PS2602L

California Eastern Laboratories Optocoupler Applications DESIGNING FOR OPTOCOUPLERS WITH BASE PIN GENERAL Optocouplers (optical couplers) are designed to isolate electrical output from input for complete elimination of noise. They have been used conventionally as substitutes for relays and pulse transformers. Today's current technology in the area of microcomputers creates new applications for optocouplers. This manual describes the characteristics of typical optocouplers. Also included are notes on designing application circuits for typical optocouplers (with a base pin) for better comprehension. NEC's typical optocouplers with or without base pins are listed on the following pages. 1 PS2600 Series Optocouplers (6-Pin Dual-in-Line Package) Internal connection Absolute Maximum Ratings (TA = 25°C) Features BV (Vr.m.s.) High isolation voltage High VCEO (80 V MIN.) Single transistor High isolation voltage High CTR Darlingtontransistor High isolation voltage A.C. input High VCEO (80 V MIN.) Single transistor High isolation voltage A.C. input High CTR Darlingtontransistor High isolation voltage Large input current Single transistor High isolation voltage A.C. input Large input current Single transistor High isolation voltage High VCEO (300 V MIN.) High CTR Darlingtontransitor High isolation voltage High VCEO (80 V MIN.) Single transistor High isolation voltage High CTR Darlingtontransistors IF (mA) IC(mA) CTR (%) Electric Characteristics (TA = 25°C) tr (µs) (TYP) tr (µs) (TYP) Product name PS2601 * PS2601L PS2602 PS2602L PS2603 * PS2603L PS2604 PS2604L PS2605 * PS2605L 5k 80 50 80 to 600 3 5 5k 80 200 200 to 2500 100 100 5k ±80 50 80 to 600 3 5 PS2606 PS2606L PS2607 * PS2607L 5k ±80 200 200 to 3400 100 100 PS2608 PS2608L PS2621 * PS2621L PS2622 PS2622L PS2625 * PS2625L 5k 150 50 20 to 50 3 5 5k ±150 50 20 to 50 3 5 PS2626 PS2626L PS2633 * PS2633L 5k 80 150 1000 to 15000 100 100 PS2634 PS2634L PS2651 * PS2651L2 5k 80 50 50 to 400 3 5 PS2652 PS2652L2 PS2653 * PS2653L2 5k 80 200 200 to 3400 100 100 PS2654 PS2654L2 * (with a base pin) Note: A product name followed by letter L indicates a product having leads formed for surface mount. 2 There are two kinds of optocouplers (a light emitting diode (LED) as an input and a phototransistor as an output) according to the type of output transistor: Single transistor type and Darlington-transistor type. The single-transistor type optocouplers are used to perform high-speed switching (with high-speed response). The Darlingtontransistor type optocouplers are used to obtain a large output current by utilizing a small input current (independently of switching speeds). Designing the circuits properly will improve the PS2601 optocoupler (Single Transistor type) by having a base pin in terms of switching speed, elimination of noise in input signals, and output leakage current (collector dark current, and application to highvoltage circuits). APPLICATIONS OF OPTOCOUPLER BASE PINS INCREASING SWITCHING SPEED The switching speed of an optocoupler with a base pin can be increased by inserting a resistor between the base and the emitter of its phototransistor even when the optocoupler is applied to a large load resistance. Generally, the phototransistor of an optocoupler such as the PS2601 has a large photo-sensitive area on it. Accordingly, the junction capacitance (CC-B) between the collector and the base of the phototransistor is great (up to 20 pF) and as a result its response speed (turn-off time toff) is low. The relationship between turn-off time toff and collector-base capacitance CC-B is expressed by: toff × CC-B x hFE x RL ................(1) where toff : Turn-off time (See Fig. 2-2.) CC-B : Collector-base capacitance hFE : D.C. current amplification factor RL : Load resistance Cc-B RL Figure 2-1. Collector-Base Capacitance CC-B of Phototransistor 3 50% Input ton 90% 90% toff Output 10% 10% Figure 2-2. ton/toff Measuring Points As judged from expression (1), the turn-off time toff is affected by collector-base capacitance CC-B, D.C. current amplification factor hFE, and load resistance LR. In actual circuit design, CC-B and hFE are fixed. Accordingly, the turn-off time is significantly affected by the resistance of load RL. Graph 1 shows the relationship between response speed (ton,toff) and load resistance (RL) in typical emitter follower (test circuit 1) having a load resistance of 100 Ω. ( PW ==100 µs ) Duty 1/10 VCC = 5 V PS2601 IF = 5 mA Input monitor Vo Input monitor 51 Ω RL = 100 Ω Vo Test Circuit 1 Graph 1 Up : Input 0.2 V/DIV DOWN : Output 0.5 V/DIV (50 µs/DIV) 4 Graph 2 shows the relationship between response speed (ton, toff) and load resistance (RL) in a typical emitter follower (Test circuit 2) having a greater load resistance (5 kΩ). VCC = 5 V PS2601 IF = 5 m A Input monitor 51 Ω Vo RL = 5 Ω Input monitor Test Circuit 2 Vo Graph 2 Up : Input 0.2 V/DIV DOWN : Output 2 V/DIV (50 µs/DIV) As shown in Graph 2, the turn-off time for load resistance of 5 kΩ is about 100 µs. Similarly, the turn-off time for load resistance of 100 kΩ is 1 to 2 ms. This is also true when the load resistance is connected to the collector of the phototransistor. Graph 3 shows the relationship between response speed (ton, toff) and load resistance (RL) in a typical circuit (Test circuit 3) having collector load resistance (5 kΩ) with the emitter grounded. VCC = 5 V RL = 5 Ω PS2601 Vo IF = 5 m A Input monitor 51 Ω Input monitor Vo Test Circuit 3 Graph 3 Up : Input 0.2 V/DIV DOWN : Output 2 V/DIV (50 µs/DIV) 5 To reduce the turn-off time toff of a test