STR3A251D [SANKEN]
Off-Line PWM Controllers with Integrated Power MOSFET;
| 型号： | STR3A251D |
| 厂家： | 
SANKEN ELECTRIC |
| 描述： | Off-Line PWM Controllers with Integrated Power MOSFET |
| 文件： | 总25页 (文件大小：681K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Off-Line PWM Controllers with Integrated Power MOSFET
STR3A200 Series
Data Sheet
Description
Package
The STR3A200 series are power ICs for switching
power supplies, incorporating a MOSFET and a current
mode PWM controller IC.
DIP8
The low standby power is accomplished by the
automatic switching between the PWM operation in
normal operation and the burst-oscillation under light
load conditions. The product achieves high
cost-performance power supply systems with few
external components.
Not to Scale
Lineup
● Electrical Characteristics
Features
fOSC(AVG) = 67 kHz
VDSS(min.) = 650 V
● Low Thermal Resistance Package
● Current Mode Type PWM Control
● Soft Start Function
Products
OVP, TSD Operation
● Auto Standby Function
No Load Power Consumption < 15mW
● Operation Mode
STR3A25×
Latched shutdown
Auto restart
STR3A25×D
Normal Operation: PWM Mode
Standby : Burst Oscillation Mode
● Random Switching Function
● Slope Compensation Function
● Leading Edge Blanking Function
● Bias Assist Function
● MOSFET オン抵抗、出力電力 POUT
*
POUT
POUT
(Open frame)
(Adapter)
RDS(ON)
(max.)
Products
AC85
AC85
~265V
AC230V
AC230V
~265V
STR3A251
STR3A251D
STR3A253
STR3A253D
STR3A255
STR3A255D
● Protections
4.0 Ω 29.5 W 19.5 W 37 W 23 W
− Two Types of Overcurrent Protection (OCP) :
Pulse-by-Pulse, built-in compensation circuit to
minimize OCP point variation on AC input voltage
− Overload Protection (OLP) : Aauto-restart
− Overvoltage Protection (OVP) : Latched shutdown or
auto-restart
1.9 Ω
1.1 Ω
37 W 27.5 W 53 W 35 W
45 W 35 W 65 W 44 W
− Thermal Shutdown (TSD) : Latched shutdown or
auto-restart with hysteresis
* The output power is actual continues power that is measured at
50 °C ambient. The peak output power can be 120 to 140 % of
the value stated here. Core size, ON Duty, and thermal design
affect the output power. It may be less than the value stated here.
Typical Application Circuit
Application
L51
BR1
D51
C51
VOUT
T1
VAC
● AC/DC adapter
● White goods
● Other SMPS
R54
R51
R1
C5
PC1
R52
C1
P
R55
D1
S
C53
C52 R53
U2
6
5
8
7
R56
D2 R2
D/ST D/ST
U1
DN/SCT D/ST
C4
GND
STR3A200
D
C2
S/OCP VCC
FB/OLP
GND
3
1
2
4
C3
ROCP
CY
PC1
TC_STR3A200_1_R1
STR3A200 - DSJ Rev.2.0
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© SANKEN ELECTRIC CO.,LTD. 2013
STR3A200 Series
CONTENTS
Description ------------------------------------------------------------------------------------------------------1
CONTENTS ----------------------------------------------------------------------------------------------------2
1. Absolute Maximum Ratings-----------------------------------------------------------------------------3
2. Electrical Characteristics --------------------------------------------------------------------------------4
3. Performance Curves --------------------------------------------------------------------------------------5
3.1 Derating Curves -------------------------------------------------------------------------------------5
3.2 MOSFET Safe Operating Area Curves---------------------------------------------------------6
3.3 Ambient Temperature versus Power Dissipation Curves -----------------------------------7
3.4 Transient Thermal Resistance Curves ----------------------------------------------------------8
4. Block Diagram ---------------------------------------------------------------------------------------------9
5. Pin Configuration Definitions---------------------------------------------------------------------------9
6. Typical Application ------------------------------------------------------------------------------------- 10
7. External Dimensions------------------------------------------------------------------------------------ 11
8. Marking Diagram --------------------------------------------------------------------------------------- 11
9. Operational Description ------------------------------------------------------------------------------- 12
9.1 Startup Operation--------------------------------------------------------------------------------- 12
9.2 Undervoltage Lockout (UVLO) ---------------------------------------------------------------- 12
9.3 Bias Assist Function------------------------------------------------------------------------------- 12
9.4 Soft Start Function-------------------------------------------------------------------------------- 13
9.5 Constant Output Voltage Control-------------------------------------------------------------- 13
9.6 Leading Edge Blanking Function -------------------------------------------------------------- 14
9.7 Random Switching Function -------------------------------------------------------------------- 14
9.8 Automatic Standby Mode Function ----------------------------------------------------------- 14
9.9 Overcurrent Protection (OCP) ----------------------------------------------------------------- 15
9.9.1
9.9.2
OCP Operation ------------------------------------------------------------------------------ 15
OCP Input Compensation Function ----------------------------------------------------- 15
9.10 Overload Protection (OLP)---------------------------------------------------------------------- 16
9.11 Overvoltage Protection (OVP)------------------------------------------------------------------ 16
9.11.1 Latched Shutdown type (STR3A2××) --------------------------------------------------- 17
9.11.2 Auto Restart Type (STR3A2××D)-------------------------------------------------------- 17
9.12 Thermal Shutdown (TSD) ----------------------------------------------------------------------- 17
9.12.1 Latched Shutdown type (STR3A2××) --------------------------------------------------- 17
9.12.2 Auto Restart Type (STR3A2××D)-------------------------------------------------------- 17
10. Design Notes---------------------------------------------------------------------------------------------- 17
10.1 External Components ---------------------------------------------------------------------------- 17
10.2 PCB Trace Layout and Component Placement --------------------------------------------- 19
11. Pattern Layout Example------------------------------------------------------------------------------- 21
12. Reference Design of Power Supply ------------------------------------------------------------------ 22
OPERATING PRECAUTIONS -------------------------------------------------------------------------- 24
IMPORTANT NOTES ------------------------------------------------------------------------------------- 25
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STR3A200 Series
1. Absolute Maximum Ratings
● The polarity value for current specifies a sink as "+," and a source as "−," referencing the IC.
