FOD2741ATV

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The optocoupler is a gallium arsenide (GaAs) light emitting diode optically coupled to a silicon phototransistor. It comes in 3 grades of reference voltage tolerance = 2%, 1%, and 0.5%. ■ ■ ■ ■ ■ ■ single package 2.5V reference CTR 100% to 200% 5,000V RMS isolation UL approved E90700, Volume 2 CSA approval 1296837 VDE approval 40002463 BSI approval 8702, 8703 Low temperature coefficient 50ppm/°C max. FOD2741A: tolerance 0.5% FOD2741B: tolerance 1% FOD2741C: tolerance 2% Applications ■ Power supplies regulation The Current Transfer Ratio (CTR) ranges from 100% to 200%. It also has an outstanding temperature coefficient of 50 ppm/°C. It is primarily intended for use as the error amplifier/reference voltage/optocoupler function in isolated AC to DC power supplies and DC/DC converters. When using the FOD2741, power supply designers can reduce the component count and save space in tightly packaged designs. The tight tolerance reference eliminates the need for adjustments in many applications. The device comes in a 8-pin dip white package. ■ DC to DC converters Functional Bock Diagram NC Package Outlines 1 8 LED C 2 7 FB E 3 6 COMP 8 1 8 NC 4 ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 5 GND 8 1 1 www.fairchildsemi.com FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier August 2008 Pin Number Pin Name Pin Description 1 NC 2 C Phototransistor Collector 3 E Phototransistor Emitter 4 NC 5 GND 6 COMP 7 FB 8 LED Not connected Not connected Ground Error Amplifier Compensation. This pin is the output of the error amplifier.* Voltage Feedback. This pin is the inverting input to the error amplifier Anode LED. This pin is the input to the light emitting diode. *The compensation network must be attached between pins 6 and 7. Typical Application V1 FAN4803 PWM Control VO FOD2741 2 8 6 3 7 5 ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 R1 R2 www.fairchildsemi.com 2 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Pin Definitions Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only. Symbol Parameter Value Units TSTG Storage Temperature -40 to +125 °C TOPR Operating Temperature -40 to +85 °C TSOL Lead Solder Temperature 260 for 10 sec. °C VLED Input Voltage 37 V ILED Input DC Current 20 mA VCEO Collector-Emitter Voltage 30 V VECO Emitter-Collector Voltage 7 V Collector Current 50 mA PD1 IC Input Power Dissipation(1) 145 mW PD2 Transistor Power Dissipation(2) 85 mW 145 mW PD3 Total Power Dissipation(3) Notes: 1. Derate linearly from 25°C at a rate of 2.42mW/°C 2. Derate linearly from 25°C at a rate of 1.42mW/°C. 3. Derate linearly from 25°C at a rate of 2.42mW/°C. ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 3 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Absolute Maximum Ratings (TA = 25°C unless otherwise specified) Input Characteristics Symbol VF VREF Parameter Test Conditions LED Forward Voltage ILED = 10mA, VCOMP = VFB (Fig.1) Reference Voltage ILED = 10mA, VCOMP = VFB Device IREF IREF (DEV)(4) Deviation of IREF Over Temperature ILED (MIN) 1.5 V FOD2741A 2.482 2.495 2.508 V FOD2741B 2.470 2.495 2.520 V FOD2741C 2.450 2.500 2.550 V 4.5 17 mV mV/V All Ratio of VREF Variation ILED = 10mA ∆VCOMP = 10V to VREF to the Output of the ∆VCOMP = 36V to 10V Error Amplifier Feedback Input Current Typ. Max. Unit All VREF (DEV)(4) Deviation of VREF Over TA = -25°C to +85°C Temperature ∆VREF/ ∆VCOMP Min. All -1.0 -2.7 -0.5 -2.0 ILED = 10mA, R1 = 10kΩ (Fig. 3) All 1.5 4 µA TA = -25°C to +85°C All 0.4 1.2 µA Minimum Drive Current VCOMP = VFB (Fig. 1) All 0.45 1.0 mA I(OFF) Off-state Error Amplifier Current VLED = 37V, VFB = 0 (Fig. 4) All 0.05 1.0 µA |ZOUT| Error Amplifier Output impedance(5) VCOMP = VREF, ILED = 1mA to 20mA, f ≥ 1.0 kHz All 0.15 0.5 Ω Output Characteristics Symbol