AD289

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P| ANALOG Precision, Wide Bandwidth, DEVICES Synchronized Isolation Amplifier Model 289 FEATURES MODEL 289 FUNCTIONAL BLOCK DIAGRAM Low Nonlinearity: #0.012% max (289L) Frequency Response: (~3dB) de to 20kHz cam (Full Power) de to 5kHz © ~~ i] Gain Adjustable 1 to 100V/V, Single Resistor = anal [+ 3-Port Isolation: +2500V CMV Isolation Input/Output © eee "8 Low Gain Drift: +0.005%/°C max Ea Floating Power Output: +15V @ +5mA an | 120dB CMR at 60Hz: Fully Shielded Input Stage = PII Meets UL Std. 544 Leakage: 2uA rms max, @ 115V ac, 60Hz Lc) He] APPLICATIONS tee ae H I Multi-Channel Data Acquisition Systems mare 2. | ‘ Le Nr Process Signal Isolator han weno {|| ple Ge | High Voltage Instrumentation Amplifier eee roe SCR Motor Control GENERAL DESCRIPTION DESIGN FEATURES AND USER BENEFITS Model 289 is a wideband, accurate, low cost isolation ampli- Isolated Power: The floating power supply section provides fier designed for instrumentation and industrial applications. isolated +15V outputs @ +5mA. Isolated power is regulated to Three accuracy selections are available offering guaranteed within £5%. This feature permits model 289 to excite floating gain nonlinearity error at 10V p-p output: #0,012% max signal conditioners, front-end buffer amplifiers and remote (289L), +0.025% max (289K), +0,05% max (289J). All ver- transducers such as thermistors or bridges, eliminating the need sions of the 289 provide a small signal frequency response for a separate isolated de/de converter. from de to 20kHz (-34B) and a large signal response from de adjustable Gain: A single external resistor adjusts the model to SkHz (full power) at a gain of 1V/V. This new design offers 289°s gain from 1V/V to 100V/V for applications in high and true 3-port isolation, +2500V de between inputs and outputs low level transducer interfacing. (or power inputs), as well as 240V rms between power supply " ; se inputs and signal outputs. Using carrier modulation tech- Synchronized: The model 289 provides a synchronization niques with transformer isolation, model 289 interrupts terminal for use in multichannel applications. Connecting the round loops and leakage paths and minimizes the effect of synchronization terminals of model 289s synchronizes their high voltage transients. It provides 120dB Common Mode internal oscillators, thereby eliminating the problem of oscil Rejection between input and output common. The high CMV _lator “beat frequency” interference that sometimes occurs i and CMR ratings of the model 289 facilitate accurate measure-__ When isolation amplifiers are closely mounted. | ments in the presence of noisy electrical equipment such as Internal Voltage Regulator: Improves power supply rejection motors and relays. and helps prevent carrier oscillator spikes from being broad- WHERE TO USE THE MODEL 289 cast via the isolator power terminal to the rest of the system. ‘The model 289 is designed to interface single and multichannel Buffered Output: Prevents gain errors when an isolation ampli- data acquisition systems with de sensors such as thermo- fier is followed by a resistive load of low impedance. Model couples, strain gauges and other low level signals in harsh in- 289 can drive a 2kS2 load. dustrial environments. Providing high accuracy with complete three-Port Isolation: Provides true galvanic isolation between galvanic isolation, and protection from line transients of fault i. ar outpur and power supply pores, Eliminates need for voltages, model 289’s performance is suitable for applications put, ourp P PPly Ports. : Heat power supply and output ports being returned through a com- such as process controllers, current loop receivers, weighing Pow ten al systems, high CMV instrumentation and computer inter- mn termina’: . . face systems. Reliability: Model 289 is conservatively designed to be capable ; of reliable operation in harsh environments. Model 289 has a Use the model 289 when data must be acquired from floating calculated MTBF of 271,835 hours. In addition, the model transducers in computerized process control systems. The 289 meets UL Std, 544 leakage, 2A mms @ 115V ac, 60H. photograph above shows a typical multichannel application allowing potential differences or interrupting ground loops, among transducers, or between transducers and local ground ISOLATION AMPLIFIERS 5-45 fi

