IL300 Linear Optocoupler Dimensions in inches (mm) FEATURES • Couples AC and DC signals • 0.01% Servo Linearity • Wide Bandwidth, >200 kHz • High Gain Stability, ±0.05%/C • Low Input-Output Capacitance • Low Power Consumption, < 15 mw • Isolation Test Voltage, 5300 VRMS, 1.0 sec. • Internal Insulation Distance, >0.4 mm for VDE • Underwriters Lab File #E52744 • VDE Approval #0884 (Available with Option 1, Add -X001 Suffix) The IL300 Linear Optocoupler consists of an AlGaAs IRLED irradiating an isolated feedback and an output PIN photodiode in a bifurcated arrangement. The feedback photodiode captures a percentage of the LED's flux and generates a control signal (IP1) that can be used to servo the LED drive current. This technique compensates for the LED's non-linear, time, and temperature characteristics. The output PIN photodiode produces an output signal (IP2) that is linearly related to the servo optical flux created by the LED. The time and temperature stability of the input-output coupler gain (K3) is insured by using matched PIN photodiodes that accurately track the output flux of the LED. A typical application circuit (Figure 1) uses an operational amplifier at the circuit input to drive the LED. The feedback photodiode sources current to R1 connected to the inverting input of U1. The photocurrent, IP1, will be of a magnitude to satisfy the relationship of (IP1=VIN /R1). .240 (6.096) .260 (6.604) 1 8 2 7 3 6 4 5 4° .016 (.406) .020 (.508 ) .040 (1.016) .050 (1.270 ) .050 (1.270) .380 (9.652) .400 (10.16) .280 (7.112) .330 (8.382) .020 (0.508) REF. .010 (0.254) REF. .300 Typ. (7.62) Typ. .010 (0.254) REF. 8 1 V DESCRIPTION Pin 1 ID. .100 (2.540) D E APPLICATIONS • Power Supply Feedback Voltage/Current • Medical Sensor Isolation • Audio Signal Interfacing • Isolate Process Control Transducers • Digital Telephone Isolation .130 (3.302) .150 (3.810) .021 (0.527) .035 (0.889) 2 K1 K2 7 3 6 4 5 3° 9 10° .008 (0.203) .012 (0.305) .110 (2.794) .130 (3.302) DESCRIPTION (continued) The magnitude of this current is directly proportional to the feedback transfer gain (K1) times the LED drive current (VIN /R1=K1 • IF). The op-amp will supply LED current to force sufficient photocurrent to keep the node voltage (Vb) equal to Va. The output photodiode is connected to a non-inverting voltage follower amplifier. The photodiode load resistor, R2, performs the current to voltage conversion. The output amplifier voltage is the product of the output forward gain (K2) times the LED current and photodiode load, R2 (VO=IF • K2 • R2). Therefore, the overall transfer gain (VO/VIN) becomes the ratio of the product of the output forward gain (K2) times the photodiode load resistor (R2) to the product of the feedback transfer gain (K1) times the input resistor (R1). This reduces to VO/VIN=(K2 • R2)/(K1 • R1). The overall transfer gain is completely independent of the LED forward current. The IL300 transfer gain (K3) is expressed as the ratio of the output gain (K2) to the feedback gain (K1). This shows that the circuit gain becomes the product of the IL300 transfer gain times the ratio of the output to input resistors [VO/VIN=K3 (R2/R1)]. Figure 1. Typical application circuit VCC + Vin Va 1 + 2 U1 Vb - IF K1 VCC lp 1 R1 3 4 IL300 8 K2 7 6 5 lp 2 VCC VCC Vc U2 Vout + R2 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) 2–128 April 3, 2000-14 IL300 Terms Absolute Maximum Ratings Symbol Min. Max. Unit Power Dissipation (TA=25°C) PLED — 160 mW KI—Servo Gain The ratio of the input photodiode current (IP1) to the LED current (IF). i.e., K1 = IP1/ IF. K2—Forward Gain Emitter The ratio of the output photodiode current (IP2) to the LED current (IF), i.e., K2 = IP2/ IF. Derate Linearly from 25°C — — 2.13 mW/°C Forward Current lF — 60 mA K3—Transfer Gain Surge Current (Pulse width <10µs) lpk — 250 mA Reverse Voltage VR — 5.0 V ∆K3—Transfer Gain Linearity Thermal Resistance Rth — 470 K/W The