● Unless otherwise specified TA = 25 °C, 5 pin = 6 pin = 7 pin = 8 pin
Parameter
Symbol
IDPEAK
Test Conditions
Single pulse
Pins
Rating
3.6
Units
A
Notes
3A251 / 51D
3A253 / 53D
3A255 / 55D
3A251 / 51D
3A253 / 53D
3A255 / 55D
Drain Peak Current(1)
8 – 1
5.2
7.2
ILPEAK = 2.13 A
ILPEAK = 2.46 A
ILPEAK = 3.05 A
53
Avalanche Energy(2)(3)
EAS
8 – 1
72
mJ
110
S/OCP Pin Voltage
VCC Pin Voltage
VOCP
VCC
VFB
1 – 3
2 – 3
4 – 3
4 – 3
8 − 3
− 2 to 6
32
V
V
FB/OLP Pin Voltage
FB/OLP Pin Sink Current
D/ST Pin Voltage
− 0.3 to 14
1.0
V
IFB
mA
V
VD/ST
− 1 to VDSS
1.68
3A251 / 51D
3A253 / 53D
3A255 / 55D
MOSFET Power
Dissipation(4)
(5)
PD1
8 – 1
1.76
W
1.81
Control Part Power
Dissipation
Operating Ambient
Temperature
VCC × ICC
PD2
TOP
2 – 3
1.3
W
−
− 40 to 125
°C
Storage Temperature
Junction Temperature
Tstg
Tch
−
−
− 40 to 125
°C
°C
150
(1) Refer to 3.2 MOSFET Safe Operating Area Curves
(2) Refer to Figure 3-2 Avalanche Energy Derating Coefficient Curve
(3) Single pulse, VDD = 99 V, L = 20 mH
(4)Refer to Section 3.3 Ta-PD1 Curve
(5)When embedding this hybrid IC onto the printed circuit board (cupper area in a 15 mm × 15 mm)
STR3A200 - DSJ Rev.2.0
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STR3A200 Series
2. Electrical Characteristics
● The polarity value for current specifies a sink as "+," and a source as "−," referencing the IC
● Unless otherwise specified, TA = 25 °C, VCC = 18 V, 5 pin = 6 pin = 7 pin = 8 pin
Test
Conditions
Parameter
Symbol
Pins
Min.
Typ.
Max.
Units
Notes
Power Supply Startup Operation
Operation Start Voltage
Operation Stop Voltage(1)
VCC(ON)
VCC(OFF)
ICC(ON)
2 − 3
2 − 3
2 − 3
13.8
7.6
−
15.0
8.5
16.2
9.2
V
V
VCC = 12 V
Circuit Current in Operation
1.7
2.3
mA
Startup Circuit Operation
Voltage
VST(ON)
ICC(ST)
8 − 3
2 − 3
2 − 3
40
− 4.5
8.0
47
− 2.5
9.6
55
V
mA
V
VCC = 13.5
V
Startup Current
− 1.2
10.5
Startup Current Biasing
Threshold Voltage
ICC=−500µA
VCC(BIAS)
Normal Operation
Average Switching Frequency
fOSC(AVG)
8 − 3
8 − 3
60
67
73
kHz
kHz
Switching Frequency
Modulation Deviation
Δf
−
5.4
−
VCC = 12 V
Maximum Feedback Current
Minimum Feedback Current
Standby Operation
IFB(MAX)
IFB(MIN)
4 − 3 − 170 − 130
− 90
− 5
µA
µA
4 − 3
− 21
− 13
3A251 / 51D
/53 / 53D
1.06
0.81
1.16
0.90
1.26
0.99
Oscillation Stop FB Voltage
VFB(OFF)
4 − 3
V
3A255 / 55D
Protection
Maximum ON Duty
DMAX
tBW
8 − 3
70
−
75
330
17.3
36
80
−
%
ns
Leading Edge Blanking Time
OCP Compensation Coefficient
OCP Compensation ON Duty
−
−
−
DPC
DDPC
−
−
mV/μs
%
−
−
OCP Threshold Voltage at
Zero ON Duty
OCP Threshold Voltage at
36% ON Duty
VOCP(L)
VOCP(H)
1 − 3 0.735 0.795 0.855
1 − 3 0.843 0.888 0.933
V
V
V
OCP Threshold Voltage During
VOCP(LEB)
1 − 3
−
1.69
−
LEB (tBW
)
VCC= 32V
VCC= 12V
OLP Threshold Voltage
OLP Operation Current
OLP Delay Time
VFB(OLP)
tOLP
4 − 3
―
6.8
55
7.3
75
7.8
90
V
ms
µA
V
ICC(OLP)
VFB(CLAMP)
VCC(OVP)
2 − 3
4 − 3
2 − 3
−
160
11.8
29.1
−
FB/OLP Pin Clamp Voltage
OVP Threshold Voltage
10.5
27.0
13.5
31.2
V
(1)
V
> VCC(OFF) always.
CC(BIAS)
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STR3A200 Series
Test
Conditions
Parameter
Symbol
Tj(TSD)
Pins
―
−
Min.
127
−
Typ.
145
80
Max.
Units
°C
Notes
Thermal Shutdown Operating
Temperature
Thermal Shutdown Hysteresis
Temperature
−
−
3A2××D
Tj(TSD)HYS
°C
MOSFET
Drain-to-Source Breakdown
Voltage
IDS = 300µA
VDS = VDSS
VDSS
IDSS
8 − 1
8 − 1
650
−
−
V
Drain Leakage Current
−
−
−
−
−
−
−
−
−
−
300
4.0
1.9
1.1
250
µA
3A251 / 51D
3A253 / 53D
3A255 / 55D
IDS = 0.4A
On Resistance
RDS(ON)
8 − 1
Ω
Switching Time
tf
8 – 1
ns
Thermal Resistance
3A251 / 51D
/53 / 53D
−
−
−
−
18
17
°C/W
°C/W
Channel to Case Thermal
Resistance(2)
θch-C
−
3A255 / 55D
(2)
θ
is thermal resistance between channel and case. Case temperature (TC) is measured at the center of the case top
ch-C
surface.
3. Performance Curves
3.1 Derating Curves
100
100
80
60
40
20
0
80
60
40
20
0
25
50
75
100
125
150
0
25
50
75
100 125 150
Channel Temperature, Tch (°C)
Figure 3-2 Avalanche Energy Derating Coefficient Curve
Channel Temperature, Tch (°C)
Figure 3-1 SOA Temperature Derating Coefficient Curve
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STR3A200 Series
3.2 MOSFET Safe Operating Area Curves
When the IC is used, the safe operating area curve should be multiplied by the temperature derating coefficient
derived from IC Figure 3-1.
● The broken line in the safe operating area curve is the drain current curve limited by on-resistance.
