IL300 Linear Optocoupler

Dimensions in inches (mm)

Pin 1 ID. FEATURES .021 (0.527) .130 (3.302) .240 (6.096) .260 (6.604) • Couples AC and DC signals .035 (0.889) .150 (3.810) .100 (2.540) • 0.01% Servo Linearity 1 8 • Wide Bandwidth, >200 kHz 4° • High Gain Stability, ±0.05%/C 2 7 .016 (.406) .040 (1.016) • Low Input-Output Capacitance .020 (.508 ) .050 (1.270 ) 3 6 • Low Power Consumption, < 15 mw 4 5 .050 (1.270) • Isolation Test Voltage, 5300 VRMS, .280 (7.112) .380 (9.652) .010 (0.254) REF. 1.0 sec. .400 (10.16) • Internal Insulation Distance, >0.4 mm .330 (8.382) .300 Typ. for VDE (7.62) Typ. .020 (0.508) REF. .010 (0.254) REF. • Underwriters Lab File #E52744 V 1 8 •DE VDE Approval #0884 (Available with 2 7 Option 1, Add -X001 Suffix) K1 K2 3° 10° • IL300G Replaced by IL300-X006 3 6 9 • APPLICATIONS 4 5 .008 (0.203) .110 (2.794) • Power Supply Feedback Voltage/Current .012 (0.305) .130 (3.302) • Medical Sensor Isolation • Audio Signal Interfacing DESCRIPTION (continued) • Isolate Process Control Transducers • Digital Telephone Isolation 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 DESCRIPTION LED current to force sufficient photocurrent to keep the node voltage (Vb) equal to Va. The IL300 Linear Optocoupler consists of an AlGaAs IRLED irradiating an isolated feed- The output photodiode is connected to a non-inverting voltage follower amplifier. back and an output PIN photodiode in a The photodiode load resistor, R2, performs the current to voltage conversion. The bifurcated arrangement. The feedback pho- output amplifier voltage is the product of the output forward gain (K2) times the todiode captures a percentage of the LED's LED current and photodiode load, R2 (VO=IF • K2 • R2). flux and generates a control signal (IP1) that Therefore, the overall transfer gain (VO/VIN) becomes the ratio of the product of can be used to servo the LED drive current. the output forward gain (K2) times the photodiode load resistor (R2) to the prod- This technique compensates for the LED's uct of the feedback transfer gain (K1) times the input resistor (R1). This reduces non-linear, time, and temperature character- to VO/VIN=(K2 • R2)/(K1 • R1). The overall transfer gain is completely indepen- istics. The output PIN photodiode produces dent of the LED forward current. The IL300 transfer gain (K3) is expressed as the an output signal (IP2) that is linearly related ratio of the output gain (K2) to the feedback gain (K1). This shows that the circuit to the servo optical flux created by the LED. gain becomes the product of the IL300 transfer gain times the ratio of the output The time and temperature stability of the to input resistors [VO/VIN=K3 (R2/R1)]. input-output coupler gain (K3) is insured by using matched PIN photodiodes that accu- Figure 1. Typical application circuit rately track the output flux of the LED. A typical application circuit (Figure 1) uses VCC Va 1 IL300 8 an operational amplifier at the circuit input to + + drive the LED. The feedback photodiode U1 2 7 Vin K2 V sources current to R1 connected to the Vb K1 CC inverting input of U1. The photocurrent, IP1, - IF - VCC 3 6 VCC will be of a magnitude to satisfy the relation- U2 Vout Vc ship of (IP1=VIN /R1). 4 5 + lp 1 R2 R1 lp 2

 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 KI—Servo Gain Emitter The ratio of the input photodiode current (IP1) to the LED cur- rent (IF). i.e., K1 = IP1/ IF. Power Dissipation PLED — 160 mW ° (TA=25 C) K2—Forward Gain Derate Linearly from 25°C ——2.13 mW/°C The ratio of the output photodiode current (IP2) to the LED current (IF), i.e., K2 = IP2/ IF. Forward Current lF — 60 mA

