The Series STR-F6600 is specifically designed to satisfy the require-

ments for increased integration and reliability in off-line quasi-resonant
flyback converters. The series incorporates a primary control and drive
circuit with discrete avalanche-rated power MOSFETs.

Covering the power range from below 25 watts up to 300 watts for

100/115/230 VAC inputs, and up to 150 watts for 85 to 265 VAC
universal input, these devices can be used in a range of applications,
from battery chargers and set top boxes, to televisions, monitors, and
industrial power supply units.

Cycle-by-cycle current limiting, under-voltage lockout with hyster-

esis, over-voltage protection, and thermal shutdown protects the power
supply during the normal overload and fault conditions. Over-voltage
protection and thermal shutdown are latched after a short delay. The
latch may be reset by cycling the input supply. Low-current startup and
a low-power standby mode selected from the secondary circuit completes
a comprehensive suite of features. The series is provided in a five-pin
overmolded TO-3P style package, affording dielectric isolation without
compromising thermal characteristics.

FEATURES

s Flyback Operation with Quasi-Resonant Soft Switching

for Low Power Dissipation and EMI

s Rugged Avalanche-Rated MOSFET
s Choice of MOSFET Voltage and

DS(on)

s Full Over-Current Protection (no blanking)
s Under-Voltage Lockout with Hysteresis
s Over-Voltage Protection
s Direct Voltage Feedback
s Low Start-up Current (<400

s Low-Frequency, Low-Power Standby Operation
s Overmolded 5-Pin Package

OFF-LINE QUASI-RESONANT

FLYBACK SWITCHING REGULATORS

Always order by complete part number, e.g., STR-F6652 .

Data Sheet

28102.8

Series STR-F6600

ABSOLUTE MAXIMUM RATINGS

at T

= +25

Control Supply Voltage, V

. . . . . . . . 35 V

Drain-Source Voltage, V

Series STR-F6620 . . . . . . . . . . . . 450 V
Series STR-F6630 . . . . . . . . . . . . 500 V
Series STR-F6650 . . . . . . . . . . . . 650 V
Series STR-F6670 . . . . . . . . . . . . 900 V

Drain Switching Current, I

. . . See Table

Peak Drain Current, I

. . . . . . See Table

Avalanche Energy, E

. . . . . . . See Table

OCP/FB Voltage Range,

OCP

. . . . . . . . . . . . . . . -0.3 V to +6 V

Package Power Dissipation, P

control (V

x I

IN(ON)

) . . . . . . . . . 0.8 W

total . . . . . . . . . . . . . . . . . . . See Graph

FET Channel Temperature, T

. . . +150

Internal Frame Temperature, T

. . +125

Operating Temperature Range,

. . . . . . . . . . . . . . . -20

C to +125

Storage Temperature Range,

. . . . . . . . . . . . . . . . -40

C to +125

LATCH

SOURCE

DRAIN

OVER-CURRENT

& FEEDBACK

GROUND

Dwg. PK-011-1

UVLO

OVP
TSD

OSC.

OCP

FDBK

SUPPLY

INTERIM DATA SHEET

(Subject to change without notice)

February 22, 2000

Series STR-F6600
OFF-LINE
QUASI-RESONANT FLYBACK
SWITCHING REGULATORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000

FUNCTIONAL BLOCK DIAGRAM

FEEDBACK &
OVER-CURRENT
PROTECTION

GROUND

SOURCE

DRAIN

Dwg. FK-002-6

0.73 V

TSD

OVER-VOLT.

PROTECT

REF.

FAULT

LATCH

1.45 V

UVLO

DRIVE

REG.

OSC

1.0

0.6

0.2

100

STARTING CHANNEL TEMPERATURE in

NORMALIZED ALLOWABLE AVALANCHE ENERGY in mJ

Dwg.

0.4

0.8

125

Allowable package power dissipation curves

are shown on page 10.