● Unless otherwise specified, TA = 25 °C, Single pulse
STR3A251 / 51D
STR3A253 / 53D
10
10
0.1ms
0.1ms
1
1
1ms
1ms
0.1
0.1
0.01
1
0.01
1
10
100
1000
10
100
1000
Drain-to-Source Voltage (V)
Drain-to-Source Voltage (V)
STR3A255 / 55D
10
0.1ms
1
1ms
0.1
0.01
1
10
100
1000
Drain-to-Source Voltage (V)
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STR3A200 Series
3.3 Ambient Temperature versus Power Dissipation Curves
● STR3A251 / 51D
● STR3A253 / 53D
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
2.0
PD1 = 1.76 W
PD1 = 1.68 W
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0
25
50
75
100 125 150
0
25
50
75
100 125 150
Ambient Temperature, TA (°C )
Ambient Temperature, TA (°C )
● STR3A255 / 55D
2.0
PD1 = 1.81 W
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0
25
50
75
100 125 150
Ambient Temperature, TA (°C )
STR3A200 - DSJ Rev.2.0
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STR3A200 Series
3.4 Transient Thermal Resistance Curves
STR3A251 /51D
10
1
0.1
0.01
1µ
10µ
10µ
10µ
100µ
100µ
100µ
1m
1m
1m
10m
10m
10m
100m
100m
100m
Time (s)
Time (s)
Time (s)
STR3A253 / 53D
10
1
0.1
0.01
1µ
STR3A255 / 55D
10
1
0.1
0.01
1µ
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STR3A200 Series
4. Block Diagram
VCC
2
D/ST
STARTUP
5~8
UVLO
REG
OVP
TSD
VREG
DRV
PWM OSC
S
Q
R
OCP
VCC
Drain Peak Current
Compensation
OLP
Feedback
Control
S/OCP
GND
FB/OLP
LEB
1
3
4
Slope
Compensation
BD_STR3A200_R1
5. Pin Configuration Definitions
Pin
1
Name
Descriptions
MOSFET source and input of Overcurrent
Protection (OCP) signal
Power supply voltage input for control part and
input of Overvoltage Protection (OVP) signal
S/OCP
D/ST
D/ST
D/ST
1
2
3
4
8
7
6
S/OCP
VCC
GND
2
3
4
VCC
GND
Ground
Input of constant voltage control signal and input
of Overload Protection (OLP) signal
FB/OLP
FB/OLP
D/ST
5
5
6
7
8
D/ST
MOSFET drain and input of startup current
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STR3A200 Series
6. Typical Application
The PCB traces of the D/ST pins should be as wide as possible, in order to enhance thermal dissipation.
In applications having a power supply specified such that VDS has large transient surge voltages, a clamp snubber
circuit of a capacitor-resistor-diode (CRD) combination should be added on the primary winding P, or a damper
snubber circuit of a capacitor (C) or a resistor-capacitor (RC) combination should be added between the D/ST pin and
the S/OCP pin.
CRD clamp snubber
L51
BR1
C1
D51
VOUT
T1
VAC
R54
R51
R1
C5
PC1
R52
P
R55
C51
D1
S
C53
C52 R53
U2
6
5
8
7
R56
D2 R2
D/ST D/ST DN/SCT D/ST
C4
U1
GND
STR3A200
D
C2
C（RC）
Damper snubber
S/OCP VCC
FB/OLP
4
GND
3
1
2
C3
ROCP
CY
PC1
TC_STR3A200_2_R1
Figure 6-1 Typical application
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STR3A200 Series
7. External Dimensions
● DIP8
NOTES:
● Dimension is in millimeters
● Pb-free. Device composition compliant with the RoHS directive
8. Marking Diagram
8
(3A2×× / 3A2××D)
Part Number
Y M D
Lot Number
Y = Last Digit of Year (0-9)
M = Month (1-9,O,N or D)
D =Period of days (1 to 3)
1 : 1st to 10th
1
2 : 11th to 20th
3 : 21st to 31st
Sanken Control Number
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STR3A200 Series
The startup time of the IC is determined by C2
capacitor value. The approximate startup time tSTART is
calculated as follows:
9. Operational Description
● All of the parameter values used in these descriptions
are typical values, unless they are specified as
minimum or maximum.
● With regard to current direction, "+" indicates sink
current (toward the IC) and "–" indicates source
current (from the IC).
VCC(ON )－VCC(INT)
tSTART C2 ×
(2)
ICC(ST )
Where,
tSTART : Startup time of the IC (s)
VCC(INT) : Initial voltage on the VCC pin (V)
9.1 Startup Operation
Figure 9-1 shows the circuit around the VCC pin.
The IC incorporates the startup circuit. The circuit is
connected to D/ST pin. When the D/ST pin voltage
reaches to Startup Circuit Operation Voltage
VST(ON) = 47 V, the startup circuit starts operation.
During the startup process, the constant current,
ICC(ST) = − 2.5 mA, charges C2 at the VCC pin. When
VCC pin voltage increases to VCC(ON) = 15.0 V, the
control circuit starts switching operation. During the IC
operation, the voltage rectified the auxiliary winding
voltage, VD, of Figure 9-1 becomes a power source to
the VCC pin. After switching operation begins, the
startup circuit turns off automatically so that its current
consumption becomes zero.
9.2 Undervoltage Lockout (UVLO)
Figure 9-2 shows the relationship of the VCC pin
voltage and circuit current ICC. When VCC pin voltage
decreases to VCC(OFF) = 8.5 V, the control circuit stops
operation by UVLO (Undervoltage Lockout) circuit, and
reverts to the state before startup.
Circuit current, ICC
Stop
Start
T1
BR1
VAC
C1
P
VCC pin
voltage
VCC（OFF）
VCC（ON）
5-8
D/ST
Figure 9-2 Relationship between
VCC pin voltage and ICC
D2 R2
U1
2
3
VCC
D
C2
VD
9.3 Bias Assist Function
GND
By the Bias Assist Function, the startup failure is
prevented and the latched state is kept.
The Bias Assist Function is activated in the following
condition. Where, VFB(OFF) is the FB/OLP Pin Oscillation
Stop Threshold Voltage, VCC(BIAS) is the Startup Current
Biasing Threshold Voltage.
Figure 9-1 VCC pin peripheral circuit
The approximate value of auxiliary winding voltage is
about 18V, taking account of the winding turns of D
winding so that the VCC pin voltage becomes Equation
(1) within the specification of input and output voltage
variation of power supply.
● Auto restart type (STR3A2××D)
When FB pin voltage is VFB(OFF) or less and VCC pin
voltage decreases to VCC(BIAS) = 9.6 V, the Bias Assist
Function is activated.
VCC(BIAS) (max.) VCC VCC(OVP ) (min.)
● Latched shutdown type (STR3A2××)
When VCC pin voltage decreases to VCC(BIAS) = 9.6 V
in the following condition, the Bias Assist Function is
activated.
10.5 (V) < VCC < 27.0 (V)
(1)
⇒
FB pin voltage is VFB(OFF) or less
or the IC is in the latched state due to activating the
protection function.
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STR3A200 Series
When the Bias Assist Function is activated, the VCC
pin voltage is kept almost constant voltage, VCC(BIAS) by
providing the startup current, ICC(ST), from the startup
circuit. Thus, the VCC pin voltage is kept more than
Since the Leading Edge Blanking Function (refer to
Section 9.6) is deactivated during the soft start period,
there is the case that ON time is less than the leading
edge blanking time, tBW = 330 ns.
VCC(OFF)
.
After the soft start period, D/ST pin current, ID, is
limited by the Overcurrent Protection (OCP), until the
output voltage increases to the target operating voltage.
This period is given as tLIM. In case tLIM is longer than
the OLP Delay Time, tOLP, the output power is limited
by the Overload Protection (OLP) operation. Thus, it is
necessary to adjust the value of output capacitor and the
turn ratio of auxiliary winding D so that the tLIM is less
than tOLP = 55 ms (min.).
Since the startup failure is prevented by the Bias
Assist Function, the value of C2 connected to the VCC
pin can be small. Thus, the startup time and the response
time of the Overvoltage Protection (OVP) become
shorter.
