® ISO212P FPO Low Cost, Two-Port Isolated, 1500Vrms ISOLATION AMPLIFIER FEATURES APPLICATIONS ● 12-BIT ACCURACY ● 2.5mA (typ) QUIESCENT CURRENT ● INDUSTRIAL PROCESS CONTROL: Transducer Channel Isolator for Thermocouples, RTDs, Pressure Bridges, Flow Meters ● LOW PROFILE (LESS THAN 0.5" HIGH) ● SMALL FOOTPRINT ● EXTERNAL POWER CAPABILITY (±8V at 5mA) ● “MASTER/SLAVES” SYNCHRONIZATION CAPABILITY ● INPUT OFFSET ADJUSTMENT ● 4mA TO 20mA LOOP ISOLATION ● MOTOR AND SCR CONTROL ● GROUND LOOP ELIMINATION ● ANALYTICAL MEASUREMENTS ● POWER PLANT MONITORING ● DATA ACQUISITION/TEST EQUIPMENT ISOLATION ● LOW POWER (53mW) ● SINGLE 10V TO 15V SUPPLY OPERATION ● MULTIPLEXED SYSTEMS WITH CHANNEL TO CHANNEL ISOLATION Isolation Barrier DESCRIPTION The ISO212P signal isolation amplifier is a member of a series of low-cost isolation products from BurrBrown. The low-profile SIL plastic package allows PCB spacings of 0.5" to be achieved, and the small footprint results in efficient use of board space. To provide isolation, the design uses high-efficiency, miniature toroidal transformers in both the signal and power paths. An uncommitted input amplifier and an isolated external bipolar supply ensure the majority of input interfacing or conditioning needs can be met. The ISO212P accepts an input voltage range of ±5V for single 15V supply operation or ±3.0V for single 10V supply operation. Offset Adjust Offset Adjust –I/P +I/P fB +VSS 1 Out Com 1 –VSS 1 Out 8 7 3 38 1 37 O/P High O/P Low 4 6 2 DC/DC Converter 31 32 5 34 35 +VCC Com 2 Clock Out Clock In International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111 • Twx: 910-952-1111 Internet: http://www.burr-brown.com/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132 © 1988 Burr-Brown Corporation PDS-881G Printed in U.S.A. December, 1995 SPECIFICATIONS ELECTRICAL At TA = +25°C and V CC = +15V, unless otherwise noted. ISO212JP PARAMETER CONDITIONS ISOLATION Voltage Rated Continuous AC, 50Hz DC 100% Test (AC, 50Hz) Isolation-Mode Rejection(1) AC DC Barrier Resistance Barrier Capacitance Leakage Current(8) GAIN Initial Error Gain vs Temperature Nonlinearity(3): KP JP-15 INPUT OFFSET VOLTAGE Offset Voltage RTI: KP JP-15 vs Temperature vs Power Supply(4) Adjustment Range Partial Discharge 1s : <5pC VISO = Rated Continuous 60Hz MIN TYP ISO212KP, JP-15 MAX MIN TYP 1500 2120 Vrms VDC 1200 2400 Vrms 115 160 1010 12 1 ±1 20 0.04 VO = –5V to +5V ✻(9) ✻ ✻ ✻ ✻ 2 1.6 ±2 50 0.05 ✻ ✻ 0.015 0.04 ±10 ±10/G ±20 30 ±30/G ±1.5 ±5 Ripple Voltage(6) Ouput Compliance FREQUENCY RESPONSE Small Signal Bandwidth Full Signal Bandwidth ISOLATED POWER OUTPUTS Voltage Outputs (±VSS 1)(7) vs Temperature vs Load Current Output (7) (Both Loaded) (One Loaded) POWER SUPPLIES Rated Voltage Voltage Range(5) Quiescent Current TEMPERATURE RANGE Specification Operating No Load mV mV µV/°C mV/V mV ✻ ✻ nA nA V Ω ✻ kΩ V 8 0.4 7.5 ✻ ✻ mVp-p mVrms V 1 ✻ kHz 200 ✻ Hz ±5 I/P = 1Vp-p, –3dB G=1 I/P = 10Vp-p, G=1 G = 10 (–3dB) ±7.5 ±7.5/G ±10 ±10/G ✻ 3 Out Hi to Out Lo Min Load = 1MΩ f = 0 to 100kHz f = 0 to 5kHz Out Hi or Out Lo % FSR(2) ppm of FSR/°C %FSR %FSR ✻ 1012 OUTPUT Output Impedance Voltage Range ✻ ✻ 0.025 0.05 ✻ ✻ 50 4 G=1 ✻ ✻ dB dB Ω pF µArms µArms ✻ INPUT CURRENT Bias Offset INPUT Voltage Range(5) Resistance UNITS 750 1060 VISO = 240Vrms, 60Hz VISO = 240Vrms, 50Hz VCC = 14V to 16V MAX ✻ 1.8 ±7.5 kHz ±8 –8 90 ✻ ✻ ✻ ✻ 5 8 Rated Performance 15 11.4 to 16 2.5 No Load 0 –25 VDC mV/°C mV/mA ✻ ✻ mA mA ✻ ✻ V V mA ✻ ✻ °C °C ✻ ✻ ✻ 3.5 +70 +85 ✻ ✻ NOTES: (1) Isolation-mode rejection is the ratio of the change in output voltage to a change in isolation barrier voltage. It is a function of frequency. (2) FSR = Full Scale Range = 10V. (3) Nonlinearity is the peak deviation of the output voltage from the best-fit straight line. It is expressed as the ratio of deviation to FSR. (4) Power Supply Rejection is the change in VOS/Supply Change. (5) At VCC = +10.0V, input voltage range = ±3.0V min. (6) Ripple is the residual component of the barrier carrier frequency generated internally. (7) Derated at VCC < +15V. (8) Tested at 2400Vrms, 50Hz limit 16µA. (9) Asterisk (✻) same as ISO212JP. ® ISO212P 2 PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS Bottom View Supply Voltage Without Damage ......................................................... 