K3—Transfer Gain Surge Current lpk — 250 mA (Pulse width <10µs) The Transfer Gain is the ratio of the Forward Gain to the Servo gain, i.e., K3 = K2/K1. Reverse Voltage VR — 5.0 V Thermal Resistance R — 470 K/W ∆K3—Transfer Gain Linearity th ° The percent deviation of the Transfer Gain, as a function of Junction Temperature TJ — 100 C LED or temperature from a specific Transfer Gain at a fixed Detector LED current and temperature. 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 cur- Reverse Voltage VR — 50 V rent is proportional to the incident optical flux supplied by the ° LED emitter. The diode is operated in the photovoltaic or pho- Junction Temperature TJ — 100 C toconductive mode. In the photovoltaic mode the diode func- Thermal Resistance Rth — 1500 K/W tions as a current source in parallel with a forward biased silicon diode. Coupler The magnitude of the output current and voltage is depen- Total Package — ° dent upon the load resistor and the incident LED optical flux. Dissipation at 25 C PT 210 mW When operated in the photoconductive mode the diode is Derate linearly from 25°C ——2.8 mW/°C connected to a bias supply which reverse biases the silicon ° diode. The magnitude of the output current is directly propor- Storage Temperature TS –55 150 C tional to the LED incident optical flux. ° 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 Isolation Resistance — — ° 12 Ω nm operates efficiently with drive current from 500 µA to 40 VIO=500 V, TA=25 C 10 V =500 V, T =100°C 1011 Ω mA. Best linearity can be obtained at drive currents between IO A 5.0 mA to 20 mA. Its output flux typically changes by –0.5%/°C over the above operational current range.

 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA IL300 www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) 2–129 April 3, 2000-14

° Characteristics TA=25 C Symbol Min. Typ. Max. Unit Test Condition LED Emitter

Forward Voltage VF — 1.25 1.50 V IF=10 mA ∆ ∆° ° VF Temperature Coefficient VF/ C —–2.2 — mV/ C µ Reverse Current IR — 1.0 10 A VR=5.0 V

Junction Capacitance CJ — 15 — pF VF=0 V, f=1.0 MHz ∆ ∆ Ω Dynamic Resistance VF/ IF — 6.0 — IF=10 mA µ ∆ Switching Time tr — 1.0 — s IF=2.0 mA, IFq=10 mA µ ∆ tf 1.0 s IF=2.0 mA, IFq=10 mA Detector µ Dark Current ID — 1.0 25 nA Vdet=-15 V, IF=0 A

Open Circuit Voltage VD — 500 — mV IF=10 mA µ Short Circuit Current ISC — 70 — A IF=10 mA

Junction Capacitance CJ — 12 — pF VF=0 V, f=1.0 MHz 14 √ Noise Equivalent Power NEP — 4 x 10 — W/ Hz Vdet=15 V Coupled Characteristics

K1, Servo Gain (IP1/IF) K1 0.0050 0.007 0.011 — IF=10 mA, Vdet=-15 V µ Servo Current, see Note 1, 2 IP1 — 70 — A IF=10 mA, Vdet=-15 V

K2, Forward Gain (IP2/IF) K2 0.0036 0.007 0.011 — IF=10 mA, Vdet=-15 V µ Forward Current IP2 — 70 — A IF=10 mA, Vdet=-15 V

K3, Transfer Gain (K2/K1) K3 0.56 1.00 1.65 K2/K1 IF=10 mA, Vdet=-15 V See Note 1, 2 ∆ ± 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 Photoconductive Operation ± Ω, Frequency Response BW (–3 db) — 200 — kHz IFq=10 mA, MOD= 4.0 mA, RL=50 Phase Response at 200 kHz ——–45 — Deg. Vdet=–15 V µ Rise Time tr — 1.75 — s — µ Fall Time tf — 1.75 — s — Package

Input-Output Capacitance 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 Ω Common Mode Rejection Ratio CMRR — 130 — dB f=60 Hz, RL=2.2 K