circuit having a greater resistance, insert a resistor RBE between the emitter and the base of the phototransistor. See Test circuit 4 and Test circuit 5. Graph 4 and 5 show their input and output waveforms. VCC = 5 V PS2601 IF = 5 mA Input monitor 51 Ω RBE Vo Input monitor RL = 5 Ω Insert resistor of 200 kΩ here. Vo Test Circuit 4 (Emitter Follower) Graph 4 Up : Input 0.2 V/DIV DOWN : Output 2 V/DIV (50 µs/DIV) VCC = 5 V RL = 5 Ω PS2601 IF = 5 mA Vo Input monitor Vo 51 Ω RBE Input monitor Insert resistor of 200 kΩ here. Test Circuit 5 (Emitter Grounded) Graph 5 Up : Input 0.2 V/DIV DOWN : Output 2 V/DIV (50 µs/DIV) 6 The turn-off time can be greatly reduced by the base-emitter resistance (RL). In Test circuit 4, the turn-off time of the test circuit having resistance RL is about 1/30 of that of the test circuit without the resistance. This is because the carrier (photocurrent) stored in the collector-base capacitor (CC-B) is quickly released through the base-emitter resistor (RBE). However, note that part of a photocurrent generating on the base of the phototransistor flows through the RBE resistor and reduces the current transfer ratio (CTR). Compare the voltage level of the output waveform in Photo 4 with that of the output waveform in Photo 2. The current transfer ratio of the test circuit having a base-emitter resistor of 200 kΩ is half or less of that of the test circuit without the resistance. (See 3.3 for reduction of the current transfer ratio CTR.) For reference, Fig. 2-3 shows the switching-time vs. RL characteristics and Fig. 2-4 shows the switching-time vs. RBE characteristics. 1000 500 200 IF = 5 mA I x 51Ω VCC = 5V Vo RL 1000 500 IF = Ix 10 mA 51Ω Vcc = 5V Vo RL tf ts tf ts 200 Switching Time (µs) 100 50 20 10 Switching Time (µs) IF = 5 mA VCC = 5 V Sample Solid line: Current transfer ratio of 166% Dotted line: Current transfer ratio of 274% at Ir = 5 mA 100 50 20 10 5 IF = 10 mA Vcc = 5 V Sample Solid line: Current transfer ratio of 166% Dotted line: Current transfer ratio of 274% at Ir = 5mA tr 5 td 2 1 100 500 1k 5k 10 k tr td 100 500 1k 5k 10 k 50 k 100 k 2 1 50 k 100 k Load Resistance RL (Ω) Load Resistance RL (Ω) Fig. 2-3 Switching-Time vs. RL Characteristics 160 140 120 100 toff 80 60 40 ton 20 0 100 200 500 1000 Vcc = 5 V, IF = 5mA R1 = 5Ω Solid line: Emitter follower Dotted line: Emitter grounded 160 140 120 100 toff 80 60 40 20 0 toff VCC = 5 V, IF = 10mA RL = 5Ω Solid line: Emitter follower Dotted line: Emitter grounded Switching Time (µs) Switching Time (µs) 8 100 200 500 1000 Base-Emitter Resistance RBE (kΩ) Fig. 2-4 Switching-Time vs. RBE Characteristics Base-Emitter Resistance RBE (kΩ) 7 8 STABILIZING OUTPUT LEVELS When an optocoupler is used with the base pin of its phototransistor open, the collector dark current (ICEO) flows as a base current. The current is amplified as a collector current and could make the output level of the phototransistor unstable. To eliminate this unwanted base current and make the output level stable, flow the collector dark current (ICEO) through the baseemitter resistor (RBE). Fig 2-5 shows the ICEO vs. TA characteristics of a PS2601 optocoupler. PS2601 ICEO-TA Characteristics 10000 Collector Dark Current ICEO (nA) 1000 IF = 0 VCE = 80V (40V for the PS2603) 2601 Solid line: PS2601 Dotted line: PS2603 RBE = 100 8 10 RBE =1MΩ 1 RBE = 1MΩ RBE =100 MΩ 0.1 - 20 0 20 40 60 80 100 Ambient Temperature TA (°C) Figure 2-5. ICEO vs. TA Characteristics ELIMINATION OF INDUCED NOISE Generally, machine-controlling equipment generates induced noise which may cause malfunctions. This unwanted noise in input signals can be isolated by means of optocouplers. However, if the noise is too strong, it may be switched to the output through the input-output capacitance C1-2 of the optocoupler. This unwanted noise in the output can be removed in the following manner. Insert a capacitor (preferably 100 pF) between the base and the emitter of the phototransistor of the optocoupler. This capacitor delays response and suppresses malfunctions. Graph 6-(a) to 6-(d) show how an external noise (surge voltage of 1000 V/µs at rise time) is eliminated as the capacitance of the base-emitter capacitor. A fluctuation in the collector-emitter voltage caused by the on/off operation of a power switch at the output of the optocoupler causes a base current to flow through the collector-base capacitor (CCB), which causes a malfunction. In Fig. 2-7, for example, an instantaneous base current flows through the collector-base capacitor (CCB) of the optocoupler. The current is multiplied by hFE (as a collector current) and causes an output voltage on both ends of the load resistance. It seems as if an input signal was applied to the optocoupler. Graph 7-(a) shows the waveforms. This unwanted instantaneous induction current can be eliminated by inserting a capacitor CBE between the emitter and the base of the phototransistor. Graph 7-(b) shows the waveforms. Fig. 2-8 shows the output-voltage vs. CBE characteristics. Vo CBE RL Figure 2-6. Figure 2-7. 