18V Continuous Isolation Voltage Across Barrier: JP ......................... 750Vrms KP, JP-15 ........... 1500Vrms Storage Temperature Range ............................................ –25°C to 100°C Lead Temperature (soldering, 10s) ................................................ +300°C Amplifier Output Short-Circuit Duration ................ Continuous to Common Output Voltage Hi or Lo to Com 2 .................................................. ±VCC /2 1 +I/P Com 1 2 3 –I/P fB 4 5 –VSS 1 +VSS1 6 7 Offset Adjust Offset Adjust 8 PACKAGE/ORDERING INFORMATION PRODUCT ISO212JP ISO212JP-15 ISO212KP 31 +VCC TEMPERATURE RANGE 38-Pin Plastic SIP 38-Pin Plastic SIP 38-Pin Plastic SIP 326 326 326 –25°C to +85°C –25°C to +85°C –25°C to +85°C NOTE: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book. Com 2 32 Clock Out 34 PACKAGE PACKAGE DRAWING NUMBER(1) 35 Clock In ELECTROSTATIC DISCHARGE SENSITIVITY 37 O/P Low O/P High 38 This integrated circuit can be damaged by ESD. Burr-Brown recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. TYPICAL PERFORMANCE CURVES At TA = +25°C, VS = ±15V, unless otherwise noted. SINE RESPONSE (f = 200Hz) VOLTAGE OUT vs SUPPLY VOLTAGE +VCC 7 +5 Output Voltage (V) Voltage Out (V) 6 5 4 VOUT +VOUT Ideal +VOUT 3 VIN –VOUT (Absolute) 2 –VOUT 1 ±VOUT 0 5 Ideal VIN = ±5V, G = 1 VIN 0 17 16 15 14 13 12 11 10 9 8 7 6 5 0 4 5 10 Time (ms) Supply Voltage VCC (V) The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant any BURR-BROWN product for use in life support devices and/or systems. ® 3 ISO212P TYPICAL PERFORMANCE CURVES (CONT) At TA = +25°C and VS = ±15V, unless otherwise noted. SINE RESPONSE (f = 2kHz) STEP RESPONSE (f = 200Hz) +5 Output Voltage (V) Output Voltage (mV) +500 0 –500 0 –5 VIN = ±0.5V, G = 1 V IN = ±5V, G = 1 0 500 0 1000 5 10 Time (ms) Time (µs) STEP RESPONSE (f = 2kHz) IMR vs FREQUENCY 85 80 +500 Output Voltage (mV) 75 IMR (dB) 70 0 65 60 55 50 –500 45 V IN = ±0.5V, G = 1 40 0 500 1000 1k 10k 100k Time (µs) 1M 10M 100M Frequency (Hz) GAIN ERROR vs CLOCK-IN RATE LINEARITY vs CLOCK-IN RATE 100 0 90 –0.5 Gain Error (% FSR) Linearity Error (m%) 80 70 60 50 40 30 20 –1 –1.5 –2 10 0 –2.5 30 40 50 60 70 80 90 30 100 ® ISO212P 40 50 60 70 Clock-In Rate (kHz) Clock-In Rate (kHz) 4 80 90 100 inverting configurations, a separate resistor is required. Neglecting this point may also lead to problems when powering on the ISO212P. DISCUSSION OF SPECIFICATIONS The ISO212P is intended for applications where isolation and input signal conditioning are required. Best signal-tonoise performance is obtained when the input amplifier gain setting is such that VOUT has a full scale range of ±5V. The bandwidth is typically 1kHz, making the device ideal for use in conjunction with sensors that monitor slowly varying processes. To power external functions or networks, 5mA at ±8V typical is available at the isolated port. USING ±VSS1 TO POWER EXTERNAL CIRCUITRY The DC/DC converter in the ISO212P runs at a switching frequency of 25kHz. Internal rectification and filtering is sufficient for most applications at low frequencies or with no external networks connected. The ripple on ±VSS1 will typically be 100mVp-p at 25kHz. Loading the supplies