percent deviation of the Transfer Gain, as a function of LED or temperature from a specific Transfer Gain at a fixed LED current and temperature. Junction Temperature TJ — 100 °C Detector Power Dissipation PDET — 50 mA Photodiode Derate linearly from 25°C — — 0.65 mW/°C A silicon diode operating as a current source. The output current is proportional to the incident optical flux supplied by the LED emitter. The diode is operated in the photovoltaic or photoconductive mode. In the photovoltaic mode the diode functions as a current source in parallel with a forward biased silicon diode. Reverse Voltage VR — 50 V Junction Temperature TJ — 100 °C Thermal Resistance Rth — 1500 K/W 210 mW The Transfer Gain is the ratio of the Forward Gain to the Servo gain, i.e., K3 = K2/K1. Coupler The magnitude of the output current and voltage is dependent upon the load resistor and the incident LED optical flux. When operated in the photoconductive mode the diode is connected to a bias supply which reverse biases the silicon diode. The magnitude of the output current is directly proportional to the LED incident optical flux. Total Package Dissipation at 25°C PT Derate linearly from 25°C — — 2.8 mW/°C Storage Temperature TS –55 150 °C Operating Temperature TOP –55 100 °C LED (Light Emitting Diode) Isolation Test Voltage — 5300 — VRMS An infrared emitter constructed of AlGaAs that emits at 890 nm operates efficiently with drive current from 500 µA to 40 mA. Best linearity can be obtained at drive currents between 5.0 mA to 20 mA. Its output flux typically changes by –0.5%/°C over the above operational current range. Isolation Resistance VIO=500 V, TA=25°C VIO=500 V, TA=100°C — 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) — 1012 1011 — Ω Ω IL300 2–129 April 3, 2000-14 Characteristics TA=25°C Symbol Min. Typ. Max. Unit Test Condition Forward Voltage VF — 1.25 1.50 V IF=10 mA VF Temperature Coefficient ∆VF/∆°C — –2.2 — mV/°C Reverse Current IR — 1.0 10 µA VR=5.0 V Junction Capacitance CJ — 15 — pF VF=0 V, f=1.0 MHz Dynamic Resistance ∆VF/∆IF — 6.0 — Ω IF=10 mA Switching Time tr tf — 1.0 1.0 — µs µs ∆IF=2.0 mA, IFq=10 mA ∆IF=2.0 mA, IFq=10 mA Dark Current ID — 1.0 25 nA Vdet=-15 V, IF=0 µA Open Circuit Voltage VD — 500 — mV IF=10 mA Short Circuit Current ISC — 70 — µA IF=10 mA Junction Capacitance CJ — 12 — pF VF=0 V, f=1.0 MHz NEP — 4 x 1014 — W/√Hz Vdet=15 V K1, Servo Gain (IP1/IF) K1 0.0050 0.007 0.011 — IF=10 mA, Vdet=-15 V Servo Current, see Note 1, 2 IP 1 — 70 — µA IF=10 mA, Vdet=-15 V K2, Forward Gain (IP2/IF) K2 0.0036 0.007 0.011 — IF=10 mA, Vdet=-15 V Forward Current IP 2 — 70 — µA IF=10 mA, Vdet=-15 V K3, Transfer Gain (K2/K1) See Note 1, 2 K3 0.56 1.00 1.65 K2/K1 IF=10 mA, Vdet=-15 V Transfer Gain Linearity ∆K3 — ±0.25 — % IF=1.0 to 10 mA Transfer Gain Linearity ∆K3 — ±0.5 — % IF=1.0 to 10 mA, TA=0°C to 75°C Frequency Response BW (–3 db) — 200 — kHz IFq=10 mA, MOD=±4.0 mA, RL=50 Ω, Phase Response at 200 kHz — — –45 — Deg. Vdet=–15 V Rise Time tr — 1.75 — µs — Fall Time tf — 1.75 — µs — CIO — 1.0 — pF VF=0 V, f=1.0 MHz Common Mode Capacitance Ccm — 0.5 — pF VF=0 V, f=1.0 MHz Common Mode Rejection Ratio CMRR — 130 — dB f=60 Hz, RL=2.2 KΩ LED Emitter Detector Noise Equivalent Power Coupled Characteristics Photoconductive Operation Package Input-Output Capacitance Notes 1. Bin Sorting: K3 (transfer gain) is sorted into bins that are ±6%, as follows: Bin A=0.557–0.626 Bin B=0.620–0.696 Bin C=0.690–0.773 Bin D=0.765–0.859 Bin E=0.851–0.955 Bin F=0.945–1.061 Bin G=1.051–1.181 Bin H=1.169–1.311 Bin I=1.297–1.456 Bin J=1.442–1.618 K3=K2/K1. K3 is tested at IF=10 mA, Vdet=–15 V. 2. Bin Categories: All IL300s are sorted into a K3 bin, indicated by an alpha character that is marked on the part. The bins range from “A” through “J”. The IL300 is shipped in tubes of 50 each. Each tube contains only one category of K3. The category of the parts in the tube is marked on the tube label as well as on each individual part. 3. Category Options: Standard IL300 orders will be shipped from the categories that are available at the time of the order. Any of the ten categories may be shipped. For customers requiring a narrower selection of bins, four different bin option parts are offered. IL300-DEFG: Order this part number to receive categories D,E,F,G only. IL300-EF: Order this part number to receive categories E, F only. IL300-E: Order this part number to receive category E only. IL300-F: Order this part number to receive category F only. 