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
r
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
A)
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
TM
Series STR-F6600
ABSOLUTE MAXIMUM RATINGS
at T
A
= +25
C
Control Supply Voltage, V
IN
. . . . . . . . 35 V
Drain-Source Voltage, V
DS
Series STR-F6620 . . . . . . . . . . . . 450 V
Series STR-F6630 . . . . . . . . . . . . 500 V
Series STR-F6650 . . . . . . . . . . . . 650 V
Series STR-F6670 . . . . . . . . . . . . 900 V
Drain Switching Current, I
D
. . . See Table
Peak Drain Current, I
DM
. . . . . . See Table
Avalanche Energy, E
AS
. . . . . . . See Table
OCP/FB Voltage Range,
V
OCP
. . . . . . . . . . . . . . . -0.3 V to +6 V
Package Power Dissipation, P
D
control (V
IN
x I
IN(ON)
) . . . . . . . . . 0.8 W
total . . . . . . . . . . . . . . . . . . . See Graph
FET Channel Temperature, T
J
. . . +150
C
Internal Frame Temperature, T
F
. . +125
C
Operating Temperature Range,
T
A
. . . . . . . . . . . . . . . -20
C to +125
C
Storage Temperature Range,
T
S
. . . . . . . . . . . . . . . . -40
C to +125
C
LATCH
SOURCE
DRAIN
OVER-CURRENT
& FEEDBACK
GROUND
Dwg. PK-011-1
V
IN
1
2
3
4
5
UVLO
OVP
TSD
OSC.
OCP
FDBK
SUPPLY
INTERIM DATA SHEET
(Subject to change without notice)
February 22, 2000
TM
Series STR-F6600
OFF-LINE
QUASI-RESONANT FLYBACK
SWITCHING REGULATORS
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
TM
2
TM
Copyright 2000 Allegro MicroSystems, Inc.
FUNCTIONAL BLOCK DIAGRAM
FEEDBACK &
OVER-CURRENT
PROTECTION
GROUND
V
IN
SOURCE
DRAIN
Dwg. FK-002-6
0.73 V
TSD
OVER-VOLT.
PROTECT
R
S
Q
REF.
FAULT
LATCH
4
3
2
1.45 V
UVLO
+
1
+
DRIVE
REG.
OSC
c
SS
r
SS
1.0
0.6
0.2
50
100
STARTING CHANNEL TEMPERATURE in
C
NORMALIZED ALLOWABLE AVALANCHE ENERGY in mJ
Dwg.
0.4
0.8
0
25
75
125
Allowable package power dissipation curves
are shown on page 10.
Series STR-F6600
OFF-LINE
QUASI-RESONANT FLYBACK
SWITCHING REGULATORS
3
OUTPUT MAXIMUM RATINGS at T
A
= +25
C
Part Number
V
DSS
(V)
r
DS(on)
(
)
E
AS
(mJ)*
I
D
(A)
I
DM
(A)
P
OUT
(W)
at V
IN
(V rms)
STR-F6624
450
0.92
204
16
19
98
100
130
120
STR-F6626
450
0.58
327
16
26
145
100
190
120
STR-F6628
450
0.35
647
22
36
225
100
290
120
STR-F6632
500
2.54
7.4
9.0
11.2
36
100
50
120
STR-F6652
650
2.8
126
7.9
10
40
85-265
86
220
STR-F6653
650
1.95
260
5.6
14
58
85-265
120
220
STR-F6654
650
1.15
399
9.7
18
92
85-265
190
220
STR-F6656
650
0.71
521
16
25
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
28
85-265
76
220
STR-F6676
900
2.81
275
7.8
12
44
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
TM
4
TM
ELECTRICAL CHARACTERISTICS at T
A
= +25
C, V
IN
= 18 V (unless otherwise specified).
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
On-State Voltage
V
INT
Turn-on, increasing V
IN
14.4
16
17.6
V
Under-Voltage Lockout
V
INQ
Turn-off, decreasing V
IN
9.0
10
11
V
Over-Voltage Threshold
V
OVP(th)
Turn-off, increasing V
IN
20.5
22.5
24.5
V
Drain-Source Breakdown Voltage
V
BR(DSS)
I
D
= 300
A
V
DS
max
V
Drain Leakage Current
I
DSS
At V
DS
max
300
A
On-State Resistance
r
DS(ON)
V
S
= 10 V, I
D
= 0.9 A, T
J
= +25
C
see table
Maximum Off Time
t
off
Drain waveform high
45
55
s
Minimum Pulse Duration for Input of
Quasi-Resonant Signals
t
w(th)
Drain waveform high
1
1.0
s
Minimum Off Time
t
off
Drain waveform high
1
1.5
s
Feedback Threshold Voltage
V
FDBK
Drain waveform low to high
1
0.68
0.73
0.78
V
Oscillation synchronized
2
1.3
1.45
1.6
V
Over-Current Protection/Feedback
Sink Current
I
OCP/FB
V
OCP/FB
= 1.0 V
1.2
1.35
1.5
mA
Latch Holding Current
I
IN(OVP)
V
IN
reduced from 24.5 V to 8.5 V
400
A
Latch Release Voltage
V
IN
I
IN
20
A, V
IN
reduced from 24.5 V
6.6
8.4
V
Switching Time
t
f
V
DD
= 200 V, I
D
= 0.9 A
250
ns
Supply Current
I
IN(ON)
Operating
3
30
mA
I
IN(OFF)
Increasing V
IN
prior to oscillation
100
A
Insulation RMS Voltage
V
WM(RMS)
All terminals simultaneous refer-
2000
V
ence to a metal plate against
the backside
Thermal Resistance
R
JM
Output channel to mounting frame
1.75
C/W
Thermal Shutdown
T
J
140
C
Notes: Typical Data is for design information only.
1. Feedback is square wave, V
IM
= 2.2 V, t
h
= 1
s, t
l
= 35
s.
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
IM
= 2.2 V, t
h
= 4
s, t
l
= 1
s.
Series STR-F6600
OFF-LINE
QUASI-RESONANT FLYBACK
SWITCHING REGULATORS
5
The voltage on the V
IN
terminal (pin 4) controls startup
and shutdown of the Series STR-F6600 devices.
Figure 1 shows a typical start up circuit. The V
IN
terminal voltage during startup is shown in figure 2.
Functional Description and Operation
continued, next page...
Figure 1 Start-Up Circuit
V
IN
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
IN
Terminal Voltage
at Startup
I
IN
V
IN
11 V
(MAX.)
30 mA
(MAX.)
100
A
(MAX.)
14.4 V
(MIN.)
I
IN(ON)
I
IN(OFF)
V
INQ
V
INT
Figure 3 Supply Terminal Current, I
IN
At startup, C2 is charged through the startup resistor R
S
.
When the V
IN
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
A
(at T
M
= 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
S
at the lowest ac input voltage
should be at least 500
A.
The value of R
S
thus determines the charge time of C2
and thus the startup delay. R
S
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
S
) 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
F.
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