Off-Line PWM Controllers with Integrated Power MOSFET
STR-A6000 Series
Data Sheet
General Descriptions
Package
The STR-A6000 series are power ICs for switching
power supplies, incorporating a MOSFET and a current
mode PWM controller IC.
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.
DIP8
Not to Scale
Lineup
Features
• Electrical Characteristics
• Current Mode Type PWM Control
• Brown-In and Brown-Out function
• Auto Standby Function
Products
No Load Power Consumption < 25mW
• Operation Mode
Normal Operation ---------------------------- PWM Mode
Standby --------------------------- Burst Oscillation Mode
• Random Switching Function
• Slope Compensation Function
• Leading Edge Blanking Function
• Bias Assist Function
• Audible Noise Suppression function during Standby
mode
• Protections
・Overcurrent Protection (OCP)*; Pulse-by-Pulse,
built-in compensation circuit to minimize OCP point
variation on AC input voltage
・Overload Protection (OLP); auto-restart
・Overvoltage Protection (OVP); latched shutdown
・Thermal Shutdown Protection (TSD); latched shutdown
VDSS (min.)
STR-A605×M
650 V
STR-A607×M
800 V
STR-A605×H
650 V
STR-A606×H
700 V
STR-A606×HD
700 V
fOSC(AVG)
67 kHz
100 kHz
100 kHz
*STR-A60××HD has two types OCP
• MOSFET ON Resistance and Output Power, POUT*
Products
RDS(ON)
(max.)
POUT
POUT
(Adapter)
(Open frame)
AC85
AC85
AC230V
AC230V
~265V
~265V
fOSC(AVG) = 67 kHz
STR-A6051M
3.95 Ω 18.5 W
14 W
31 W
21 W
2.8 Ω
22 W 17.5W
35 W 24.5 W
STR-A6053M
1.9 Ω
26 W
21W
40 W
28 W
STR-A6079M
19.2 Ω
8W
6W
13 W
9W
17 W
11 W
30 W 19.5 W
3.95Ω 20.5 W
15 W
35 W 23.5 W
2.8 Ω
18 W
38 W 26.5 W
STR-A6052M
fOSC(AVG) = 100 kHz
*STR-A60××HD has two types OCP
STR-A6059H
STR-A6069H
Typical Application Circuit
BR1
STR-A6069HD
VOUT
(+)
PC1
C1
P
D1
S
D2
D/ST D/ST
RA
C5
NC
R52
U51
VCC
C2
STR-A6062H
STR-A6062HD
C53
C52 R53
R2
5
7
R51
R55
C51
8
D
R56
(-)
U1
S/OCP BR GND FB/OLP
RC
2
ROCP
3
4
C4
C3
23 W
STR-A6063HD 2.3 Ω 25 W 20 W 40 W 28 W
* 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.
STR-A6000
RB
1
STR-A6061HD
R54
R1
C6
STR-A6061H
L51
D51
T1
VAC
6Ω
PC1
Applications
CY
TC_STR-A6000_1_R1
• Low power AC/DC adapter
• White goods
• Auxiliary power supply
• OA, AV and industrial equipment
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
https://www.sanken-ele.co.jp/en
© SANKEN ELECTRIC CO., LTD. 2008
1
STR-A6000 Series
Contents
General Descriptions ----------------------------------------------------------------------- 1
1. Absolute Maximum Ratings --------------------------------------------------------- 3
2. Electrical Characteristics ------------------------------------------------------------ 4
3. Performance Curves ------------------------------------------------------------------ 6
3.1
Derating Curves --------------------------------------------------------------- 6
3.2
Ambient Temperature versus Power Dissipation Curve ------------- 6
3.3
MOSFET Safe Operating Area Curves ---------------------------------- 7
3.4
Transient Thermal Resistance Curves ----------------------------------- 9
4. Functional Block Diagram ---------------------------------------------------------- 11
5. Pin Configuration Definitions ------------------------------------------------------ 11
6. Typical Application Circuit -------------------------------------------------------- 12
7. Package Outline ----------------------------------------------------------------------- 13
8. Marking Diagram -------------------------------------------------------------------- 13
9. Operational Description ------------------------------------------------------------- 14
9.1
Startup Operation ----------------------------------------------------------- 14
9.2
Undervoltage Lockout (UVLO) ------------------------------------------- 15
9.3
Bias Assist Function --------------------------------------------------------- 15
9.4
Constant Output Voltage Control ---------------------------------------- 15
9.5
Leading Edge Blanking Function ---------------------------------------- 16
9.6
Random Switching Function ---------------------------------------------- 16
9.7
Automatic Standby Mode Function-------------------------------------- 16
9.8
Brown-In and Brown-Out Function ------------------------------------- 17
9.8.1DC Line Detection --------------------------------------------------------- 17
9.8.2AC Line Detection --------------------------------------------------------- 18
9.9
Overcurrent Protection Function (OCP) ------------------------------- 19
9.10 Overload Protection Function (OLP) ----------------------------------- 20
9.11 Overvoltage Protection (OVP) -------------------------------------------- 20
9.12 Thermal Shutdown Function (TSD) ------------------------------------- 20
10. Design Notes --------------------------------------------------------------------------- 21
10.1 External Components ------------------------------------------------------- 21
10.2 PCB Trace Layout and Component Placement ----------------------- 22
11. Pattern Layout Example ------------------------------------------------------------ 24
12. Reference Design of Power Supply ----------------------------------------------- 25
Important Notes ---------------------------------------------------------------------------- 27
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
https://www.sanken-ele.co.jp/en
© SANKEN ELECTRIC CO., LTD. 2008
2
STR-A6000 Series
1.
Absolute Maximum Ratings
Current polarities are defined as follows: current going into the IC (sinking) is positive current (+); and current coming
out of the IC (sourcing) is negative current (−).
Unless otherwise specified, TA = 25 °C, 7 pin = 8 pin.
