FAIRCHILD SEMICONDUCTOR FOD2743A FOD2743B FOD2743C Manual(1)
Contents
1. voltage an error amplifier and an optocoupler It is functionally equivalent to the popular KA431 shunt voltage regulator plus the CNY17F X optocoupler Powering the Secondary Side The LED pin in the FOD2743 powers the secondary side and in particular provides the current to run the LED The actual structure of the FOD2743 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 2V 3 7V This voltage can be generated either directly from the output of the converter or else from a slaved second ary 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 Feedback Output voltage of a converter is determined by selecting a resistor divider from the regulated output to the FB pin The FOD2743 attempts to regulate its FB pin to the reference voltage 2 5V The ratio of the two resistors should thus be Rrop_ _ Vout a iE eH cod HaorroM VREF The absolute value of the top resistor is set by the input offset current of 5 2pA To achieve 0 5 accuracy the resistanc2. x 0 1 Pocket Location Cover Tape Thickness 0 1 max Max Component Rotation or Tilt 10 Min Bending Radius 30 m D eO oOo kuuuiiiux xxiuiiiDi dAmhjwXNqu x AL ANE KCeQIQ3SSCIIISLe9 I O RZXASmucIEE LE EGAX L e 2004 Fairchild Semiconductor Corporation Page 13 of 15 4 8 04 OPTICALLY ISOLATED FAIRCHILD ERROR AMPLIFIER SEMICONDUCTOR FOD2743A FOD2743B FOD2743C Fig 22 Recommended IR Reflow Profile Peak reflow temperature 260 C package surface temperature Time of temperature higher than 245 C 40 seconds or less Number of reflows Three 300 3 250 3 o 900 4 o Jj 5 J 5 J 2 150 4 E j oO Jj j 100 4 50 4 50 100 150 200 250 Time s 2004 Fairchild Semiconductor Corporation Page 14 of 15 4 8 04 OPTICALLY ISOLATED FAIRCHILD ERROR AMPLIFIER SEMICONDUCTOR FOD2743A FOD2743B FOD2743C DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY FUNCTION OR DESIGN FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS NOR THE RIGHTS OF OTHERS LIFE SUPPORT POLICY FAIRCHILD S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVA
3. 0 250 6 35 0 070 1 78 0 m iu 62 0 045 1 14 nc j 0 016 0 41 us N 51 016 0 41 0 E 0 20 0 022 0 56 0 045 1 14 omz sn 0315 6 00 0 E n 54 0 M m 30 Lead Coplanarity 0 004 0 10 M 8 Pin Dip N mem Lj Ei ME 0 060 1 52 0 100 2 54 Ll 0 295 7 49 0 415 10 54 7 l 0 030 0 76 i OUL FOD2743C 4 8 04 OPTICALLY ISOLATED FAIRCHILD ERROR AMPLIFIER SEMICONDUCTOR FOD2743A FOD2743B FOD2743C ORDERING INFORMATION Example FOD2743A X Y X Y Packaging Option T 0 4 Lead Spacing V VDE tested S Surface Mount Lead Bend SD Surface Mount Tape and Reel 1000 per reel MARKING INFORMATION 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 Page 12 of 15 4 8 04 OPTICALLY ISOLATED FAIRCHILD ERROR AMPLIFIER SEMICONDUCTOR FOD2743A FOD2743B FOD2743C Carrier Tape Specifications Description Dimension in mm Tape Width 16 0 0 3 Tape Thickness 0 30 0 05 Sprocket Hole Pitch 4 0 0 1 Sprocket Hole Diameter 1 55 0 05 Sprocket Hole Location E 1 75 x 0 10 7 5 x 0 1 4 0 x 0 1 Pocket Pitch 12 0 0 1 10 30 0 20 Pocket Dimensions 10 30 0 20 4 90 0 20 Cover Tape Width 1 6