SPECIFICATIONS (typical @ +25°C and ¥, = + 144V to +25V dc unless otherwise noted) ee ase 7 a Aes a te AA SS Aa Modet 2895 289K 2691. ~ OUTLINE DIMENSIONS GAIN (NONINVERTING) [ + “Dimensions shown in inches and (nm). Range Tro 10ovw 0k 2.02 (61.18) MAX. Formals Gets 3 | Eaasaas Sa Deviation from Formula 41.5% max i vs, Temperature (0 to +70°C)! 15ppm/C yp (S0ppm/"C max) o7 Nonlinearity. (¢5V Swing)? 40.05% max £0.025% max 10,012% max MODEL 289 886) INPUT VOLTAGE RATINGS Wine Dieta Rage (6 = V) ‘10 ii cm : ase Max Safe Differential input [oosttaco® se Continuous 120V rms Tczoro0 = :

1 Minute 240V rms pepe prcoecery

‘Max CMV (Inputs to Outputs) Fetiomeoctiittt cod Continuous ac or de 42500V peak max fee eee ac, 602, 1 Minute Duration 2500V rms Heb sv't0 fat rowencom 7 oH OME: Lops Crea atte Res cvisopett tiene 8FH a1. Rs S1kO, Balanced Source Impedance 12048 Perera dah Rg S1kQ, HI IN Lead Only 1044B min is pro TH max. Max Leakage Current, Input to Output @ Lesminpeettt wour oH | Ss Nermig Ott ae aia cn a Reed INPUT IMPEDANCE : Seekcesoenneueanoael Differential 33pFin0°@ Sea0keeaRSRRee Eee) Overload 100k ; Common Mode 2opFis K 102 eereat warthams ~e} Fe 03,258) crip => Input DIFFERENCE CURRENT | She Initial @ +25°C 10nA (75nA max) Bee temperame 10 70°) o.1snarc SHIELDED MATING SOCKET INPUT NOISE (GAIN = 100V/V) Th: AC1214 ‘ : Voltage ‘0.051 to 1008: av pp om, awit Ie 3uV ms Siacerae gen FREQUENCY RESPONSE. 7 Faso Small Signal -34B. AL (12.7) MAX Geren aout aos FEEDTHROUGH WIRE 1 G=100v/v Sktte ner Full Power, 10V pp Output — SoS 2 : fe Fre Sten PH SoA Ga toon tt EEE Ties SS Tee ull Power. tp Hoo FFE] owen com 2 OFT G=100v~v 2.akHe Sot erane isaae SHAH 32h Settling Time* 40.05%, £10V Step 400us Has eer Meu eOR Tr UE geen Pea EEPHEE asaoc oevices aciau TET ETH 2 100 0 vs. Temperature (0 t0 +70°C) £20270 max, £15 +200 max £10 252 pvc max BOTTOM VIEW é “e" G ace eTONN EN LN =| 011250 cA10 vs, Supply Voltage (+15V to +20V change) Oy COPPER CLAD Ge att Lt EAE aa ET © BARS eS RATED OUTPUT "Voleage, 2482 Load +10V min INTERCONNECTIONS AND SHIELDING ‘Output Impedance <1M(de to 100Hz) TECHNIQUE ‘Output Ripple, 0.1MH: Bandwidth : ‘No Signal IN sav oi To preserve the high CMR performance of HOVe SOmV pp model 289, care must be taken to keep the . feo dren eowee SUPE. saya capacitance balanced about the input terminals. pds Tow A shield should be provided on the printed cir- Current +5mA, min cuit board under model 289 as illustrated in the Ne Cun bates net ced pido outline drawing above (screened area). The LO Fall Load ; 75mV pp IN/ISO PWR COM (pin 1) must be connected POWER SUPPLY, SINGLE POLARITY? to this shield. This shield is provided with the Molen eel Besos Aan mounting socket, model AC1214 (solder feed-, Gurrent, Quiescent (@ Vg = +15V) 425mA through wire to the socket pin 1 and copper p TEMPERATURERANGE.—==SSCSCSSCSCSC~<“<‘“SS~Cséfil surface). A recommended shielding tech- Rated Performance OTE a nique using model AC1214 is illustrated in Storage : é : 55°C to +85°C Figure 1. i ‘CASE DIMENSIONS 15° 20°KO7S" Best CMR performance will be achieved by ee ee ee using twisted, shielded cable for the input signal Eirealicn paar op pr app eatin rhi preg emepa to reduce inductive and capacitive pickup. To 3 When isolated power output is used, nonlinearity increases by #0.002%/mA of current drawn. oS f Sooper ar tee mam rea further reduce effective cable capacitance, the {commented poner mp AD mode 94, #1 @ Sah up cable shield should be connected to the com- f Se ee mon mode signal source as close to signal low L as possible (see Figure 1). 5-46 ISOLATION AMPLIFIERS