8 6a) CBE = No capacitance 6b) CBE = 10 pF Vin Vin Vo Vo 6d) CBE = 1000 pF 6c) CBE = 100 pF Vin Vin Vo Vo Graph 6 Up : Input Surge Voltage (Vin :1000 V/DIV) DOWN : PS2601 output (VO: 1 V/DIV) C1-2 5V Vo CBE 470 Ω Vin Test Circuit 9 Vin (dV/dt = 10 V/µs, 2 V/DIV) CCB Vin Vo Vo (0.1 V/DIV) 5 kΩ (500 ns/DIV) Graph 7-(a) Input Voltage Fluctuation and Output Vin (dV/dt = 10 V/µs, 2 V/DIV) CCB Vin Vo 1000 pF Vo (0.1 V/DIV) 5 kΩ (500 ns/DIV) Graph 7-(b) Effect of Collector-Base Capacitance on Voltage Fluctuation 10 1 PS2601 RL = 5 k Ω Output Voltage, Vo (V) 0.1 0.01 100 Base-Emitter Capacitance, CBE (pF) 1000 Figure 2-8. Vo vs. CBE Characteristics As mentioned above, noise induced by the fluctuation of supply voltage can be removed by proper treatment of the base pin. For switching of input free from induced noise at normal switching speed, optocouplers with a base pin such as the PS2602 series are available. If the base pin of an optocoupler is left unused or opened, it typically will pick up external noise. Cutting off the base pin is also effective in order to prevent it from picking up external noise. See Graph 8-(b). 11 (PS2601) Vin Base pin Vo Graph 8-(a) Up : Input Surge Voltage (Vin: 1000 V/DIV) DOWN : PS2601 Output (Vo: 1 V/DIV) Cut the base pin (pin 6) (PS2601) Vin Vo Graph 8-(b) 5V Vo 470 Ω Vin Test Circuit 12 ELIMINATION OF INPUT SURGES Unwanted external noise and output leakage currents (e.g., collector current IC) of a preceding transistor may cause the lightemitting diode (LED) of an optocoupler to light involuntarily. Usually, a circuit (connecting a resistor in parallel to the LED) is provided to absorb such input surges. To prevent malfunction of an optocoupler, it is also effective to insert a resistor (RBE) that increases the input threshold current (by the use of the input-output characteristics) between the base and the emitter of the phototransistor. In this case, the current transfer ratio (CTR) must be low. (See 3.3 for Reduction of CTR.) 60 VCE = 5 V (PS2601) 50 RBE = 8 Collector Current IC (mA) 40 200 kΩ 100 kΩ 50 kΩ 30 kΩ 20 kΩ 30 20 10 kΩ 10 5 kΩ 0 1 2 3 45 10 20 30 40 50 Forward Current IF (mA) Figure 2-9. IC vs. IF Characteristics (Example) APPLICATION TO HIGH POTENTIAL CIRCUIT The withstanding voltage between the collector and the emitter of the PS2601 optocoupler is 80 V (MAX). To make the optocoupler available to higher withstanding voltages, use the collector-base junction photodiode as a light-sensitive element and connect a high-voltage circuit to the output of the optocoupler. In this case, the output of the photodiode must be amplified because it is smaller than the usual output. Fig. 2-10 shows an example of an optocoupler applied to a high-voltage circuit. In this sample circuit, the photocurrent (ICBL) of the optocoupler is fed to the base of the high-voltage transistor and a current (IF) passes forward through the light-emitting diode (LED). Fig. 2-11 shows the ICBL vs. IF characteristics. Before working on applications outside the rated values of the optocouplers, evaluate the practical circuits fully by contacting CEL. 200 VCB = 100V (PS2601) IF ICBL 100V A PS2601 Collector-Base Photocurrent ICBL (µA) 100 50 40 30 20 10 5 4 3 2 1 1 High-voltage transistor (Tr) CTR = 274% CTR = 166% ICBL Figure 2-10. Application to a High Voltage Circuit 2 3 45 10 20 30 40 50 80 Figure 2-11. ICBL vs. IF Characteristic 13 NOTES ON USE OF OPTOCOUPLER BASE PIN This chapter explains the reduction of a current transfer ratio of an optocoupler whose base and emitter are connected by a resistor (RBE) and other optocouplers that seem to be significant in the treatment of the base pin of an optocoupler. EQUIVALENT CIRCUIT (FOR PS2601 OPTOCOUPLER) Fig. 3-1 shows an equivalent circuit of a single-transistor optocoupler such as the PS2601. C1-2 A RD Cj ICBL Tr K B E CBE CCB C Figure 3-1. Equivalent Circuit (for PS2601 Optocoupler) Cj CBE RD ICBL C1-2 Tr : Junction capacity of LED : Base-emitter capacitance : Resistor serially connected to LED : Collector-base photocurrent generated by the light of the LED : Input-output capacitance : Amplifying transistor DEFINITION OF CURRENT TRANSFER RATIO (CTR) A current transfer ratio (CTR) of an optocoupler indicates the rate of an output current IC of its phototransistor to a forward input current (IF) flowing through its light-emitting diode (LED). The CTR is expressed by: IC CTR = IF where IC = ICBL•hFE ..............................(3) (hFE: D.C. current amplification factor of the phototransistor) x = 100 (%) ................(2) 14 REDUCTION OF CURRENT TRANSFER RATIO (CTR) BY INSERTION OF BASEEMITTER RESISTOR A resistor (RBE) connected to the base and emitter pins of an optocoupler causes the reduction of the output current (reduction of current transfer ratio). This is because a part (I1) of the base current flows through the base-emitter resistor and causes a voltage equivalent to the emitter-base voltage (VBE). The base current is reduced by this current component (I1) and, as the result, the current transfer ratio (CTR) goes down. The output current IC' is expressed as follows: ICBL ICBL-I1 VBE RBE I1 Figure 3-2. IC' = hFE' (ICBL-I1) = hFE' ( ICBL• • • IC' VBE RBE ) = hFE' • ICBL ( 1 - VBE ICBL • RBE ) ................ (4) Note IC' hFE' : Output current of an optocoupler having RBE : Amplification factor of an optocoupler having RBE Accordingly, the ratio of output current IC' (of the optocoupler having RBE) to output current IC (of the optocoupler with the base open) is expressed by: IC' IC hFE' hFE VBE ICBL • RBE =(1- ) ................ (5) As hFE' is equal to hFE if IF = approx. 5 mA, IC = approx. 15 mA, and RBC > 100 kΩ, expression (5) is simplified as follows: IC' IC =1- VBE ICBL • RBE ................ (6) 15 Expression (6) indicates that the current transfer ratio (CTR) is significantly affected by the value of ICBL • RBE. For example, if the forward current IF of the light-emitting diode is smaller (that is, ICBL is smaller) or if the base-emitter resistance RBE is smaller, the reduction rate (rate of IC') becomes greater. The above CTR reduction must be considered when inserting a resistor between the emitter and the base of the phototransistor of the optocoupler to increase the switching speed. The performance of the optocoupler might become unstable because the CTR will be affected by time elapse or temperature change (even if it is initially stable). Fig. 3-3 shows the ∆CTR-RBE characteristics. 1.0 Normalized to 1.0 at RBE = × IF = 1 mA, VCE = 5V 0.8 0.8 1.0 CTR = 274% CTR Relative Values CTR Relative Values CTR =166% 0.6 0.6 CTR = 274% 0.4 CTR =166% 0.2 0.4 0.2 Normalized to 1.0 at RBE = × IF = 5 mA, VCE = 5V 100 200 300 400 500 1000 8 0 0 100 200 300 400 500 1000 8 Base Emitter Resistance RBE (kΩ) Base Emitter Resistance RBE (kΩ) 1.0 CTR = 274% CTR =166% 0.8 CTR Relative Values 0.6 0.4 0.2 Normalized to 1.0 at RBE = × IF = 10 mA, VCE = 5V 100 200 300 400 500 1000 0 8 Base Emitter Resistance RBE (kΩ) Figure 3-3. ∆CTR-RBE Characteristics 16 The reduction of a CTR is greatly affected by the positional relationship between load resistor RL and base-emitter resistor RBE, as shown in Fig. 3-4 (b) and 3-4 (c). Figure 3-4 (a). Open Figure 3-4 (b). RBE Serial to RL Figure 3-4 (c). RBE Parallel to RL ICBL ICBL ICBL VBE Vo RBE1 VBE1 V1 RBE2 VBE2 V2 RL RL RL The output voltage V0, V1, and V2 of the above circuits (a), (b), and (c) are related as follows: V1 hFE1 = V2 hFE0 (1- VBE ) ................ (7) ICBL • RBE1 V2 hFE2 V0 = hFE0 ( VBE2 ICBL • RBE1 RL • hFE2 1+ RBE2 1- ) ................ (8) When resistor RBE is serially connected to resistor RL (see Fig. 3-4 (c)), the reduction of a CTR becomes greater even if hFE2 is approximately equal to hFE0 in expression (8) as the expression includes RL as a parameter. Fig. 3-5 shows typical V0 vs. IF characteristics of the above circuits (a), (b), and (c). 10 Vcc = 10 V RL = 470 Ω CTR = 190% (PS2601) (a) RB open IF PS2601 Vcc = 10V 8 Output voltage Vo (V) (b) RBE = 100 kΩ 6 RBE = 100 kΩ Vo 4 RL = 470 kΩ 2 (c) RBG = 100 kΩ 0 1 2 5 10 20 50 Forward current IF (mA) Figure 3-5. Vo vs. IF Characteristics 17 CIRCUIT DESIGN EXAMPLE (USING THE PS2601) Fig. 4-1 shows a design example of an optocoupler circuit having a base-emitter resistor for improvement of response ability. PS2601 R2 = 510 Ω TTL I0 A resistor of 510 kΩ is inserted here. R0 = 1 kΩ Tn1 I1 I3 R1 = 2 kΩ Ib I4 Vcc = 5 V IF = 5 mA VOUT G Figure 4-1. Circuit Design Example The minimum current transfer ratio (CTR) required for TTL operation is calculated as follows: Current I4 must be 1.6 mA to drive the TTL and the collector-emitter voltage of transistor Tr1 must be 0.8 V or less. Accordingly, I2 must be as follows: VCC - VCE = R2 5 - 0.8 0.51 (kΩ) = 8.2 (mA) ................(9) I2 ⊕ Therefore I3 = I2 + I4 = 8.2 + 1.6 = 9.8 (mA) ................(10) Let's assume that hFE of transistor Tr1 is 40 (worst). Ib must be as follows: Ib ⊕ I3 = hFE 9.9 (mA) = 0.247 (mA) ................(11) 40 Similarly, let's assume that VBE of transistor Tr1 is 0.8 V (worst), I1 must be as follows: VBE I1 = R1 = 0.8 2 (kΩ) = 0.4 (mA) ................(12) Therefore, the output current I0 of the optocoupler is I0 ⊕ I1 + Ib = 0.647 (mA) ................ (13) If forward current IF is 3 mA (worst) (normally IF = 5 mA), the CTR is calculated as follows: I0 CTR = IF x 100 = 0.647(mA) x 100 = 21.6% ................(14) 3 (mA) 18 Accordingly, the CTR value including reduction of CTR by time elapse, temperature change, and insertion of RBE must be 21.6 % or more. A design example of an optocoupler circuit that operates for at least ten years is shown below (using Fig. 3-3, 4-2 and 4-3). The major causes of CTR reduction area as follows: (From Fig. 3-3) CTR-relative-value vs. RBE characteristics 15% down (with respect to initial value, RBE = ×) CTR change with time (10 years, Ta = 60 °C) 40% down (with respect to initial value, 0 year) CTR-relative-value vs. ambient-temperature characteristics (Ta = 60 °C) 15% down (with respect to initial value ta = 25 °C) (From Fig. 4-2) (From Fig. 4-3) Considering the above characteristics and safety factor = 2 (twice margin), the recommended CTR is: 21.6 x 1.4 x 1.15 x 1.15 x 2 = 80%.................(15) (Reference) 1.2 1.0 IF = 5 mA TA = 25˚C 1.2 1.0 CTR Relative Value CTR Relative Value 0.8 0.6 0.4 0.2 0 0 10 2 IF = 20 mA TA = 25˚C IF = 5 mA TA = 60˚C Normalized to CTR test conditon IF = 5 mA, VCE = 5V 10 3 10 4 10 5 0.8 0.6 0.4 Normalized to 100 at TA = 25˚C IF = 5 mA, VCE = 5 V -55 -40 -20 0 20 40 60 80 100 0.2 Time (Hr) Figure 4-2. Change of CTR with Time (PS2601) 0 Ambient Temperature TA (°C) Figure 4-3. CTR-Relative-Value vs. TA Characteristics 19 PS2500-SERIES MULTI-CHANNEL OPTOCOUPLERS GENERAL Recently, optocouplers have been supplanting relays and pulse transformers for complete noise elimination, level conversion, and high-potential isolation. Microprocessor systems are requiring more and more optocouplers on the limited area of PC boards for I/O interface and other purposes. For these requirements, NEC has manufactured multi-channel optocouplers having 4 pins (for one channel) to 16 pins (for four channels). These multi-channel optocouplers are called the PS2500 series optocouplers. The PS2500 series optocouplers are divided into PS2501, PS2502, PS2505, and PS2506 according to their functions. (PS2501L, PS2502L, PS2505L, and PS2506L have leads formed for surface installation.) This manual describes features, structures, and basic characteristics of the PS2500 series optocouplers. FEATURES, STRUCTURES, AND PACKAGE DIMENSIONS Features The major feature of PS2500 is very high isolation voltage