The operation of the Bias Assist Function in startup is
as follows. It is necessary to check and adjust the startup
process based on actual operation in the application, so
that poor starting conditions may be avoided.
Figure 9-3 shows the VCC pin voltage behavior
during the startup period.
Startup of IC Startup of SMPS
VCC pin
voltage
Normal opertion
After the VCC pin voltage increases to VCC(ON) = 15.0
V at startup, the IC starts the operation. Then circuit
current increases and the VCC pin voltage decreases. At
the same time, the auxiliary winding voltage, VD,
increases in proportion to output voltage. These are all
balanced to produce the VCC pin voltage.
tSTART
VCC(ON)
VCC(OFF)
Time
When the VCC pin voltage is decrease to
VCC(OFF) = 8.5 V in startup operation, the IC stops
switching operation and a startup failure occurs.
When the output load is light at startup, the output
voltage may become more than the target voltage due to
the delay of feedback circuit. In this case, the FB pin
voltage is decreased by the feedback control. When the
FB pin voltage decreases to VFB(OFF) or less, the IC stops
switching operation and the VCC pin voltage decreases.
When the VCC pin voltage decreases to VCC(BIAS), the
Bias Assist function is activated and the startup failure is
prevented.
Soft start period
approximately 8.75 ms (fixed)
D/ST pin
current, ID
Limited by OCP operation
tLIM < tOLP (min.)
Time
Figure 9-4 VCC and ID behavior during startup
9.5 Constant Output Voltage Control
VCC pin
voltage
Startup success
Target operating
voltage
Increase with rising of
output voltage
The IC achieves the constant voltage control of the
power supply output by using the current-mode control
method, which enhances the response speed and
provides the stable operation.
IC starts operation
VCC(ON)
VCC(BIAS)
The FB/OLP pin voltage is internally added the slope
compensation at the feedback control (refer to Section
4.Block Diagram), and the target voltage, VSC, is
generated. The IC compares the voltage, VROCP, of a
current detection resistor with the target voltage, VSC, by
the internal FB comparator, and controls the peak value
of VROCP so that it gets close to VSC, as shown in Figure
9-5 and Figure 9-6.
Bias assist period
VCC(OFF)
Startup failure
Time
Figure 9-3 VCC pin voltage during startup period
● Light load conditions
9.4 Soft Start Function
When load conditions become lighter, the output
voltage, VOUT, increases. Thus, the feedback current
from the error amplifier on the secondary-side also
increases. The feedback current is sunk at the FB/OLP
pin, transferred through a photo-coupler, PC1, and the
FB/OLP pin voltage decreases. Thus, VSC decreases,
and the peak value of VROCP is controlled to be low,
and the peak drain current of ID decreases.
Figure 9-4 shows the behavior of VCC pin voltage
and drain current during the startup period.
The IC activates the soft start circuitry during the
startup period. Soft start time is fixed to around 8.75 ms.
during the soft start period, overcurrent threshold is
increased step-wisely (7 steps). This function reduces
the voltage and the current stress of a power MOSFET
and the secondary side rectifier diode.
This control prevents the output voltage from
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increasing.
Target voltage
without slope compensation
● Heavy load conditions
When load conditions become greater, the IC
performs the inverse operation to that described above.
Thus, VSC increases and the peak drain current of ID
increases.
This control prevents the output voltage from
decreasing.
tON1
T
tON2
In the current mode control method, when the drain
current waveform becomes trapezoidal in continuous
operating mode, even if the peak current level set by the
target voltage is constant, the on-time fluctuates based
on the initial value of the drain current.
T
T
Figure 9-7 Drain current, ID, waveform in subharmonic
oscillation
This results in the on-time fluctuating in multiples of
the fundamental operating frequency as shown in Figure
9-7. This is called the subharmonics phenomenon.
In order to avoid this, the IC incorporates the Slope
Compensation Function. Because the target voltage is
added a down-slope compensation signal, which reduces
the peak drain current as the on-duty gets wider relative
to the FB/OLP pin signal to compensate VSC, the
subharmonics phenomenon is suppressed.
Even if subharmonic oscillations occur when the IC
has some excess supply being out of feedback control,
such as during startup and load shorted, this does not
affect performance of normal operation.
9.6 Leading Edge Blanking Function
The constant voltage control of output of the IC uses
the peak-current-mode control method.
In peak-current-mode control method, there is a case
that the power MOSFET turns off due to unexpected
response of a FB comparator or Overcurrent Protection
(OCP) circuit to the steep surge current in turning on a
power MOSFET.
In order to prevent this response to the surge voltage
in turning-on the power MOSFET, the Leading Edge
Blanking Time, tBW = 330 ns is built-in. During tBW, the
OCP threshold voltage becomes VOCP(LEB) = 1.69 V
which is higher than the normal OCP threshold voltage
in order not to respond to the turn-on drain current surge
(refer to Section 9.9).
U1
S/OCP
1
FB/OLP
4
GND
3
9.7 Random Switching Function
PC1
ROCP
VROCP
IFB
The IC modulates its switching frequency randomly
by superposing the modulating frequency on fOSC(AVG) in
normal operation. This function reduces the conduction
noise compared to others without this function, and
simplifies noise filtering of the input lines of power
supply.
C3
Figure 9-5 FB/OLP pin peripheral circuit
Target voltage including
slope compensation
9.8 Automatic Standby Mode Function
VSC
-
Automatic standby mode is activated automatically
when FB/OLP pin voltage decreases to VFB(OFF)
The operation mode becomes burst oscillation, as
shown in Figure 9-8.
.
+
VROCP
Voltage on both
sides of ROCP
FB comparator
Burst oscillation mode reduces switching losses and
improves power supply efficiency because of periodic
non-switching intervals.
Generally, in order to improve efficiency under light
load conditions, the frequency of the burst oscillation
mode becomes just a few kilohertz. Because the IC
suppresses the peak drain current well during burst
oscillation mode, audible noises can be reduced.
If VCC pin voltage decreases to VCC(BIAS) = 9.6 V
Drain current,
ID
Figure 9-6 Drain current, ID, and FB comparator
operation in steady operation
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tBW
during the transition to the burst oscillation mode, the
Bias Assist Function is activated and stabilizes the
Standby mode operation, because the Startup Current,
ICC(ST) is provided to the VCC pin so that the VCC pin
VOCP(LEB)
VOCP
’
voltage does not decrease to VCC(OFF)
.
However, if the Bias Assist Function is always
activated during steady-state operation including
standby mode, the power loss increases. Therefore, the
VCC pin voltage should be more than VCC(BIAS), for
example, by adjusting the turns ratio of the auxiliary
winding and the secondary-side winding and/or reducing
the value of R2 in Figure 10-2 (refer to Section 10.1)
Surge pulse voltage width at turning-on
Figure 9-9 S/OCP pin voltage
C（RC）
Damper snubber
T1
Output current,
Burst oscillation
IOUT
D51
C51
C1
U1
Below several kHz
5~8
Drain current,
ID
D/ST
C（RC）
Damper snubber
Normal
operation
Standby
operation
Normal
operation
S/OCP
1
ROCP
Figure 9-8 Auto Standby mode timing
9.9 Overcurrent Protection (OCP)
9.9.1 OCP Operation
Figure 9-10 Damper snubber
9.9.2 OCP Input Compensation Function
ICs with PWM control usually have some propagation
delay time. The steeper the slope of the actual drain
current at a high AC input voltage is, the larger the
detection voltage of actual drain peak current is,
compared to VOCP. Thus, the peak current has some
variation depending on AC input voltage in OCP state.
