FOD2741BTV

FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier August 2008 FOD2741A, FOD2741B, FOD2741C Optically Isolated Error Amplifier Features ■ Optocoupler, precision reference and error amplifier in ■ ■ ■ ■ Description The FOD2741 Optically Isolated Amplifier consists of the popular KA431 precision programmable shunt reference and an optocoupler. 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%. 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. ■ ■ 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 ■ DC to DC converters Functional Bock Diagram Package Outlines NC 1 8 LED 8 1 C 2 7 FB E 3 6 COMP 8 8 1 1 NC 4 5 GND ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Pin Definitions Pin Number 1 2 3 4 5 6 7 8 Pin Name NC C E NC GND COMP FB LED Not connected Phototransistor Collector Phototransistor Emitter Not connected Ground Pin Description 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 R1 3 7 R2 5 ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 2 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Absolute Maximum Ratings (TA = 25°C unless otherwise specified) 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 TSTG TOPR TSOL VLED ILED VCEO VECO IC PD1 PD2 PD3 Parameter Storage Temperature Operating Temperature Lead Solder Temperature Input Voltage Input DC Current Collector-Emitter Voltage Emitter-Collector Voltage Collector Current Input Power Dissipation(1) Transistor Power Dissipation(2) Total Power Dissipation(3) Value -40 to +125 -40 to +85 260 for 10 sec. 37 20 30 7 50 145 85 145 Units °C °C °C V mA V V mA mW mW mW 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 Electrical Characteristics (TA = 25°C unless otherwise specified) Input Characteristics Symbol VF VREF Parameter LED Forward Voltage Reference Voltage Test Conditions ILED = 10mA, VCOMP = VFB (Fig.1) ILED = 10mA, VCOMP = VFB Device All FOD2741A FOD2741B Min. 2.482 2.470 Typ. Max. Unit 1.5 2.495 2.495 2.500 4.5 -1.0 -0.5 2.508 2.520 2.550 17 -2.7 -2.0 4 1.2 1.0 1.0 0.5 µA µA mA µA Ω V V V V mV mV/V FOD2741C 2.450 VREF (DEV)(4) Deviation of VREF Over TA = -25°C to +85°C Temperature ∆VREF/ ∆VCOMP IREF Ratio of VREF Variation ILED = 10mA ∆VCOMP = 10V to VREF to the Output of the ∆VCOMP = 36V to 10V Error Amplifier Feedback Input Current ILED = 10mA, R1 = 10kΩ (Fig. 3) TA = -25°C to +85°C All All All All All All All 1.5 0.4 0.45 0.05 0.15 IREF (DEV)(4) Deviation of IREF Over Temperature ILED (MIN) I(OFF) |ZOUT| Off-state Error Amplifier Current Error Amplifier Output impedance(5) Minimum Drive Current VCOMP = VFB (Fig. 1) VLED = 37V, VFB = 0 (Fig. 4) VCOMP = VREF, ILED = 1mA to 20mA, f ≥ 1.0 kHz Output Characteristics Symbol ICEO BVECO BVCEO Parameter Collector Dark Current Emitter-Collector Voltage Breakdown Collector-Emitter Voltage Breakdown Test Conditions VCE = 10V (Fig. 5) IE = 100µA IC = 1.0mA Min. 7 70 Typ. Max. 50 Unit nA V V Transfer Characteristics Symbol Parameter CTR Current Transfer Ratio Test Conditions ILED = 10mA, VCOMP = VFB, VCE = 5V (Fig. 6) ILED = 10mA, VCOMP = VFB, IC = 2.5mA (Fig. 6) Min. 100 Typ. Max. 200 0.4 Unit % V VCE (SAT) Collector-Emitter Saturation Voltage 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: { V REF ( DEV ) /V REF ( T A = 25°C ) } × 10 ∆ V REF ( ppm/°C ) = ---------------------------------------------------------------------------------------------------∆ TA 6 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 (Continued) (TA = 25°C unless otherwise specified) Isolation Characteristics Symbol II-O VISO RI-O Parameter Input-Output Insulation Leakage Current Withstand Insulation Voltage Resistance (Input to Output) Test Conditions RH = 45%, TA = 25°C, t = 5s, VI-O = 3000 VDC(6) RH ≤ 50%, TA = 25°C, t = 1 min.