between input and output (substantially two to three times that of the conventional PS2400 series optocouplers). This can be proved because none of the 1300 test optocouplers were destroyed in a strict product test (applying 10 kVac to each optocoupler for one minute). The improvement in dielectric strength of the PS2500 optocouplers has been accomplished by the double molding package structure. In addition to high isolation voltage, the PS2500 optocouplers boast high heat resistance and high moisture resistance. Table 1 lists the major features of the PS2500 series optocouplers. Features Product name PS2501 PS2501L (*) PS2502 PS2502L (*) High isolation Voltage Abundant I/O functions High CTR (TYP) High VCEO (MIN) Response (TYP) tr = 3 µs tr = 5 µs tr, tf = 100 µs tr = 3 µs tr = 5 µs tr, tf = 100 µs D.C. input, Single transistor output D.C. input, Darlington pair transistor output 5 kVac A.C. input, single transistor output A.C. input, Darlington pair transistor output 300% 80V 2000% 40V PS2505 PS2505L (*) PS2506 PS2506L (*) 300% 80V 2000% 40V Table 1. Features of PS2500 Optocouplers Note: Tested in oil (In the air, unwanted arc discharging will occur at 6 to 7 kVac.) * The product name followed by letter L is for a product having leads for surface mount. 20 Optocoupler Structure Figure 1 shows the internal perspective view of a PS2500 optocoupler and Figure 2 shows the sectional view of the optocoupler. Figure 2 below shows the optocoupler in a light-tight epoxy resin housing, and a light-sensitive element (phototransistor or photo Darlington transistor) with light-transmittable epoxy resin medium between them. A light signal emitted by the LED is transferred to the photosensitive transistor via the internal resin medium. Both the housing resin and the internal resin have the same expansion coefficient. Namely, the optocoupler elements are molded twice with epoxy resin. (This structure is referred to as a double molding structure.) The high isolation voltage is obtained by the long adjacent area of the inner and outer resins (inner boundary) and identical expansion coefficient of the inner and outer resins (eliminating arc discharges on the inner boundary). Figure 1. Internal perspective view of optocoupler Outer resin (Black) Inner resin (White) Inner boundary Figure 2. Sectional view of optocoupler 21 Dimensions Figures 3 and 4 show the dimensions of the PS2500 series optocouplers. The PS2500 series optocouplers are very compact and fit for high-density installation on PC boards. For example, the package area occupied by a single channel of the PS2500 series is half that of the PS2600 series (6-pin Dual in-line package). PS250X-1 43 5.1 MAX 12 1. 2. 3. 4. 7.62 Anode Cathode Emitter Collector PS250X-2 8765 10.2 MAX 1234 1,3. 2,4. 5,7. 6,8. 2.54 7.62 Anode Cathode Emitter Collector 6.5 3.8 MAX 2.54 4.55 MAX 2.8 MIN 0.65 2.8 MIN 0.50±0.10 0.25 M 0 to 15˚ 4.55 MAX 0.65 3.8 MAX 6.5 1.34 1.34 0.50±0.10 0.25 M 0 to 15˚ PS250X-4 161514131211 10 9 20.3 MAX 12345678 1,3,5,7. Anode 2,4,6,8. Cathode 9,11,13,15. Emitter 10,12,14,16. Collector 2.54 7.62 2.8 MIN 4.55 MAX 0.65 3.8 MAX 6.5 1.34 0.50±0.10 0.25 M 0 to 15˚ Figure 3. Package Dimensions (Units in mm) (PS2501, PS2502, PS2505, and PS2506) 22 Lead Bending type (Gull-wing) PS250XL-1 43 PS250XL-2 8765 5.1 MAX 12 1. 2. 3. 4. 7.62 Anode Cathode Emitter Collector 7.62 10.2 MAX 1234 1,3. 2,4. 5,7. 6,8. Anode Cathode Emitter Collector 0.05 to 0.2 2.54 6.5 3.8 MAX. 9.60±0.4 1.34±0.10 0.25 M 0.9±0.25 3.8 MAX. 9.60±0.4 1.34±0.10 0.25 M 0.05 to 0.2 0.9±0.25 6.5 2.54 PS250XL-4 16 15 14 13 12 11 10 9 20.3 MAX 123456 78 1,3,5,7. Anode 2,4,6,8. Cathode 9,11,13,15. Emitter 10,12,14,16. Collector 7.62 6.5 3.8 MAX. 9.60±0.4 1.34±0.10 0.25 M 0.05 to 0.2 0.9±0.25 2.54 Fig. 4 Package Dimensions (Units in mm) (PS2501L, PS2502L, PS2505L, and PS2506L) 23 CHARACTERISTICS OF PS2501 AND PS2505 OPTOCOUPLERS Current Transfer Ratio (CTR) The current transfer ratio (CTR) of an optocoupler is the ratio of the value of output current IC to the value of input forward current IF (IC/IF x 100%). The CTR is a parameter equivalent to the D.C. current amplification factor hFE of a transistor. The CTR is one of the most significant characteristics of optocouplers, as well as isolation voltage. In circuit designing, CTR must be considered first of all because the CTR: 1 varies as time goes by, 2 is affected by ambient temperature, and 3 is dependent upon forward current IF flowing through the LED. Both PS2505 and PS2506 optocouplers (bidirectional input type) have two current transfer ratios (CTRs) because they have two LEDs in the input. For further information, refer to Applications of Optocouplers for A.C. input. Change of CTR over time The current transfer ratio (CTR) of an optocoupler is determined by the light-emission efficiency of the LED (emitting infrared light), efficiency of light transmission between the LED and the phototransistor, light sensitivity of the phototransistor, and hFE of the transistor. The change of a CTR over time is mainly caused by reduction of the light-emission efficiency of the LED. Generally, the CTR is reduced to a greater extent as the forward current IF increases or as the operating temperature increases. Figure 5 and 6 respectively show estimated changes of CTRs of PS2501 and PS2505 optocouplers over time. Estimated change of CTRs with time lapse (Standard values) 1.2 1.0 1.2 Standard value Continuous supply of 20 mA (IF) Standard characteristics 1.0 CTR Relative Value CTR Relative Value 0.8 0.6 0.4 0.2 0.8 0.6 TA = 60˚C TA = 25˚C