ATOoF 6-033 ‘6-047 : I est TLH/7876~12 Note 1: 1 nF capacitors from pin 3 and pin 7 to ground may be required on older devices. Note 2: Where not otherwise specified, component tolerances are + 10%, Note 3: For LM1112AN use 2% components for C304, R903, R305. (5% components may cause errors up to +0.3 dB.) Connection Diagram Dual-in-Line Package VARIABLE ie MPECNPUT POSITIVE SUPPLY AMPUIFIE mene 2 18 VARIABLE IMPEDANCE AMPUFIER B 2 x ER RECTIFIER OUTPUT bias — 1 RECTIER Bias ampunen a “2 RECTER WPUT AMPLIFIER A 6. 11 AMPURIER D ouTPUT ‘ouruT AMPLIFIER EK {8 AMPLIFIER D OUTPUT FEEDBACK DECOUPLING 1 DecourLina — 2. anouno TUH/7876-13, Order Number LM1112AN, LM1112BN or LM1112CN ‘See NS Package Number N16E 1-123