Series STR-F6600

OFF-LINE

QUASI-RESONANT FLYBACK

SWITCHING REGULATORS

OUTPUT MAXIMUM RATINGS at T

= +25

Part Number

DSS

(V)

DS(on)

(

)

(mJ)*

(A)

OUT

(W)

at V

(V rms)

STR-F6624

450

0.92

204

100

130

120

STR-F6626

450

0.58

327

145

100

190

120

STR-F6628

450

0.35

647

225

100

290

120

STR-F6632

500

2.54

7.4

9.0

11.2

100

120

STR-F6652

650

2.8

126

7.9

85-265

220

STR-F6653

650

1.95

260

5.6

85-265

120

220

STR-F6654

650

1.15

399

9.7

85-265

190

220

STR-F6656

650

0.71

521

150

85-265

300

220

STR-F6672

900

7.7

163

4.6

6.4

25 (no heatsink)

220

50 (with heat sink)

220

STR-F6674

900

4.49

242

6.0

9.2

85-265

220

STR-F6676

900

2.81

275

7.8

85-265

115

220

* Derate per graph, page 2

Derate per graph, page 12

Series STR-F6600
OFF-LINE
QUASI-RESONANT FLYBACK
SWITCHING REGULATORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000

ELECTRICAL CHARACTERISTICS at T

= +25

C, V

= 18 V (unless otherwise specified).

Limits

Characteristic

Symbol

Test Conditions

Min.

Typ.

Max.

Units

On-State Voltage

INT

Turn-on, increasing V

14.4

17.6

Under-Voltage Lockout

INQ

Turn-off, decreasing V

9.0

Over-Voltage Threshold

OVP(th)

Turn-off, increasing V

20.5

22.5

24.5

Drain-Source Breakdown Voltage

BR(DSS)

= 300

max

Drain Leakage Current

DSS

At V

max

300

On-State Resistance

DS(ON)

= 10 V, I

= 0.9 A, T

= +25

see table

Maximum Off Time

off

Drain waveform high

Minimum Pulse Duration for Input of
Quasi-Resonant Signals

w(th)

Drain waveform high

1.0

Minimum Off Time

off

Drain waveform high

1.5

Feedback Threshold Voltage

FDBK

Drain waveform low to high

0.68

0.73

0.78

Oscillation synchronized

1.3

1.45

1.6

Over-Current Protection/Feedback
Sink Current

OCP/FB

= 1.0 V

1.2

1.35

1.5

Latch Holding Current

IN(OVP)

reduced from 24.5 V to 8.5 V

400

Latch Release Voltage

A, V

reduced from 24.5 V

6.6

8.4

Switching Time

= 200 V, I

= 0.9 A

250

Supply Current

IN(ON)

Operating

IN(OFF)

Increasing V

prior to oscillation

100

Insulation RMS Voltage

WM(RMS)

All terminals simultaneous refer-

2000

ence to a metal plate against
the backside

Thermal Resistance

Output channel to mounting frame

1.75

C/W

Thermal Shutdown

140

Notes: Typical Data is for design information only.

1. Feedback is square wave, V

= 2.2 V, t

= 1

s, t

= 35

2. For quasi-resonant operation, the input signal must be longer than t

w(th)

and greater than V

FDBK

3. Feedback is square wave, V

= 2.2 V, t

= 4

s, t

= 1

Series STR-F6600

OFF-LINE

QUASI-RESONANT FLYBACK

SWITCHING REGULATORS

The voltage on the V

terminal (pin 4) controls startup

and shutdown of the Series STR-F6600 devices.

Figure 1 shows a typical start up circuit. The V

terminal voltage during startup is shown in figure 2.

Functional Description and Operation

continued, next page...

Figure 1 Start-Up Circuit

TIME

DRIVE WINDING
VOLTAGE

16 V

(TYP.)

OPERATION START

UNDER-VOLTAGE LOCKOUT (V

INQ

)

11 V

(MAX.)

ON-STATE VOLTAGE (V

INT

)

STARTUP

DELAY

Figure 2 Waveform of V

Terminal Voltage

at Startup

11 V

(MAX.)

30 mA

(MAX.)

100

(MAX.)

14.4 V
(MIN.)

IN(ON)

IN(OFF)

INQ

INT

Figure 3 Supply Terminal Current, I

At startup, C2 is charged through the startup resistor R

When the V

terminal voltage reaches 16 V (typ.), the

control circuit enables regulator operation. Once the
regulator starts, it draws up to 30 mA from C2 causing the
voltage on C2 to fall momentarily. Once the regulator
output voltage is established, the drive winding D starts to
charge C2 via D2. The voltage on C2 thus recovers to the
nominal drive voltage (18 V).