will increase the ripple unless extra filtering is added externally; a capacitor of 1µF is normally sufficient for most applications, although in some cases 10µF may be required. Noise introduced onto ±VSS1 should be decoupled to prevent degraded performance. LINEARITY PERFORMANCE The ISO212P offers linearity performance compatible with 12-bit resolution systems (0.025%). Note that the specification is based on a best-fit straight line. THEORY OF OPERATION OPTIONAL OFFSET VOLTAGE ADJUSTMENT In many applications, the untrimmed input offset voltage will be adequate. For situations where it is necessary to trim the offset, a potentiometer can be used. See Figure 1 for details. It is important to keep the traces to the offset adjust pins as short as practical, because noise can be injected into the input op amp via this route. The ISO212P has no galvanic connection between the input and output. The analog input signal referenced to the input common (Com 1) is multiplied by the gain of the input amplifier and accurately reproduced at the output. The output section uses a differential design so either the HI or LO pin may be referenced to the output common (Com 2). This allows simple input signal inversion while maintaining the high impedance input configuration. A simplified diagram of the ISO212P is shown in Figure 2. The design consists of a DC/DC converter, an uncommitted input operational amplifier, a modulator circuit and a demodulator circuit. Magnetic isolation is provided by separate transformers in the power and signal paths. INPUT PROTECTION If the ISO212P is used in systems where a transducer or sensor does not derive its power from the isolated power available from the device, then some input protection must be present to prevent damage to the input op amp when the ISO212P is not powered. A resistor of 5kΩ should be included to limit the output impedance of the signal source. Where the op amp is configured for an inverting gain, then RIN of the gain setting network can be used. For non- The DC/DC converter provides power and synchronization signals across the isolation barrier to operate the operational amplifier and modulator circuitry. It also has sufficient capacity to power external input signal conditioning net- Isolation Barrier 3 –I/P 5kΩ 1 +I/P 2 Com 1 4 35 fB 34 Clock Clock In Out O/P High 38 VIN O/P Low 37 VOUT Com 2 32 +V SS 1 –V SS 1 Offset Out Adjust Out +V CC 6 (2) 10µF + 0.1µF (1) (2) + 31 5 7 100kΩ 8 10µF Tantalum + 10µF 100µH Input Ground Plane Output Ground Plane NOTES: (1) Optional voltage offset adjust components. (2) 10µF decoupling to be used with external loads connected. FIGURE 1. Power Supply and Signal Connections Shown for Non-Inverting, Unity Gain Configuration. ® 5 ISO212P works. The uncommitted operational amplifier may be configured for signal buffering or amplification, depending on the application. Recent improvements in high voltage stress testing have produced a more meaningful test for determining maximum permissible voltage ratings, and Burr-Brown has chosen to apply this new technology in the manufacture and testing of the ISO212P. The modulator converts the input signal to an amplitudemodulated AC signal that is magnetically coupled to the demodulator by a miniature transformer providing the signal-path isolation. The demodulator recovers the input signal from the modulated signal using a synchronous technique to minimize noise and interference. PARTIAL DISCHARGE When an insulation defect such as a void occurs within an insulation system, the defect will display localized corona or ionization during exposure to high voltage stress. This ionization requires a higher applied voltage to start the discharge and a lower voltage to extinguish it once