Fairchild Semiconductor FOD2711 Datasheet

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.

OPTICALLY ISOLATED

ERROR AMPLIFIER

FOD2711

8

1

8

1

8

1

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

APPLICATIONS

•Power supplies regulation

• DC to DC converters

PIN DEFINITIONS

Pin Number Pin Name Pin function description

1NCNot connected

2CPhototransistor Collector

3EPhototransistor Emitter

4NCNot connected

5 GND Ground

6 COMP Error Amplifier Compensation. This pin is the output of the error amplifier. *

7FBVoltage Feedback. This pin is the inverting input to the error amplifier

8 LED Anode LED. This pin is the input to the light emitting diode.

FUNCTIONAL BLOCK DIAGRAM

NC

1

C

2

E

3

NC

4 5

8

7

6

LED

FB

COMP

GND

* The compensation network must be attached between pins 6 and 7.

© 2003 Fairchild Semiconductor Corporation

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TYPICAL APPLICATION

FAN4803

V

1

PWM

Control

FOD2711

OPTICALLY ISOLATED

ERROR AMPLIFIER

FOD2711

V

O

2

3

ABSOLUTE MAXIMUM RATINGS

Parameter Symbol Value Units

Storage Temperature T

Operating Temperature T

Lead Solder Temperature T

Input Voltage V

Input DC Current I

Collector-Emitter Voltage V

Emitter-Collector Voltage V

Collector Current I

Input Power Dissipation (note 1) PD1 145 mW

Tr ansistor Power Dissipation (note 2) PD2 85 mW

Total Power Dissipation (note 3) PD3 145 mW

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.

(T

= 25°C Unless otherwise specified.)

A

STG

OPR

SOL

LED

LED

CEO

ECO

8

6

7

5

-55 to +125 °C

-40 to +85 °C

260 for 10 sec. °C

13.2 V

20 mA

30 V

7V

C

50 mA

R1

R2

© 2003 Fairchild Semiconductor Corporation

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/ ∆

∆

/ ∆

OPTICALLY ISOLATED

ERROR AMPLIFIER

FOD2711

ELECTRICAL CHARACTERISTICS

INPUT CHARACTERISTICS

Parameter Test Conditions Symbol Min Typ** Max Unit

LED forward voltage (I

Reference voltage

(-40 to +85°C) (V

(25°C) 1.228 1.240 1.252

Deviation of V

Ratio of Vref variation
to the output of the error amplifier

Feedback input current (I

Deviation of I

Minimum drive current (V

Off-state error amplifier current (V

Error amplifier
output impedance - See Note 2

over temperature - See Note 1

REF

over temperature - See Note 1

REF

(V

(T

= 25°C Unless otherwise specified.)

A

= 10 mA, V

LED

= V

COMP

LED

, I

FB

, I

FB

= V

= 6 V, V

LED

COMP

V

= 10 mA, R1 = 10 k Ω ) (Fig.3) I

LED

= V

COMP

= V

COMP

= 10 mA (Fig.1)

LED

(T

= -40 to +85°C) V

A

(I

LED

to 12 V) (Fig.2)

REF

= -40 to +85°C) I

(T

A

= V

COMP

= 0) (Fig.4) I

FB

= 0.1 mA to 15 mA,

)(Fig.1) V

FB

= 10 mA,

) (Fig.1) I

FB

f<1 kHZ)

F

V

REF

REF (DEV)

V

REF

V

COMP

REF

REF (DEV)

LED (MIN)

(OFF)

|Z

OUT

1.221 1.259

4 12 mV

-1.5 -2.7 mV/V

0.15 0.5 µA

0.15 0.3 µA

55 80 µA

0.001 0.1 µA

| 0.25 Ohm

1.5 V

V

1. 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
is defined as:

A

OUT

25°C=(){}106×

| = ∆ V

COMP

I

. When the device is operating with two external resistors (see

LED

V

∆V

REF

where ∆ T

ppm/°C()

is the rated operating free-air temperature range of the device.

