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FOD2742C Dataheets PDF



Part Number FOD2742C
Manufacturers Fairchild Semiconductor
Logo Fairchild Semiconductor
Description OPTICALLY ISOLATED ERROR AMPLIFIER
Datasheet FOD2742C DatasheetFOD2742C Datasheet (PDF)

OPTICALLY ISOLATED ERROR AMPLIFIER FOD2742A DESCRIPTION The FOD2742 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 .

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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2742A DESCRIPTION The FOD2742 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. FUNCTIONAL BLOCK DIAGRAM FOD2742B FOD2742C When using the FOD2742, 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 small outline package. FEATURES • Optocoupler, precision reference and error amplifier in single package • 2.5V reference • CTR 100% to 200% • 2,500V RMS isolation • UL approval E90700, Volume 2 • VDE approval 136616 • FOD2742A: tolerance 0.5% FOD2742B: tolerance 1% FOD2742C: tolerance 2% • BSI approval 8661, 8662 • CSA approval 1113643 NC 1 8 LED C 2 7 FB E 3 6 COMP NC 4 5 GND • Low temperature coefficient 50 ppm/°C max APPLICATIONS • Power supplies regulation • DC to DC converters PIN DEFINITIONS Pin Number 1 2 3 4 5 6 7 8 Pin Name NC C E NC GND COMP FB LED Pin function description Not connected Phototransistor Collector Phototransistor Emitter 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. © 2003 Fairchild Semiconductor Corporation Page 1 of 13 8/27/03 OPTICALLY ISOLATED ERROR AMPLIFIER FOD2742A TYPICAL APPLICATION FOD2742B FOD2742C V1 FAN4803 PWM Control VO FOD2742 2 8 6 R1 3 7 R2 5 ABSOLUTE MAXIMUM RATINGS (TA = 25°C Unless otherwise specified.) Parameter Storage Temperature Operating Temperature Reflow Temperature Profile (refer to fig. 21) Input Voltage Input DC Current Collector-Emitter Voltage Emitter-Collector Voltage Collector Current Input Power Dissipation (note 1) Transistor Power Dissipation (note 2) Total Power Dissipation (note 3) VLED ILED VCEO VECO IC PD1 PD2 PD3 37 20 70 7 50 145 85 145 V mA V V mA mW mW mW Symbol TSTG TOPR Value -40 to +125 -25 to +85 Units °C °C Notes 1. Derate linearly from 25°C at a rate of 2.42 mW/ °C 2. Derate linearly from 25°C at a rate of 1.42 mW/ °C. 3. Derate linearly from 25°C at a rate of 2.42 mW/ °C. 4. Functional operation under these conditions is not implied. Permanent damage may occur if the device is subjected to conditions outside these ratings. © 2003 Fairchild Semiconductor Corporation Page 2 of 13 8/27/03 OPTICALLY ISOLATED ERROR AMPLIFIER FOD2742A FOD2742B FOD2742C ELECTRICAL CHARACTERISTICS (TA = 25°C Unless otherwise specified.) INPUT CHARACTERISTICS Parameter LED Forward Voltage Test Conditions (ILED = 10 mA, VCOMP = VFB) (fig. 1) ILED = 10 mA, VCOMP = VFB (fig. 1) Symbol VF VREF Device ALL A Reference Voltage Deviation of VREF over temperature Ratio of VREF variation to the output of the error amplifier Feedback Input Current Deviation of IREF over temperature Minimum Drive Current Off-state error amplifier current Error amplifier output impedance (see note 2) B C TA = -25°C to +85°C (fig. 1) VREF (DEV) ILED = 10 mA ∆VCOMP = 10V to VREF (fig. 2) ∆VCOMP = 36V to 10V ILED = 10mA, R1 = 10KΩ (fig. 3) TA = -25°C to +85°C (fig. 3) VCOMP = VFB (fig. 1) VLED = 37V, VFB = 0 (fig. 4) VCOMP = VREF, ILED = 1mA to 20mA, f ≥ 1.0 kHz ∆VREF/ ∆VCOMP IREF IREF (DEV) ILED (MIN) I(OFF) |ZOUT| ALL ALL ALL ALL ALL ALL ALL 2.482 2.470 2.450 Min. Typ. 1.20 2.495 2.495 2.500 3.5 -0.5 -0.3 2.2 1.0 0.45 0.01 0.15 Max. 1.5 2.508 2.520 2.550 17 -2.7 -2.0 4 1.2 1.0 1.0 0.5 Unit V V V V mV mV/ V µA µA mA µA Ω 1. 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 where ∆TA is the rated operating free-air temperature range of the device. 2. 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 6 © 2003 Fairchild Semiconductor Corporation Page 3 of 13 8/27/03 OPTICALLY ISOLATED ERROR AMPLIFIER FOD2742A FOD2742B FOD2742C OUTPUT CHARACTERI.


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