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) IL300 2–130 April 3, 2000-14 Figure 6. Normalized servo photocurrent vs. LED current and temperature Figure 2. LED forward current vs. forward voltage 35 Normalized Photocurrent IF - LED Current - mA 3.0 30 25 20 15 10 5 Normalized to: IP1@ IF=10 mA, TA=25°C, 0°C VD=–15 V 25°C 50°C 75°C 2.5 2.0 1.5 1.0 0.5 0.0 0 1.0 1.1 1.2 1.3 0 1.4 5 VF - LED Forward Voltage - V Figure 3. LED forward current vs. forward voltage IP1 - Normalized Photocurrent IF - LED Current - mA 10 1 1.1 1.2 1.3 VF - LED Forward Voltage - V 1.4 250 200 VD = 15 V 150 100 50 0 .1 1 10 IF - LED Current - mA NK1 - Normalized Servo Gain IP1 - Servo Photocurrent - µA VD=–15 V 1 1 10 .1 .01 .1 1 10 IF - LED Current - mA 100 1.2 0°C 25°C 50°C 75°C 85°C 1.0 0.8 0.6 0.4 0.2 0.0 1 10 100 Figure 9. Normalized servo gain vs. LED current and temperature 10 .1 1 IF - LED Current - mA 1000 100 Normalized to: IP1@ IF=10 mA, TA=25°C, 0°C VD=–15 V 25°C 50°C 75°C .1 100 Figure 5. Servo photocurrent vs. LED current and temperature 0°C 25°C 50°C 75°C 10 Figure 8. Servo gain vs. LED current and temperature 300 NK1 - Normalized Servo Gain IP1 - Servo Photocurrent - µA Figure 4. Servo photocurrent vs. LED current and temperature 0°C 25°C 50°C 75°C 25 Figure 7. Normalized servo photocurrent vs. LED current and temperature 100 .1 1.0 10 15 20 IF - LED Current - mA 100 1.2 0°C 25°C 50°C 75°C 100°C 1.0 0.8 0.6 0.4 Normalized to: IF=10 mA, TA=25°C 0.2 0.0 .1 IF - LED Current - mA 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) 1 10 IF - LED Current - mA 100 IL300 2–131 April 3, 2000-14 Figure 14. Common mode rejection -60 1.010 CMRR - Rejection Ratio - dB K3 - Transfer Gain - (K2/K1) Figure 10. Transfer gain vs. LED current and temperature 0°C 1.005 25°C 1.000 50°C 75°C 0.995 0.990 0 5 10 15 20 IF - LED Current - mA -100 -110 -120 100 1000 10000 100000 1000000 Figure 15. Photodiode junction capacitance vs. reverse voltage 14 Normalized to: IF=10 mA, TA=25°C 0°C 1.005 25°C 1.000 12 Capacitance - pF K3 - Transfer Gain - (K2/K1) -90 F - Frequency - Hz 1.010 50°C 75°C 0.995 10 8 6 4 2 0 0.990 0 5 10 15 20 IF - LED Current - mA 25 0 5 -5 -15 105 F - Frequency - Hz 0 -45 -5 -90 -10 IFq=10 mA Mod=±4.0 mA TA=25°C RL=50 Ω -15 -20 103 104 105 106 F - Frequency - Hz -135 Ø - Phase Response - ° 45 dB PHASE 0 10 A PIN photodiode on the input side is optically coupled to the LED and produces a current directly proportional to flux falling on it. This photocurrent, when coupled to an amplifier, provides the servo signal that controls the LED drive current. 106 Figure 13. Amplitude and phase response vs. frequency 5 8 The IL300 eliminates the problems of gain nonlinearity and drift induced by time and temperature, by monitoring LED output flux. RL=10 KΩ -20 104 6 In applications such as monitoring the output voltage from a line powered switch mode power supply, measuring bioelectric signals, interfacing to industrial transducers, or making floating current measurements, a galvanically isolated, DC coupled interface is often essential. The IL300 can be used to construct an amplifier that will meet these needs. RL=1.0 KΩ -10 4 Application Considerations IF=10 mA, Mod=±2.0 mA (peak) 0 2 Voltage - Vdet Figure 12. Amplitude response vs. frequency Amplitude Response - dB -80 -130 10 25 Figure 11. Normalized transfer gain vs. LED current