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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
DESCRIPTION
The FOD2711 Optically Isolated Amplifier consists of the popular RC431A precision programmable shunt reference and an optocoupler. The optocoupler is a gallium arsenide (GaAs) light emitting diode optically coupled to a silicon phototransistor. The reference voltage tolerance is 1%. The current transfer ratio (CTR) ranges from 100% to 200%. 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 FOD2711, 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.
8 1
8 1
8 1
FUNCTIONAL BLOCK DIAGRAM
FEATURES
* * * * * Optocoupler, precision reference and error amplifier in single package 1.240V 1% reference CTR 100% to 200% 5,000V RMS isolation UL approval E90700, Volume 2 CSA approval 1296837 VDE approval 40002463 BSI approval 8702, 8703
NC 1 8 LED
C
2
7 FB
E
3
6 COMP
APPLICATIONS
* Power supplies regulation * DC to DC converters
NC
4
5 GND
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.
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
TYPICAL APPLICATION
V1
FAN4803 PWM Control
VO
FOD2711 2 8
6
R1
3
7 R2
5
ABSOLUTE MAXIMUM RATINGS (TA = 25C Unless otherwise specified.)
Parameter Storage Temperature Operating Temperature Lead Solder Temperature 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) Symbol TSTG TOPR TSOL VLED ILED VCEO VECO IC PD1 PD2 PD3 Value -55 to +125 -40 to +85 260 for 10 sec. 13.2 20 30 7 50 145 85 145 Units C C C V mA V V mA mW mW mW
Notes 1. Derate linearly from 25C at a rate of 2.42 mW/ C 2. Derate linearly from 25C at a rate of 1.42 mW/ C. 3. Derate linearly from 25C 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.
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
ELECTRICAL CHARACTERISTICS (TA = 25C Unless otherwise specified.) INPUT CHARACTERISTICS
Parameter LED forward voltage Reference voltage (-40 to +85C) (25C) Deviation of VREF over temperature - See Note 1 Ratio of Vref variation to the output of the error amplifier Feedback input current Deviation of IREF over temperature - See Note 1 Minimum drive current Off-state error amplifier current Error amplifier output impedance - See Note 2 (VCOMP = VFB, ILED = 10 mA (Fig.1) VREF 1.221 1.228 1.240 4 -1.5 0.15 0.15 55 0.001 0.25 1.259 1.252 12 -2.7 0.5 0.3 80 0.1 V mV mV/V A A A A Ohm Test Conditions (ILED = 10 mA, VCOMP = VFB)(Fig.1) Symbol VF Min Typ** Max 1.5 Unit V
(TA = -40 to +85C) VREF (DEV) (ILED = 10 mA, VCOMP = VREF to 12 V) (Fig.2) VREF/ VCOMP IREF IREF (DEV) ILED (MIN) I(OFF) |ZOUT|
(ILED = 10 mA, R1 = 10 k) (Fig.3) (TA = -40 to +85C) (VCOMP = VFB) (Fig.1) (VLED = 6 V, VFB = 0) (Fig.4) (VCOMP = VFB, ILED = 0.1 mA to 15 mA, f<1 kHZ)
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 = 25C ) } x 10 V REF ( ppm/C ) = ---------------------------------------------------------------------------------------------------T A 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 x 1 + ------I R2
6
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
OUTPUT CHARACTERISTICS (TA = 25C Unless otherwise specified.)
Parameter Collector dark current Emitter-collector voltage breakdown Collector-emitter voltage breakdown Test Conditions (VCE = 10 V) (Fig. 5) (IE = 100 A) (IC = 1.0mA) Symbol ICEO BVECO BVCEO 7 70 Min Typ Max 50 Unit nA V V
TRANSFER CHARACTERISTICS (TA = 25C Unless otherwise specified.)
Parameter Current transfer ratio Collector-emitter saturation voltage Test Conditions (ILED = 10 mA, VCOMP = VFB, VCE = 5 V) (Fig. 6) Symbol CTR Min 100 Typ Max 200 0.4 Unit % V
(ILED = 10 mA, VCOMP = VFB, VCE (SAT) IC = 2.5 mA) (Fig. 6)
ISOLATION CHARACTERISTICS (TA = 25C Unless otherwise specified.)