4. 5V reference If we select a 10k resistor for the LED the maximum current the LED can see is 12V 4V 10kQ 800pA The CTR of the opto isolator is a minimum of 50 so the minimum collector current of the photo transistor when the diode is full on is 400pA The collector resistor must thus be such that _10V 5V_ R lt 400A or Roo_tector gt 12 5KQ COLLECTOR select 20kQ to allow some margin 2004 Fairchild Semiconductor Corporation Page 10 of 15 4 8 04 FAIRCHILD SEMICONDUCTOR FOD2743A Package Dimensions Through Hole 0 270 6 86 0 250 6 35 5 8 LT LI LL 0 390 9 91 0 370 9 40 0 070 1 78 0 045 1 14 0 200 5 08 0 020 0 51 MIN 0 140 3 55 SEATING PLANE 0 154 3 90 t 0 120 3 05 seo 15 max 0 008 0 20 0 300 7 62 j TYP Ej 100 2 54 TYP 0 022 0 56 0 016 xd L Package Dimensions 0 4 Lead Spacing 0 270 6 86 0 250 6 35 0 390 9 91 7 0370 940 0 070 1 78 0 045 1 14 0 200 5 08 0 140 3 55 SEATING PLANE 0 154 3 90 0 120 0 120 8 05 0 022 0 56 0 016 0 40 veis v 0 016 0 41 0 008 0 20 6 008 020 100 2 54 TYP 9400 ee NOTE All dimensions are in inches millimeters 2004 Fairchild Semiconductor Corporation FOD2743B Page 11 of 15 OPTICALLY ISOLATED ERROR AMPLIFIER Package Dimensions Surface Mount 0 390 9 91 0 370 9 40 ID 0 270 6 86
5. B b O O 6 2 5 3 VCM 10Vp p Fig 8 CMH and CML Test Circuit ees 2004 Fairchild Semiconductor Corporation Page 6 of 15 4 8 04 OPTICALLY ISOLATED FAIRCHILD ERROR AMPLIFIER SEMICONDUCTOR FOD2743A FOD2743B FOD2743C TYPICAL PERFORMANCE CURVES Fig 9a LED Current vs Cathode Voltage Fig 9b LED Current vs Cathode Voltage Ta 25 C Vcomp VFB ILED Supply Current mA ILED Supply Current mA 1 0 1 2 3 Vcomp Cathode Voltage V Vcomp Cathode Voltage V Fig 10 Reference Voltage Variation vs Ambient Temperature 1 0 0 8 ILED 1mA 10mA Normalized to TA 25 C Fig 11 Reference Current vs Ambient Temperature ILED 1mA 10mA R1 10kQ 0 6 0 4 0 2 0 0 0 2 0 4 Ingr Reference Current uA 0 6 AVrer Reference Voltage Variation 0 8 1 0 E 40 20 0 20 40 60 80 100 40 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 lorr Off State Current nA Ir Forward Current mA 3 0 9 1 0 1 1 2 1 3 1 4 Ta Ambient Temperatur
6. D ERROR AMPLIFIER SEMICONDUCTOR FOD2743A FOD2743B FOD2743C ELECTRICAL CHARACTERISTICS T 25 C Unless otherwise specified INPUT CHARACTERISTICS San ewe mn Tue Tunr LED Forward Voltage lLgp 1 MA Vcomp Ves fig 1 2 482 2 495 2 508 Reference Voltage li gp 1 MA Vcomp VFB VREF 2 470 2 495 2 520 2 450 2 500 2 550 Deviation of Vggr over TA 25 C to 85 C VREF DEV temperature Ratio of Vggr variation to the AVcomp 10V to VReF AVper ILED 1mA output of the error amplifier AVcomp 36V to 10V 4Vcomp Feedback Input Current ILED 1MA Ry 10kQ fig 3 IREF Deviation of IRef over temperature TA 25 C to 85 C IREF DEV Minimum Drive Current Vcomp Vea fig 1 ligp MIN Off state error amplifier current VLED 37V Vep O fig 4 OFF Error amplifier output impedance Vcomp Vrer lLep 1mA to 20mA IZgu1l see note 2 f2 1 0 kHz our 1 The deviation parameters Vggre pev and Inge pev 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 AVagg is defined as Vneripev Vagr TA 25 C x 10 ATA where AT is the rated operating free air temperature range of the device AVage ppm C 2 The dynamic impedance is defined as IZoy1l AVcoyp Al gp When the device is operati
7. L OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION As used herein 1 Life support devices or systems are devices or systems 2 A critical component in any component of a life support which a are intended for surgical implant into the body or device or system whose failure to perform can be b support or sustain life and c whose failure to perform reasonably expected to cause the failure of the life support when properly used in accordance with instructions for use device or system or to affect its safety or effectiveness provided in the labeling can be reasonably expected to result in a significant injury of the user 2004 Fairchild Semiconductor Corporation Page 15 of 15 4 8 04