In order to reduce the variation of peak current in OCP
state, the IC has Input Compensation Function.
This function corrects OCP threshold voltage
depending on AC input voltage, as shown in Figure
9-11.
When AC input voltage is low (ON Duty is broad),
the OCP threshold voltage is controlled to become high.
The difference of peak drain current become small
compared with the case where the AC input voltage is
high (ON Duty is narrow).
Overcurrent Protection (OCP) detects each drain peak
current level of a power MOSFET on pulse-by-pulse
basis, and limits the output power when the current level
reaches to OCP threshold voltage.
During Leading Edge Blanking Time, the OCP
threshold voltage becomes VOCP(LEB) = 1.69 V which is
higher than the normal OCP threshold voltage as shown
in Figure 9-9. Changing to this threshold voltage
prevents the IC from responding to the surge voltage in
turning-on the power MOSFET. This function operates
as protection at the condition such as output windings
shorted or unusual withstand voltage of secondary-side
rectifier diodes.
When the power MOSFET turns on, the surge voltage
width of the S/OCP pin should be less than tBW, as
shown in Figure 9-9. In order to prevent surge voltage,
pay extra attention to ROCP trace layout (refer to Section
10.2). In addition, if a C (RC) damper snubber of Figure
9-10 is used, reduce the capacitor value of damper
snubber.
The compensation signal depends on ON Duty. The
relation between the ON Duty and the OCP threshold
voltage after compensation VOCP' is expressed as
Equation (3). When ON Duty is broader than 36 %, the
VOCP' becomes a constant value VOCP(H) = 0.888 V
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intermittent operation is short compared with oscillation
stop period. When the abnormal condition is removed,
the IC returns to normal operation automatically.
1.0
VOCP(H)
VOCP(L)
U1
VCC
2
GND FB/OLP
4
3
D2 R2
PC1
DDPC=36%
DMAX=75%
C3
0.5
0
C2
50
100
D
ON Duty (%)
Figure 9-11 Relationship between ON Duty and Drain
Current Limit after compensation
Figure 9-12 FB/OLP pin peripheral circuit
Non-switching interval
VCC pin voltage
VCC(ON)
VOCP ' VOCP(L) DPCONTime
VCC(OFF)
ONDuty
VOCP(L) DPC
(3)
FB/OLP pin voltage
VFB(OLP)
tOLP
fOSC (AVG )
tOLP
Where,
VOCP(L): OCP Threshold Voltage at Zero ON Duty (V)
DPC: OCP Compensation Coefficient (mV/μs)
ONTime: On-time of power MOSFET (μs)
Drain current,
ID
ONDuty: On duty of power MOSFET (%)
fOSC(AVG): Average PWM Switching Frequency (kHz)
Figure 9-13 OLP operational waveforms
9.10 Overload Protection (OLP)
9.11 Overvoltage Protection (OVP)
Figure 9-12 shows the FB/OLP pin peripheral circuit,
and Figure 9-13 shows each waveform for Overload
Protection (OLP) operation.
When a voltage between the VCC pin and the GND
pin increases to VCC(OVP) = 29.1 V or more, Overvoltage
Protection (OVP) is activated. The IC has two operation
types of OVP. One is the latched shutdown. The other is
the auto restart.
When VCC pin voltage is provided by using auxiliary
winding of transformer, the VCC pin voltage is
proportional to output voltage. Thus, the VCC pin can
detect the overvoltage conditions such as output voltage
detection circuit open. The approximate value of the
output voltage VOUT(OVP) in OVP condition is calculated
by using Equation (4).
When the peak drain current of ID is limited by
Overcurrent Protection operation, the output voltage,
VOUT, decreases and the feedback current from the
secondary photo-coupler becomes zero. Thus, the
feedback current, IFB, charges C3 connected to the
FB/OLP pin and FB/OLP pin voltage increases. When
the FB/OLP pin voltage increases to VFB(OLP) = 7.3 V or
more for the OLP delay time, tOLP = 75 ms or more, the
OLP is activated, the IC stops switching operation.
During OLP operation, Bias Assist Function is
disabled. Thus, VCC pin voltage decreases to VCC(OFF)
,
the control circuit stops operation. After that, the IC
reverts to the initial state by UVLO circuit, and the IC
starts operation when VCC pin voltage increases to
VCC(ON) by startup current. Thus the intermittent
operation by UVLO is repeated in OLP state.
This intermittent operation reduces the stress of parts
such as a power MOSFET and secondary side rectifier
diodes. In addition, this operation reduces power
consumption because the switching period in this
VOUT (NORMAL )
VOUT(OVP)
29.1 (V)
(4)
VCC(NORMAL )
Where,
VOUT(NORMAL): Output voltage in normal operation
VCC(NORMAL): VCC pin voltage in normal operation
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to VCC(BIAS), the Bias Assist Function is activated and the
VCC pin voltage is kept to over the VCC(OFF)
9.11.1 Latched Shutdown type (STR3A2××)
.
When the OVP is activated, the IC stops switching
operation at the latched state. In order to keep the
latched state, when VCC pin voltage decreases to
VCC(BIAS), the Bias Assist Function is activated and VCC
pin voltage is kept to over the VCC(OFF). Releasing the
latched state is done by turning off the input voltage and
When the temperature reduces to less than
Tj(TSD)−Tj(TSD)HYS, the Bias Assist Function is disabled
and the VCC pin voltage decreases to VCC(OFF). At that
time, the IC stops operation and reverts to the state
before startup. After that, the startup circuit is activated,
the VCC pin voltage increases to VCC(ON), and the IC
starts switching operation again.
by dropping the VCC pin voltage below VCC(OFF)
.
In this way, the intermittent operation by the TSD and
the UVLO is repeated while there is an excess thermal
condition. When the fault condition is removed, the IC
returns to normal operation automatically.
9.11.2 Auto Restart Type (STR3A2××D)
When the OVP is activated, the IC stops switching
operation. During OVP operation, the Bias Assist
Function is disabled, the intermittent operation by
UVLO is repeated (refer to Section 9.10). When the
fault condition is removed, the IC returns to normal
operation automatically (refer to Figure 9-14).
Junction Temperature,
Tj
Tj(TSD)
Tj(TSD)−Tj(TSD)HYS
VCC pin voltage
VCC(OVP)
Bias assist
function
ON
ON
OFF
OFF
VCC pin voltage
VCC(ON)
VCC(OFF)
VCC(ON)
VCC(BIAS)
VCC(OFF)
Drain current
ID
Drain current,
ID
Figure 9-15 TSD operational waveforms
Figure 9-14 OVP operational waveforms
10. Design Notes
9.12 Thermal Shutdown (TSD)
When the temperature of control circuit increases to
Tj(TSD) = 145 °C or more, Thermal Shutdown (TSD) is
activated. The IC has two operation types of TSD. One
is latched shutdown, the other is auto restart.