(6) VI-O = 500 VDC(6) Min. Typ. Max. 1.0 Unit µA Vrms 5000 1012 Ω Switching Characteristics Symbol BW CMH CML Parameter Bandwidth Common Mode Transient Immunity at Output HIGH Common Mode Transient Immunity at Output LOW Test Conditions (Fig. 7) ILED = 0mA, Vcm = 10 VPP, RL = 2.2kΩ(7) (Fig. 8) (ILED = 1mA, Vcm = 10 VPP, RL = 2.2kΩ(7) (Fig. 8) Min. Typ. 50 1.0 1.0 Max. Unit kHZ kV/µs 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 Test Circuits I(LED) I(LED) 8 VF 6 V 7 VREF 5 3 V R1 6 7 VCOMP R2 VREF 5 3 2 8 2 Figure 1. VREF, VF, ILED (min.) Test Circuit Figure 2. ∆VREF / ∆VCOMP Test Circuit I(LED) 8 2 I(OFF) 8 2 IREF 6 V R1 5 5 7 3 V 6 V(LED) 7 3 Figure 3. IREF Test Circuit Figure 4. I(OFF) Test Circuit 8 ICEO 2 VCE I(LED) 8 2 VCE 6 V 7 VCOMP VREF 3 IC 6 7 3 5 5 Figure 5. ICEO Test Circuit Figure 6. CTR, VCE(sat) Test Circuit ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 6 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Test Circuits (Continued) VCC = +5V DC IF = 1mA RL 47Ω 8 1 1µF VOUT 7 4 0.1 VPP VIN 0.47V 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 AB 6 2 5 3 _ 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 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Typical Performance Curves Fig. 9a – LED Current vs. Cathode Voltage 15 ILED – SUPPLY CURRENT (mA) TA = 25°C VCOMP = VFB 1.0 ILED – SUPPLY CURRENT (mA) Fig. 9b – LED Current vs. Cathode Voltage TA = 25°C VCOMP = VFB 10 0.5 5 0 0.0 -5 -0.5 -10 -15 -1 0 1 2 3 VCOMP – CATHODE VOLTAGE (V) -1.0 –1 0 1 2 3 VCOMP – CATHODE VOLTAGE (V) Fig. 10 – Reference Voltage vs. Ambient Temperature 2.510 VREF – REFERENCE VOLTAGE (V) 2.508 2.506 2.504 2.502 2.500 2.498 2.496 2.494 2.492 2.490 -40 -20 0 20 40 60 80 100 IREF – REFERENCE CURRENT (µA) ILED = 10mA 1.30 Fig. 11 – Reference Current vs Ambient Temperature ILED = 10mA R1 = 10kΩ 1.25 1.20 1.15 1.10 1.05 -40 -20 0 20 40 60 80 100 TA – AMBIENT TEMPERATURE (°C) TA – AMBIENT TEMPERATURE (°C) Fig. 12 – Off–State Current vs. Ambient Temperature 100 VCC = 37V IOFF – OFF–STATE CURRENT (nA) IF – FORWARD CURRENT (mA) 20 Fig. 13 – Forward Current vs. Forward Voltage 15 10 10 70°C 25°C 0°C 5 1 -40 -20 0 20 40 60 80 100 0.9 1.0 1.1 1.2 1.3 1.4 TA – AMBIENT TEMPERATURE (°C) VF – FORWARD VOLTAGE (V) ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 8 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Typical Performance Curves (Continued) Fig. 14 – Dark Current vs. Ambient Temperature 10000 ICEO – DARK CURRENT (nA) IC – COLLECTOR CURRENT (mA) VCE = 10V 30 VCE = 5V 25 ILED = 20mA Fig. 15 – Collector Current vs. Ambient Temperature 1000 20 100 15 ILED = 10mA 10 ILED = 6mA 5 ILED = 1mA 10 1 0.1 -40 -20 0 20 40 60 80 100 0 0 10 20 30 40 50 60 70 80 90 100 TA – AMBIENT TEMPERATURE (°C) TA – AMBIENT TEMPERATURE (°C) Fig. 16 – Current Transfer Ratio vs. LED Current 0.26 (IC/IF) – CURRENT TRANSFER RATIO (%) VCE(sat) – SATURATION VOLTAGE (V) 140 VCE = 5V 0.24 0.22 0.20 0.18 0.16 0.14 0.12 Fig. 17 – Saturation Voltage vs. Ambient Temperature 120 0°C 25°C 80 70°C 60 100 40 0 5 10 15 20 25 30 35 40 45 50 ILED – FORWARD CURRENT (mA) 0.10 -40 -20 0 20 40 60 80 100 TA – AMBIENT TEMPERATURE (°C) Fig. 18 – Collector Current vs. Collector Voltage 35 TA = 25°C IC – COLLECTOR CURRENT (mA) 30 25 20 15 10 ILED = 5mA 5 ILED = 1mA 0 0 1 2 3 4 5 6 7 8 9 10 ILED = 10mA ILED = 20mA DELTA Vref / DELTA Vout ( mV/V) -0.34 -0.36 -0.38 -0.40 -0.42 -0.44 -0.32 Fig. 19 – Rate of Change Vref to Vout vs. Temperature -0.46 -60 -40 -20 0 20 40 60 80 100 120 VCE – COLLECTOR-EMITTER VOLTAGE (V) TEMPERATURE (°C) ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 9 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Typical Performance Curves (Continued) Fig. 20 – Voltage Gain vs. Frequency VCC=10V IF=10mA 0 VOLTAGE GAIN (dB) RL = 100Ω -5 RL = 500Ω RL = 1kΩ -10 -15 0.1 1 10 FREQUENCY (kHz) 100 1000 ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 10 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier The FOD2741 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. Compensation 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. 