8. OPTICALLY ISOLATED FAIRCHILD ERROR AMPLIFIER SEMICONDUCTOR FOD2743A FOD2743B FOD2743C DESCRIPTION The FOD2743 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 50 to 100 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 con verters When using the FOD2743 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 FEATURES e Optocoupler precision reference and error amplifier in single package e 2 5V reference e CTR 50 to 100 at 1mA e 5 000V RMS isolation UL approval E90700 Vol 2 CSA approval 1296837 VDE approval pending BSI approval pending Low temperature coefficient 50 ppm C max e FOD2743XA tolerance 0 5 FOD2743B tolerance 1 FOD2743C tolerance 2 APPLICATIONS Power supplies regulation e DC to DC converters PIN DEFINITIONS LED Anode LED This pin is the in
9. Vout vs Temperature 35 0 32 Ta 25 C 30 0 34 ILED 20mA gt z 25 0 36 z E 9 20 gt 0 38 5 sS o o 5 15 lLep 10mA Q 0 40 9 gt OQ 10 g 0 42 D ILED 5MA 5 0 44 ILED 1mA 0 0 46 0 1 2 3 4 5 6 7 8 9 10 60 40 20 0 20 40 60 80 100 120 VCE Collector Emitter Voltage V Temperature C 2004 Fairchild Semiconductor Corporation Page 8 of 15 4 8 04 OPTICALLY ISOLATED FAIRCHILD ERROR AMPLIFIER SEMICONDUCTOR FOD2743A FOD2743B FOD2743C Fig 20 Voltage Gain vs Frequency Voc 10V 0 lp 10mA m RL 25000 S oO O 5 lp 1mA g Ry 2 4kQ S lp 10mA o R 1000 gt lp 10mA IT 10 RL 1kQ 15 1 10 100 1000 Frequency kHz Fig 21 Package Power Dissipation vs Ambient Temperature 200 a o e eo 50 Package Power Dissipation mW 40 20 0 20 40 60 80 100 Ta Ambient Temperature C 2004 Fairchild Semiconductor Corporation Page 9 of 15 4 8 04 FAIRCHILD SEMICONDUCTOR OPTICALLY ISOLATED ERROR AMPLIFIER FOD2743A FOD2743B FOD2743C The FOD2743 The FOD2743 is an optically isolated error amplifier It incor porates three of the most common elements necessary to make an isolated power supply a reference
10. d 4 are shorted together and Pins 5 6 7 and 8 are shorted together 2 Common mode transient immunity at output high is the maximum tolerable positive dVcm dt on the leading edge of the com mon 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 Page 4 of 15 4 8 04 a OPTICALLY ISOLATED A n ERROR AMPLIFIER SEMICONDUCTOR FOD2743A FOD2743B FOD2743C po 1 leto LED pr 1 lc 1 jT inca 1 7 4 tada d tepid D el T 4 o 4 li Vcomp FIG 5 Icgo TEST CIRCUIT FIG 6 CTR Vce san TEST CIRCUIT 2004 Fairchild Semiconductor Corporation Page 5 of 15 4 8 04 OPTICALLY ISOLATED FAIRCHILD ERROR AMPLIFIER See SEMICONDUCTOR FOD2743A FOD2743B FOD2743C Voc 5V DC RL 8 1 kaii NS Vour 7 fm 4 AL v J 0 1 Ver AS T 047V Fig 7 Frequency Response Test Circuit Vcc 5V DC IF 0 mA A IF 1 mA B R1 8 1 N 2 2kQ AVA Vour o 7 f AS 4 A
11. e C Vr Forward Voltage V 2004 Fairchild Semiconductor Corporation Page 7 of 15 4 8 04 ee OPTICALLY ISOLATED FAIRCHILD ERROR AMPLIFIER SEMICONDUCTOR FOD2743A FOD2743B FOD2743C Fig 14 Dark Current vs Ambient Temperature Fig 15 Collector Current vs Ambient Temperature 10000 Vcg 10V 1000 T 2 r1 lt 5 100 ET E e t t 5 oR S lt o 5 16 EE x os 37 xs za amp 10 Sa Ba D E LU E u Q En 57 O Oz 9 1 2 01 40 20 0 20 40 60 80 100 40 20 0 20 40 60 80 100 TA Ambient Temperature C Ta Ambient Temperature C Fig 16 Current Transfer Ratio vs LED Current Fig 17 Saturation Voltage vs Ambient Temperature 0 26 0 24 S S 0 22 o 8 0 20 pa o ILED 10mA 3 LL lc 2 5mA S S 016 a ILED 1mA c 9 G 014 Ic 0 11mA 5 0 12 E TE W 0 10 0 08 0 06 0 1 1 10 40 20 0 20 40 60 80 100 ILED Forward Current mA Ta Ambient Temperature C Fig 18 Collector Current vs Collector Voltage Fig 19 Rate of Change Vref to