Parameter
Symbol
Test Conditions
Pins
Rating
Units
Remarks
1.2
A6079M
1.8
Drain Peak Current(1)
IDPEAK
Single pulse
8–1
2.5
A
3.0
4.0
Avalanche Energy(2)(3)
EAS
A6053M / 63HD
ILPEAK=1.2A
7
A6079M
ILPEAK=1.8A
24
A6059H / 69H
/ 69HD
ILPEAK=2A
46
A6061H / 61HD
ILPEAK=2A
47
8–1
mJ
56
A6062H / 62HD
ILPEAK=2.3A
62
A6052M
ILPEAK=2.5A
72
A6063HD
ILPEAK=2.7A
86
A6053M
1−3
−2 to 6
V
BR Pin Voltage
VBR
2−3
−0.3 to 7
V
BR Pin Sink Current
IBR
2−3
1.0
mA
FB/OLP Pin Voltage
VFB
4−3
−0.3 to 14
V
FB/OLP Pin Sink Current
IFB
4−3
1.0
mA
VCC Pin Voltage
MOSFET Power
Dissipation(4)
Control Part Power
Dissipation
Operating Ambient
Temperature(6)
Storage Temperature
VCC
5−3
32
V
8–1
1.35
W
PD2
5–3
1.2
W
TOP
—
−20 to 125
°C
Tstg
—
−40 to 125
°C
Channel Temperature
Tch
—
150
°C
PD1
A6051M
ILPEAK=2.2A
VS/OCP
S/OCP Pin Voltage
A6059H / 69H
/ 69HD
A6051M / 61H
/ 61HD
A6052M / 62H
/ 62HD
(5)
(1)
Refer to 3.3 MOSFET Safe Operating Area Curves
Refer to Figure 3-2. Avalanche Energy Derating Coefficient Curve
(3)
Single pulse, VDD = 99 V, L = 20 mH
(4)
Refer to Figure 3-3. Ambient Temperature Versus Power Dissipation Curve
(5)
When embedding this hybrid IC onto the printed circuit board (cupper area in a 15 mm × 15 mm)
(6)
The recommended internal frame temperature, TF, is 115°C (max.)
(2)
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
https://www.sanken-ele.co.jp/en
© SANKEN ELECTRIC CO., LTD. 2008
3
STR-A6000 Series
2.
Electrical Characteristics
Current polarities are defined as follows: current going into the IC (sinking) is positive current (+); and current
coming out of the IC (sourcing) is negative current (−).
Unless otherwise specified, TA = 25 °C, VCC = 18 V, 7 pin = 8 pin.
Test
Parameter
Symbol
Pins
Min.
Typ.
Max.
Units
Remarks
Conditions
Power Supply Startup Operation
Operation Start Voltage
Operation Stop Voltage
(1)
VCC(ON)
5−3
13.8
15.3
16.8
V
VCC(OFF)
5−3
7.3
8.1
8.9
V
5−3
—
—
2.5
mA
—
38
—
V
− 3.7
− 2.5
− 1.5
mA
8.5
9.5
10.5
V
60
67
74
90
100
110
—
5
—
—
8
—
77
83
89
%
—
540
—
ns
—
470
—
—
340
—
—
280
—
—
20
—
—
33
—
Circuit Current in Operation
ICC(ON)
Startup Circuit Operation
Voltage
VST(ON)
8−3
Startup Current
ISTARTUP
VCC = 13.5 V 5 − 3
VCC(BIAS)
ICC
= − 100 µA
Startup Current Biasing
Threshold Voltage
Normal Operation
Average Switching
Frequency
Switching Frequency
Modulation Deviation
VCC = 12 V
5−3
8−3
fOSC(AVG)
Δf
8−3
Maximum ON Duty
DMAX
8−3
Minimum ON Time
tON(MIN)
8−3
A60××M
kHz
A60××H / HD
A60××M
kHz
A60××H / HD
A60××M
A60××H / HD
Protection Function
Leading Edge Blanking Time
—
tBW
A60××M
ns
A60××H / HD
OCP Compensation
Coefficient
DPC
OCP Compensation ON Duty
DDPC
—
—
36
—
%
VOCP(L)
1−3
0.70
0.78
0.86
V
VOCP(H)
1−3
0.81
0.9
0.99
V
VOCP(LEB)
1−3
1.32
1.55
1.78
V
4−3
− 340
− 230
− 150
µA
OCP Threshold Voltage at
Zero ON Duty
OCP Threshold Voltage at
36% ON Duty
OCP Threshold Voltage in
Leading Edge Blanking Time
—
mV/μs
A60××H / HD
Maximum Feedback Current
IFB(MAX)
Minimum Feedback Current
IFB(MIN)
4−3
− 30
− 15
−7
µA
FB/OLP pin Oscillation Stop
Threshold Voltage
VFB(STB)
4−3
0.85
0.95
1.05
V
OLP Threshold Voltage
VFB(OLP)
4−3
7.3
8.1
8.9
V
OLP Operation Current
ICC(OLP)
5−3
−
300
600
µA
—
54
68
82
ms
OLP Delay Time
(1)
tOLP
VCC = 12 V
VCC = 12 V
A60××M
A60××HD
VCC(BIAS) > VCC(OFF) always.
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
https://www.sanken-ele.co.jp/en
© SANKEN ELECTRIC CO., LTD. 2008
4
STR-A6000 Series
Parameter
Symbol
Test
Conditions
Pins
Min.
Typ.
Max.
Units
Remarks
FB/OLP Pin Clamp Voltage
VFB(CLAMP)
4−3
11
12.8
14
V
Brown-In Threshold Voltage
VBR(IN)
2−3
5.2
5.6
6
V
Brown-Out Threshold
Voltage
VBR(OUT)
2−3
4.45
4.8
5.15
V
BR Pin Clamp Voltage
VBR(CLAMP)
2−3
6
6.4
7
V
BR Function Disabling
Threshold
VBR(DIS)
2−3
0.3
0.48
0.7
V
OVP Threshold Voltage
VCC(OVP)
5−3
26
29
32
V
5−3
—
700
—
μA
—
135
—
—
°C
650
—
—
700
—
—
800
—
—
—
—
300
—
—
19.2
—
—
6
—
—
3.95
—
—
2.8
—
—
2.3
A6063HD
—
—
1.9
A6053M
—
—
250
ns
—
—
400
ns
—
—
22
°C/W
Latch Circuits Holding
Current(2)
Thermal Shutdown Operating
Temperature
ICC(LATCH)
VCC = 9.5 V
Tj(TSD)
MOSFET
Drain-to-Source Breakdown
Voltage
Drain Leakage Current
On Resistance
Switching Time
8–1
VDSS
8–1
IDSS
RDS(ON)
tf
IDS = 0.4A
8−1
8–1
A605×
V
A606×
A607×
μA
A6079M
Ω
A6059H / 69H
/ 69HD
A6051M / 61H
/ 61HD
A6052M / 62H
/ 62HD
A6053M
Thermal Resistance
Channel to Case Thermal
Resistance(3)
θch-C
—
(2)
A latch circuit is a circuit operated with Overvoltage Protection function (OVP) and/or Thermal Shutdown function
(TSD) in operation.