started. The higher start voltage is known as the inception voltage and the lower voltage is called the extinction voltage. Just as the total insulation system has an inception voltage, so do the individual voids. A voltage will build up across a void until its inception voltage is reached. At this point, the void will ionize, effectively shorting itself out. This action redistributes electrical charge within the dielectric and is known as partial discharge. If the applied voltage gradient across the device continues to rise, another partial discharge cycle begins. The importance of this phenomenon is that if the discharge does not occur, the insulation system retains its integrity. If the discharge begins and is allowed to continue, the action of the ions and electrons within the defect will eventually degrade any organic insulation system in which they occur. The measurement of partial discharge is both useful in rating the devices and in providing quality control of the manufacturing process. The inception voltage of these voids tends to be constant, so that the measurement of total charge being re-distributed within the dielectric is a very good indicator of the size of the voids and their likelihood of becoming an incipient failure. ABOUT THE BARRIER For any isolation product, barrier integrity is of paramount importance in achieving high reliability. The ISO212P uses miniature toroidal transformers designed to give maximum isolation performance when encapsulated with a high-dielectric-strength material. The internal component layout is designed so that circuitry associated with each side of the barrier is positioned at opposite ends of the package. Areas where high electric fields can exist are positioned in the center of the package. The result is that the dielectric strength of the barrier typically exceeds 3kVrms. ISOLATION VOLTAGE RATINGS Because a long term test is impractical in a manufacturing situation, the generally accepted practice is to perform a production test at a high voltage for some shorter time. The relationship between actual test voltage and the continuous derated maximum specification is an important one. Historically, Burr-Brown has chosen a deliberately conservative one: VTEST = (2 x ACrms continuous rating) + 1000V for ten seconds, followed by a test at rated ACrms voltage for one minute. This choice was appropriate for conditions where system transients were not well defined. fB 4 Off Adjust 7 –I/P 3 Signal – 38 Modulator +I/P Off Adjust 1 + 37 8 31 +8V +VSS 1 O/P –VSS 1 O/P 6 Oscillator –8V 25kHz Rectifier 2 FIGURE 2. Simplified Diagram of Isolation Amplifier. ® ISO212P 35 32 5 0.47µF Com 1 50kHz Power 34 0.47µF O/P High Demodulator 6 O/P Low +VCC Clock Out Clock In Com 2 The bulk inception voltage, on the other hand, varies with the insulation system and the number of ionization defects. This directly establishes the absolute maximum voltage (transient) that can be applied across the test device before destructive partial discharge can begin. the barrier will increase AC leakage and, in conjunction with ground line resistance, may degrade high frequency IMR. VOLTAGE GAIN MODIFICATIONS The uncommitted operational amplifier at the input can be used to provide gain, signal inversion, active filtering or current to voltage conversion. The standard design approach for any op-amp stage can be used, provided that the full scale voltage appearing on fB does not exceed ±5V. Measuring the bulk extinction voltage provides a lower, more conservative, voltage from which to derive a safe continuous rating. In production, it’s acceptable to measure at a level somewhat below the expected inception voltage and then de-rate by a factor related to expectations about the system transients. The