and temperature Amplitude Response - dB -70 -180 107 The LED flux is also coupled to an output PIN photodiode. The output photodiode current can be directly or amplified to satisfy the needs of succeeding circuits. Isolated Feedback Amplifier The IL300 was designed to be the central element of DC coupled isolation amplifiers. Designing the IL300 into an amplifier that provides a feedback control signal for a line powered switch mode power is quite simple, as the following example will illustrate. See Figure 17 for the basic structure of the switch mode supply using the Infineon TDA4918 Push-Pull Switched Power Supply Control Chip. Line isolation and insulation is provided by the high frequency transformer. The voltage monitor isolation will be provided by the IL300. 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) IL300 2–132 April 3, 2000-14 The isolated amplifier provides the PWM control signal which is derived from the output supply voltage. Figure 16 more closely shows the basic function of the amplifier. Figure 16. Isolated control amplifier The power supply voltage is scaled by R1 and R2 so that there is +3.0 V at the non-inverting input (Va) of U1. This voltage is offset by the voltage developed by photocurrent flowing through R3. This photocurrent is developed by the optical flux created by current flowing through the LED. Thus as the scaled monitor voltage (Va) varies it will cause a change in the LED current necessary to satisfy the differential voltage needed across R3 at the inverting input. The first step in the design procedure is to select the value of R3 given the LED quiescent current (IFq) and the servo gain (K1). For this design, IFq=12 mA. Figure 4 shows the servo photocurrent at IFq is found to be 100 µA. With this data R3 can be calculated. V 3V R3 = -----b- = ----------------- = 30KΩ I Pl 100µA + ISO AMP +1 To Control Input The control amplifier consists of a voltage divider and a noninverting unity gain stage. The TDA4918 data sheet indicates that an input to the control amplifier is a high quality operational amplifier that typically requires a +3.0 V signal. Given this information, the amplifier circuit topology shown in Figure 18 is selected. R1 Voltage Monitor - R2 For best input offset compensation at U1, R2 will equal R3. The value of R1 can easily be calculated from the following. V MONITOR R1 = R2 --------------------------- – 1 Va The value of R5 depends upon the IL300 Transfer Gain (K3). K3 is targeted to be a unit gain device, however to minimize the part to part Transfer Gain variation, Infineon offers K3 graded into ± 5 % bins. R5 can determined using the following equation, V OUT R3 ( R1 + R2 ) R5 = -------------------------- • ----------------------------------V MONITOR R2K3 Or if a unity gain amplifier is being designed (VMONITOR=VOUT, R1=0), the equation simplifies to: R3 R5 = ------K3 Figure 17. Switch mode power supply DC OUTPUT 110/ 220 MAIN AC/DC RECTIFIER SWITCH SWITCH MODE REGULATOR TDA4918 AC/DC RECTIFIER XFORMER CONTROL ISOLATED FEEDBACK Figure 18. DC coupled power supply feedback amplifier Vmonitor R1 20 KΩ R2 30 KΩ IL300 7 V 3 + R4 CC 100 Ω Va 6 U1 LM201 2 1 Vb 8 VCC 4 100 pF - R3 30 KΩ 1 8 2 K2 7 K1 3 6 4 5 VCC Vout R5 30 KΩ 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) To control input IL300 2–133 April 3, 2000-14 Table 1 gives the value of R5 given the production K3 bins. Figure 19. Transfer gain Bins Min. Max. 3 R5 Resistor KΩ 1% KΩ Typ. A 0.560 0.623 0.59 50.85 51.1 B 0.623 0.693 0.66 45.45 45.3 C 0.693 0.769 0.73 41.1 41.2 D 0.769 0.855 0.81 37.04 37.4 E 0.855 0.950 0.93 32.26 32.4 F 0.950 1.056 1.00 30.00 30.0 G 1.056 1.175 1.11 27.03 27.0 H 1.175 1.304 1.24 24.19 24.0 I 1.304 1.449 1.37 21.90 22.0 J 1.449 1.610 1.53 19.61 19.4 Vout - Ooutput Voltage - V 3.75 Table 1, R5 selection Vout = 14.4 mV + 0.6036 x Vin 3.50 LM 201 Ta = 25°C 3.25 3.00 2.75 2.50 2.25 4.0 4.5 Vin 5.0 5.5 - Input Voltage - V 6.0 Figure 20. Linearity error vs. input voltage 0.025 The DC transfer characteristics are shown in Figure 19. The amplifier was designed to have a gain of 0.6 and was measured to be 0.6036. Greater accuracy can be achieved by adding a balancing circuit, and potentiometer in the input divider, or at R5. The circuit shows exceptionally good gain linearity with an RMS error of only 0.0133% over the input voltage range of 4.0 V–6.0 V in a servo mode; see Figure 20. Linearity Error - % 0.010 0.005 0.000 -0.005 -0.015 4.0 4.5 Vin - 5.0 5.5 Input Voltage - V 6.0 The AC characteristics are also quite impressive offering a 3.0 dB bandwidth of 100 kHz, with a –45° phase shift at 80 kHz as shown in Figure 21. Figure 21. Amplitude and phase power supply control 2 45 dB PHASE 0 0 -2 -45 -4 -90 -6 -135 Phase Response - ° The circuit was constructed with an LM201 differential operational amplifier using the resistors selected. The amplifier was compensated with a 100 pF capacitor connected between pins 1 and 8. LM201 0.015 -0.010 Amplitude Response - dB The last step in the design is selecting the LED current limiting resistor (R4). The output of the operational amplifier is targeted to be 50% of the VCC, or 2.5 V. With an LED quiescent current of 12 mA the typical LED (VF) is 1.3 V. Given this and the operational output voltage, R4 can be calculated. V opamp – V F 2.5V – 1.3V R4 = -------------------------------- = ------------------------------ = 100Ω 12mA I Fq 0.020 -180 -8 103 104 105 F - Frequency - Hz 106 The same procedure can be used to design isolation amplifiers that accept bipolar signals referenced to ground. These amplifiers circuit configurations are shown in Figure 22. In order for the amplifier to respond to a signal that swings above and below ground, the LED must be prebiased from a separate source by using a voltage reference source (Vref1). In these designs, R3 can be determined by the following equation. V ref1 V ref1 R3 = ------------- = --------------I P1 K1I Fq 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) IL300 2–134 April 3, 2000-14 Figure 22. Non-inverting and inverting amplifiers Non-Inverting Input Non-Inverting Output –Vcc 3 + 7 Vcc 1 100Ω 6 2 R2 2– –Vcc +Vcc 3 4 20pF 4 R3 Vin R1 +Vref2 R5 IL 300 8 7 6 R6 7 Vcc 2– 6 Vo –Vcc 4 Vcc 3+ 5 R4 –Vref1 Inverting Output Inverting Input Vin R1 3 + 7 Vcc 6 100Ω 1 R2 Vcc +Vcc 2 2 – 4 20pF 3 R3 –Vcc IL 300 8 7 6 4 +Vref2 3+ Vcc 5 2– 7 Vcc –Vcc 4 6 Vout +Vref1 R4 Table 2. Optolinear amplifiers Amplifier Input Output Inverting Inverting Non-Inverting Non-Inverting Inverting Non-Inverting Non-Inverting Inverting Non-Inverting Inverting Gain Offset VOUT K3 R4 R2 = VIN R3 (R1+R2) VOUT K3 R4 R2 (R5+R6) = VIN R3 R5 (R1 +R2) Vref2= Vref2= Vref1 R4 K3 R3 –Vref1 R4 (R5+R6) K3 R3 R6 VOUT –K3 R4 R2 (R5+R6) = VIN R3 R5 (R1 +R2) Vref2= Vref1 R4 (R5+R6) K3 R3 R6 VOUT –K3 R4 R2 = VIN R3 (R1 +R2) Vref2= –Vref1 R4 K3 R3 These amplifiers provide either an inverting or non-inverting transfer gain based upon the type of input and output amplifier. Table 2 shows the various configurations along with the specific transfer gain equations. The offset column refers to the calculation of the output offset or Vref2 necessary to provide a zero voltage output for a zero voltage input. The non-inverting input amplifier requires the use of a bipolar supply, while the inverting input stage can be implemented with single supply operational amplifiers that permit operation close to ground. For best results, place a buffer transistor between the LED and output of the operational amplifier when a CMOS opamp is used or the LED IFq drive is targeted to operate beyond 15 mA. Finally the bandwidth is influenced by the magnitude of the closed loop gain of the input and output amplifiers. Best bandwidths result when the amplifier gain is designed for unity. 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) IL300 2–135 April 3, 2000-14