10.1 External Components
Take care to use properly rated, including derating as
necessary and proper type of components.
CRD clamp snubber
9.12.1 Latched Shutdown type (STR3A2××)
BR1
T1
VAC
When the TSD is activated, the IC stops switching
operation at the latched state. In order to keep the
latched state, when VCC pin voltage decreases to
VCC(BIAS), the Bias Assist Function is activated and VCC
C5 R1
P
C1
D1
pin voltage is kept to over the VCC(OFF)
.
D2 R2
6
5
8
7
Releasing the latched state is done by turning off the
input voltage and by dropping the VCC pin voltage
D/ST D/ST DN/SCT D/ST
C4
U1
D
C2
STR3A200
C（RC）
Damper snubber
below VCC(OFF)
.
S/OCP VCC
FB/OLP
4
GND
3
1
2
9.12.2 Auto Restart Type (STR3A2××D)
C3
ROCP
Figure 9-15 shows the TSD operational waveforms.
When Thermal Shutdown (TSD) is activated, and the
IC stops switching operation. After that, VCC pin
voltage decreases. When the VCC pin voltage decreases
PC1
Figure 10-1 The IC peripheral circuit
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● Input and Output Electrolytic Capacitor
Apply proper derating to ripple current, voltage, and
temperature rise. Use of high ripple current and low
impedance types, designed for switch mode power
supplies, is recommended.
・ A clamp snubber circuit of a capacitor-resistor-
diode (CRD) combination should be added on the
primary winding P.
・ A damper snubber circuit of a capacitor (C) or a
resistor-capacitor (RC) combination should be
added between the D/ST pin and the S/GND pin.
In case the damper snubber circuit is added, this
components should be connected near D/ST pin
and S/OCP pin.
● S/OCP Pin Peripheral Circuit
In Figure 10-1, ROCP is the resistor for the current
detection. A high frequency switching current flows
to ROCP, and may cause poor operation if a high
inductance resistor is used. Choose a low inductance
and high surge-tolerant type.
● Peripheral circuit of secondary side shunt
regulator
Figure 10-3 shows the secondary side detection circuit
with the standard shunt regulator IC (U51).
C52 and R53 are for phase compensation. The value
of C52 and R53 are recommended to be around 0.047
μF to 0.47 μF and 4.7 kΩ to 470 kΩ, respectively.
They should be selected based on actual operation in
the application.
● VCC Pin Peripheral Circuit
The value of C2 in Figure 10-1 is generally
recommended to be 10 µF to 47 μF (refer to Section
9.1 Startup Operation, because the startup time is
determined by the value of C2)
In actual power supply circuits, there are cases in
which the VCC pin voltage fluctuates in proportion to
the output current, IOUT (see Figure 10-2), and the
Overvoltage Protection (OVP) on the VCC pin may
be activated. This happens because C2 is charged to a
peak voltage on the auxiliary winding D, which is
caused by the transient surge voltage coupled from the
primary winding when the power MOSFET turns off.
For alleviating C2 peak charging, it is effective to add
some value R2, of several tenths of ohms to several
ohms, in series with D2 (see Figure 10-1). The
optimal value of R2 should be determined using a
transformer matching what will be used in the actual
application, because the variation of the auxiliary
winding voltage is affected by the transformer
structural design.
L51
T1
VOUT
(+)
D51
R54
R51
PC1
R52
R55
C51
S
C53
C52 R53
U51
R56
(-)
Without R2
VCC pin voltage
Figure 10-3 Peripheral circuit of secondary side shunt
regulator (U51)
With R2
Output current, IOUT
Figure 10-2 Variation of VCC pin voltage and power
● FB/OLP Pin Peripheral Circuit
C3 (see Figure 10-1) is for high frequency noise
rejection and phase compensation, and should be
connected close to the FB/OLP pin and the GND pin.
The value of C3 is recommended to be about 2200 pF
to 0.01 µF, and should be selected based on actual
operation in the application.
Snubber Circuit
If the serge voltage of VDS is large, the circuit should
be added as follows (see Figure 10-1);
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● Transformer
Apply proper design margin to core temperature rise
by core loss and copper loss.
Margin tape
Because the switching currents contain high
frequency currents, the skin effect may become a
consideration.
Choose a suitable wire gauge in consideration of the
RMS current and a current density of 4 to 6 A/mm2.
If measures to further reduce temperature are still
necessary, the following should be considered to
increase the total surface area of the wiring:
P1 S1 P2 S2 D
Margin tape
Winding structural example (a)
Margin tape
・ Increase the number of wires in parallel.
・ Use litz wires.
P1 S1 D S2 S1 P2
・ Thicken the wire gauge.
Margin tape
In the following cases, the surge of VCC pin voltage
becomes high.
Winding structural example (b)
・ The surge voltage of primary main winding, P, is
high (low output voltage and high output current
power supply designs)
Figure 10-4 Winding structural examples
・ The winding structure of auxiliary winding, D, is
susceptible to the noise of winding P.
10.2 PCB Trace Layout and Component
Placement
When the surge voltage of winding D is high, the
VCC pin voltage increases and the Overvoltage
Protection (OVP) may be activated. In transformer
design, the following should be considered;
Since the PCB circuit trace design and the component
layout significantly affects operation, EMI noise, and
power dissipation, the high frequency PCB trace should
be low impedance with small loop and wide trace.
In addition, the ground traces affect radiated EMI
noise, and wide, short traces should be taken into
account.
・ The coupling of the winding P and the secondary
output winding S should be maximized to reduce
the leakage inductance.
・ The coupling of the winding D and the winding
S should be maximized.
Figure 10-5 shows the circuit design example.
(1) Main Circuit Trace Layout:
・ The coupling of the winding D and the winding
P should be minimized.
This is the main trace containing switching currents,
and thus it should be as wide trace and small loop as
possible.
If C1 and the IC are distant from each other, placing
a capacitor such as film capacitor (about 0.1 μF and
with proper voltage rating) close to the transformer
or the IC is recommended to reduce impedance of
the high frequency current loop.
In the case of multi-output power supply, the
coupling of the secondary-side stabilized output
winding, S1, and the others (S2, S3 ) should be
…
maximized to improve the line-regulation of those
outputs.
Figure 10-4 shows the winding structural examples of
two outputs.
(2) Control Ground Trace Layout
Since the operation of IC may be affected from the
large current of the main trace that flows in control
ground trace, the control ground trace should be
separated from main trace and connected at a single
point grounding of point A in Figure 10-5 as close to
the ROCP pin as possible.
Winding structural example (a):
S1 is sandwiched between P1 and P2 to maximize the
coupling of them for surge reduction of P1 and P2.
D is placed far from P1 and P2 to minimize the
coupling to the primary for the surge reduction of D.