IF = 5 m A TA = 60˚C IF = 20 mA T A = 2 5 ˚C IF = 5 m A TA = 25˚C 0.4 0.2 0 10 2 10 3 10 4 10 5 10 6 0 10 2 10 3 10 4 10 5 Figure 5. Time (Hr) Figure 6. Time (Hr) CTR vs. TA Characteristics (TA: Ambient Temperature) The CTR-Temperature characteristic is greatly affected by the total characteristics of light-emission efficiency of the LED and hFE of the phototransistor as the light-emission efficiency has a negative temperature coefficient and hFE has a positive temperature coefficient. See Figure 7. Light-emission efficiency of LED hFE of phototransistor TA Figure 7. CTR vs. TA Characteristics 24 TA CTR TA Figure 8-(a) to Figure 8-(g) show CTR vs. TA characteristics under various conditions. (b) (a) 1.2 Standard characteristics IF = 5 mA, VCE = 5V 1.0 1.25 1.50 Standard characteristics IF = 1 mA, VCE = 5V CTR Relative Value CTR Relative Value 0.8 1.00 0.6 0.75 0.4 0.50 0.2 Normalized to 1.0 at TA = 25˚C 0.25 Normalized to 1.0 at TA = 25˚C 0 -50 -25 0 25 50 75 100 0 -50 -25 0 25 50 75 100 Ambient Temperature TA (°C) (c) 1.6 1.50 Standard characteristics IF = 0.3 mA, VCE = 5V 1.2 Ambient Temperature TA (°C) (d) Standard characteristics CTR = approx. 200% CTR Relative Value 1.25 CTR Relative Value 1.0 1.00 0.8 0.75 0.6 0.50 Normalized to 1.0 at TA = 25˚C 0.4 Normalized to 1.0 at TA = 25*C IF = 5 mA,VCE = 5V 0.25 0.2 0 -50 -25 0 25 50 75 100 0 -50 -25 0 25 50 75 100 Ambient Temperature TA (°C) (e) 1.2 Standard characteristics CTR = approx. 300% 1.2 Ambient Temperature TA (°C) (f) Standard characteristics CTR = approx. 400% CTR Relative Value CTR Relative Value 1.0 1.0 0.8 0.8 0.6 0.6 0.4 Normalized to 1.0 at TA = 25˚C IF = 5 mA,VCE = 5V 0.4 Normalized to 1.0 at TA = 25˚C IF = 5 mA, VCE = 5V 0.2 0.2 0 -50 -25 0 25 50 75 100 0 -50 -25 0 25 50 75 100 Ambient Temperature TA (°C) (g) 1.2 Standard charcteristics CTR = approx. 500% Ambient Temperature TA (°C) CTR Relative Value 1.0 0.8 0.6 0.4 Normalized to 1.0 at TA = 25˚C IF = 5 mA, VCE = 5V 0.2 0 -50 -25 0 25 50 75 100 Ambient Temperature TA (°C) 25 CTR vs. IF Characteristics (IF: Forward Current Flowing Through the LED) The current transfer ratio (CTR) depends upon the magnitude of a forward current (IF). When IF goes lower or higher than a proper magnitude, the CTR becomes smaller. Figure 9 shows the CTR vs. IF characteristics. Note that rate changes of CTRs are very diffrent at low IF magnitude (approx. 5 mA), middle IF magnitude (approx. 5 mA), and high IF magnitude (approx. 20 mA). Namely, the CTR depends heavily upon the magnitude of forward current IF in lower and higher current ranges. For low-input and high-output switching, see Chapter 4. 600 Standard characteristics VCE = 5V 500 400 CTR (%) Sample A Sample B 300 200 100 0 0.1 0.5 1 5 10 50 Forward Current IF (mA) Figure 9. CTR vs. IF Characteristics (Standard Value) Response Characteristics The response characteristics of optocouplers are the same as those phototransistors. The fall time tf is expressed by: tf RL•hFE•CCB RL: Load resistance hFE: Amplification factor CCB: Collector-base capacitance If RL is too high, tf becomes too high to be fit for high-speed signal transmission. Select the proper load resistance for the desired signal rate. Similarly, the collector current must fully satisfy the minimum value of the CTR, CTR vs. TA characteristics, and CTR vs. time characteristics. Otherwise, the phototransistor will operate unsaturated, causing lower response characteristics and malfunction. Figures 10 to 13 show the response-time vs. forward current characteristics and response-time vs. VCC characteristics, using load resistance and ambient temperature as parameters. 26 1000 500 200 Standard characteristics VCC = 5 V TA = 25˚C RL = 4.7 kΩ TA = 85˚C 1000 500 200 Standard characteristics VCC = 5 V TA = 25˚C RL = 10 kΩ TA = 85˚C Response Time (µs) Response Time (µs) toff 100 50 ts 100 50 toff ts 20 10 5 2 1 0 5 10 td ton 20 10 ton 5 2 1 0 td Forward Current IF (mA) 5 Forward Current IF (mA) 10 Figure 10. Response-Time vs. IF Characteristics Figure 11. Response-Time vs. IF Characteristics 1000 500 200 Standard characteristics IF = 10 mA TA = 25˚C RL = 3 kΩ TA = 85˚C toff 1000 500 200 Standard characteristics IF = 10 mA TA = 25˚C RL = 10 kΩ TA = 85˚C toff ts Response Time (µs) 100 50 Response Time (µs) 100 50 20 ts 10 5 td 2 1 0 5 10 ton 20 10 ton 5 2 1 0 5 10 td VCC (V) Figure 12. Response-Time vs. VCC Characteristics VCC (V) Figure 13. Response-Time vs. VCC Characteristics For reference, a voltage-gain vs. frequency characteristic using CTR as a parameter is shown below. 27 5 Standard characteristics 0 Test Circuit and Condition 1 kΩ 51 Ω 330 µF IC = 2.25 mA CTR = 156% Voltage Gain (dB) -5 VCC = 10 V -10 -15 CTR = 186% VO 1 kΩ -20 CTR = 304% -25 100 500 1 k 5 k 10 k 50 k 100 k 500 k Frequency f (HZ) Figure 14. Voltage-Gain vs. Frequency Characteristics (Standard Value) (PS2501, PS2505). Other Temperature Characteristics Almost all characteristics of optocouplers are apt to be affected by ambient temperature (see 3.1.2). Figures 15 to 21 show how VF (Forward Voltage), ICEO (Collector Cut-Off Current), and VCE (sat) (Collector Saturation Voltage) are affected by ambient temperature. 1.2 1.1 IF = 10 m Forward Voltage VF (V) IF = A 1.0 0.9 0.8 0.7 0.6 0.5 -30 0 25 5 mA 1m A IF = 50 75 100 Ambient Temperature TA (°C) Figure 15. VF vs. TA Characteristics 28 10000 5000 (1 µA) 1000 500 100 50 10 5 1 0.5 0.1 -50 Standard characteristics CTR = approx. 400% VCE = 80 V 40 V 24 V 10 V 5V 10000 5000 Standard characteristics CTR = approx. 