Parameter Input-output insulation leakage current Withstand insulation voltage Resistance (input to output) Test Conditions (RH = 45%, TA = 25C, t = 5s, VI-O = 3000 VDC) (note. 1) (RH <= 50%, TA = 25C, t = 1 min) (note 1) VI-O = 500 VDC (note. 1) Symbol II-O VISO RI-O 5000 1012 Min Typ Max 1.0 Unit A Vrms Ohm
SWITCHING CHARACTERISTICS (TA = 25C Unless otherwise specified.)
Parameter Bandwidth Common mode transient immunity at output high Common mode transient immunity at output low Test Conditions (Fig. 7) (ILED = 0 mA, Vcm = 10 VPP RL = 2.2 k (Fig. 8) (note 2) (ILED = 10 mA, Vcm = 10 VPP RL = 2.2 k (Fig. 8) (note 2) Symbol BW CMH CML Min Typ 10 1.0 1.0 Max Unit kHZ kV/s kV/s
Notes 1. 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. 2. 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.
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
I(LED) I(LED) 8 VF 6 V 7 VREF 5 3 V R1 6 7 VCOMP R2 VREF 5 3 2 8 2
FIG. 1. VREF, VF, ILED (min) TEST CIRCUIT
FIG. 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
FIG. 3. IREF TEST CIRCUIT
FIG. 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
FIG. 5. ICEO TEST CIRCUIT
FIG. 6. CTR, VCE(sat) TEST CIRCUIT
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
VCC = +5V DC IF = 10 mA RL 47
1
8
1f
VOUT
2
7
0.1 VPP
VIN 0.47V
3
6
4
5
Fig. 7 Frequency Response Test Circuit
VCC = +5V DC IF = 0 mA (A) IF = 10 mA (B) R1 2.2k VOUT
1
8
2
7
AB
3
6
4
5
_
VCM
+
10VP-P
Fig. 8 CMH and CML Test Circuit
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
TYPICAL PERFORMANCE CURVES
Fig. 9a LED Current vs Cathode Voltage
15
150
Fig. 9b LED Current vs Cathode Voltage
TA = 25C VCOMP = VFB
ILED- SUPPLY CURRENT (mA)
5 0 -5 -10 -15 -1.0
ILED - SUPPLY CURRENT (mA)
10
TA = 25C VCOMP = VFB
100
50
0
-50
-100
-150
-0.5
0.0
0.5
1.0
1.5
-1
VCOMP - CATHODE VOLTAGE (V)
0 1 VCOMP - CATHODE VOLTAGE (V)
2
Fig. 10 Reference Voltage vs Ambient Temperature
1.244 VREF - REFERENCE VOLTAGE (V) 1.242 1.240 1.238 1.236 1.234 1.232 1.230 -40
Fig. 11 Reference Current vs Ambient Temperature
280 IREF - REFERENCE CURRENT (nA)
ILED = 10mA R1 = 10 k
ILED = 10mA
260 240 220 200 180 160 140 120 -40
-20
0
20
40
60
80
100
-20
0
20
40
60
80
100
TA - AMBIENT TEMPERATURE (C)
TA - AMBIENT TEMPERATURE (C)
Fig. 12 Off-State Current vs Ambient Temperature
1000 IOFF - OFF-STATE CURRENT (NA)
VCC = 13.2V
100
10
1
0.1 -40 -20 0 20 40 60 80 100 TA - AMBIENT TEMPERATURE (C)
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
Fig. 13 Forward Current vs Forward Voltage
20 10000
Fig. 14 Dark Current vs Ambient Temperature
VCE = 10V
IF - FORWARD CURRENT (mA)
15
ICEO - DARK CURRENT (nA)
1000
100
70C
25C
0C
10
10
5
1
0.9
1.0
1.1
1.2
1.3
1.4
0.1 -40
-20
0
20
40
60
80
100
VF - FORWARD VOLTAGE (V)
TA - AMBIENT TEMPERATURE (C)
Fig. 15 Collector Current vs Ambient Temperature
30
VCE = 5V
Fig. 16 Current Transfer Ratio vs LED Current
140
VCE = 5V
IC - COLLECTOR CURRENT (mA)
25
ILED = 20mA
(IC/IF) - CURRENT TRANSFER RATIO (%)
120
0C
20
100
25C
15
ILED = 10mA
10
ILED = 5mA
80
70C
5
ILED = 1mA
60
0 0 10 20 30 40 50 60 70 80 90 100 TA - AMBIENT TEMPERATURE (C)
40 0
5
10
15
20
25
30
35
40
45
50
ILED - FORWARD CURRENT (mA)
Fig. 17 Saturation Voltage vs Ambient Temperature
0.26 VCE(SAT) - SATURATION VOLTAGE (V) 0.24 0.22 0.20 0.18 0.16 0.14 0.12 0.10 -40
-20
0
20
40
60
80
100
TA - AMBIENT TEMPERATURE (C)
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
Fig. 18 Collector Current vs Collector Voltage
35 30 25 20 15 10
ILED = 5mA ILED = 10mA ILED = 20mA T A = 250C
Fig. 19 Rate of Change Vref to Vcomp vs Temperature
-0.2 -0.4 -0.6 -0.8 -1.0 -1.2 -1.4 -1.6 -60 -40 -20 0 20 40 60 80 100 120
5
ILED = 1mA
0 0 1 2 3 4 5 6 7 8 9 10 VCE - COLLECTOR-EMITTER VOLTAGE (V) TEMPERATURE - C
Fig. 20 Voltage Gain vs Frequency
VCC = 10 V IF = 10 mA
0 VOLTAGE GAIN - DB
RL=100
-5
-10
DELTA VREF / DELTA VCOMP ( mV/V)
IC - COLLECTOR CURRENT (mA)
RL=1k
RL=500
-15 0.1 1 10 FREQUENCY - KHZ 100 1000
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
The FOD2711
The FOD2711 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 RC431A shunt voltage regulator plus the CNY17F-3 optocoupler.