(3) VCC Trace Layout:
Winding structural example (b)
This is the trace for supplying power to the IC, and
thus it should be as small loop as possible. If C2 and
the IC are distant from each other, placing a
capacitor such as film capacitor Cf (about 0.1 μF to
1.0 μF) close to the VCC pin and the GND pin is
recommended.
P1 and P2 are placed close to S1 to maximize the
coupling of S1 for surge reduction of P1 and P2.
D and S2 are sandwiched by S1 to maximize the
coupling of D and S1, and that of S1 and S2. This
structure reduces the surge of D, and improves the
line-regulation of outputs.
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STR3A200 Series
(4) ROCP Trace Layout
carrying the switching current, and thus it should be
as wide trace and small loop as possible. If this trace
is thin and long, inductance resulting from the loop
may increase surge voltage at turning off the power
MOSFET. Proper rectifier smoothing trace layout
helps to increase margin against the power MOSFET
breakdown voltage, and reduces stress on the clamp
snubber circuit and losses in it.
ROCP should be placed as close as possible to the
S/OCP pin. The connection between the power
ground of the main trace and the IC ground should
be at a single point ground (point A in Figure 10-5)
which is close to the base of ROCP
.
(5) FB/OLP Trace Layout
The components connected to FB/OLP pin should be
as close to FB/OLP pin as possible. The trace
between the components and FB/OLP pin should be
as short as possible.
(7) Thermal Considerations
Because the power MOSFET has a positive thermal
coefficient of RDS(ON), consider it in thermal design.
Since the copper area under the IC and the D/ST pin
trace act as a heatsink, its traces should be as wide as
possible.
(6) Secondary Rectifier Smoothing Circuit Trace
Layout:
This is the trace of the rectifier smoothing loop,
(1)Main trace should be wide
trace and small loop
(6)Main trace of secondary side should
be wide trace and small loop
D51
T1
R1
C5
C1
P
(7)Trace of D/ST pin should be
wide for heat release
C51
D1
S
5
8
7
6
D2
C2
R2
D/ST D/ST DN/CST D/ST
C4
U1
STR3A200
D
S/OCP VCC
FB/OLP
4
GND
3
1
2
(3) Loop of the power
supply should be small
ROCP
PC1
(5)The components connected to
FB/OLP pin should be as close
to FB/OLP pin as possible
C3
A
CY
(4)ROCP Should be as close to S/OCP pin as
possible.
(2) Control GND trace should be connected at a
single point as close to the ROCP as possible
Figure 10-5 Peripheral circuit example around the IC
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STR3A200 Series
11. Pattern Layout Example
The following show the two outputs PCB pattern layout example and the schematic of circuit using STR3A200 series.
The PCB pattern layout example is made usable to other ICs in common. The parts in Figure 11-1 are only used.
Figure 11-1 PCB circuit trace layout example
F1
1
L1
L51
CN51
VOUT1
C10
C11
D1
D4
D2
D3
TH1
T1
D51
C2
C1
R5
R54
R55
R51
C4
R1
C56 R62
3
C3
J1
P1
R52
C53
R4
D5
PC1
R53
U51
C51
R57
S1
JW52
C52
R56
6
5
8
7
GND
D/ST
D/ST D/ST D/ST
JW51
R60
R59
U1
C8
JW53
STR3A200
L52
R58
D52
D6
R2
GND
S/OCP VCC
FB/OLP
4
OUT2
GND
1
2
3
D
C5
C57 R63
C54
C55
R61
C7
R3
C6
PC1
CN52
C9
Figure 11-2 Circuit schematic for PCB circuit trace layout
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STR3A200 Series
12. Reference Design of Power Supply
As an example, the following show the power supply specification, the circuit schematic, the bill of materials, and
the transformer specification.
● Power supply specification
STR3A255
IC
AC85V to AC265V
34.8 W (40.4 W peak)
8 V / 0.5 A
Input voltage
Maximum output power
Output 1
14 V / 2.2 A (2.6 A peak)
Output 2
● Circuit schematic
Refer to Figure 11-2
● Bill of materials
Recommended
Sanken Parts
Recommended
Sanken Parts
Symbol
Part type
Fuse
Ratings(1)
Symbol
Part type
Inductor
Ratings(1)
Short
F1
AC 250 V, 3 A
3.3 mH
L51
L52
D51
D52
(2)
L1
TH1
D1
D2
D3
D4
D5
D6
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
R1
R2
R3
R4
R5
PC1
U1
CM inductor
NTC thermistor
General
Inductor
Schottky
Schottky
Electrolytic
Ceramic
Electrolytic
Electrolytic
Electrolytic
Ceramic
Ceramic
General
Short
(2)
Short
90 V, 1.5 A
150V, 10A
680 μF, 25 V
0.1 μF, 50 V
680 μF, 25 V
470 μF, 16 V
Open
EK19
600 V, 1 A
600 V, 1 A
600 V, 1 A
600 V, 1 A
800 V, 1.2 A
200 V, 1 A
0.1 μF, 275 V
Open
EM01A
EM01A
EM01A
EM01A
SARS01
AL01Z
FMEN-210B
(2)
General
C51
C52
C53
C54
C55
C56
C57
R51
R52
R53
R54
R55
R56
R57
R58
R59
R60
R61
R62
R63
JW51
JW52
(2)
(2)
General
General
General
(2)
(2)
(2)
Fast recovery
Film, X2
Electrolytic
Electrolytic
Ceramic
(2)
(2)
Open
Open
150 μF, 400 V
1000 pF, 2 kV
22 μF, 50 V
0.01 μF
Open
General
1.5 kΩ
(2)
Electrolytic
Ceramic
General
47 kΩ
(2)
(2)
(2)
General
Open, 1%
Open, 1%
10 kΩ, 1%
Open
Ceramic
Open
General
Ceramic
15 pF / 2 kV
2200 pF, 250 V
Open
General
Ceramic, Y1
Ceramic
General
(2)
(2)
(3)
(2)
(2)
(2)
(3)
General
1 kΩ
(2)
Ceramic
Open
General
6.8 kΩ
Metal oxide
General
330 kΩ, 1 W
10 Ω
General
39 kΩ, 1%
Open
General
(2)
(2)
General
0.47 Ω, 1/2 W
47 Ω, 1 W
Open
General
Open
General
General
Open
Metal oxide
Photo-coupler
IC
Short
PC123 or equiv
－
Short
STR3A255 JW53
U51
Short
See
VREF = 2.5 V
TL431 or equiv
T1
Transformer
Shunt regulator
the specification
(1)
Unless otherwise specified, the voltage rating of capacitor is 50 V or less and the power rating of resistor is 1/8 W or less.
It is necessary to be adjusted based on actual operation in the application.
Resistors applied high DC voltage and of high resistance are recommended to select resistors designed against electromigration or use
combinations of resistors in series for that to reduce each applied voltage, according to the requirement of the application.