ICEO Parameter Test Conditions Min. Typ. Max. Unit 50 nA Collector Dark Current VCE = 10V (Fig. 5) BVECO Emitter-Collector Voltage Breakdown IE = 100µA 7 V BVCEO Collector-Emitter Voltage Breakdown IC = 1.0mA 70 V Transfer Characteristics Symbol Parameter CTR Current Transfer Ratio VCE (SAT) Collector-Emitter Saturation Voltage Test Conditions ILED = 10mA, VCOMP = VFB, VCE = 5V (Fig. 6) ILED = 10mA, VCOMP = VFB, IC = 2.5mA (Fig. 6) Min. 100 Typ. Max. Unit 200 % 0.4 V Notes: 4. The deviation parameters VREF(DEV) and IREF(DEV) are defined as the differences between the maximum and minimum values obtained over the rated temperature range. The average full-range temperature coefficient of the reference input voltage, ∆VREF, is defined as: 6 { V REF ( DEV ) /V REF ( T A = 25°C ) } × 10 ∆V REF ( ppm/°C ) = ---------------------------------------------------------------------------------------------------∆T A where ∆TA is the rated operating free-air temperature range of the device. 5. The dynamic impedance is defined as |ZOUT| = ∆VCOMP / ∆ILED. When the device is operating with two external resistors (see Figure 2), the total dynamic impedance of the circuit is given by: ∆V R1 Z OUT, TOT = -------- ≈ Z OUT × 1 + -------∆I R2 ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 4 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Electrical Characteristics (TA = 25°C unless otherwise specified) Isolation Characteristics Symbol II-O Parameter Test Conditions Input-Output Insulation Leakage Current RH = 45%, TA = 25°C, t = 5s, VI-O = 3000 VDC(6) VISO Withstand Insulation Voltage RH ≤ 50%, TA = 25°C, t = 1 min.(6) RI-O Resistance (Input to Output) VI-O = 500 VDC(6) Min. Typ. Max. Unit 1.0 µA 5000 Vrms Ω 1012 Switching Characteristics Symbol BW Parameter Test Conditions Min. Typ. Max. Unit Bandwidth (Fig. 7) 50 kHZ CMH Common Mode Transient Immunity at Output HIGH ILED = 0mA, Vcm = 10 VPP, RL = 2.2kΩ(7) (Fig. 8) 1.0 kV/µs CML Common Mode Transient Immunity at Output LOW (ILED = 1mA, Vcm = 10 VPP, RL = 2.2kΩ(7) (Fig. 8) 1.0 kV/µs Notes: 6. Device is considered as a two terminal device: Pins 1, 2, 3 and 4 are shorted together and Pins 5, 6, 7 and 8 are shorted together. 7. Common mode transient immunity at output high is the maximum tolerable (positive) dVcm/dt on the leading edge of the common mode impulse signal, Vcm, to assure that the output will remain high. Common mode transient immunity at output low is the maximum tolerable (negative) dVcm/dt on the trailing edge of the common pulse signal,Vcm, to assure that the output will remain low. ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 5 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Electrical Characteristics (Continued) (TA = 25°C unless otherwise specified) I(LED) I(LED) 8 8 2 2 VF 6 6 V 7 V R1 3 3 7 VCOMP R2 VREF VREF 5 5 Figure 2. ∆VREF / ∆VCOMP Test Circuit Figure 1. VREF, VF, ILED (min.) Test Circuit I(LED) I(OFF) 8 8 2 2 IREF 6 6 3 7 V 3 V(LED) 7 V R1 5 5 Figure 4. I(OFF) Test Circuit Figure 3. IREF Test Circuit 8 I(LED) ICEO 8 2 VCE 6 IC 2 VCE 6 3 7 V 3 7 VCOMP VREF 5 5 Figure 5. ICEO Test Circuit ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 Figure 6. CTR, VCE(sat) Test Circuit www.fairchildsemi.com 6 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Test Circuits FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Test Circuits (Continued) VCC = +5V DC IF = 1mA RL 47Ω 1 8 1µF VOUT 4 7 VIN 0.47V 0.1 VPP 6 2 5 3 Figure 7. Frequency Response Test Circuit. VCC = +5V DC IF = 0mA (A) IF = 1mA (B) R1 2.2kΩ VOUT 8 1 7 4 6 2 5 3 _ A B VCM + 10VP-P Figure 8. CMH and CML Test Circuit ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 7 Fig. 9a – LED Current vs. Cathode Voltage Fig. 9b – LED Current vs. Cathode Voltage 1.0 TA = 25°C VCOMP = VFB ILED – SUPPLY CURRENT (mA) ILED – SUPPLY