(3)
θch-C is thermal resistance between channel and case. Case temperature (TC) is measured at the center of the case top
surface.
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
https://www.sanken-ele.co.jp/en
© SANKEN ELECTRIC CO., LTD. 2008
5
STR-A6000 Series
3.
Performance Curves
3.1
Derating Curves
EAS Temperature Derating Coefficient (%)
Safe Operating Area
Temperature Derating Coefficient (%)
100
80
60
40
20
0
0
25
50
75
100
125
150
100
80
60
40
20
0
25
50
3.2
SOA Temperature Derating Coefficient
Curve
100
125
150
Channel Temperature, Tch (°C)
Channel Temperature, Tch (°C)
Figure 3-1.
75
Figure 3-2.
Avalanche Energy Derating Coefficient
Curve
Ambient Temperature versus Power Dissipation Curve
1.6
1.4
Power Dissipation, PD1 (W)
1.35W
1.2
1
0.8
0.6
0.4
0.2
0
0
20
40
60
80 100 120 140 160
Ambient Temperature, TA (°C )
Figure 3-3.
Ambient Temperature Versus Power
Dissipation Curve
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
https://www.sanken-ele.co.jp/en
© SANKEN ELECTRIC CO., LTD. 2008
6
STR-A6000 Series
3.3
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 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.
• STR-A6051M
• STR-A6052M
10
10
0.1ms
Drain Current, ID (A)
Drain Current, ID (A)
0.1ms
1
1ms
0.1
1
1ms
0.1
0.01
0.01
1
10
100
Drain-to-Source Voltage (V)
1
1000
10
100
1000
Drain-to-Source Voltage (V)
• STR-A6053M
• STR-A6079M
10
10
0.1ms
1
Drain Current, ID (A)
Drain Current, ID (A)
0.1ms
1ms
0.1
0.01
1
1ms
0.1
0.01
1
10
100
Drain-to-Source Voltage (V)
1000
1
10
100
Drain-to-Source Voltage (V)
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
https://www.sanken-ele.co.jp/en
© SANKEN ELECTRIC CO., LTD. 2008
1000
7
STR-A6000 Series
• STR-A6059H
• STR-A6061H / 61HD
10
10
1
Drain Current, ID (A)
Drain Current, ID (A)
0.1ms
0.1
0.01
1
1ms
0.1
0.01
1
10
100
1000
1
Drain-to-Source Voltage (V)
10
100
Drain-to-Source Voltage (V)
• STR-A6062H / 62HD
• STR-A6063HD
10
10
0.1ms
1
0.1ms
Drain Current, ID (A)
Drain Current, ID (A)
1000
1ms
0.1
1
1ms
0.1
0.01
0.01
1
10
100
Drain-to-Source Voltage (V)
1000
1
10
100
1000
Drain-to-Source Voltage (V)
• STR-A6069H / 69HD
10
Drain Current, ID (A)
0.1ms
1
1ms
0.1
0.01
1
10
100
1000
Drain-to-Source Voltage (V)
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
https://www.sanken-ele.co.jp/en
© SANKEN ELECTRIC CO., LTD. 2008
8
STR-A6000 Series
3.4
Transient Thermal Resistance Curves
• STR-A6051M / 61H / 61HD
Transient Thermal Resistance,
θch-c (°C/W)
10
1
0.1
0.01
1µ
10µ
STR-A6252
100µ
1m
過渡熱抵抗曲線
Time (s) curve
Transient thermal resistance
10m
100m
• STR-A6052M / 62H / 62HD
過渡熱抵抗 θch-c[℃/W]
Resistance,
Thermal
Transient
resistance
thermal
Transient
θch-c (°C/W)
10
10
11
0.1
0.1
0.01
0.01
1µ
1.0E-06
10µ
1.0E-05
100µ
1.0E-04
• STR-A6053M / 63HD
1.0E-03
10m
1.0E-02
100m
1.0E-01
時間 t [sec]
time
10
Transient Thermal Resistance,
θch-c (°C/W)
1m
Time (s)
1
0.1
0.01
1µ
10µ
100µ
1m
10m
100m
Time (s)
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
https://www.sanken-ele.co.jp/en
© SANKEN ELECTRIC CO., LTD. 2008
9
STR-A6000 Series
• STR-A6059M / 69H / 69HD
Transient Thermal Resistance
θch-c (°C/W)
10
1
0.1
0.01
1µ
10µ
100µ
1m
10m
100m
Time (s)
• STR-A6079M
Transient Thermal Resistance
θch-c (°C/W)
10
1
0.1
0.01
100n
1µ
10µ
100µ
1m
10m
100m
Time (s)
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
https://www.sanken-ele.co.jp/en
© SANKEN ELECTRIC CO., LTD. 2008
10
STR-A6000 Series
4.
Functional Block Diagram
VCC
5
Startup
UVLO
BR
2
REG
VREG
OVP
D/ST
7,8
TSD
Brown-in
Brown-out
6.4V
DRV
PWM OSC
S Q
R
OCP
7V
VCC
Drain peak current
compensation
OLP
Feedback
control
FB/OLP
4
12.8V
LEB
S/OCP
1
GND
3
Slope
compensation
BD_STR-A6000_R1
5.
Pin Configuration Definitions
Pin
Name
S/OCP
1
8
D/ST
1
S/OCP
BR
2
7
D/ST
2
BR
3
GND
GND
3
6
4
FB /OLP
FB/OLP
4
5
5
VCC
6
−
VCC
7
8
D/ST
Descriptions
MOSFET source and overcurrent protection
(OCP) signal input
Brown-In and Brown-Out detection voltage input
Ground
Constant voltage control signal input and over
load protection (OLP) signal input
Power supply voltage input for control part and
overvoltage protection (OVP) signal input
(Pin removed)
MOSFET drain and startup current input
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
https://www.sanken-ele.co.jp/en
© SANKEN ELECTRIC CO., LTD. 2008
11
STR-A6000 Series
6.