Applications

MULTICHANNEL APPLICATIONS : we Isolation amplifiers containing internal oscillators may exhibit aw a siowly varying offset voltage at the output when used in eT ee Gy | multichannel applications. This offset voltage is the result of 2 Bb | adjacent internal oscillators beating together. For example, if nt as . two adjacent isolation amplifiers have oscillator frequencies of 'SOUATOR! ——ggoreur g wv 100.0kHz and 100.1kHz respectively, a portion of the dif- z cn ference frequency may appear as a slowly varying output offset voltage error. Model 289 eliminates this problem by wv BV offering a synchronization terminal (pin 8). When this terminal L018 A BUFFER AMPLIFIER is interconnected with other model 289 synchronization ter- . — minals, the units are synchronized. Alternately, one or more Figure 13. 2-Pole, 5kHz Active Filter units may be synchronized to an external 100kHz +2% square- wave generator by the connection of synchronization termi- Noise Reduction in Data Acquisition Systems: Transformer al(s) to that generator. The generator output should be coupled isolators must have a carrier to pass de signals through j 2,5V—5.0V p-p with 1k source impedance to each unit. their signal transformers. Inevitably some carrier frequency | Use an external oscillator when you need to sync to an ex- ripple passes through to the isolator output. As the bandwidth ternal 100kHz source, such as a sub-multiple of a micropro- of an isolator becomes a larger fraction of its carrier frequency, cessor clock. A differential line driver, such as SN75158, can this ripple becomes more difficult to control. Despite this dif- | be used to drive large clusters of model 289. When using the ficulty, the model 289 produces very low ripple; therefore, synchronization pin, keep leads as short as possible and do additional filtration will usually be unnecessary. However, in not use shielded wire, These precautions are necessary to avoid some applications, particularly where a fast analog-to-digital capacitance from the synchronization terminal to other points. converter is used following the isolator, it may be desirable to It should be noted that units synchronized must share the same add filtration; otherwise, ripple may cause inaccurate conver- power common to ensure a return path. sions. The 2-pole low-pass shown in Figure 13 limits isolator APPLICATIONS IN INDUSTRIAL MEASUREMENT AND bandwidth to kHz, which is the full power bandwidth of the CONTROL SYSTEMS model 289. Carrier ripple is much reduced. Another beneficial | Isolated DAS: In data acquisition systems where multiple effect of an output filter is smoothing of discontinuous high transducers are powered by a single supply and the magnitude frequency waveforms. | of that supply is low enough for a multiplexer to handle the Motor Control and AC Load Control: Phase shift and band- voltages on all the transducers, it is economical to multiplex width are important considerations for motor control and ac | ahead of an isolator. The fast settling time of the model 289 load control applications. The model 289 possesses sufficient makes this configuration practical where slower isolators would bandwidth and acceptable phase shift for such tasks. not be usable. Figure 14 shows two model 289's sensing the armature voltage | Figure 12 shows an application where the difference in voltage and current of a motor. Faithful replicas of the waveforms between any two terminals of any of the transducers does not of these variables are applied to the motor control. Al oper- | exceed 30 volts. Though the input of the model 289 is pro- ates at unity gain from divided R1—R3 to deliver an output tected against line voltage, its power terminals are not; neither that is 1/100 of the armature voltage of the motor. A2 | is the multiplexer so protected. This circuit will not, therefore, operates at a gain of 100V/V to deliver a voltage 100 times withstand the differential application of line voltage. that developed across the current sensing shunt. Multiplexer addressing is binary, an enable providing selection | of the circuit shown as a signal source. Optical isolation is pro- | vided for digital signals, When several of these circuits are used | for several groups of transducers, the model 289’s should be m synchronized, a } i 289 sTT 146 _ eunee| — Y | foo . gy $22, | “ene weur | contmo ne . | 1 | oy F © be e dee Aa | 1) gy > 289 6 [iyo | [J ds soc consent] ES Gn | Oye [peer Es Qo] | Payee] = FUo woe | Poet | Figure 12. DAS with MUX Ahead of Isolator Figure 14. Isolating a Motor Controller ISOLATION AMPLIFIERS 5-49