str6a169hz ds en

Off-Line PWM Controllers with Integrated Power MOSFET
STR6A100HZ Series
Data Sheet
Description
Package
The STR6A100HZ series are power ICs for switching
power supplies, incorporating a MOSFET and a current
mode PWM controller IC.
The operation mode is automatically changed, in
response to load, to the fixed switching frequency, to the
switching frequency control, and to the burst oscillation
mode. Thus the power efficiency is improved.
The product achieves high cost-performance power
supply systems with few external components.
DIP8
Features
 Electrical Characteristics
● Improving circuit efficiency (Since the step drive
control can keep VRM of secondary rectification
diodes low, the circuit efficiency can be improved by
low VF)
● Current Mode Type PWM Control
● Brown-In and Brown-Out Function
● No Load Power Consumption, PIN < 25mW
● Automatically changed operation mode in response to
load conditions
- Fixed switching frequency mode, 100 kHz (typ.) in
normal opetation.
- Green mode, 25 kHz (typ.) to 100 kHz (typ.) in
middle to light load.
- Burst oscillation mode in light loat.
● Random Switching Function
● Slope Compensation Function
● Leading Edge Blanking Function
● Bias Assist Function
● Protections
- Two Types of Overcurrent Protection (OCP):
Pulse-by-Pulse, built-in compensation circuit to
minimize OCP point variation on AC input voltage
- Overload Protection with timer (OLP): Ato restart
- Overvoltage Protection (OVP): Latch shutdown
- Thermal Shutdown (TSD): Latch shutdown
Typical Application
VAC
BR1
Not to Scale.
STR6A100HZ Series
fOSC(AVG) = 100 kHz
Products
MOSFET
VDSS(min.)
RDS(ON)(max.)
700 V
3.95 Ω
6.0 Ω
STR6A169HZ
STR6A161HZ
2.3 Ω
STR6A163HZ
 Output Power, POUT*
Adapter
Products
STR6A169HZ
17 W
AC85
~265V
11 W
STR6A161HZ
20.5 W
15 W
AC230V
Open frame
AC230V
AC85
~265V
30 W
19.5 W
35 W
23.5 W
STR6A163HZ
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.
Application
●
●
●
●
●
White goods
Office Automation Equipment
Audio Visual Equipment
Industrial Equipment
Other Switched Mode Power Supplies
D51
T1
P
RA
C1
ROCP
C4
RB
U1
1
2
C3
3
BR
GND
D/ST
D/ST
S
7
5
4
FB/OLP
C51
8
NC
RC
S/OCP
D2
VCC
STR6A100HZ
C2
D
PC1
CY
TC_STR6A100xZ_1_R1
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
1
STR6A100HZ Series
CONTENTS
Description ------------------------------------------------------------------------------------------------------ 1
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 Curve ------------------------------------ 6
3.4. Transient Thermal Resistance Curves ---------------------------------------------------------- 7
4. Block Diagram --------------------------------------------------------------------------------------------- 8
5. Pin Configuration Definitions --------------------------------------------------------------------------- 8
6. Typical Application --------------------------------------------------------------------------------------- 9
7. External Dimensions ------------------------------------------------------------------------------------ 10
8. Marking Diagram --------------------------------------------------------------------------------------- 10
9. Operational Description ------------------------------------------------------------------------------- 11
9.1. Startup Operation --------------------------------------------------------------------------------- 11
9.1.1. Without Brown-In / Brown-Out Function -------------------------------------------- 11
9.1.2. With Brown-In / Brown-Out Function -------------------------------------------------- 11
9.2. Undervoltage Lockout (UVLO) ---------------------------------------------------------------- 12
9.3. Bias Assist Function------------------------------------------------------------------------------- 12
9.4. Soft Start Function -------------------------------------------------------------------------------- 12
9.5. Constant Output Voltage Control-------------------------------------------------------------- 13
9.6. Leading Edge Blanking Function -------------------------------------------------------------- 14
9.7. Random Switching Function -------------------------------------------------------------------- 14
9.8. Step Drive Control -------------------------------------------------------------------------------- 14
9.9. Operation Mode ----------------------------------------------------------------------------------- 14