Typical Application Circuit
The following drawings show circuits enabled and disabled the Brown-In/Brown-Out function.
The PCB traces D/ST pins should be as wide as possible, in order to enhance thermal dissipation.
In applications having a power supply specified such that D/ST pin 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
BR1
VOUT
(+)
R54
R1
C6
RA
L51
D51
T1
VAC
R51
PC1
C1
P
R55
C51
D1
RB
S
D2
8
U51
VCC
NC
C53
C52 R53
R2
5
7
D/ST D/ST
C5
R52
R56
D
C2
(-)
U1
STR-A6000
S/OCP BR GND FB/OLP
C（RC）
damper snubber
1
RC
2
3
4
C4
C3
PC1
ROCP
CY
TC_STR-A6000_2_R1
Figure 6-1.
Typical Application Circuit (enabled Brown-In/Brown-Out function, DC line detection)
CRD clamp snubber
BR1
L51
D51
T1
VAC
VOUT
(+)
R54
R1
C6
PC1
C1
P
R55
C51
D1
S
D2
8
D/ST D/ST
C5
NC
R52
U51
VCC
C2
C53
C52 R53
R2
5
7
R51
R56
D
(-)
U1
STR-A6000
S/OCP BR GND FB/OLP
C（RC）
damper snubber
1
2
3
4
C3
ROCP
PC1
CY
TC_STR-A6000_3_R1
Figure 6-2.
Typical Application Circuit (disabled Brown-In/Brown-Out function)
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
https://www.sanken-ele.co.jp/en
© SANKEN ELECTRIC CO., LTD. 2008
12
STR-A6000 Series
7.
Package Outline
• DIP8 (The following show a representative type of DIP8.)
NOTES:
1) dimensions in millimeters
2) Pb-free (RoHS compliant)
8.
Marking Diagram
STR-A60××M
STR-A60××H
8
A60×××
Part Number
S KY MD
Lot Number:
Y is the last digit of the year of manufacture (0 to 9)
M is the month of the year (1 to 9, O, N, or D)
D is a period of days:
1: the first 10 days of the month (1st to 10th)
2: the second 10 days of the month (11th to 20th)
3: the last 10–11 days of the month (21st to 31st)
1
Control Number
STR-A60××HD
8
A60××H
S KY MD D
1
Part Number
Lot Number:
Y is the last digit of the year of manufacture (0 to 9)
M is the month of the year (1 to 9, O, N, or D)
D is a period of days:
1: the first 10 days of the month (1st to 10th)
2: the second 10 days of the month (11th to 20th)
3: the last 10–11 days of the month (21st to 31st)
Control Number
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9.
Operational Description
All of the parameter values used in these descriptions
are typical values, unless they are specified as minimum
or maximum.
Current polarities are defined as follows: current
going into the IC (sinking) is positive current (+); and
current coming out of the IC (sourcing) is negative
current (−).
With Brown-In / Brown-Out function
When BR pin voltage is more than VBR(DIS) = 0.48 V
and less than VBR(IN) = 5.6 V, the Bias Assist Function
(refer to Section 9.3) is disabled. Thus, VCC pin
voltage repeats increasing to VCC(ON) and decreasing to
VCC(OFF) (shown in Figure 9-3). When BR pin voltage
becomes VBR(IN) or more, the IC starts switching
operation.
BR1
9.1
Startup Operation
Figure 9-1 shows the circuit around IC. Figure 9-2
shows the start up operation.
The IC incorporates the startup circuit. The circuit is
connected to D/ST pin. When D/ST pin voltage reaches
to Startup Circuit Operation Voltage VST(ON) = 38 V, the
startup circuit starts operation.
During the startup process, the constant current,
ISTARTUP = − 2.5 mA, charges C2 at VCC pin. When
VCC pin voltage increases to VCC(ON) = 15.3 V, the
control circuit starts 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.
The approximate value of auxiliary winding voltage is
about 15 V to 20 V, taking account of the winding turns
of D winding so that VCC pin voltage becomes
Equation (1) within the specification of input and output
voltage variation of power supply.
Without Brown-In / Brown-Out function (BR pin
voltage is VBR(DIS) = 0.48 V or less)
When VCC pin voltage increases to VCC(ON), the IC
starts switching operation, As shown in Figure 9-2.
The startup time of IC is determined by C2 capacitor
value. The approximate startup time tSTART (shown in
Figure 9-2) is calculated as follows:
VCC ( ON)－VCC ( INT)
ISTRATUP
where,
tSTART : Startup time of IC (s)
VCC(INT) : Initial voltage on VCC pin (V)
7, 8
D/ST
U1
VCC
5
D2
C2
BR
2
GND
P
R2
D
VD
3
Figure 9-1. VCC Pin Peripheral Circuit
(Without Brown-In / Brown-Out)
VCC pin
voltage
VCC(ON)
tSTART
(1)
The oscillation start timing of IC depends on
Brown-In / Brown-Out function (refer to Section 9.8).
t START = C2 ×
C1
Drain current,
ID
VCC ( BIAS) (max .) VCC VCC ( OVP) (min .)
⇒10.5 (V) VCC 26 (V)
T1
VAC
(2)
Figure 9-2. Startup Operation
(Without Brown-In / Brown-Out)
VCC pin
voltage
tSTART
VCC(ON)
VCC(OFF)
BR pin
voltage
VBR(IN)
Drain current,
ID
Figure 9-3. Startup Operation
(With Brown-In / Brown-Out)
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9.2
Undervoltage Lockout (UVLO)
Figure 9-4 shows the relationship of VCC pin voltage
and circuit current ICC. When VCC pin voltage decreases
to VCC(OFF) = 8.1 V, the control circuit stops operation by
UVLO (Undervoltage Lockout) circuit, and reverts to
the state before startup.
Circuit current, ICC
ICC（ON）
Stop
Start
pin voltage decreases to the startup current threshold
biasing voltage, VCC(BIAS) = 9.5 V. While the Bias Assist
function is activated, any decrease of the VCC pin
voltage is counteracted by providing the startup current,
ISTARTUP, from the startup circuit. Thus, the VCC pin
voltage is kept almost constant.