100% VCE = 80 V 40 V 24 V 10 V 5V Collector Cut-off Current ICEO (nA) Collector Cut-off Current ICEO (nA) (1 µA) 1000 500 100 50 10 5 1 0.5 0.1 -50 -25 0 25 50 75 100 Ambient Temperature TA (°C) Figure 16. ICEO vs. TA Characteristics 0.3 CTR = approx. 200% -25 Ambient Temperature TA (°C) 0 25 50 75 100 Figure 17. ICEO vs. TA Characteristics 0.3 CTR = approx. 200% Collector Saturation Voltage VCE (sat) (V) 0.2 Collector Saturation Voltage VCE (sat) (V) 0.2 CTR = approx. 400% 0.1 CTR = approx. 400% 0.1 IF = 1 mA IC = 1 mA 0 -50 -25 0 25 50 75 100 IF = 5 m A IC = 4 m A 0 -50 -25 0 25 50 75 100 Ambient Temperature TA (°C) Figure 18. VCE (sat) vs. TA Characteristics 0.20 18 Ambient Temperature TA (°C) Figure 19. VCE (sat) vs. TA Characteristics IF = 10 mA, TA = 25˚C IF = 8 mA, TA = 25˚C 15 0.15 CTR = 400% 330% 200% Collector Current IC (mA) Collector Saturation Voltage VCE (sat) (V) 10 IF = 10 mA, TA = 85˚C IF = 8 mA,TA = 85˚C 5 Standard characteristics CTR = 200% 0 0.5 1.0 1.5 2.0 0.10 IF = 5 mA IC = 1 mA 0.05 -50 -25 0 25 50 75 100 Ambient Temperature TA (°C) Figure 20. VCE (sat) vs. TA Characteristics 29 Collector Saturation Voltage VCE (sat) (V) Figure 21. IC vs. VCE (sat) Characteristics At normal temperature (TA = 25 °C), the collector cut-off current ICEO is very little (about 1 nA (at VCE = 80 V and CTR = about 400% )), but it will be multiplied by about 10 at an increment of 25°C. This needs to be kept in mind when using a small output current (IC) of an optocoupler with a high load. The rate change of VCE (sat) (Collector Saturation Voltage) is about 0.7% per °C at ambient temperature of 0°C to 70°C. In circuit design, the collector output current IC should be determined under the condition of half or less of the CTR rated values. Otherwise, the saturation voltage VCE (sat) will become greater. CHARACTERISTICS OF PS2502 AND PS2506 OPTOCOUPLERS The PS2502 and PS2506 optocouplers are higher in sensitivity than the PS2501 and PS2505 optocouplers and can be driven by low currents. CTR-Related Characteristics The PS2502 and PS2506 optocouplers assure CTR ⊕ 200% at IF = 1 mA and can be directly driven by CMOS output signals. See 3.1 for CTR definition and characteristics. Change of CTR Over time Figure 22 shows the CTR vs. time characteristics of the PS2502 and PS2506 optocouplers. 1.2 Standard values Continuous supply of IF = 1 mA 1.0 TA = 25˚C CTR Relative Value 0.8 TA = 60˚C 0.6 0.4 0.2 0 10 102 103 104 10 5 10 Time (Hr) Figure 22. CTR vs. Time Characteristics (Standard Value) 30 CTR vs. Temperature Characteristics Figure 23-(a) to 23-(f) show CTR vs. Temperature Characteristics under various conditions. 23-(a) 1.4 Standard characteristics 1.2 23-(b) 1.4 Standard characteristics 1.2 CTR relative value 1.0 0.8 0.6 0.4 0.2 0 -50 Normalized to 1.0 at TA = 25˚C IF = 1 mA, VCE = 2V -25 0 25 50 75 100 CTR Relative Value 1.0 0.8 0.6 0.4 0.2 0 -50 Normalized to 1.0 at TA = 25˚C IF = 0.3 mA, VCE = 2V -25 0 25 50 75 100 Ambient Temperature TA (°C) 23-(c) 1.4 Standard characteristics 1.2 1.2 1.4 Ambient Temperature TA (°C) 23-(d) Standard characteristics CTR = approx. 2500% CTR Relative Value CTR relative value Normalized to 1.0 at TA = 25˚C IF = 0.1 mA, VCE = 2V -25 0 25 50 75 100 1.0 0.8 0.6 0.4 0.2 0 -50 1.0 0.8 0.6 0.4 0.2 0 -50 Normalized to 1.0 at TA = 25˚C IF = 1 mA, VCE = 2V -25 0 25 50 75 100 Ambient Temperature TA (°C) 23-(e) 1.4 1.2 Standard characteristics CTR = approx. 3500% Ambient Temperature TA (°C) 23-(f) 1.4 1.2 Standard characteristics CTR = approx. 4500% CTR Relative Value 1.0 0.8 0.6 0.4 0.2 0 -50 Normalized to 1.0 at TA = 25˚C IF = 1 mA, VCE = 2V -25 0 25 50 75 100 CTR Relative Value 1.0 0.8 0.6 0.4 0.2 0 -50 Normalized to 1.0 at TA = 25˚C IF = 1 mA, VCE = 2V -25 0 25 50 75 100 Ambient Temperature TA (°C) 31 Ambient Temperature TA (°C) CTR vs. IF Characteristics As shown in Figure 8, the CTR of a single-transistor output optocoupler (such as the PS2501 and PS2505 optocouplers) is at most 20% in a low-current area (e.g. IF = 0.1 mA). However, the CTR of a Darlington-transistor output optocoupler (such as the PS2502 and PS2506 optocouplers) can be greater than 200% in a low-current area (e.g. IF = 0.1 mA). Figure 24 shows the CTR vs. IF characteristics of the PS2502 and PS2506 optocouplers. 7000 Standard characteristics VCE = 2V 6000 5000 4000 3000 2000 1000 0 0.05 0.1 CTR (%) 0.5 1 5 10 50 Forward Current IF (mA) Figure 24. CTR vs. IF Characteristics (Standard Value) (PS2502, PS2506) CONCLUSION Demand for optocouplers featuring higher insulation and noise elimination is steadily increasing. At the same time, various problems (change of characteristics by ambient temperature and time elapse) will occur in their circuit design. We hope this manual will be helpful in solving such problems. 32 APPLICATION OF AC INPUT COMPATIBLE OPTOCOUPLER INTRODUCTION With the rapid penetration and diversification of electronic systems, demand for optocouplers is strengthening. Most popular are products featuring compact design, low cost, and high added value. To meet the market needs, NEC is expanding the optocoupler. This manual focuses on optocouplers compatible with AC input, and covers configuration, principles of operation, and application examples. CONFIGURATION (INTERNAL PIN CONNECTION DIAGRAM) (LED2) (LED1) 1 4 1 4 2 3 2 3 Figure 1. PS2505-1 Figure 2. PS2501-1 Figure 1 shows the internal pin connection of the AC input compatible optocoupler PS2505-1, and Figure 2, of the optocoupler PS2501-1. The most significant difference from the optocoupler (PS2501-1) is that the PS2505-1 incorporates an input circuit with two LEDs