CURRENT (mA) 15 10 5 0 -5 TA = 25°C VCOMP = VFB 0.5 0.0 -0.5 -10 -15 -1 0 1 2 -1.0 –1 3 0 VCOMP – CATHODE VOLTAGE (V) Fig. 10 – Reference Voltage vs. Ambient Temperature 2 3 Fig. 11 – Reference Current vs Ambient Temperature 2.510 1.30 ILED = 10mA 2.508 IREF – REFERENCE CURRENT (µA) VREF – REFERENCE VOLTAGE (V) 1 VCOMP – CATHODE VOLTAGE (V) 2.506 2.504 2.502 2.500 2.498 2.496 2.494 ILED = 10mA R1 = 10kΩ 1.25 1.20 1.15 1.10 2.492 2.490 -40 -20 0 20 40 60 80 1.05 -40 100 -20 0 20 40 60 80 100 TA – AMBIENT TEMPERATURE (°C) TA – AMBIENT TEMPERATURE (°C) Fig. 12 – Off–State Current vs. Ambient Temperature Fig. 13 – Forward Current vs. Forward Voltage 20 100 IF – FORWARD CURRENT (mA) IOFF – OFF–STATE CURRENT (nA) VCC = 37V 10 15 25°C 10 0°C 70°C 5 1 -40 -20 0 20 40 60 80 0.9 100 ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 1.0 1.1 1.2 1.3 1.4 VF – FORWARD VOLTAGE (V) TA – AMBIENT TEMPERATURE (°C) www.fairchildsemi.com 8 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Typical Performance Curves Fig. 14 – Dark Current vs. Ambient Temperature Fig. 15 – Collector Current vs. Ambient Temperature 30 VCE = 10V IC – COLLECTOR CURRENT (mA) ICEO – DARK CURRENT (nA) 10000 1000 100 10 1 VCE = 5V 25 ILED = 20mA 20 15 ILED = 10mA 10 ILED = 6mA 5 ILED = 1mA 0.1 -40 -20 0 20 40 60 80 0 100 0 10 20 30 TA – AMBIENT TEMPERATURE (°C) 40 50 60 70 80 90 100 TA – AMBIENT TEMPERATURE (°C) Fig. 16 – Current Transfer Ratio vs. LED Current Fig. 17 – Saturation Voltage vs. Ambient Temperature VCE = 5V 140 VCE(sat) – SATURATION VOLTAGE (V) (IC/IF) – CURRENT TRANSFER RATIO (%) 0.26 120 0°C 100 25°C 80 70°C 60 5 10 15 20 25 30 35 40 45 0.22 0.20 0.18 0.16 0.14 0.12 0.10 -40 40 0 0.24 50 -20 ILED – FORWARD CURRENT (mA) 0 20 60 40 80 100 TA – AMBIENT TEMPERATURE (°C) Fig. 19 – Rate of Change Vref to Vout vs. Temperature Fig. 18 – Collector Current vs. Collector Voltage -0.32 35 -0.34 DELTA Vref / DELTA Vout ( mV/V) IC – COLLECTOR CURRENT (mA) TA = 25°C 30 ILED = 20mA 25 20 15 ILED = 10mA 10 ILED = 5mA 5 -0.36 -0.38 -0.40 -0.42 -0.44 ILED = 1mA 0 0 1 2 3 4 5 6 7 8 9 -0.46 -60 10 ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) VCE – COLLECTOR-EMITTER VOLTAGE (V) www.fairchildsemi.com 9 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Typical Performance Curves (Continued) FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Typical Performance Curves (Continued) Fig. 20 – Voltage Gain vs. Frequency VCC=10V IF=10mA VOLTAGE GAIN (dB) 0 RL = 100Ω -5 RL = 500Ω RL = 1kΩ -10 -15 0.1 ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 1 10 FREQUENCY (kHz) 100 1000 www.fairchildsemi.com 10 Compensation The FOD2741 is an optically isolated error amplifier. It incorporates three of the most common elements necessary to make an isolated power supply, a reference voltage, an error amplifier, and an optocoupler. It is functionally equivalent to the popular KA431 shunt voltage regulator plus the CNY17F-X optocoupler. The compensation pin of the FOD2741 provides the opportunity for the designer to design the frequency response of the converter. A compensation network may be placed between the COMP pin and the FB pin. In typical low-bandwidth systems, a 0.1µF capacitor may be used. For converters with more stringent requirements, a network should be designed based on measurements of the system’s loop. An excellent reference for this process may be found in “Practical Design of Power Supplies” by Ron Lenk, IEEE Press, 1998. Powering the Secondary Side The LED pin in the FOD2741 powers the secondary side, and in particular provides the current to run the LED. The actual structure of the FOD2741 dictates the minimum voltage that can be applied to the LED pin: The error amplifier output has a minimum of the reference voltage, and the LED is in series with that. Minimum voltage applied to the