By the Bias Assist function, the value of C2 is
allowed to be small and the startup time becomes shorter.
Also, because the increase of VCC pin voltage becomes
faster when the output runs with excess voltage, the
response time of the OVP function becomes shorter.
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.
9.4
VCC（ON） VCC pin
voltage
VCC（OFF）
Figure 9-4. Relationship between
VCC Pin Voltage and ICC
9.3
Bias Assist Function
Figure 9-5 shows VCC pin voltage behavior during
the startup period.
After VCC pin voltage increases to VCC(ON) = 15.3 V
at startup, the IC starts the operation. Then circuit
current increases and 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 VCC pin voltage.
Constant Output Voltage Control
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.
The FB/OLP pin voltage is internally added the slope
compensation at the feedback control (refer to Section 4
Functional Block Diagram), and the target voltage, VSC,
is generated. The IC compares the voltage, VROCP, of a
current detection resistor with the target voltage, V SC, by
the internal FB comparator, and controls the peak value
of VROCP so that it gets close to VSC, as shown in Figure
9-6 and Figure 9-7.
U1
S/OCP
1
VCC pin
voltage
VCC(ON)
VCC(BIAS)
VCC(OFF)
3
4
Startup success
IC starts operation
Target operating
voltage
Increase with rising of
output voltage
PC1
VROCP
ROCP
Figure 9-6.
Bias assist period
C3
IFB
FB/OLP Pin Peripheral Circuit
Target voltage including
Slope Compensation
Startup failure
Time
Figure 9-5.
GND FB/OLP
VCC Pin Voltage during Startup Period
The surge voltage is induced at output winding at
turning off a power MOSFET. When the output load is
light at startup, the surge voltage causes the unexpected
feedback control. This results the lowering of the output
power and VCC pin voltage. When the VCC pin voltage
decreases to VCC(OFF) = 8.1 V, the IC stops switching
operation and a startup failure occurs. In order to prevent
this, the Bias Assist function is activated when the VCC
-
VSC
+
VROCP
FB Comparator
Voltage on both
sides of ROCP
Drain current,
ID
Figure 9-7. Drain Current, ID, and FB Comparator
Operation in Steady Operation
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• Light load conditions
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.
This control prevents the output voltage from
increasing.
• 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.
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.
This results in the on-time fluctuating in multiples of
the fundamental operating frequency as shown in Figure
9-8. 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.
for the constant voltage control of output.
In peak-current-mode control method, there is a case
that the power MOSFET turns off due to unexpected
response of FB comparator or overcurrent protection
circuit (OCP) 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, tBW (STR-A60××M for 340 ns, STR-A60××H
and STR-A60××HD for 280 ns) is built-in. During tBW,
the OCP threshold voltage becomes about 1.7 V which
is higher than the normal OCP threshold voltage (refer
to Section 9.9).
9.6
Random Switching Function
The IC modulates its switching frequency randomly
by superposing the modulating frequency on f OSC(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.
9.7
Automatic Standby Mode Function
In light load operation, the drain current, ID decreases,
and then the FB/OLP pin voltage decreases.
Automatic standby mode is activated automatically
when FB/OLP pin voltage decreases to VFB(STB) = 0.95 V.
The operation mode becomes burst oscillation, as shown
in Figure 9-9.
Burst oscillation mode reduces switching losses and
improves power supply efficiency because of periodic
non-switching intervals.
Output current,
IOUT
Burst oscillation
Target voltage
without slope compensation
Below several kHz
Drain current,
ID
Normal
operation
tON1
T
Auto Standby Mode Timing
T
Figure 9-8. Drain Current, ID, Waveform
in Subharmonic Oscillation
9.5
Normal
operation
tON2
Figure 9-9.
T
Standby
operation
Leading Edge Blanking Function
The IC uses the peak-current-mode control method
Generally, 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 the VCC pin voltage decreases to VCC(BIAS) = 9.5 V
during the transition to the burst oscillation mode, the
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Bias Assist function is activated and stabilizes the
Standby mode operation, because ISTARTUP is provided to
the VCC pin so that the VCC pin 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 secondary winding and/or reducing the
value of R2 in Figure 10-2 (refer to Section 10.1
Peripheral Components for a detail of R2).
9.8
Brown-In and Brown-Out Function
This function stops switching operation when it
detects low input line voltage, and thus prevents
excessive input current and overheating.
This function turns on and off switching operation
according to the BR pin voltage detecting the AC input
voltage. When BR pin voltage becomes more than
VBR(DIS) = 0.48 V, this function is activated.
Figure 9-10 shows waveforms of the BR pin voltage
and the drain currnet.
Even if the IC is in the operating state that the VCC
pin voltage is VCC(OFF) or more, when the AC input
voltage decreases from steady-state and the BR pin
voltage falls to VBR(OUT) = 4.8 V or less for the OLP
Delay Time, tOLP = 68 ms, the IC stops switching
operation. When the AC input voltage increases and the
BR pin voltage reaches VBR(IN) = 5.6 V or more in the
operating state that the VCC pin voltage is VCC(OFF) or
more, the IC starts switching operation.
In case the Brown-In and Brown-Out function is
unnecessary, connect the BR pin trace to the GND pin
trace so that the BR pin voltage is VBR(DIS) or less.
mode and the sum of switching operation period
becomes tOLP = 68 ms or more, the IC stops switching
operation.
● STR-A60××HD:
When the BR pin voltage falls to VBR(OUT) = 4.8 V or
less for tOLP = 68 ms, the IC stops switching operation.
There are two types of detection method as follows:
9.8.1 DC Line Detection
Figure 9-11 shows BR pin peripheral circuit of DC
line detection. There is a ripple voltage on C1 occurring
at a half period of AC cycle. In order to detect each peak
of the ripple voltage, the time constant of RC and C4
should be shorter than a half period of AC cycle.
Since the cycle of the ripple voltage is shorter than
tOLP, the switching operation does not stop when only the
bottom part of the ripple voltage becomes lower than
VBR(OUT).
Thus it minimizes the influence of load conditions on
the voltage detection.
BR1
VAC
RA
VDC
U1
C1
RB
RC
Figure 9-11.