connected in reverse parallel. In the optocoupler (PS2501-1), one LED is connected in the input circuit so that the LED emits light to provide a signal when a current flows in one direction (1-2 in Figure 2) (one-direction input type). However, in the configuration shown in Figure 1, when a current flows in direction 1 to 2, LED1 emits light to send a signal, and when it flows from 2 to 1, LED2 emits light to send a signal (bidirectional input type). Namely, even if the voltage level between 1 and 2 varies, and the positive and negative polarities are changed, either of two LEDs emits light to send a signal. This means that the one direction input optocoupler permits DC input only, while the bidirectional input type permits AC input as well. Therefore, the PS2505-1 is described as an AC input compatible optocoupler. The next section describes the status of output signals when 100 Vac power is directly input to an AC input compatible optocoupler (PS2505-1) via a current limit resistor. 33 DIRECT INPUT OF 100 Vac Figure 3 shows the circuit diagram when 100 Vac power is directly input to an AC input compatible optocoupler via a current limit resistor. The relationship between input and output signals is as shown in Figure 4. (LED2) (LED1) VCC = 10 V AC 100 V 11 kΩ PS2505-1 Output signal 100 Ω Figure 3. 100 Vac Direct Input Circuit + Input signal AC 100 V LED light emission output 0 _ Deviation due to the differences in light emission and coupling efficiencies of LEDs LED 1 LED 2 LED 1 LED 2 LED 1 LED 2 Output signal + 0 Figure 4. Input/Output Signal Graph 1 Upper: 100 Vac Input Signal 100 V/DIV Lower: Output Signal 1 V/DIV As described above, when an AC input compatible optocoupler is used, an AC input signal can be extracted as a full-wave rectified output signal. The output signal is smoothed by inserting a capacitor in the last stage of the circuit of a phototransistor if necessary. In the one-direction input optocoupler (PS2501 series), when an AC signal is to be input, it must be full-or half-wave rectified by a diode bridge or CR circuit. On the other hand, the AC input compatible optocoupler permits direct input of an AC signal. This enables simpler configuration, space saving, and reduced design cost. The next section demonstrates three examples of applications. 34 APPLICATION EXAMPLES Example 1: AC-DC converter VCC VCC AC 100V AC 100 V PS2505-1 PS2501-1 + 0 _ + 0 + 0 (a) AC input compatible optocoupler (bidirectional input) (b) Conventional optocoupler (one-direction input) (Full-wave rectification by means of diode bridge) Example 2: Detection of a telephone bell signal Station line (75 Vr.m.s., 16 HZ) PS2505-1 Station line (75 Vr.m.s., 16 HZ) PS2501-1 + + + 0 _ 0 _ 0 _ (a) AC input compatible optocoupler (bidirectional input) (b) Conventional optocoupler (one-direction input) (rectification by CR circuit) 35 Example 3: Sequencer circuit input section Common PS2501-2 AC 100 V PS2505-2 AC 100V Common (a) AC input compatible optocoupler (bidirectional input) (b) Conventional optocoupler (one-direction input) (Full-wave rectified by diode bridge) PRECAUTIONS FOR DESIGN The AC input compatible optocoupler is identical to the conventional optocoupler except for the presence of two LEDs connected in reverse parallel in the input circuit. Therefore, the circuit configuration can be designed as conventionally. The difference is that there are two types of current transfer ratios (CRT) because two LEDs are connected in the input circuit. The two CTRs are not necessarily the same, owing to the differences in light emission and coupling efficiencies of LEDs. Consequently, this causes deviation in output signal level. The differences are rated under the item of the current efficiency ratio (CTR1/CTR2) for electric characteristics. Current transfer ratio (CTR1/CTR2) IC1 CTR1 = IF1 x (current flowing in LED1) IC2 CTR2 = IF2 x (current flowing in LED2) A IF2 LED 2 LED 1 IC2 IF1 A IC1 A VCE = 5 V Figure 5. CTR Measuring Circuit 36 The transfer efficiency ratio (CTR1/CTR2) is rated as 0.3 (MIN.), 1.0 (TYP.), and 3.0 (MAX.). Assuming that CTR1 is 200%, CTR2 is in the range of 66 to 600%. Therefore, an AC input compatible optocoupler should be designed to operate with CTR 66 to 600%. For reference, the electric characteristics of the AC input compatible optocoupler (PS2505 series) are as follows: Electric Characteristics (TA = 25°C) ITEM Forward voltage Diode Pin-to-pin capacitance Transistor Collector cutoff current Current transfer ratio Ct ICEO CTR(IC/IF) V = 0, f = 1.0 MHZ VCE = 80 V, IF = 0 IF = ± 5 mA VCE = 5.0 V IF = ±10 mA IC = 2.0 mA Vin-out = 1.0 kV V = 0, f = 1.0 MHZ VCC = 10 V, IC = 2 mA, RL = 100Ω VCC = 10 V, IC = 2 mA, RL = 100Ω IF = 5 mA, VCE = 5.0 V 1011 0.5 80 300 50 100 600 pF nA % CODE VF CONDITIONS IF = ±10 mA MIN. TYP. 1.1 MAX. 1.4 UNIT V Collector saturation voltage VCE(sat) 0.3 V Ω pF µs Insulation resistance Input-to-output capacitance Coupled Rise time R1-2 C1-2 tr 3 Fall time tf 5 µs Transfer efficiency ratio CTR1/CTR2 0.3 1.0 3.0 For the external drawing, absolute maximum ratings, and characteristics curves, refer to the specific documents (AC input compatible multi-optocoupler series). EXCLUSIVE NORTH AMERICAN AGENT FOR RF, MICROWAVE & OPTOELECTRONIC SEMICONDUCTORS CALIFORNIA EASTERN LABORATORIES • Headquarters • 4590 Patrick Henry Drive • Santa Clara, CA 95054-1817 • (408) 988-3500 • Telex 34-6393 • FAX (408) 988-0279 24-Hour Fax-On-Demand: 800-390-3232 (U.S. and Canada only) • Internet: http://WWW.CEL.COM DATA SUBJECT TO CHANGE WITHOUT NOTICE 07/17/2000 37