As shown in figure 3, the input current is below 100

(at T

= 25

C) prior to control circuit turn on. The latch

circuit holding current is 400

A (max.). To ensure latch

operation, the current in R

at the lowest ac input voltage

should be at least 500

The value of R

thus determines the charge time of C2

and thus the startup delay. R

is typicaly 68 k

for wide

operation (90 V ac to 265 V ac) and 100 k

for 220 volt

ac operation.

The choice of C2 is a compromise between an accept-

able startup delay (in conjunction with R

) and a hold-up

time sufficient to keep pin 4 above its under-voltage
shutdown threshold of 11 V. Typically C2 is in the range
of 47

F to 100

Series STR-F6600
OFF-LINE
QUASI-RESONANT FLYBACK
SWITCHING REGULATORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000

Functional Description and Operation (cont'd)

Figure 4 Output Current I

OUT

 Terminal Voltage V

Figure 5 Soft-Start Operation

The drive winding voltage is set such that in normal

operation the C2 voltage is above the specified maximum
shutdown voltage (11 V) and below the specified mini-
mum over-voltage threshold (20.5 V).

In applications where there is a significant variation in

load current, the V

terminal voltage may vary, as shown

in figure 4. This is due to peak charging of C2. In this
case, adding a resistor in the range of a few ohms to tens of
ohms in series with the rectifier diode D2 will bring the
voltage variation within limits.

Soft Start, Quasi Resonant and Voltage Regulation

Refer to the Functional Block Diagram and the Typical

Application Diagram (figure 6). The internal oscillator
uses the charge/discharge of an internal 4700 pF capacitor
(c

) to generate the MOSFET drive signals.

The regulator has two modes of operation:

1. fixed 50

s off time (soft start) and

2. demagnetization sensing quasi-resonant mode --

normal operation.

In both cases, voltage regulation is achieved by taking

the composite optocoupled voltage error and superimposed
drain current ramp (current-mode control) and comparing
this to an internal 0.73 V reference. The FBK/OCP

comparator output pre-terminates the oscillator, which
turns off the MOSFET drive signal.

The MOSFET is turned on again when either c

discharges or a quasi-resonance signal is detected on pin 1.

Fixed 50

s Off-Time: Soft-Start Mode

This is the mode of operation in the absence of a quasi-

resonance signal on pin 1 (see figure 5), and occurs at

startup and in overload. It also can be commanded exter-
nally to provide low-power standby operation.

In the absence of a feedback signal (such as at startup,

or a short circuit) the drain current ramp, sensed across R5
and noise filtered by R4/C5 appears on pin 1. When the
ramp voltage on C5 exceeds the 0.73 V reference signal,
the FBK/OCP comparator changes state, shutting down the
oscillator and turning off the MOSFET. Thus the voltage
on c

is held high (6.5 V) by the comparator. When the

comparator changes state, c

discharges via r

; the

voltage on c

ramps down until it reaches 3.7 V. The

oscillator turns on the MOSFET. This ramp-down time is
internally trimmed to 50

s. The comparator changes state

again and the cycle repeats. Thus in the absence of
feedback, the current-sense resistor R5 accurately controls
the MOSFET maximum current.

OUT

Series STR-F6600

OFF-LINE

QUASI-RESONANT FLYBACK

SWITCHING REGULATORS

Functional Description and Operation (cont'd)

Figure 6 Series STR-F6600 Typical Application

FULL-BRIDGE

RECTIFIER

AC INPUT

Dwg. EK-003-5A

0.73 V

TSD

OVER-VOLT.

PROTECT

REF.

FAULT
LATCH

1.45 V

UVLO

OSC

DRIVE

REG.

VOLTAGE

SENSE

+ OUTPUT

OUTPUT

WARNING --

These devices are designed to be operated at lethal voltages and energy levels. Circuit

designs that embody these components must conform with applicable safety requirements. Precau-
tions must be taken to prevent accidental contact with power-line potentials. Do not connect
grounded test equipment.

The use of an isolation transformer is recommended during circuit development and breadboarding.

Soft Start with Voltage Feedback (refer to figure 7)

Output voltage control is achieved by sensing the opto-

coupled feedback current (proportional to the output
voltage error signal) across resistor R4 and summing this
with the drain current ramp on R5. The signal on pin 1 is
therefore the opposite of the output voltage error signal
and the drain current ramp. The dc bias signal across R4 is
thus a function of the load. Consequently at light load, the
bias signal on R4 is closer to the threshold voltage of the
comparator.