9.10. Brown-In and Brown-Out Function ----------------------------------------------------------- 15
9.10.1. DC Line Detection --------------------------------------------------------------------------- 15
9.10.2. AC Line Detection --------------------------------------------------------------------------- 16
9.11. Overcurrent Protection (OCP) ----------------------------------------------------------------- 16
9.11.1. Overcurrent Protection Operation------------------------------------------------------- 16
9.11.2. Input Compensation Function ------------------------------------------------------------ 17
9.12. Overload Protection (OLP) ---------------------------------------------------------------------- 17
9.13. Overvoltage Protection (OVP) ------------------------------------------------------------------ 18
9.14. Thermal Shutdown (TSD) ----------------------------------------------------------------------- 18
10. Design Notes ---------------------------------------------------------------------------------------------- 18
10.1. External Components ---------------------------------------------------------------------------- 18
10.1.1. Input and Output Electrolytic Capacitor ----------------------------------------------- 19
10.1.2. S/OCP Pin Peripheral Circuit ------------------------------------------------------------ 19
10.1.3. BR Pin peripheral circuit ------------------------------------------------------------------ 19
10.1.4. FB/OLP Pin Peripheral Circuit ---------------------------------------------------------- 19
10.1.5. VCC Pin Peripheral Circuit --------------------------------------------------------------- 19
10.1.6. Snubber Circuit ------------------------------------------------------------------------------ 19
10.1.7. Phase Compensation ------------------------------------------------------------------------ 19
10.1.8. Transformer ---------------------------------------------------------------------------------- 20
10.2. PCB Trace Layout and Component Placement --------------------------------------------- 20
11. Pattern Layout Example ------------------------------------------------------------------------------- 22
12. Reference Design of Power Supply ------------------------------------------------------------------ 23
IMPORTANT NOTES ------------------------------------------------------------------------------------- 25
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
2
STR6A100HZ Series
1.
Absolute Maximum Ratings
● Current polarities are defined as follows: a current flow going into the IC (sinking) is positive current (+); and a
current flow coming out of the IC (sourcing) is negative current (−).
● Unless specifically noted, TA = 25°C, 7 pin and 8 pin are shorted.
Parameter
Symbol
Conditions
Pins
Rating
Units
1.8
Drain Peak Current (1)
IDPEAK
Maximum Switching Current (2)
IDMAX
Single pulse
TA =
− 40 ~ 125 °C
8−1
8−1
ILPEAK=1.8A
Avalanche Energy (3)(4)
EAS
ILPEAK=1.78A
8−1
2.5
STR6A169HZ
A
STR6A163HZ
1.8
STR6A169HZ
2.5
A
STR6A163HZ
24
STR6A169HZ
36
mJ
− 2 to 6
V
BR Pin Voltage
VBR
2−3
− 0.3 to 7.5
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
VCC
5−3
−0.3 to 32
V
8−3
− 1 to VDSS
V
8−1
1.35
W
D/ST Pin Voltage
MOSFET Power Dissipation
VD/ST
(5)
PD1
(6)
STR6A161HZ
STR6A163HZ
1−3
IFB ≤ 1mA
STR6A161HZ
4.0
VS/OCP
S/OCP Pin Voltage
STR6A161HZ
4.0
53
ILPEAK=2.15A
Remarks
Control Part Power Dissipation
PD2
5−3
1.2
W
Operating Ambient Temperature
TOP
−
− 40 to 125
°C
Storage Temperature
Tstg
−
− 40 to 125
°C
Junction Temperature
Tj
−
150
°C
(1)
See Section 3.2, MOSFET Safe Operating Area Curves.
The Maximum Switching Current is the drain current determined by the drive voltage of the IC and threshold voltage
of the MOSFET, VGS(th).
(3)
See Figure 3-2 Avalanche Energy Derating Coefficient Curve.
(4)
Single pulse, VDD = 99 V, L = 20 mH.
(5)
See 3.3, Ambient Temperature versus Power Dissipation Curve.
(6)
When embedding this hybrid IC onto the printed circuit board (copper area in a 15 mm × 15 mm).
(2)
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
3
STR6A100HZ Series
2.
Electrical Characteristics
● Current polarities are defined as follows: a current flow going into the IC (sinking) is positive current (+); and a
current flow coming out of the IC (sourcing) is negative current (−).
● Unless specifically noted, TA = 25°C, 7 pin and 8 pin are shorted.
Parameter
Symbol
Conditions
Pins
Min.
Typ.
Max.
