Fairchild Semiconductor FOD2712 Datasheet

OPTICALLY ISOLATED

ERROR AMPLIFIER

FOD2712

DESCRIPTION

The FOD2712 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 FOD2712, 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 compact 8-pin small outline package.

FEATURES

• Optocoupler, precision reference and error ampliﬁer in single package

• 1.240V ± 1% reference

• CTR 100% to 200%

• 2,500V RMS isolation

• VDE approval 136616

• BSI approval 8661 and 8662

• UL approval E90700

• CSA approval 1113643

FUNCTIONAL BLOCK DIAGRAM

NC

1

C

2

E

3

NC

4 5

8

7

6

LED

FB

COMP

GND

APPLICATIONS

•Power system for workstations

•Telecom central ofﬁce supply

•Telecom bricks

PACKAGE DIMENSIONS

0.164 (4.16)

0.144 (3.66)

1

0.202 (5.13)

0.182 (4.63)

SEATING PLANE

0.143 (3.63)

0.123 (3.13)

0.008 (0.20)

0.021 (0.53)

0.011 (0.28)

Lead Coplanarity : 0.004 (0.10) MAX

0.003 (0.08)

0.050 (1.27) TYP

NOTE

All dimensions are in inches (millimeters)

0.244 (6.19)

0.224 (5.69)

0.010 (0.25)

0.006 (0.16)

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.

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

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TYPICAL APPLICATION

FAN4803

V

1

PWM

Control

FOD2712

OPTICALLY ISOLATED

ERROR AMPLIFIER

FOD2712

V

O

2

3

ABSOLUTE MAXIMUM RATINGS

Parameter Symbol Value Units

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) 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

T

STG

T

OPR

V

LED

I

LED

V

CEO

V

ECO

I

C

8

6

7

5

-55 to +125 °C

-40 to +85 °C

13.2 V

20 mA

30 V

7V

50 mA

R1

R2

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/ ∆

∆

/ ∆

OPTICALLY ISOLATED

ERROR AMPLIFIER

FOD2712

ELECTRICAL CHARACTERISTICS

(V

CC

= 12V, T

= 25°C Unless otherwise speciﬁed.)

A

INPUT CHARACTERISTICS

Parameter Test Conditions Symbol Min Typ** Max Unit

(I

LED forward voltage

= 10 mA, V

LED

Reference voltage

(-40 to +85°C)

(V

COMP

= V

FB

, I

(25°C) 1.228 1.240 1.252

Deviation of V

over temperature - See Note 1 (T

REF

Ratio of Vref variation to the output of the error ampliﬁer

Feedback input current

Deviation of I

over temperature - See Note 1 (T

REF

Minimum drive current

Off-state error ampliﬁer current

Error ampliﬁer

(V

(I

COMP

LED

= V

V

COMP

= 10 mA, R1 = 10 k Ω ) (Fig.3) I

(V

= 6 V, V

LED

, I

FB

LED

output impedance - See Note 2

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

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:

= V

COMP

= 10 mA (Fig.1)

LED

= -40 to +85°C) V

A

to 12 V) (Fig.2)

REF

= -40 to +85°C) I

A

COMP

)(Fig.1) V

FB

(I

= 10 mA,

LED

= V

) (Fig.1) I

FB

= 0) (Fig.4) I

FB

= 0.1 mA to 15 mA,

f<1 kHZ)

F

V

REF

REF (DEV)

V

REF

V

COMP

REF

REF (DEV)

LED (MIN)

(OFF)

|

|Z

OUT

1.221 1.259

-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

4 12 mV

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

V

REF

,

Z

OUT, TOT

∆V

=

--------Z

∆I

OUT

R1

1

--------+×≈ R2

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4/10/03

OPTICALLY ISOLATED

ERROR AMPLIFIER

FOD2712

OUTPUT CHARACTERISTICS

(T

= 25°C Unless otherwise speciﬁed.)

A

Parameter Test Conditions Symbol Min Typ Max Unit

(V

Collector dark current

Collector-emitter voltage breakdown

Emitter-collector voltage breakdown

TRANSFER CHARACTERISTICS

(T

= 10 V) (Fig. 5) I

CE

(I

= 1.0mA) BV

C

(I

= 100 µA) BV

E

= 25°C Unless otherwise speciﬁed.)

A

CEO

ECO

50 nA

70 V

7V

Parameter Test Conditions Symbol Min Typ Max Unit

(I

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)

(RH = 45%, T

V

= 3000 VDC) (note. 1)

I-O

(RH <= 50%, T

V

I-O

= 25°C, t = 5s,

A

= 25°C, t = 1 min)

A

(notes. 1)

= 500 VDC (note. 1) R

I

I-O

V

ISO

I-O

2500 Vrms

12

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)

(I

Common mode transient immunity at output high

Common mode transient immunity at output low

= 0 mA, Vcm = 10 V

LED

RL = 2.2 kΩ (Fig. 8) (note. 2)

(I

= 10 mA, Vcm = 10 V

LED

RL = 2.2 kΩ (Fig. 8) (note. 2)

PP

B

W

CMH 1.0 kV/µs

CML 1.0 kV/µs

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.

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4/10/03