2
BR
C4
GND
3
DC Line Detection
The components around BR pin:
BR Pin Voltage
VBR(IN)
VBR(OUT)
Drain Current,
ID
tOLP
・ RA and RB are a few megohms. Because of high
voltage applied and high resistance, it is
recommended to select a resistor designed against
electromigration or use a combination of resistors
in series for that to reduce each applied voltage,
according to the requirement of the application.
・ RC is a few hundred kilohms
Figure 9-10.
BR Pin Voltage and Drain Current
Waveforms
During burst oscillation mode, this function operates
as follows:
● STR-A60××M and STR-A60××H:
This function is disabled during switching operation
stop period in burst oscillation mode. When the BR
pin voltage falls to VBR(OUT) or less in burst oscillation
・ C4 is 470 pF to 2200 pF for high frequency noise
reduction
Neglecting the effect of both input resistance and
forward voltage of rectifier diode, the reference value of
C1 voltage when Brown-In and Brown-Out function is
activated is calculated as follows:
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R + RB
VDC( OP) = VBR ( TH) 1 + A
R C
where,
VDC(OP)
(3)
: C1 voltage when Brown-In and
Brown-Out function is activated
: Any one of threshold voltage of BR pin
(see Table 9-1)
VBR(TH)
Table 9-1.
BR Pin Threshold Voltage
Parameter
VBR(IN)
Value
(Typ.)
5.6 V
VBR(OUT)
4.8 V
Symbol
Brown-In Threshold Voltage
Brown-Out Threshold Voltage
VDC(OP) can be expressed as the effective value of AC
input voltage using Equation (4).
VAC( OP) RMS =
1
2
VDC( OP)
(4)
* High-Speed Latch Release
When Overvoltage Protection function (OVP) or
Thermal Shutdown function (TSD) are activated,
the IC stops switching operation in latch mode.
Releasing the latch mode is done by decreasing the
VCC pin voltage below VCC(OFF) or by decreasing
the BR pin voltage below VBR(OUT).
In case of the DC line detection or without
Brown-in / Brown-Out function, the release time
depends on discharge time of C1 and takes longer
time until VCC pin voltage decreases to release
voltage.
In case of the AC line detection, BR pin voltage is
decreased quickly when AC input voltage, VAC, is
turned off, and thus the latch mode is quickly
released.
The components around BR pin:
・ RA and RB are a few megohms. Because of high
voltage applied and high resistance, it is
recommended to select a resistor designed against
electromigration or use a combination of resistors
in series for that to reduce each applied voltage,
according to the requirement of the application.
・ RC is a few hundred kilohms
RA, RB, RC and C4 should be selected based on actual
operation in the application.
・ RS must be adjusted so that the BR pin voltage is
more than VBR(DIS) = 0.48 V when the VCC pin
voltage is VCC(OFF) = 8.1 V
9.8.2 AC Line Detection
・ C4 is 0.22 μF to 1 μF for averaging AC input
voltage and high frequency noise reduction.
Figure 9-12 shows BR pin peripheral circuit of AC
line detection. In order to detect the AC input voltage,
the time constant of RC and C4 should be longer than the
period of AC cycle. Thus the response of BR pin
detection becomes slow compared with the DC line
detection.
This method detects the AC input voltage, and thus it
minimizes the influence from load conditions. Also, this
method is free of influence from C1 charging and
discharging time, the latch mode can be released
quickly*
VAC
BR1
RA
3
VCC
RS
VDC
RB
C1
2
RC
Figure 9-12.
BR
C4
U1
Neglecting the effect of input resistance is zero, the
reference effective value of AC input voltage when
Brown-In and Brown-Out function is activated is
calculated as follows:
VAC( OP) RMS =
R + RB
VBR ( TH) 1 + A
R C
2
(5)
where,
VAC(OP)RMS :The effective value of AC input voltage
when Brown-In and Brown-Out function
is activated
VBR(TH)
:Any one of threshold voltage of BR pin
(see Table 9-1)
RA, RB, RC and C4 should be selected based on actual
operation in the application.
GND
3
AC Line Detection
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Overcurrent Protection Function
(OCP)
Overcurrent Protection Function (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 operation of
OCP is different depending on the products as follows.
● STR-A60××HD:
During Leading Edge Blanking Time, the OCP
threshold voltage becomes VOCP(LEB) = 1.55 V which
is higher than the normal OCP threshold voltage as
shown in Figure 9-13. 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.
● STR-A60××M and STR-A60××H:
OCP is disabled during Leading Edge Blanking Time.
When power MOSFET turns on, the surge voltage
width of S/OCP pin should be less than tBW, as shown in
Figure 9-13. In order to prevent surge voltage, pay extra
attention to ROCP trace layout (refer to Section ).
In addition, if a C (RC) damper snubber of Figure
9-14 is used, reduce the capacitor value of damper
snubber.
tBW
VOCP(LEB)(STR-A60××HD)
VOCP’
< 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 the AC input voltage in OCP
state. In order to reduce the variation of peak current in
OCP state, the IC incorporates a built-in Input
Compensation function.
The Input Compensation Function is the function of
correction of OCP threshold voltage depending with AC
input voltage, as shown in Figure 9-15. 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).
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 (6). When ON Duty is broader than 36 %, the
VOCP' becomes a constant value VOCP(H) = 0.9 V
1.0
OCP Threshold Voltage after
compensation, VOCP'
9.9
VOCP(H)
VOCP(L)
0.5
DDPC
DMAX
50
100
0
ON Duty (%)
Surge pulse voltage width at turning on
Figure 9-13.
S/OCP Pin Voltage
C（RC）
Damper snubber
Figure 9-15. Relationship between ON Duty and Drain
Current Limit after Compensation
VOCP ' = VOCP( L ) + DPC ONTime
T1
D51
C1
C51
7,8
D/ST
U1
C（RC）
Damper snubber
S/OCP
1
ROCP
Figure 9-14.