Units
VCC(ON)
5−3
13.8
15.0
16.2
V
VCC(OFF)
5−3
7.6
8.5
9.2
V
5−3
−
1.5
3.0
mA
8–3
40
47
55
V
Remarks
Power Supply Startup Operation
Operation Start Voltage
( )
Operation Stop Voltage *
Circuit Current in Operation
Startup Circuit Operation
Voltage
VST(ON)
Startup Current
ICC(ST)
VCC = 13.5 V
VD/ST = 100 V
5−3
−4.05
−2.50
−1.08
mA
VCC(BIAS)
ICC = −500 µA
5−3
8.0
9.6
10.5
V
fOSC(AVG)
8–3
90
100
110
kHz
Δf
8−3
−
8.4
−
kHz
4−3
−170
−130
−85
µA
4−3
−21
−13
−5
µA
Startup Current Biasing
Threshold Voltage
Normal Operation
Average Switching
Frequency
Switching Frequency
Modulation Deviation
Maximum Feedback Current
Minimum Feedback Current
Light Load Operation
FB/OLP Pin Starting Voltage
of Frequency Decreasing
FB/OLP Pin Ending Voltage
of Frequency Decreasing
Minimum Switching
Frequency
Standby Operation
FB/OLP Pin Oscillation Stop
Threshold Voltage
ICC(ON)
IFB(MAX)
VCC = 12 V
VCC = 12 V
IFB(MIN)
VFB(FDS)
fOSC(AVG)× 0.9
1−8
2.88
3.60
4.32
V
VFB(FDE)
fOSC(MIN)× 1.1
1−8
2.48
3.10
3.72
V
fOSC(MIN)
5−8
18
25
32
kHz
VFB(OFF)
4−3
1.61
1.77
1.92
V
VBR(IN)
2–3
5.43
5.60
5.77
V
VBR(OUT)
2−3
4.65
4.80
4.95
V
2−3
6.5
6.9
7.3
V
VBR(DIS)
2−3
0.4
0.6
0.8
V
DMAX
8−3
70
75
80
%
tBW
−
−
330
−
ns
DPC
−
−
25.8
−
mV/μs
DDPC
−
−
36
−
%
Brown-In / Brown-Out Function
Brown-In Threshold Voltage
Brown-Out Threshold Voltage
BR Pin Clamp Voltage
BR Function Disabling
Threshold Voltage
VBR(CLAMP)
IBR = 100 µA
Protection
Maximum ON Duty
Leading Edge Blanking Time
OCP Compensation
Coefficient
OCP Compensation ON Duty
( )
* VCC(BIAS) > VCC(OFF) always.
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
4
STR6A100HZ Series
Parameter
OCP Threshold Voltage at
Zero ON Duty
OCP Threshold Voltage at
36% ON Duty
OCP Threshold Voltage in
Leading Edge Blanking Time
OLP Threshold Voltage
OLP Delay Time
OLP Operation Current
FB/OLP Pin Clamp Voltage
OVP Threshold Voltage
Thermal Shutdown Operating
Temperature
MOSFET
Drain-to-Source Breakdown
Voltage
Drain Leakage Current
On-Resistance
Symbol
Conditions
Pins
Min.
Typ.
Max.
Units
VOCP(L)
1−3
0.735
0.795
0.855
V
VOCP(H)
1−3
0.843
0.888
0.933
V
VOCP(LEB)
1−3
−
1.69
−
V
VFB(OLP)
4−3
6.8
7.3
7.8
V
tOLP
4−3
55
75
90
ms
ICC(OLP)
5−3
−
260
−
µA
VFB(CLAMP)
4−3
10.5
11.8
13.5
V
VCC(OVP)
5−3
27.0
29.1
31.2
V
Tj(TSD)
−
125
145
−
°C
Remarks
VDSS
IDS = 300 µA
8−1
700
−
−
V
IDSS
VDS = 700 V
8−1
−
−
300
µA
−
−
6.0
Ω
STR6A169HZ
−
−
3.95
Ω
STR6A161HZ
−
−
2.3
Ω
STR6A163HZ
RDS(ON)
IDS = 0.4 A
8−1
tf
8−1
−
−
250
ns
θch-C
−
−
−
22
°C/W
Switching Time
Thermal Resistance
Channel to Case
3.
3.1.
Performance Curves
Derating Curves
100
EAS Temperature Derating Coefficient
(%)
Safe Operating Area
Temperature Derating Coefficient (%)
100
80
60
40
20
0
0
25
50
75
100
125
150
80
60
40
20
0
25
Ambient Temperature, TA (°C )
Figure 3-1
SOA Temperature Derating Coefficient
Curve
50
75
100
125
150
JunctionTemperature,Tj (°C)
Figure 3-2
Avalanche Energy Derating Coefficient
Curve
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
5
STR6A100HZ 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 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.
