STR-X6729
Off-Line Quasi-Resonant Switching Regulators
▪
Quasi-resonant topology IC
Low EMI noise and soft
switching
▪
Bottom-skip mode
Improved system efficiency over
the entire output load by avoiding increase of switching
frequency
▪
Standby mode
Lowers input power at very light output
load condition
▪
Avalanche-guaranteed MOSFET
Improves system-level
reliability and does not require V
DSS
derating
▪
450 V
DSS
/ 0.189
Ω
R
DS(on)
▪
Various protections
Improved system-level reliability
▫
Pulse-by-pulse drain overcurrent limiting
▫
Overvoltage Protection (bias winding voltage sensing),
with latch
▫
Overload Protection with latch
▫
Maximum on-time limit
Features and Benefits
Description
The STR-X6729 is a quasi-resonant topology IC designed for
SMPS applications. It shows lower EMI noise characteristics
than conventional PWM solutions, especially at greater than
2 MHz. It also provides a soft-switching mode to turn on the
internal MOSFET at close to zero voltage (V
DS
bottom point)
by use of the resonant characteristic of primary inductance
and a resonant capacitor.
The package is a fully molded TO-3P, which contains the
controller chip (MIC) and MOSFET, enabling output
power up to
360
W at 120 VAC input. The bottom-skip
mode skips the first bottom of V
DS
and turns on the MOSFET
at the second bottom point, to minimize an increase of
operating frequency at light output load, improving system-
level efficiency over the entire load range.
A standby mode is executed by clamping the secondary output.
In general applications, standby mode reduces input power.
The soft-start mode minimizes surge voltage and reduces power
stress to the MOSFET and to the secondary rectifying diodes
during the start-up sequence.
Various protections such as overvoltage, overload, overcurrent,
maximum on-time protections and avalanche-energy guaranteed
MOSFET secure good system-level reliability.
Continued on the next page…
Not to scale
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STRX6729DS
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SANKEN ELECTRIC CO., LTD.
http://www.sanken-ele.co.jp
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Typical Application
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Package: 7-Pin TO-3P
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STR-X6729
Description (continued)
Applications include the following:
▪
Set Top Box
▪
LCD PC monitor, LCD TV
▪
Printer, Scanner
▪
SMPS power supplies
Off-Line Quasi-Resonant Switching Regulators
Selection Guide
Part Number
STR-X6729
Package
TO-3P
Absolute Maximum Ratings
at T
A
= 25°C
Parameter
Drain
Maximum Switching Current
2
Single Pulse Avalanche Energy
3
Input Voltage for Controller (MIC)
SS/OLP Terminal Voltage
FB Terminal Inflow Current
FB Terminal Voltage
OCP/BD Terminal Voltage
MOSFET Power Dissipation
4
Current
1
Symbol
I
D
peak
I
Dmax
E
AS
V
CC
V
SSOLP
I
FB
V
FB
V
OCPBD
P
D1
Conditions
ew
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All performance characteristics given are typical values for circuit or
system baseline design only and are at the nominal operating voltage and
an ambient temperature, T
A
, of 25°C, unless otherwise stated.
es
With infinite heatsink
Without heatsink
V
CC
× I
CC
Recommended operation temperature, see cautions
ig
ns
Rating
22
22
472
35
–0.5 to 6.0
10
–0.5 to 9.0
–1.5 to 5.0
46
2.8
0.8
–20 to 125
–20 to 125
–40 to 125
150
Unit
A
A
mJ
V
V
mA
V
V
W
W
W
°C
°C
°C
°C
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Controller (MIC) Power Dissipation
P
D2
Operating Internal Leadframe Temperature
T
F
Operating Ambient Temperature
T
OP
Storage Temperature
T
stg
Channel Temperature
T
ch
1
Refer to MOSFET ASO curve
2
I
DMAX
is the drain current determined by the drive voltage of the IC and the threshold voltage, V
th
, of the MOSFET
3
Refer to Avalanche Energy Derating curve
4
Refer to MOSFET Ta-PD1 curve
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d
I
FB
within the limits of I
FB
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Single pulse
T
A
= –20°C to 125°C
Single pulse, V
DD
= 30 V, L = 50 mH, I
Lpeak
= 4.2 A
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STRX6729DS
SANKEN ELECTRIC CO., LTD.
2
STR-X6729
Functional
Block Diagram
Off-Line Quasi-Resonant Switching Regulators
Terminal List Table
Number
1
2
3
4
5
6
7
Name
D
S
GND
VCC
SS/OLP
FB
Drain
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Description
MOSFET drain
MOSFET source
Ground
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Functions
ec
Source
Ground terminal
Soft Start/Overload Protection terminal
ot
R
Power supply terminal
Input of power supply for control circuit
Input to set delay for Overload Protection and Soft Start operation
Input for Constant Voltage Control and Burst (intermittent) Mode
oscillation control signals
Input for Overcurrent Detection and Bottom Detection signals
Feedback terminal
N
OCP/BD
Overcurrent Protection/Bottom Detection
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STRX6729DS
SANKEN ELECTRIC CO., LTD.
3
STR-X6729
Off-Line Quasi-Resonant Switching Regulators
STR-X6729
MOS FET A.S.O. Curve
Ta=25℃ Single Pulse
STR-X6729
A.S.O. temperature derating coefficient curve
100
100
Determined by On-
Resistance
A.S.O. temperature derating coefficient (%)
80
100μs
60
I
D
[A]
Drain Current
10
20
0
20
Internal frame temperature
T
F
[℃]
40
60
80
100
120
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0
N
0.1
1
100
V
DS
[V]
Drain-to-Source Voltage
10
1000
[E
AS
temperature derating coefficient (%)
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100
80
60
40
20
0
25
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STR-X6729
Avalanche energy derating curve
50
Tch[℃]
Channel temperature
75
100
ew
1
125
150
D
40
Apply ASO temperature
derating coefficient from the
left graph to this curve for
evaluating actual operation’s
safety
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1ms
STRX6729DS
SANKEN ELECTRIC CO., LTD.
4
STR-X6729
Off-Line Quasi-Resonant Switching Regulators
STR-X6729
MOSFET Ta-PD1 Curve
STR-X6729
MIC T
F
-P
D2
Curve
1
60
PD1=46[W]
With infinite heatsink
0.8
PD1[Ｗ]
Power dissipation
40
P
D2
[Ｗ]
Power dissipation
0.6
20
Without heatsink
10
PD1=2.8[W]
N
ew
0.2
0
0
20
40
60
80
100 120 140
T
F
[℃]
Internal frame temperature
0
0
20 40 60 80 100 120 140 160
Ta [℃]
Ambient temperature
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Transient thermal resistance
θch-c[℃/W]
N
ot
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ec
1
0.1
0.01
0.001
½
[sec]
Ti e
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STR-X6729
Transient thermal resistance curve
d
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D
30
0.4
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5
50
STRX6729DS
SANKEN ELECTRIC CO., LTD.
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