= VOCP( L ) + DPC
ONDuty
f OSC( AVG)
(6)
where,
VOCP(L): OCP Threshold Voltage at Zero ON Duty
DPC: OCP Compensation Coefficient
ONTime: On-time of power MOSFET
ONDuty: On duty of power MOSFET
fOSC(AVG): Average PWM Switching Frequency
Damper Snubber
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9.10 Overload Protection Function (OLP)
9.11 Overvoltage Protection (OVP)
Figure 9-16 shows the FB/OLP pin peripheral circuit,
and Figure 9-17 shows each waveform for OLP
operation. When the peak drain current of ID is limited
by OCP 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 the
FB/OLP pin voltage increases. When the FB/OLP pin
voltage increases to VFB(OLP) = 8.1 V or more for the
OLP delay time, tOLP = 68 ms or more, the OLP function
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 power MOSFET and secondary side rectifier
diode. In addition, this operation reduces power
consumption because the switching period in this
intermittent operation is short compared with oscillation
stop period. When the abnormal condition is removed,
the IC returns to normal operation automatically.
When a voltage between VCC pin and GND pin
increases to VCC(OVP) = 29 V or more, OVP function 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 by dropping the VCC pin voltage
below VCC(OFF), or by dropping the BR pin voltage below
VBR(OUT).
In case the VCC pin voltage is provided by using
auxiliary winding of transformer, the overvoltage
conditions such as output voltage detection circuit open
can be detected because the VCC pin voltage is
proportional to output voltage. The approximate value of
output voltage VOUT(OVP) in OVP condition is calculated
by using Equation (7).
VOUT(OVP) =
VOUT( NORMAL)
VCC ( NORMAL)
29 (V)
(7)
where,
VOUT(NORMAL): Output voltage in normal operation
VCC(NORMAL): VCC pin voltage in normal operation
U1
GND
FB/OLP
4
3
9.12 Thermal Shutdown Function (TSD)
VCC
5
D2 R2
PC1
C3
C2
D
Figure 9-16.
FB/OLP Pin Peripheral Circuit
When the temperature of control circuit increases to
Tj(TSD) = 135 °C (min.) or more, Thermal Shutdown
function (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
pin voltage is kept to over the VCC(OFF).
Releasing the latched state is done by turning off the
input voltage and by dropping the VCC pin voltage
below VCC(OFF), or by dropping the BR pin voltage below
VBR(OUT).
Non-switching interval
VCC pin voltage
VCC(ON)
VCC(OFF)
FB/OLP pin voltage
VFB(OLP)
tOLP
tOLP
Drain current,
ID
Figure 9-17.
OLP Operational Waveforms
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10. Design Notes
10.1 External Components
Take care to use properly rated, including derating as
necessary and proper type of components.
CRD clamp snubber
BR1
T1
VAC
R1
C6
RA
C1
P
D1
RB
D2
8
D/ST D/ST
C5
R2
5
7
NC
VCC
C2
D
U1
S/OCP BR GND FB/OLP
C(RC) damper snubber
1
RC
Figure 10-1.
2
3
4
C4
C3
PC1
ROCP
The IC Peripheral Circuit
• 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.
• FB/OLP Pin Peripheral Circuit
C3 is for high frequency noise reduction and phase
compensation, and should be connected close to these
pins. The value of C3 is recommended to be about
2200 pF to 0.01µF, and 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 10µ to 47μF (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 function (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.
VCC pin voltage
• 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.
• BR pin peripheral circuit
Because RA and RB (see Figure 10-1) are applied high
voltage and are high resistance, the following should be
considered according to the requirement of the
application:
▫ Select a resistor designed against electromigration,
or
▫ Use a combination of resistors in series for that to
reduce each applied voltage
See the section 9.8 about the AC input voltage
detection function and the components around BR pin.
When the detection resistor (RA, RB, RC) value is
decreased and the C4 value is increased to prevent
unstable operation resulting from noise at the BR pin,
pay attention to the low efficiency and the slow
response of BR pin.
Without R2
With R2
Output current, IOUT
Figure 10-2.
Variation of VCC Pin Voltage and Power
• Snubber Circuit
In case the surge voltage of VDS is large, the circuit
should be added as follows (see Figure 10-1);
・ A clamp snubber circuit of a capacitor-resistordiode (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/OCP pin.
In case the damper snubber circuit is added, this
components should be connected near D/ST pin
and S/OCP pin.
STR-A6000-DSE Rev.4.5
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STR-A6000 Series
VOUT
(+)
D51
PC1
R55
C51
S
R54
R51
R52
C53
C52 R53
U51
R56
(-)
Figure 10-3.
Peripheral Circuit of Secondary Side
Shunt Regulator (U51)
• Transformer
Apply proper design margin to core temperature rise
by core loss and copper loss.
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:
▫ Increase the number of wires in parallel.
▫ Use litz wires.
▫ Thicken the wire gauge.
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.
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.
Winding structural example (b)
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.
Margin tape
Bobbin
L51
T1
▫ 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.
▫ The coupling of the winding D and the winding P
should be minimized.
P1 S1 P2 S2 D
Margin tape
Winding structural example (a)
Margin tape
Bobbin
• 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
0.047μF to 0.47μF and 4.7 kΩ to 470 kΩ, respectively.
They should be selected based on actual operation in
the application.
P1 S1 D S2 S1 P2
Margin tape
In the following cases, the surge of VCC pin
voltage becomes high.
▫ The surge voltage of primary main winding, P, is
high (low output voltage and high output current
power supply designs)
▫ The winding structure of auxiliary winding, D, is
susceptible to the noise of winding P.
When the surge voltage of winding D is high, the
VCC pin voltage increases and the Overvoltage
Protection function (OVP) may be activated. In
transformer design, the following should be
considered;
Winding structural example (b)
Figure 10-4.
Winding Structural Examples
10.2 PCB Trace Layout and Component
Placement
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.
STR-A6000-DSE Rev.4.5
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Jun. 20, 2021
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22
STR-A6000 Series
In addition, the ground traces affect radiated EMI noise,
and wide, short traces should be taken into account.
Figure 10-5 shows the circuit design example.
(4) ROCP Trace Layout
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.
(1) Main Circuit Trace Layout
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.
(5) Peripheral components of the IC
The components for control connected to the IC
should be placed as close as possible to the IC, and
should be connected as short as possible to the each
pin.
(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.
(6) Secondary Rectifier Smoothing Circuit Trace
Layout:
This is the trace of the rectifier smoothing loop,
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.
(3) VCC Trace Layout
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.
(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.