(2)
(3)
STR3A200 - DSJ Rev.2.0
May.18, 2015
SANKEN ELECTRIC CO.,LTD.
http://www.sanken-ele.co.jp
22
© SANKEN ELECTRIC CO.,LTD. 2013
STR3A200 Series
● Transformer specification
・ Primary inductance, LP ：518 μH
・ Core size
・ Al-value
：EER-28
：245 nH/N2 (Center gap of about 0.56 mm)
・ Winding specification
Winding
Symbol
P1
Number of turns (T)
18
Construction
Single-layer,
solenoid winding
Single-layer,
Wire diameter (mm)
Primary winding
φ 0.23 × 2
Primary winding
P2
28
φ 0.30
solenoid winding
Auxiliary winding
Output 1 winding
Output 1 winding
Output 2 winding
Output 2 winding
D
12
6
φ 0.30 × 2
φ 0.4 × 2
φ 0.4 × 2
φ 0.4 × 2
φ 0.4 × 2
Solenoid winding
Solenoid winding
Solenoid winding
Solenoid winding
Solenoid winding
S1-1
S1-2
S2-1
S2-2
6
4
4
4mm
2mm
VDC
8V
P2
P1
S1-1
S2-1
S1-2
S2-2
S2-2 S1-2
D
S1-1
S2-1
P2
P1
Drain
14V
VCC
D
Bobbin
GND
Core
GND
Cross-section view
●: Start at this pin
STR3A200 - DSJ Rev.2.0
SANKEN ELECTRIC CO.,LTD.
23
May.18, 2015
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
STR3A200 Series
OPERATING PRECAUTIONS
In the case that you use Sanken products or design your products by using Sanken products, the reliability largely
depends on the degree of derating to be made to the rated values. Derating may be interpreted as a case that an operation
range is set by derating the load from each rated value or surge voltage or noise is considered for derating in order to
assure or improve the reliability. In general, derating factors include electric stresses such as electric voltage, electric
current, electric power etc., environmental stresses such as ambient temperature, humidity etc. and thermal stress caused
due to self-heating of semiconductor products. For these stresses, instantaneous values, maximum values and minimum
values must be taken into consideration. In addition, it should be noted that since power devices or IC’s including power
devices have large self-heating value, the degree of derating of junction temperature affects the reliability significantly.
Because reliability can be affected adversely by improper storage environments and handling methods, please
observe the following cautions.
Cautions for Storage
Ensure that storage conditions comply with the standard temperature (5 to 35°C) and the standard relative humidity
(around 40 to 75%); avoid storage locations that experience extreme changes in temperature or humidity.
Avoid locations where dust or harmful gases are present and avoid direct sunlight.
Reinspect for rust on leads and solderability of the products that have been stored for a long time.
Cautions for Testing and Handling
When tests are carried out during inspection testing and other standard test periods, protect the products from power
surges from the testing device, shorts between the product pins, and wrong connections. Ensure all test parameters are
within the ratings specified by Sanken for the products.
Remarks About Using Thermal Silicone Grease
When thermal silicone grease is used, it shall be applied evenly and thinly. If more silicone grease than required is
applied, it may produce excess stress.
The thermal silicone grease that has been stored for a long period of time may cause cracks of the greases, and it
cause low radiation performance. In addition, the old grease may cause cracks in the resin mold when screwing the
products to a heatsink.
Fully consider preventing foreign materials from entering into the thermal silicone grease. When foreign material
is immixed, radiation performance may be degraded or an insulation failure may occur due to a damaged insulating
plate.
The thermal silicone greases that are recommended for the resin molded semiconductor should be used.
Our recommended thermal silicone grease is the following, and equivalent of these.
Type
G746
YG6260 Momentive Performance Materials Japan LLC
SC102 Dow Corning Toray Co., Ltd.
Suppliers
Shin-Etsu Chemical Co., Ltd.
Soldering
When soldering the products, please be sure to minimize the working time, within the following limits:
• 260 ± 5 °C 10 ± 1 s (Flow, 2 times)
• 380 ± 10 °C 3.5 ± 0.5 s (Soldering iron, 1 time)
Soldering should be at a distance of at least 1.5 mm from the body of the products.
Electrostatic Discharge
When handling the products, the operator must be grounded. Grounded wrist straps worn should have at least 1MΩ
of resistance from the operator to ground to prevent shock hazard, and it should be placed near the operator.
Workbenches where the products are handled should be grounded and be provided with conductive table and floor
mats.
When using measuring equipment such as a curve tracer, the equipment should be grounded.
When soldering the products, the head of soldering irons or the solder bath must be grounded in order to prevent
leak voltages generated by them from being applied to the products.
The products should always be stored and transported in Sanken shipping containers or conductive containers, or
be wrapped in aluminum foil.
STR3A200 - DSJ Rev.2.0
May.18, 2015
SANKEN ELECTRIC CO.,LTD.
http://www.sanken-ele.co.jp
24
© SANKEN ELECTRIC CO.,LTD. 2013
STR3A200 Series
IMPORTANT NOTES
The contents in this document are subject to changes, for improvement and other purposes, without notice. Make
sure that this is the latest revision of the document before use.
Application examples, operation examples and recommended examples described in this document are quoted for
the sole purpose of reference for the use of the products herein and Sanken can assume no responsibility for any
infringement of industrial property rights, intellectual property rights, life, body, property or any other rights of
Sanken or any third party which may result from its use.
Unless otherwise agreed in writing by Sanken, Sanken makes no warranties of any kind, whether express or
implied, as to the products, including product merchantability, and fitness for a particular purpose and special
environment, and the information, including its accuracy, usefulness, and reliability, included in this document.
Although Sanken undertakes to enhance the quality and reliability of its products, the occurrence of failure and
defect of semiconductor products at a certain rate is inevitable. Users of Sanken products are requested to take, at
their own risk, preventative measures including safety design of the equipment or systems against any possible
injury, death, fires or damages to the society due to device failure or malfunction.
Sanken products listed in this document are designed and intended for the use as components in general purpose
electronic equipment or apparatus (home appliances, office equipment, telecommunication equipment, measuring
equipment, etc.).
When considering the use of Sanken products in the applications where higher reliability is required (transportation
equipment and its control systems, traffic signal control systems or equipment, fire/crime alarm systems, various
safety devices, etc.), and whenever long life expectancy is required even in general purpose electronic equipment
or apparatus, please contact your nearest Sanken sales representative to discuss, prior to the use of the products
herein.
The use of Sanken products without the written consent of Sanken in the applications where extremely high
reliability is required (aerospace equipment, nuclear power control systems, life support systems, etc.) is strictly
prohibited.
When using the products specified herein by either (i) combining other products or materials therewith or (ii)
physically, chemically or otherwise processing or treating the products, please duly consider all possible risks that
may result from all such uses in advance and proceed therewith at your own responsibility.
Anti radioactive ray design is not considered for the products listed herein.
Sanken assumes no responsibility for any troubles, such as dropping products caused during transportation out of
Sanken’s distribution network.
The contents in this document must not be transcribed or copied without Sanken’s written consent.
STR3A200 - DSJ Rev.2.0
May.18, 2015
SANKEN ELECTRIC CO.,LTD.
http://www.sanken-ele.co.jp
25
© SANKEN ELECTRIC CO.,LTD. 2013
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