To eliminate the possibility of false shutdown at

MOSFET turn on (when there is a current spike due to the
discharge of primary capacitance), a constant-current sink
of 1.35 mA is turned on, effectively lowering the input
impedance on pin 1, and momentarily increasing the
shutdown threshold.

Series STR-F6600
OFF-LINE
QUASI-RESONANT FLYBACK
SWITCHING REGULATORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000

Functional Description and Operation (cont'd)

Figure 7 - Voltage Regulation Waveforms

Normal Operation (Quasi-Resonant) Mode

Refer to the Functional Block Diagram, Typical Appli-

cation diagram (figure 6), and Quasi-Resonance Wave-
forms (figure 8).

Regulation is achieved as in fixed off-time mode but

instead of having a fixed off-time, the demagnetization of
the transformer is sensed by a second comparator. This
comparator threshold, V

th(2)

is nominally 1.45 V. Quasi-

resonance sensing makes use of the natural magnetizing
and leakage inductances and self-capacitances of the
power circuit.

Figure 8 shows the drain voltage waveform, (V

), on

pin 3 of the STR-F66xx, as well as V

, the voltage on the

primary of the transformer.

Once the current in the output diode stops flowing, the

primary stored energy `rings' as shown by V

and V

The resonant frequency (f

) is determined by the magne-

tizing inductance of the transformer and the capacitor C4.

The addition of this capacitor sets the ringing frequency

and reduces the harmonic content in the V

waveform,

lowering EMI. Also since V

falls to a minimum during

the first half-cycle of the ring this point can be sensed and
used to turn on the MOSFET with minimum voltage
across it. Thus the MOSFET is low voltage and zero
current switched (LVS/ZCS).

Figure 8 Quasi-Resonance Waveforms

Dwg. GK-021

t =

= 1/2

(min)

OCP

2.8 V

th(2)

1.45 V

th(1)

0.73 V

FDBK

Series STR-F6600

OFF-LINE

QUASI-RESONANT FLYBACK

SWITCHING REGULATORS

Functional Description and Operation (cont'd)

The voltage V

OCP

(pin 1) has the same form as the V

waveform. The condition for quasi-resonant operation is
given by:

2.0 V < V

OCP

> 5.5 V for >1

Transformer design is exactly as for any other discon-

tinuous-mode type flyback.

For optimum EMI/efficiency performance, quasi-

resonance turn off is achieved when the MOSFET is at
zero voltage and zero current; that is, at one half cycle of
the quasi-resonance frequency, f

Over-Current Protection (OCP) Functions

Refer to the Functional Block diagram and Typical

Application diagram (figure 6).

The regulator implements pulse-by-pulse over-current

protection, which limits the maximum drain current in the
MOSFET on every pulse by switching off the internal
drive to the MOSFET, and the MOSFET drain current is
detected across R5.

Drive Circuit

Refer to the Functional Block Diagram.

This circuit is driven from the oscillator and provides

the current drive to charge and discharge the MOSFET
gate-source capacitance, thereby switching the device on
and off. The basic circuit configuration is totem-pole type
with an additional limiting resistor in the gate circuit at
turn on. This limits the turn on speed of the MOSFET,
thereby reducing EMI due to the discharge of primary
capacitance. This is possible because of the low-voltage
switching, zero-current switching nature of the turn on.

The value of the turn-off resistance is lower, allowing

the device turn-off current to be increased. This reduces
the turn-off loss in the MOSFET.

The gate drive voltage (8.3 V) is such that even with

0.73 V across R5 (drain current sense resistor), the
MOSFET is fully enhanced, allowing full use to be made
of its high current handling capacity.

Latch Circuit

The latch circuit keeps the oscillator output low to

inhibit operation of the regulator when over-voltage
protection (OVP) and thermal shutdown (TSD) circuits are
in operation. As long as the latch hold-in current is
400

A (max., supplied via R

) with V

at 8.5 V (pin 4),

the regulator will stay in the off state.

An internal noise filter provides 10

s of noise immu-

nity to prevent spurious operation of the over-voltage
protection or thermal shutdown.

With the latch `on', the voltage on pin 4 cycles between

16 V and 10 V as shown in figure 9. This is due to the
higher current drawn when the pin 4 is at 16 V compared
to that drawn close to shutdown (10 V).

Pulling V

(pin 4) below 6.5 V will reset the latch

circuit, re-enabling the regulator.