12. e of Rrop should be Vour 2 5 OO WA Rrop Compensation The compensation pin of the FOD2743 provides the opportu nity 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 1uF 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 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 FOD2743 In a normal configuration the collector will be attached to a pull up resistor and the emitter grounded There is no base connection neces sary The value of the pull up resistor and the current limiting resis tor 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 FAN4803 which has a
13. ng with two external resistors see Figure 2 the total dynamic impedance of the circuit is given by H1 Zour ror A Zour x 7 2004 Fairchild Semiconductor Corporation Page 3 of 15 4 8 04 OPTICALLY ISOLATED FAIRCHILD ERROR AMPLIFIER SEMICONDUCTOR FOD2743A FOD2743B FOD2743C OUTPUT CHARACTERISTICS T 25 C Unless otherwise specified Parameter Test Conditions Symbol Mm Typ Mex Unit Collector dark current Vcg 10 V Fig 5 Emitter collector voltage breakdown lg 100 pA Collector emitter voltage breakdown Ic 1 0mA TRANSFER CHARACTERISTICS T 25 C Unless otherwise specified Parameter Test Conditions Symbol Min Ty Max Unit Current transfer ratio Collector emitter saturation voltage Parameter Input output insulation leakage current Withstand insulation voltage ILED 1 mA Vcomp VFB ligp 1 MA Vcomp Vra Ic 0 1 mA Fig 6 RH 45 T4 25 C t 5s Vi o 3000 VDC note 1 RH lt 50 Ty 25 C t 1 min notes 1 Resistance input to output Parameter Bandwidth Vi o 500 VDC note 1 Fig 7 Common mode transient immunity at output high ILED 0 mA Vem 10 Vpp RL 2 2 KQ Fig 8 note 2 Common mode transient immunity at output low Notes LED 1 mA Vem 10 Vpp RL 2 2 kQ Fig 8 note 2 1 Device is considered as a two terminal device Pins 1 2 3 an
14. put to the light emitting diode COMP Error Amplifier Compensation This pin is the output of the error amplifier Ground FB Voltage Feedback This pin is the inverting input to the error amplifier Not connected Phototransistor Emitter Phototransistor Collector 1 2 3 4 5 6 7 8 Not connected The compensation network must be attached between pins 2 and 4 2004 Fairchild Semiconductor Corporation Page 1 of 15 4 8 04 OPTICALLY ISOLATED FAIRCHILD ERROR AMPLIFIER SEMICONDUCTOR FOD2743A FOD2743B FOD2743C TYPICAL APPLICATION FAN4803 PWM Control FOD2743 ABSOLUTE MAXIMUM RATINGS T 25 C Unless otherwise specified Parameter 00000000 Symbol Value ae a eeaeee Temperature EL NM to 125 Operating Temperature ToPR 25 to 85 Lead Solder Temperature 260 for 10 sec Input Voltage Input DC Current Collector Emitter Voltage Emitter Collector Voltage Collector Current Input Power Dissipation Transistor Power Dissipation Total Power Dissipation note 1 Notes 1 See derating graph fig 21 2 Functional operation under these conditions is not implied Permanent damage may occur if the device is subjected to conditions outside these ratings 2004 Fairchild Semiconductor Corporation Page 2 of 15 4 8 04 OPTICALLY ISOLATED FAIRCHIL
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FAIRCHILD SEMICONDUCTOR FOD2743A FOD2743B FOD2743C Manual(1)