Notes 2. Bin Categories: All IL300s are sorted into a K3 bin, indicated by an 1. Bin Sorting: alpha character that is marked on the part. The bins range from “A” K3 (transfer gain) is sorted into bins that are ±6%, as follows: through “J”. Bin A=0.557–0.626 The IL300 is shipped in tubes of 50 each. Each tube contains only Bin B=0.620–0.696 one category of K3. The category of the parts in the tube is marked Bin C=0.690–0.773 on the tube label as well as on each individual part. Bin D=0.765–0.859 3. Category Options: Standard IL300 orders will be shipped from the Bin E=0.851–0.955 categories that are available at the time of the order. Any of the ten Bin F=0.945–1.061 categories may be shipped. For customers requiring a narrower Bin G=1.051–1.181 selection of bins, four different bin option parts are offered. Bin H=1.169–1.311 IL300-DEFG: Order this part number to receive categories Bin I=1.297–1.456 D,E,F,G only. Bin J=1.442–1.618 IL300-EF: Order this part number to receive categories E, F only. K3=K2/K1. K3 is tested at IF=10 mA, Vdet=–15 V. 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 IL300 www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) 2–130 April 3, 2000-14 Figure 2. LED forward current vs. forward voltage Figure 6. Normalized servo photocurrent vs. LED 35 current and temperature 3.0 30 Normalized to: IP1@ IF=10 mA, 2.5 T =25°C, 0°C A 25 V =–15 V 25°C D 2.0 20 50°C ° 1.5 75 C 15 1.0 10 IF - LED Current mA 5 0.5 Normalized Photocurrent

0 0.0 1.0 1.1 1.2 1.3 1.4 0 5 10 15 20 25 VF - LED Forward Voltage - V IF - LED Current - mA

Figure 3. LED forward current vs. forward voltage Figure 7. Normalized servo photocurrent vs. LED 100 current and temperature 10 Normalized to: IP1@ IF=10 mA, T =25°C, 0°C A 10 V =–15 V 25°C D 1 50°C 75°C

1

IF - LED Current mA .1

.1

1.0 1.1 1.2 1.3 1.4 IP1 - Normalized Photocurrent .01 VF - LED Forward Voltage - V .1 1 10 100 IF - LED Current - mA Figure 4. Servo photocurrent vs. LED current and temperature Figure 8. Servo gain vs. LED current and temperature 300 1.2 ° A 0 C

µ ° V = 15 V 0 C D 25°C 250 ° 1.0 25 C ° ° 50 C 50 C 0.8 ° 200 75°C 75 C ° 0.6 85 C 150 0.4 100 0.2 50 0.0 NK1 - Normalized Servo Gain NK1 - Normalized Servo IP1 - Servo Photocurrent - IP1 - Servo 0 .1 1 10 100 .1 1 10 100 IF - LED Current - mA IF - LED Current - mA

Figure 5. Servo photocurrent vs. LED current Figure 9. Normalized servo gain vs. LED current and temperature and temperature 1000 1.2 A 0°C µ 0°C VD=–15 V 25°C 25°C 1.0 ° 50°C 50 C ° 100 75°C 0.8 75 C 100°C 0.6

10 0.4 Normalized to: 0.2 IF=10 mA, TA=25°C IP1 - Servo Photocurrent - IP1 - Servo 1 Gain NK1 - Normalized Servo 0.0 .1 1 10 100 .1 1 10 100 I - LED Current - mA F IF - LED Current - mA

 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA IL300 www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) 2–131 April 3, 2000-14 Figure 10. Transfer gain vs. LED current and temperature Figure 14. Common mode rejection 1.010 -60

0°C -70

1.005 -80 25°C -90 1.000 50°C -100 ° 0.995 75 C -110

CMRR - Rejection Ratio dB -120 K3 - Transfer Gain - (K2/K1) Transfer K3 - 0.990 -130 0 5 10 15 20 25 10 100 1000 10000 100000 1000000 IF - LED Current - mA F - Frequency - Hz

Figure 11. Normalized transfer gain vs. LED current Figure 15. Photodiode junction capacitance vs. reverse and temperature voltage 1.010 14 Normalized to: 0°C 12 IF=10 mA, 1.005 TA=25°C 10 25°C 8 1.000 50°C 6

75°C 4 0.995 2 Capacitance - pF

K3 - Transfer Gain - (K2/K1) Transfer K3 - 0.990 0 0 5 10 15 20 25 02 46810 Voltage - V IF - LED Current - mA det

Application Considerations Figure 12. Amplitude response vs. frequency In applications such as monitoring the output voltage from a 5 IF=10 mA, Mod=±2.0 mA (peak) line powered switch mode power supply, measuring bioelectric signals, interfacing to industrial transducers, or making floating 0 RL=1.0 KΩ current measurements, a galvanically isolated, DC coupled -5 interface is often essential. The IL300 can be used to construct an amplifier that will meet these needs. -10 The IL300 eliminates the problems of gain nonlinearity and drift R =10 KΩ L induced by time and temperature, by monitoring LED output -15 flux.