Thermal Shutdown

This internal feature triggers the latch if the internal

frame temperature exceeds 140

C (typ.).

The temperature is sensed on the control IC, but also

protects against overheating of the MOSFET as the
MOSFET and the control IC are mounted on the same lead
frame. Additionally, protection is provided for other on-
board components.

TIME

16 V

(TYP.)

10 V

(TYP.)

Figure 9 Example of V

Terminal Voltage

Waveform at Latch Circuit On

Series STR-F6600
OFF-LINE
QUASI-RESONANT FLYBACK
SWITCHING REGULATORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000

Functional Description and Operation (cont'd)

Over-Voltage Protection Circuit

This feature of the STR-F66xx triggers the latch circuit

when the V

voltage (pin 4) exceeds 22.5 V (typ.).

Because the voltage on pin 4 is proportional to the output
voltage (they are linked by the transformer turns ratio), the
regulator protects the output against over-voltage. This
function is entirely independant of the output-voltage
regulation loop and indeed will protect against output
over-voltage should the voltage error signal be lost. The
measure of over-voltage is given by:

OUT(OVP)

= V

OUT(NOM)

x V

IN(OVP)

IN(NOM)

where V

IN(OVP)

is the drive voltage on pin 4.

In an over-voltage sensitive application, the drive

voltage can be set to close to 20 V and thus will protect the
output, if it rises more than 10% above nominal.

OUT

AC LOW

AC HIGH

Figure 10 Power Supply Output

Overload Characteristics

100

140

LIMITED BY FRAME
TEMP. = +125

C MAX.

RECOMMENDED MAX.
FRAME TEMP. = +115

TEMPERATURE in

ALLOWABLE PACKAGE POWER DISSIPATION in WATTS

Dwg. GK-0

CONTROLLER
0.8 W MAX.

MOUNTING SURFACE
TEMPERATURE
STR-F6676, 53 W MAX.
STR-F6672, 45 W MAX.

FREE AIR
ALL DEVICES
2.8 W MAX.

100

140

LIMITED BY FRAME
TEMP. = +125

C MAX.

RECOMMENDED MAX.
FRAME TEMP. = +115

TEMPERATURE in

ALLOWABLE PACKAGE POWER DISSIPATION in WATTS

Dwg. GK-0

CONTROLLER
0.8 W MAX.

MOUNTING SURFACE
TEMPERATURE
STR-F6656, 56 W MAX.
STR-F6654, 55 W MAX.
STR-F6653, 48 W MAX.
STR-F6652, 43 W MAX.

FREE AIR
ALL DEVICES
2.8 W MAX.

STR-F665x

STR-F667x

ALLOWABLE PACKAGE POWER DISSIPATION

Series STR-F6600

OFF-LINE

QUASI-RESONANT FLYBACK

SWITCHING REGULATORS

MOSFET Safe Operating Areas

(single pulse at T

= +25

0.5

0.05

DRAIN-SOURCE VOLTAGE in VOLTS

DRAIN CURRENT in AMPERES

Dwg. GK

0.15

1.5

3.0

100

300

= +25

= 1 m

s SIN

GLE

LSE

= 0.1 ms SINGLE PULSE

LIMITED

max

LIMITED
BY

DS(on)

0.5

0.05

DRAIN-SOURCE VOLTAGE in VOLTS

DRAIN CURRENT in AMPERES

Dwg. GK

0.15

1.5

3.0

100

300

= +25

= 1 m

s S

GLE

ULS

= 0.1 m

s SING

LE PULSE

LIMITED

max

LIMITED
BY

DS(on)

0.5

0.05

DRAIN-SOURCE VOLTAGE in VOLTS

DRAIN CURRENT in AMPERES

Dwg. GK

0.15

1.5

3.0

100

300

= +25

= 1 ms SINGLE PULSE

= 0.1 ms SINGLE PULSE

LIMITED

max

LIMITED
BY

DS(on)

0.5

0.05

DRAIN-SOURCE VOLTAGE in VOLTS

DRAIN CURRENT in AMPERES

Dwg. GK

0.15

1.5

3.0

100

300

= +25

= 1 ms SINGLE PULSE

= 0.1 ms SINGLE PULSE

LIMITED

max

LIMITED
BY

DS(on)