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. 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. Photo-Transistor 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. 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. 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: (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: 10V – 5V ----------------------------------- < 800 µ A or R COLLECTOR > 6.25k Ω ; R COLLECTOR select 12kΩ to allow some margin. Feedback 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: 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: V OUT – 2.5 ---------------------------- > 1040 µ A R TOP ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 11 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Package Dimensions Through Hole PIN 1 ID. 4 3 2 1 4 3 2 1 0.4" Lead Spacing PIN 1 ID. 0.270 (6.86) 0.250 (6.35) 5 6 7 8 0.270 (6.86) 0.250 (6.35) 0.390 (9.91) 0.370 (9.40) 5 6 7 8 SEATING PLANE 0.070 (1.78) 0.045 (1.14) 0.200 (5.08) 0.140 (3.55) 0.020 (0.51) MIN SEATING PLANE 0.390 (9.91) 0.370 (9.40) 0.070 (1.78) 0.045 (1.14) 0.200 (5.08) 0.140 (3.55) 0.004 (0.10) MIN 0.154 (3.90) 0.120 (3.05) 0.022 (0.56) 0.016 (0.41) 0.100 (2.54) TYP 0.016 (0.40) 0.008 (0.20) 15° MAX 0.300 (7.62) TYP 0.154 (3.90) 0.120 (3.05) 0.022 (0.56) 0.016 (0.41) 0.100 (2.54) TYP 0.016 (0.40) 0.008 (0.20) 0° to 15° 0.400 (10.16) TYP Surface Mount 0.390 (9.91) 0.370 (9.40) 4 3 2 1 8-Pin DIP – Land Pattern 0.070 (1.78) PIN 1 ID. 0.270 (6.86) 0.250 (6.35) 0.060 (1.52) 5 6 7 8 0.100 (2.54) 0.295 (7.49) 0.415 (10.54) 0.030 (0.76) 0.070 (1.78) 0.045 (1.14) 0.020 (0.51) MIN 0.300 (7.62) TYP 0.016 (0.41) 0.008 (0.20) 0.022 (0.56) 0.016 (0.41) 0.100 (2.54) TYP Lead Coplanarity : 0.004 (0.10) MAX 0.045 (1.14) 0.315 (8.00) MIN 0.405 (10.30) MAX. Note: All dimensions are in inches (millimeters) ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 12 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Ordering Information Option No Option S SD T V TV SV SDV Example Part Number FOD2741A FOD2741AS FOD2741ASD FOD2741AT FOD2741AV FOD2741ATV FOD2741ASV FOD2741ASDV Description Standard Through Hole Surface Mount Lead Bend Surface Mount; Tape and Reel 0.4" Lead Spacing VDE0884 VDE0884; 0.4” Lead Spacing VDE0884; Surface Mount VDE0884; Surface Mount; Tape and Reel Marking Information 1 2741A V 3 4 2 6 XX YY B 5 Definitions 1 2 3 4 5 6 Fairchild logo Device number VDE mark (Note: Only appears on parts ordered with VDE option – See order entry table) Two digit year code, e.g., ‘03’ Two digit work week ranging from ‘01’ to ‘53’ Assembly package code ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 13 FOD2741A, FOD2741B, FOD2741C — Optically Isolated Error Amplifier Carrier Tape Specifications D0 K0 t P0 P2 E A0 W1 B0 F W d User Direction of Feed P D1 Symbol W t P0 D0 E F P2 P A0 B0 K0 W1 d R Pocket Pitch Tape Width Description Tape Thickness Sprocket Hole Pitch Sprocket Hole Diameter Sprocket Hole Location Pocket Location Dimension in mm 16.0 ± 0.3 0.30 ± 0.05 4.0 ± 0.1 1.55 ± 0.05 1.75 ± 0.10 7.5 ± 0.1 4.0 ± 0.1 12.0 ± 0.1 10.30 ±0.20 10.30 ±0.20 4.90 ±0.20 Pocket Dimensions Cover Tape Width Cover Tape Thickness Max. Component Rotation or Tilt Min. Bending Radius 1.6 ± 0.1 0.1 max 10° 30 Reflow Profile 300 Temperature (°C) 250 200 150 100 50 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Time (Minute) • Peak reflow temperature: 260 C (package surface temperature) • Time of temperature higher than 183 C for 160 seconds or less • One time soldering reflow is recommended ©2004 Fairchild Semiconductor Corporation FOD2741A, FOD2741B, FOD2741C Rev. 1.0.1 www.fairchildsemi.com 14 245 C, 10–30 s 260 C peak Time above 183C,