FOD2711 — Optically Isolated Error Amplifier
August 2008
FOD2711
Optically Isolated Error Amplifier
Features
■
Optocoupler, precision reference and error amplifier in
■
■
■
■
Description
The FOD2711 Optically Isolated Amplifier consists of the
popular RC431A precision programmable shunt refer-
ence and an optocoupler. The optocoupler is a gallium
arsenide (GaAs) light emitting diode optically coupled to
a silicon phototransistor. The reference voltage toler-
ance 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 elimi-
nates the need for adjustments in many applications.
The device comes in a 8-pin dip white package.
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
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
©2003 Fairchild Semiconductor Corporation
FOD2711 Rev. 1.0.1
www.fairchildsemi.com
FOD2711 — 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
V
1
FAN4803
PWM
Control
V
O
FOD2711
2
8
6
R1
3
7
R2
5
©2003 Fairchild Semiconductor Corporation
FOD2711 Rev. 1.0.1
www.fairchildsemi.com
2
FOD2711 — Optically Isolated Error Amplifier
Absolute Maximum Ratings
(T
A
= 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
T
STG
T
OPR
T
SOL
V
LED
I
LED
V
CEO
V
ECO
I
C
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.
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 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.
©2003 Fairchild Semiconductor Corporation
FOD2711 Rev. 1.0.1
www.fairchildsemi.com
3
FOD2711 — Optically Isolated Error Amplifier
Electrical Characteristics
(T
A
= 25°C unless otherwise specified)
Input Characteristics
Symbol
V
F
V
REF
Parameter
LED Forward Voltage
Reference Voltage
-40°C to +85°C
25°C
Test Conditions
I
LED
= 10mA, V
COMP
= V
FB
(Fig. 1)
V
COMP
= V
FB
, I
LED
= 10mA (Fig.1)
Min. Typ.* Max.
1.5
1.221
1.228
1.240
4
-1.5
1.259
1.252
12
-2.7
Unit
V
V
mV
mV/V
V
REF (DEV)
Deviation of V
REF
Over
Temperature
(4)
∆
V
REF
/
∆
V
COMP
I
REF
I
REF (DEV)
I
LED (MIN)
I
(OFF)
| Z
OUT
|
Ratio of Vref Variation
to the Output of the Error
Amplifier
Feedback Input Current
Deviation of I
REF
Over
Temperature
(4)
Minimum Drive Current
Off-State Error Amplifier
Current
Error Amplifier Output
Impedance
(5)
T
A
= -40 to +85°C
I
LED
= 10 mA, V
COMP
= V
REF
to 12V
(Fig. 2)
I
LED
= 10mA, R1 = 10k
Ω
(Fig. 3)
T
A
= -40°C to +85°C
V
COMP
= V
FB
(Fig. 1)
V
LED
= 6V, V
FB
= 0 (Fig. 4)
V
COMP
= V
FB
, I
LED
= 0.1mA to 15mA,
f<1 kHZ)
0.15
0.15
55
0.001
0.25
0.5
0.3
80
0.1
µA
µA
µA
µA
Ω
Output Characteristics
Symbol
I
CEO
BV
ECO
BV
CEO
Parameter
Collector Dark Current
Emitter-Collector Voltage Breakdown
Collector-Emitter Voltage Breakdown
Test Conditions
V
CE
= 10V (Fig. 5)
I
E
= 100µA
I
C
= 1.0mA
Min.
7
70
Typ.
Max.
50
Unit
nA
V
V
Transfer Characteristics
Symbol
Parameter
CTR
Current Transfer Ratio
Test Conditions
I
LED
= 10mA, V
COMP
= V
FB
,
V
CE
= 5V (Fig. 6)
I
LED
= 10mA, V
COMP
= V
FB,
I
C
= 2.5mA (Fig. 6)
Min.
100
Typ.
Max.
200
0.4
Unit
%
V
V
CE (SAT)
Collector-Emitter Saturation
Voltage
Notes:
4. The deviation parameters V
REF(DEV)
and I
REF(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,
∆
V
REF
, is defined as:
∆V
REF
{
V
REF
(
DEV
)
/V
REF
(
T
A
= 25°C
) } ×
10
(
ppm/°C
)
= ----------------------------------------------------------------------------------------------------
-
∆T
A
6
where
∆
T
A
is the rated operating free-air temperature range of the device.
5. The dynamic impedance is defined as |Z
OUT
| =
∆
V
COMP
/
∆
I
LED
. 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
©2003 Fairchild Semiconductor Corporation
FOD2711 Rev. 1.0.1
www.fairchildsemi.com
4
FOD2711 — Optically Isolated Error Amplifier
Electrical Characteristics
(Continued) (T
A
= 25°C unless otherwise specified)
Isolation Characteristics
Symbol
I
I-O
V
ISO
R
I-O
Parameter
Input-Output Insulation
Leakage Current
Withstand Insulation
Voltage
Resistance (Input to Output)
Test Conditions
RH = 45%, T
A
= 25°C, t = 5s,
V
I-O
= 3000 VDC
(6)
RH
≤
50%, T
A
= 25°C, t = 1 min.
(6)
V
I-O
= 500 VDC
(6)
Min.
Typ.
Max.
1.0
Unit
µA
Vrms
5000
10
12
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)
I
LED
= 0mA,
Vcm
= 10 V
PP
,
R
L
= 2.2kΩ
(7)
(Fig. 8)
I
LED
= 1mA,
Vcm
= 10 V
PP,
R
L
= 2.2kΩ
(7)
(Fig. 8)
Min.
Typ.
10
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.
©2003 Fairchild Semiconductor Corporation
FOD2711 Rev. 1.0.1
www.fairchildsemi.com
5
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