Amplitude Response - dB A PIN photodiode on the input side is optically coupled to the -20 104 105 106 LED and produces a current directly proportional to flux falling F - Frequency - Hz on it. This photocurrent, when coupled to an amplifier, provides the servo signal that controls the LED drive current. Figure 13. Amplitude and phase response vs. frequency The LED flux is also coupled to an output PIN photodiode. The output photodiode current can be directly or amplified to sat- 5 45 dB isfy the needs of succeeding circuits.

PHASE ° 0 0 Isolated Feedback Amplifier The IL300 was designed to be the central element of DC cou- -5 -45 pled isolation amplifiers. Designing the IL300 into an amplifier that provides a feedback control signal for a line powered -10 -90 switch mode power is quite simple, as the following example IFq=10 mA will illustrate. Mod=±4.0 mA -15 -135 TA=25°C Ø - Phase Response See Figure 17 for the basic structure of the switch mode supply Amplitude Response - dB RL=50 Ω using the Infineon TDA4918 Push-Pull Switched Power Supply -20 -180 Control Chip. Line isolation and insulation is provided by the 103 104 105 106 107 high frequency transformer. The voltage monitor isolation will F - Frequency - Hz be provided by the IL300.

 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA IL300 www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) 2–132 April 3, 2000-14 The isolated amplifier provides the PWM control signal which is Figure 16. Isolated control amplifier derived from the output supply voltage. Figure 16 more closely shows the basic function of the amplifier. + ISO R1 To Control Voltage The control amplifier consists of a voltage divider and a non- AMP Input Monitor inverting unity gain stage. The TDA4918 data sheet indicates +1 that an input to the control amplifier is a high quality opera- - tional amplifier that typically requires a +3.0 V signal. Given R2 this information, the amplifier circuit topology shown in Figure 18 is selected. The power supply voltage is scaled by R1 and R2 so that there For best input offset compensation at U1, R2 will equal R3. The is +3.0 V at the non-inverting input (Va) of U1. This voltage is value of R1 can easily be calculated from the following. offset by the voltage developed by photocurrent flowing through R3. This photocurrent is developed by the optical flux VMONITOR R1= R2------– 1 created by current flowing through the LED. Thus as the scaled V monitor voltage (Va) varies it will cause a change in the LED a current necessary to satisfy the differential voltage needed The value of R5 depends upon the IL300 Transfer Gain (K3). K3 across R3 at the inverting input. is targeted to be a unit gain device, however to minimize the The first step in the design procedure is to select the value of part to part Transfer Gain variation, Infineon offers K3 graded into ±5 % bins. R5 can determined using the following equation, R3 given the LED quiescent current (IFq) and the servo gain (K1). For this design, I =12 mA. Figure 4 shows the servo VOUT R3()R1 + R2 Fq R5= ------• ------photocurrent at I is found to be 100 µA. With this data R3 can Fq VMONITOR R2K3 be calculated. Vb 3V Or if a unity gain amplifier is being designed R3= ------= ------Ω µ = 30K IPl 100 A (VMONITOR=VOUT, R1=0), the equation simplifies to: R3 R5= ------K3 Figure 17. Switch mode power supply

110/ DC OUTPUT AC/DC AC/DC 220 SWITCH XFORMER MAIN RECTIFIER RECTIFIER

SWITCH CONTROL MODE ISOLATED REGULATOR FEEDBACK TDA4918

Figure 18. DC coupled power supply feedback amplifier

R1 IL300 20 KΩ 1 8 3 7 R4 Vmonitor + VCC 100 Ω Va U1 6 LM201 2 7 R2 K2 2 1 K1 30 KΩ Vb - 8 VCC 3 6 VCC 4 100 pF Vout To 4 5 control R3 R5 input 30 KΩ 30 KΩ