isolation amplifier has been extensively evaluated under a combination of high temperatures and high voltage to confirm its performance in this respect. The ISO212P is free of partial discharges at rated voltages. If the input op-amp is overdriven, ripple at the output will result. To prevent this, the feedback resistor should have a minimum value of 10kΩ. Also, it should be noted that the current required to drive the equivalent impedance of the feedback network is supplied by the internal DC/DC converter and must be taken into account when calculating the loading added to ±VSS1. PARTIAL DISCHARGE TESTING IN PRODUCTION Not only does this test method provide far more qualitative information about stress withstand levels than did previous stress tests, but it also provides quantitative measurements from which quality assurance and control measures can be based. Tests similar to this test have been used by some manufacturers such as those of high voltage power distribution equipment for some time, but they employed a simple measurement of RF noise to detect ionization. This method was not quantitative with regard to energy of the discharge and was not sensitive enough for small components such as isolation amplifiers. Now, however, manufacturers of HV test equipment have developed means to measure partial discharge, and VDE, the German standards group, has adopted use of this method for the testing of opto-couplers. To accommodate poorly defined transients, the part under test is exposed to a voltage that is 1.6 times the continuous rated voltage and must display < 5pC partial discharge level in a 100% production test. Since gain inversion can be incorporated in either the input or output stage of the ISO212P, it is possible to use the input amplifier in a non-inverting configuration and preserve the high impedance this configuration offers. Signal inversion at the output is easily accomplished by connecting O/P High to Com 2 instead of O/P Low. ISOLATED POWER OUTPUT DRIVE CAPABILITY On the input side of the ISO212P, there are two power supplies capable of delivering 5mA at ±8V to power external circuitry. When using these supplies with external loads, it is recommended that additional decoupling in the form of 10µF tantalum bead capacitors be added to improve the voltage regulation. Loss of linearity will result if additional filtering is not used with an output load. Again, power dissipated in the feedback loop around the input op amp must be subtracted from the available power output at ±VSS1. If the ISO212P is to be used in multiple applications, care should be taken in the design of the power distribution INSTALLATION AND OPERATING INSTRUCTIONS POWER SUPPLY AND SIGNAL CONNECTIONS As with any mixed analog and digital signal component, correct decoupling and signal routing precautions must be used to optimize performance. Figure 1 shows the proper power supply and signal connections. VCC should be bypassed to Com 2 with a 0.1µF ceramic capacitor as close to the device as possible. Short leads will minimize lead inductance. A ground plane will also reduce noise problems. If a low impedance ground plane is not used, signal common lines, and either O/P High or O/P Low pin should be tied directly to the ground at the supply and Com 2 returned via a separate trace to the supply ground. CEXT 1 has minimal effect on total IMR. fB CEXT 2 and R have a direct effect. – O/P High CINT R Load Circuit + O/P Low CEXT 2 Com 2 –VCC +VCC CEXT 1 To avoid gain and isolation mode (IMR) errors introduced by the external circuit, connect grounds as indicated in Figure 3. Layout practices associated with isolation amplifiers are very important. In particular, the capacitance associated with the barrier, and series