STR-F6652

STR-F6653

STR-F6654

STR-F6656

Series STR-F6600
OFF-LINE
QUASI-RESONANT FLYBACK
SWITCHING REGULATORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000

MOSFET Safe Operating Areas (cont)

(single pulse at T

= +25

0.5

0.05

DRAIN-SOURCE VOLTAGE in VOLTS

DRAIN CURRENT in AMPERES

Dwg. GK

0.15

1.5

3.0

100

300

= +25

= 1 ms SINGLE PULSE

= 0

.1 m

s S

E P

LIMITED BY

LIMITED
BY

DS(on)

0.5

0.05

DRAIN-SOURCE VOLTAGE in VOLTS

DRAIN CURRENT in AMPERES

Dwg. GK

0.15

1.5

3.0

100

300

= +25

= 1 ms SINGLE PULSE

= 0.1 ms SINGLE PULS

LIMITED

LIMITED
BY

DS(on)

STR-F6672

STR-F6676

1.0

0.6

0.2

100

FRAME TEMPERATURE in

NORMALIZED SAFE OPERATING AREA

Dwg. G

0.4

0.8

125

S.O.A. Derating

Drain Switching Current (I

) Derating

4.0

1.0

SOURCE-TO-GROUND VOLTAGE (V

-V

) in VOLTS

MAXIMUM SWITCHING CURRENT (I

) in AMPERES

Dwg

8.0

0.8

0.9

1.1

STR-F6656

STR-F6654

STR-F6652 & STR-F6672

STR-F6653

STR-F6672

= -20

C to +125

Series STR-F6600
OFF-LINE
QUASI-RESONANT FLYBACK
SWITCHING REGULATORS

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000

Capacitors

Electrolytic capacitors carrying large switching fre-

quency ripple currents (C1 and the output capacitors)
should be capable of handling the high rms currents
involved. Capacitors with low ESR are suitable. The
quasi-resonance capacitor C4 should be a high-voltage
ceramic type suitable for pulsed current operation.

The safety critical nature of the off-line application

must be considered when selecting both X and Y capaci-
tors for common- and differential-mode noise filtering.
Use of the low-noise quasi-resonant Series STR-F6600
will allow optimization of these capacitor values.

C5, the 470 pF filtering capacitor should be a 50 V

temperature-stable (COG) ceramic type.

Resistors

Resistor R5 carries high-frequency current, and so a low

internal inductance type of 1 W rating should be used.

Resistor R9 (R

) should be 2 W metal oxide.

All other resistors can be 1/4 watt or 1/2 watt metal

film.

Diodes

Diodes carrying the high-frequency flyback currents

(such as the transformer rectifier diodes) should have a fast
or ultrafast reverse-recovery characteristic, adequate
current handing and peak reverse-voltage rating. Allegro/
Sanken supplies a range of suitable diodes, and these are
described in the Allegro/Sanken short-form catalogue
(AMS-127) or latest issue of Bulletin D01EC0.

Optocoupler

Both Toshiba TLP 621 and Siemens SFH 610A2 or

615A2 are suitable. A current-transfer ratio of 50% to
200% is acceptable.

Error Amplifier

A standard TL431 transconductance amplifier or an

Allegro/Sanken Series SE error-amplifier IC can be used.
The Series SE is particularly well-suited to high-voltage
(70 V to 140 V) power outputs.

If a Series SE error-amplifier IC is used, normally phase

compensation is not required. Should additional high-
frequency attenuation be required, a capacitor (0.022

F or

less) can be connected across the primary side (collector-
emitter) of the optocoupler, a diode to maintain quasi-
resonant operation should be added in series with the
phototransistor emitter.

Applications Information

The products described here are manufactured in Japan by Sanken

Electric Co., Ltd. for sale by Allegro MicroSystems, Inc.

Sanken Electric Co., Ltd. and Allegro MicroSystems, Inc. reserve the

right to make, from time to time, such departures from the detail
specifications as may be required to permit improvements in the
performance, reliability, or manufacturability of their products.
Therefore, the user is cautioned to verify that the information in this
publication is current before placing any order.

These products are not authorized for use as critical components in

life-support appliances, devices, or systems without express written
approval.

The information included herein is believed to be accurate and

reliable. However, Sanken Electric Co., Ltd. and Allegro
MicroSystems, Inc. assume no responsibility for its use; nor for any
infringements of patents or other rights of third parties which may
result from its use.

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: STRF6672

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