(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
C6
RA
C1
P
DST
(7)Trace of D/ST pin should be
wide for heat release
C51
D1
RB
S
D2
8
D/ST D/ST
C5
R2
5
7
NC
C2
VCC
D
U1
STR-A6000
(3) Loop of the power
supply should be small
S/OCP BR GND FB/OLP
1
2
3
4
ROCP
C3
C4 RC
PC1
(5)The components connected to
the IC should be as close to the
IC as possible, and should be
connected as short as possible
CY
A
(4)ROCP should be as close to S/OCP pin as
possible.
Figure 10-5.
(2) Control GND trace should be connected at a
single point as close to the ROCP as possible
Peripheral Circuit Example Around the IC
STR-A6000-DSE Rev.4.5
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Jun. 20, 2021
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23
STR-A6000 Series
11. Pattern Layout Example
The following show the PCB pattern layout example and the schematic of circuit using STR-A6000 series.
The above circuit symbols correspond to these of Figure 11-1.Only the parts in the schematic are used. Other parts
in PCB are leaved open.
Figure 11-1.
PCB Circuit Trace Layout Example
T1
L52
D52
CN51
1
OUT2(+)
2
OUT2(-)
3
OUT1(+)
4
OUT1(-)
R59
C57
R58
C55
R61
C56
R60
CN1
1
F1
L1
JW51
JW52
JW54
JW6
C1
D1
C12
C2
D4
C13
L51
L2
D2 TH1
D51
D3
C3
C4
P1
C5
3
R55
R52
PC1
R2
S1
R54
R51
C54
R1
C51
C53
D7
C52
U51
JW2
R57
R53
R56
R7
D2
JW10
R6
U1
8
7
D/ST
D/ST
5
NC
JW4
D8
R3
JW31
D1
C9
C8
STR-A6000
C31
C32
BR
GND FB/OLP
C11
1
2
3
4
JW3
JW8
JW7
C6
C7
Figure 11-2.
2
OUT4(-)
JW53
U21
D21
1 IN
R4
OUT4(+)
JW21
JW11
R5
1
R31
C10
S/OCP
CN31
D31
VCC
CP1
JW9
C21
CN21
3
OUT
GND
2
C22
1
OUT3(+)
2
OUT3(-)
R21
Circuit Schematic for PCB Circuit Trace Layout
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
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© SANKEN ELECTRIC CO., LTD. 2008
24
STR-A6000 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
IC
Input voltage
Maximum output power
Output voltage
Output current
STR-A6059H
AC85V to AC265V
7.5W
5V
1.5A (max.)
⚫ Circuit Schematic
1
F1
L1
D1
D2
D4
D3
L51
L2
TH1
T1
D51
C1
3
C4
R1
C3
R51
C55
R4
VOUT(+)
5V/1.5A
4
VOUT(-)
S1
C2
R55
R52
PC1
D5
3
R54
R57
C51
P1
C53
R53
C52
S2
U51
R8
7
D/ST
D/ST
NC
VCC
R2
C5
S/OCP
BR
1
2
R56
D
STR-A6000
GND FB/OLP
3
C7
R7
D6
U1
C8
R9
5
8
4
C6
PC1
R3
C9
TC_STR-A6000_4_R1
⚫ Bill of Materials
Symbol
F1
L1
L2
TH1
D1
D2
Part Type
Ratings(1)
Recommended
Sanken Parts
Symbol
(3)
Part Type
Fuse
CM inductor
Inductor
NTC thermistor
General
General
AC250V, 3A
3.3mH
470μH
Short
600V, 1A
600V, 1A
EM01A
EM01A
R4
R7
R8
R9
PC1
U1
D3
General
600V, 1A
EM01A
T1
Transformer
D4
D5
D6
C1
C2
C3
C4
C5
C6
C7
C8
C9
R1
General
Fast recovery
Fast recovery
Film, X2
Electrolytic
Electrolytic
Ceramic
Electrolytic
Ceramic
Ceramic
Ceramic
Ceramic, Y1
General
600V, 1A
1000V, 0.5A
200V, 1A
0.047μF, 275V
10μF, 400V
10μF, 400V
1000pF, 630V
22μF, 50V
0.01μF
1000pF
Open
2200pF, 250V
Open
EM01A
EG01C
AL01Z
L51
D51
C51
C52
C53
C55
R51
R52
R53
R54
R55
R56
R57
Inductor
Schottky
Electrolytic
Ceramic
Electrolytic
Ceramic
General
General
General
General, 1%
General, 1%
General, 1%
General
General
4.7Ω
R2
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
U51
(3)
(3)
(2)
(2)
(2)
Metal oxide
General
General
General
Photo-coupler
IC
Shunt regulator
Ratings(1)
330kΩ, 1W
330kΩ
2.2MΩ
2.2MΩ
PC123 or equiv
－
See
the specification
5μH
90V, 4A
680μF, 10V
0.1μF, 50V
330µF, 10V
1000pF, 1kV
220Ω
1.5kΩ
22kΩ
Short
10kΩ
10kΩ
Open
VREF=2.5V
TL431 or equiv
Recommended
Sanken Parts
STR-A6059H
FMB-G19L
R3
General
1.5Ω, 1/2W
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.
(2) It is necessary to be adjusted based on actual operation in the application.
(3)
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.
(1)
STR-A6000-DSE Rev.4.5
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STR-A6000 Series
⚫ Transformer Specification
▫ Primary Inductance, LP
▫ Core Size
▫ Al-value
▫ Winding Specification
Winding
：704 μH
：EI-16
：132 nH/N2 (Center gap of about 0.26 mm)
Wire Diameter (mm)
Symbol
Number of Turns (T)
Primary Winding
P1
73
2UEW-φ0.18
Auxiliary Winding
D
17
2UEW-φ0.18×2
Output Winding 1
S1
6
TEX-φ0.3×2
Output Winding 2
S2
6
TEX-φ0.3×2
VDC
D
S2
S1
Construction
Two-layer,
solenoid winding
Single-layer,
solenoid winding
Single-layer,
solenoid winding
Single-layer,
solenoid winding
VOUT(+)
5V
P1
S1
P1
D/ST
VCC
Bobbin
GND
VOUT(-)
D
S2
Cross-section view
STR-A6000-DSE Rev.4.5
SANKEN ELECTRIC CO., LTD.
Jun. 20, 2021
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© SANKEN ELECTRIC CO., LTD. 2008
: Start at this pin
26
STR-A6000 Series
Important Notes
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DSGN-CEZ-16003
STR-A6000-DSE Rev.4.5
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