LED pin is thus 2.5V + 1.5V = 4.0V. This voltage can be generated either directly from the output of the converter, or else from a slaved secondary winding. The secondary winding will not affect regulation, as the input to the FB pin may still be taken from the output winding. Secondary Ground The GND pin should be connected to the secondary ground of the converter. No Connect Pins The NC pins have no internal connection. They should not have any connection to the secondary side, as this may compromise the isolation structure. The LED pin needs to be fed through a current limiting resistor. The value of the resistor sets the amount of current through the LED, and thus must be carefully selected in conjunction with the selection of the primary side resistor. Photo-Transistor Feedback The value of the pull-up resistor, and the current limiting resistor feeding the LED, must be carefully selected to account for voltage range accepted by the PWM IC, and for the variation in current transfer ratio (CTR) of the opto-isolator itself. The Photo-transistor is the output of the FOD2741. In a normal configuration the collector will be attached to a pull-up resistor and the emitter grounded. There is no base connection necessary. Output voltage of a converter is determined by selecting a resistor divider from the regulated output to the FB pin. The FOD2741 attempts to regulate its FB pin to the reference voltage, 2.5V. The ratio of the two resistors should thus be: Example: The voltage feeding the LED pins is +12V, the voltage feeding the collector pull-up is +10V, and the PWM IC is the Fairchild KA1H0680, which has a 5V reference. If we select a 10kΩ resistor for the LED, the maximum current the LED can see is: R TOP V OUT ------------------------- = -------------–1 R BOTTOM V REF The absolute value of the top resistor is set by the input offset current of 5.2µA. To achieve 0.5% accuracy, the resistance of RTOP should be: (12V–4V) / 10kΩ = 800µA. The CTR of the opto-isolator is a minimum of 100%, so the minimum collector current of the photo-transistor when the diode is full on is also 800µA. The collector resistor must thus be such that: V OUT – 2.5 ----------------------------- > 1040µA R TOP 10V – 5V ----------------------------------- < 800µA or R COLLECTOR > 6.25kΩ; R COLLECTOR select 12kΩ to allow some margin. ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 11 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier The FOD2741 Option Example Part Number Description No Option FOD2741A S FOD2741AS SD FOD2741ASD T FOD2741AT 0.4" Lead Spacing V FOD2741AV VDE0884 TV FOD2741ATV VDE0884; 0.4” Lead Spacing SV FOD2741ASV VDE0884; Surface Mount SDV FOD2741ASDV Standard Through Hole Surface Mount Lead Bend Surface Mount; Tape and Reel VDE0884; Surface Mount; Tape and Reel Marking Information 1 V 3 2741A 2 XX YY B 6 4 5 Definitions 1 Fairchild logo 2 Device number 3 VDE mark (Note: Only appears on parts ordered with VDE option – See order entry table) 4 Two digit year code, e.g., ‘03’ 5 Two digit work week ranging from ‘01’ to ‘53’ 6 Assembly package code ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 12 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Ordering Information D0 P0 t K0 P2 E F A0 W1 W B0 P User Direction of Feed d Symbol Description W t D1 Dimension in mm Tape Width 16.0 ± 0.3 Tape Thickness 0.30 ± 0.05 P0 Sprocket Hole Pitch 4.0 ± 0.1 D0 Sprocket Hole Diameter 1.55 ± 0.05 E Sprocket Hole Location 1.75 ± 0.10 F Pocket Location 7.5 ± 0.1 4.0 ± 0.1 P2 P Pocket Pitch 12.0 ± 0.1 A0 Pocket Dimensions 10.30 ±0.20 B0 10.30 ±0.20 K0 4.90 ±0.20 W1 d R Cover Tape Width 1.6 ± 0.1 Cover Tape Thickness 0.1 max Max. Component Rotation or Tilt 10° Min. Bending Radius 30 Reflow Profile 245 C, 10–30 s Temperature (°C) 300 260 C peak 250 200 150 Time above 183C,