A

REF DEV()/VREFTA

-----------------------------------------------------------------------------------------------------=

∆T

2. The dynamic impedance is defined as |Z
Figure 2), the total dynamic impedance of the circuit is given by:

Z

OUT, TOT

∆V

=

--------Z

∆I

OUT

R1

1

--------+×≈
R2

REF

,

© 2003 Fairchild Semiconductor Corporation

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OPTICALLY ISOLATED

ERROR AMPLIFIER

FOD2711

OUTPUT CHARACTERISTICS

(T

= 25°C Unless otherwise specified.)

A

Parameter Test Conditions Symbol Min Typ Max Unit

Collector dark current (V

Emitter-collector voltage breakdown (I

Collector-emitter voltage breakdown (I

TRANSFER CHARACTERISTICS

(T

= 10 V) (Fig. 5) I

CE

= 100 µA) BV

E

= 1.0mA) BV

C

= 25°C Unless otherwise specified.)

A

CEO

ECO

CEO

50 nA

7V

70 V

Parameter Test Conditions Symbol Min Typ Max Unit

(I

(I

LED

LED

Current transfer ratio

Collector-emitter
saturation voltage

ISOLATION CHARACTERISTICS

= 10 mA, V

V

CE

= 10 mA, V

I

= 2.5 mA) (Fig. 6)

C

(T

= 25°C Unless otherwise specified.)

A

= V

COMP

FB

= 5 V) (Fig. 6)

= V

COMP

FB

,

CTR 100 200 %

,

V

CE

(SAT)

0.4 V

Parameter Test Conditions Symbol Min Typ Max Unit

Input-output insulation
leakage current

Withstand insulation
voltage

Resistance (input to output) V

(RH = 45%, T

V

= 3000 VDC) (note. 1)

I-O

(RH <= 50%, T

I-O

= 25°C, t = 5s,

A

= 25°C, t = 1 min)

A

(note 1)

= 500 VDC (note. 1) R

I

I-O

V

5000 Vrms

ISO

12

I-O

10

1.0 µA

Ohm

SWITCHING CHARACTERISTICS (T

= 25°C Unless otherwise specified.)

A

Parameter Test Conditions Symbol Min Typ Max Unit

Bandwidth (Fig. 7) B

Common mode transient
immunity at output high

Common mode transient
immunity at output low

= 0 mA, Vcm = 10 V

(I

LED

RL = 2.2 kΩ (Fig. 8) (note 2)

= 10 mA, Vcm = 10 V

(I

LED

RL = 2.2 kΩ (Fig. 8) (note 2)

PP

CMH 1.0 kV/µs

PP

CML 1.0 kV/µs

W

10 kHZ

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.

© 2003 Fairchild Semiconductor Corporation

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4/14/03

OPTICALLY ISOLATED

ERROR AMPLIFIER

FOD2711

I

I

(LED)

V

82

V

F

6

7

V

REF

5

3

V

R2

(LED)

8

6R1

7

V

COMP

V

REF

5

2

3

FIG. 1. V

V

, VF, I

REF

FIG. 3. I

8

6

7

5

(min) TEST CIRCUIT

LED

I

(LED)

8

I

REF

6

7

R1

5

TEST CIRCUIT

REF

2

V

3

FIG. 2. ∆V

2

3

V

REF/∆VCOMP

I

(OFF)

V

(LED)

FIG. 4. I

I

I

CEO

CE

(LED)

V

TEST CIRCUIT

(OFF)

8

6

7

V

REF

5

8

6

7

5

TEST CIRCUIT

V

COMP

2

3

I

C

2

V

CE

3

FIG. 5. I

TEST CIRCUIT FIG. 6. CTR, V

CEO

© 2003 Fairchild Semiconductor Corporation

Page 5 of 15

TEST CIRCUIT

CE(sat)

4/14/03