resistance in the signal and reference leads, must be minimized. Any capacitance across Power Supply Com 1 Input Common VISO FIGURE 3. Technique for Connecting Com 1 and Com 2. ® 7 ISO212P external driver connected to Clk In. See Figure 5. The driver may be an external component with Series 4000 CMOS characteristics, or one of the ISO212Ps in the system can be used as the master clock for the system. See Figure 6 and 7 for connections in multiple ISO212P installations. network, especially when all ISO212Ps are synchronized. It is best to use a well decoupled distribution point and to take power to individual ISO212Ps from this point in a star arrangement as shown in Figure 4. NOISE Output noise is generated by residual components of the 25kHz carrier that have not been removed from the signal. This noise may be reduced by adding an output low pass filter (see Figure 8). The filter time constants should be set below the carrier frequency. The output from the ISO212P is a switched capacitor and requires a high impedance load to prevent degradation of linearity. Loads of less than 1MΩ will cause an increase in noise at the carrier frequency and will appear as ripple in the output waveform. Since the output signal power is generated from the input side of the barrier, decoupling of the ±VSS 1 outputs will improve the signal to noise ratio. CHARGE ISOLATION When more than one ISO212P is used in synchronous mode, the charge which is returned from the timing capacitor (220pF in Figure 5) on each transition of the clock becomes significant. Figure 7 illustrates a method of isolating the “Clk Out” clamp diodes (Figure 5) from this charge. A 22kΩ resistor (recommended maximum to use) together with the 39kΩ internal oscillator timing resistor (Figure 5) forms a potential divider. The ratio of these resistors should be greater than 0.6 which ensures that the input voltage triggers the inverter connected to “Clk In”. If using a single resistor, then account must be taken of the paralleled timing resistors. This means that the 22kΩ resistor must be halved to drive two ISO212Ps, or divided by 8 if driving 8 ISO212Ps to insure that the ratio of greater than 0.6 is maintained. The series resistors shown in Figure 7 reduce the high frequency content of the power supply current. SYNCHRONIZATION OF THE INTERNAL OSCILLATOR The ISO212P has an internal oscillator and associated timing components, which can be synchronized, incorporated into the design. This alleviates the requirement for an external high-power clock driver. The typical frequency of oscillation is 50kHz. The internal clock will start when power is applied to the ISO212P and Clk In is not connected. APPLICATIONS The ISO212P isolation amplifier, together with a few low cost components, can isolate and accurately convert a 4-to20mA input to a ±10V output with no external adjustment. Its low height (0.43" (11mm) ) and small footprint (2.5" x 0.33" (57mm x 8mm) ) make it the solution of choice in 0.5" board spacing systems and in all applications where board area savings are critical. Because the frequencies of several ISO212Ps can be marginally different, “beat” frequencies ranging from a few Hz to a few kHz can exist in multiple amplifier applications. The design of the ISO212P accommodates “internal synchronous” noise, but a synchronous beat frequency noise will not be strongly attenuated, especially at very low frequencies if it is introduced via the power, signal, or potential grounding paths. To overcome this problem in systems where several ISO212Ps are used, the design allows synchronization of each oscillator in a system to one frequency. Do this by forcing the timing node on the internal oscillator with an Power In The ISO212P operates from a single +15V supply and offers low power consumption and 12-bit accuracy. On the input side, two isolated power supplies capable of supplying 5mA at ±8V are available to power external circuitry. +VCC Track Resistance/Inductance 100µF 10µF 0.1µF 0.1µF 10µF 0.1µF 39kΩ ISO212P ISO212P ISO212P Clock In 10µF Clock Out 0.1µF 220pF Clamp Diodes Ground Plane Com 2 FIGURE 4. Recommended Decoupling and Power Distribution. FIGURE 5. Equivalent Circuit, Clock Input/Output. Inverters are CMOS. ® ISO212P 8 APPLICATIONS FLEXIBILITY In Figure 8, the ISO212P’s +Vss 1 isolated supply powers a REF200 to provide an accurate 100µA current source. This current is opposed by an equal but opposite current through the 75kΩ feedback resistor to establish an offset of –7.5V at Iin = 0mA. With Iin = 4-to-20mA, the output is –5 to +5V. The ratio of the 75kΩ and 3.12kΩ resistors assures the correct gain. ISO212P/Master +V CC Clk Out Clk In Com 2 ISO212P/Slave +V CC Clk Out Clk In Com 2 The polarity of the output can be reversed by simply reversing the O/P HI and O/P LO pins. This could be used in the Figure 8 circuit to change the –5V to +5V output to a +5V to –5V output range. ISO212P/Slave +V CC Clk Out Clk In Com 2 The primary function of the output circuitry is to add gain to produce a ±10V output and to reduce output impedance. The addition of a few resistors and capacitors provides a low pass filter with a cut-off frequency equal to the full signal bandwidth of the ISO212P, typically 200Hz. The filter response is flat to 1dB and rolls off from cut off at –12dB per octave. 0V +15V Sync FIGURE 6. Oscillator Connections for Synchronous Operation in Multiple ISO212P Installations. Clk In Clk In Clk In The accuracy of the REF200 and external resistors eliminates the need for expensive trim pots and adjustments. The errors introduced by the external circuitry only add about 10% of the ISO212P’s specified gain and offset voltage error. 22k Ω Slave Clk In Slave 22k Ω Slave 22k Ω Slave 22k Ω Slave Master Clk Out 22k Ω RS Clk In Slave 4 Slave N Clk In Slave 3 Clk In Slave 2 Clk In Slave 1 Master Clk Out FIGURE 7. Isolating the Clk Out Node. +VSS 1 +15V 6.8nF (10%) 10µF 0.1µF 2 1 4-20mA 25Ω +15V 6 + 37 (O/P Low) +VSS 1 38 (O/P High) 8 3 REF 200 100µA 0.1µF 31 100kΩ 32 – (5%) 4 ISO212P 1 75kΩ 0.02µF 100kΩ 4mA to 20mA –5V to +5V (5%) 3 4mA to 20mA –10V to +10V + OPA27 2 – 6.8nF (10%) 6 0.1µF NOTE: All resistors are 0.1% unless otherwise stated. –15V 3.12kΩ 22kΩ 22kΩ FIGURE 8. Isolated 4-20mA Current Receiver with Output Filter. ® 9 ISO212P +15V +VISO REF03 0.1µF +2.5V 3 – 31 1kΩ 1kΩ 1 OPA1013 +VISO 1kΩ 38 VOUT ISO212P 99kΩ 1kΩ(1) 37 32 + 5 4 6 2 OPA1013 –2.5V 10µF 100Ω 10µF –VISO +VISO –VISO NOTE: (1) e.g., strain gauge, pressure transducer, RTD, gas detection and analysis. FIGURE 9. Instrument Bridge Isolation Amplifier. 100kΩ +15V 4 0.1µF 100kΩ 3 0.1µF – 31 38 ISO212P 250kΩ 1 VOUT 37 32 + +VISO 5 Siemens BPW21 6 2 OPA128J 10µF 10µF –VISO +VISO –VISO FIGURE 10. Photodiode Isolation Amplifier. +15V –VISO +VISO 8kΩ OPA177 4kΩ 1 1MΩ ISO212JP –VISO 100Ω VOUT 4 T.C. 99kΩ 1kΩ 3 –VISO FIGURE 11. Thermocouple Amplifier with Ground Loop Elimination, Cold Junction Compensation and Down-Scale Burn-Out. ® ISO212P 10 100kΩ +500VDC ISO212P 4 1kΩ 3 – VD +15V 1 V D = 50mV (FS) + 0.1µF 2 DC Motor 6.8nF 31 +15V 37 100kΩ 38 100kΩ 32 3 2 6.8nF 6 OPA27 –10V to +10V or 90kΩ 120Vrms 100A –15V 22kΩ 4 3 3-Phase Y-Connected Power Transformer 22kΩ – 10kΩ 200kΩ 1 + 2 4.7V 0.1µF 4.7V 200kΩ FIGURE 12. Isolated Current Monitoring Applications. +VSS1 8 7.87k Ω 100µA +15V 7 4 0.1µF 4 3 REF200 5 1 6 2 3 – 31 150Ω 38 ISO212P 200µA –VSS1 1 37 1 to 5V 32 + 5 6 PT100 –200°C to 850°C 2 10µF 10µF +VSS1–VSS1 FIGURE 13. Isolated Temperature Sensing and Amplification. ® 11 ISO212P