Compensation
The compensation pin of the FOD2711 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 0.1F 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 FOD2711 powers the secondary side, and in particular provides the current to run the LED. The actual structure of the FOD2711 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 1.24V + 1.5V = 2.74V. 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 FOD2711. 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 10K resistor for the LED, the maximum current the LED can see is (12V-2.74V) /10K = 926A. The CTR of the opto-isolator is a minimum of 100%, and so the minimum collector current of the photo-transistor when the diode is full on is also 926A. The collector resistor must thus be such that: 10V - 5V ----------------------------------- < 926A or R COLLECTOR > 5.4K; R COLLECTOR select 10K 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 FOD2711 attempts to regulate its FB pin to the reference voltage, 1.24V. 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 0.8A. To achieve 1% accuracy, the resistance of RTOP should be: V OUT - 1.24 ------------------------------- > 80A R TOP
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
Package Dimensions (Through Hole) Package Dimensions (0.4"Lead Spacing)
PIN 1 ID.
4 3 2 1
PIN 1 ID.
4
3
2
1
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
SEATING PLANE
0.070 (1.78) 0.045 (1.14) 0.200 (5.08) 0.140 (3.55) 0.020 (0.51) MIN
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
Package Dimensions (Surface Mount)
0.390 (9.91) 0.370 (9.40)
4 3 2 1
8 - Pin Dip
PIN 1 ID.
0.070 (1.78)
0.270 (6.86) 0.250 (6.35)
0.060 (1.52)
5 6 7 8
0.070 (1.78) 0.045 (1.14) 0.020 (0.51) MIN
0.300 (7.62) TYP
0.100 (2.54) 0.295 (7.49)
0.016 (0.41) 0.008 (0.20)
0.415 (10.54)
0.030 (0.76)
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) MIN
NOTE All dimensions are in inches (millimeters)
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
ORDERING INFORMATION Example: FOD2711 X Y
Y V: VDE tested
X Packaging Option T: 0.4" Lead Spacing S: Surface Mount Lead Bend SD: Surface Mount Tape and Reel (1000 per reel)
MARKING INFORMATION
1
2711 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
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
Carrier Tape Specifications
K0
t
P0
P2
D0 E
A0 W1 B0
F W
d
User Direction of Feed
P
D1
Description Tape Width Tape Thickness Sprocket Hole Pitch Sprocket Hole Diameter Sprocket Hole Location Pocket Location Pocket Pitch Pocket Dimensions Cover Tape Width Cover Tape Thickness Max. Component Rotation or Tilt Min. Bending Radius
Symbol W t P0 D0 E F P2 P A0 B0 K0 W1 d R
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 1.6 0.1 0.1 max 10 30
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
Reflow Profile
300 Temperature (C) 250 200 150 100 50 0 0 0.5 1 1.5 2 2.5 260 C peak
245 C, 10-30 s
Time above 183C, <160 sec Ramp up = 2-10C/sec 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
(c) 2003 Fairchild Semiconductor Corporation
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OPTICALLY ISOLATED ERROR AMPLIFIER FOD2711
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 APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.
(c) 2003 Fairchild Semiconductor Corporation
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