 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA IL300 www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) 2–133 April 3, 2000-14 Table 1 gives the value of R5 given the production K3 bins. Figure 19. Transfer gain 3.75 Table 1, R5 selection Vout = 14.4 mV + 0.6036 x Vin 3.50 Bins Min. Max. R5 1% LM 201 Ta = 25°C 3 Resistor KΩ KΩ 3.25 Typ. 3.00 A 0.560 0.623 0.59 50.85 51.1 B 0.623 0.693 0.66 45.45 45.3 2.75 C 0.693 0.769 0.73 41.1 41.2 2.50 Vout - Ooutput Voltage V

D 0.769 0.855 0.81 37.04 37.4 2.25 4.0 4.5 5.0 5.5 6.0 E 0.855 0.950 0.93 32.26 32.4 Vin - Input Voltage - V F 0.950 1.056 1.00 30.00 30.0 Figure 20. Linearity error vs. input voltage G 1.056 1.175 1.11 27.03 27.0 0.025 H 1.175 1.304 1.24 24.19 24.0 0.020 I 1.304 1.449 1.37 21.90 22.0 LM201 0.015

J 1.449 1.610 1.53 19.61 19.4 0.010

The last step in the design is selecting the LED current limiting 0.005 resistor (R4). The output of the operational amplifier is targeted 0.000

to be 50% of the VCC, or 2.5 V. With an LED quiescent current Linearity Error - % -0.005 of 12 mA the typical LED (VF) is 1.3 V. Given this and the oper- ational output voltage, R4 can be calculated. -0.010 V – V -0.015 opamp F 2.5V – 1.3V 4.0 4.5 5.0 5.5 6.0 R4= ------= ------= 1 0 0 Ω Vin - Input Voltage - V IFq 12mA The AC characteristics are also quite impressive offering a - 3.0 dB bandwidth of 100 kHz, with a –45° phase shift at 80 kHz The circuit was constructed with an LM201 differential opera- as shown in Figure 21. tional amplifier using the resistors selected. The amplifier was compensated with a 100 pF capacitor connected between Figure 21. Amplitude and phase power supply control pins 1 and 8. 2 45 The DC transfer characteristics are shown in Figure 19. The dB amplifier was designed to have a gain of 0.6 and was mea- PHASE 0 0 ° sured 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 lin- -2 -45 earity 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. -4 -90

-6 -135 Phase Response - Amplitude Response - dB

-8 -180 103 104 105 106 F - Frequency - Hz

The same procedure can be used to design isolation amplifiers that accept bipolar signals referenced to ground. These amplifi- ers 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.

Vref1 Vref1 R3= ------= ------IP1 K1IFq

 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA IL300 www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) 2–134 April 3, 2000-14 Figure 22. Non-inverting and inverting amplifiers

Non-Inverting Input Non-Inverting Output +Vref2 R5 Vin 7 –Vcc 3 + Vcc 1 IL300 8 100Ω R6 R1 6 2 – 7 R2 2 7 Vcc 2 –Vcc Vcc 6 – +Vcc 3 6 4 Vo 20pF 3 + –Vcc 4 5 4 R3 R4 –Vref1

Inverting Input Inverting Output

Vin 7 3 + Vcc Ω +Vref2 6 100 IL300 R1 R2 1 8 +Vcc 2 Vcc 3 + 7 – 2 7 Vcc 4 20pF Vcc 6 3 6 Vout 2 R3 4 5 – –Vcc –Vcc 4 +Vref1 R4

Table 2. Optolinear amplifiers Amplifier Input Output Gain Offset Inverting Inverting VOUT K3 R4 R2 Vref1 R4 K3 Non-Inverting = Vref2= VIN R3 (R1+R2) R3 Non-Inverting Non-Inverting VOUT K3 R4 R2 (R5+R6) –Vref1 R4 (R5+R6) K3 = Vref2= VIN R3 R5 (R1 +R2) R3 R6 Inverting Non-Inverting VOUT –K3 R4 R2 (R5+R6) Vref1 R4 (R5+R6) K3 Inverting = Vref2= VIN R3 R5 (R1 +R2) R3 R6 Non-Inverting Inverting VOUT –K3 R4 R2 –Vref1 R4 K3 = Vref2= VIN R3 (R1 +R2) R3

These amplifiers provide either an inverting or non-inverting transfer gain based upon the type of input and output ampli- fier. 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 IL300 www.infineon.com/opto • 1-888-Infineon (1-888-463-4636) 2–135 April 3, 2000-14