● STR6A161HZ
● STR6A163HZ
1ms
0.1
0.1ms
Drain Current, ID (A)
1
S_STR6A161HZ_R1
Drain Current, ID (A)
0.1ms
1
S_STR6A163HZ_R1
10
10
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)
● STR6A169HZ
Drain Current, ID (A)
0.1ms
1
S_STR6A169HZ_R1
10
1ms
0.1
0.01
1
10
100
1000
Drain-to-Source Voltage (V)
3.3.
Ambient Temperature versus Power Dissipation Curve
Power Dissipation, PD1 (W)
1.4
PD1_STR6A100HZ_R2
PD1_STR6A100HZ_R1
1.6
PD1=1.35W
1.2
1
0.8
0.6
0.4
0.2
0
0
25
50
75
100
125
150
Ambient Temperature, TA (°C )
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
6
STR6A100HZ Series
3.4.
Transient Thermal Resistance Curves
● STR6A161HZ
TR_STR6A161HZ_R1
Transient Thermal Resistance
θch-c (°C/W)
100
10
1
0.1
0.01
1µ
10µ
100µ
1m
10m
100m
1s
10m
100m
1s
10m
100m
1s
Time (s)
● STR6A163HZ
TR_STR6A163HZ_R1
Transient Thermal Resistance
θch-c (°C/W)
100
10
1
0.1
0.01
1µ
10µ
100µ
1m
Time (s)
● STR6A169HZ
TR_STR6A169HZ_R1
Transient Thermal Resistance
θch-c (°C/W)
100
10
1
0.1
0.01
1µ
10µ
100µ
1m
Time (s)
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
7
STR6A100HZ Series
4.
Block Diagram
VCC
5
Startup
UVLO
BR
2
REG
VREG
OVP
D/ST
7,8
TSD
Brown-in
Brown-out
DRV
PWM OSC
S Q
R
OCP
VREG
VCC
Drain peak current
compensation
OLP
Feedback
control
FB/OLP
4
LEB
S/OCP
1
GND
3
Slope
compensation
BD_STR6A100xZ_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
Overload 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
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
8
STR6A100HZ Series
6.
Typical Application
● The following drawings show circuits enabled and disabled the Brown-In/Brown-Out Function.
● 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 the D/ST pins have 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.
C（RC）
damper snubber
BR1
CRD Clamp snubber
VAC
RA
C1
L51
D51
T1
VOUT
(+)
R54
R1
C6
PC1
C5
R51
P
RB
R55
C51
D1
U1
ROCP
1
C4
2
3
D/ST
BR
D/ST
GND
C53
C52 R53
7
D2
R2
U51
R56
(-)
FB/OLP
D
C2
5
4
C3
S
8
NC
RC
S/OCP
R52
VCC
STR6A100HZ
PC1
CY
TC_STR6A100xZ_2_R1
Figure6-1
Typical application circuit (enabled Brown-In/Brown-Out Function, DC line detection)
C（RC）
damper snubber
BR1
CRD Clamp snubber
VAC
C1
L51
D51
T1
VOUT
(+)
R54
R1
C6
PC1
C5
R51
P
R55
C51
D1
U1
ROCP
1
2
D/ST
BR
D/ST
GND
FB/OLP
C3
PC1
C52 R53
7
D2
R2
U51
R56
(-)
5
4
C53
8
NC
3
S/OCP
S
R52
C2
D
VCC
STR6A100HZ
CY
TC_STR6A100xZ_3_R1
Figure6-2
Typical application circuit (disabled Brown-In/Brown-Out Function)
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
9
STR6A100HZ Series
7.
External Dimensions
● DIP8
NOTES:
1) Dimension is in millimeters
2) Pb-free. Device composition compliant with the RoHS directive
8.
Marking Diagram
8
6A1××H
SKYMD Z
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 : 1st to 10th
2 : 11th to 20th
3 : 21st to 31st
Control Number
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
10
STR6A100HZ Series
9.
Operational Description
9.1.2.
All the characteristic values given in this section are
typical values, unless they are specified as minimum or
maximum.
Current polarities are defined as follows: a current
flow going into the IC (sinking) is positive current (+);
and a current flow coming out of the IC (sourcing) is
negative current (−).
9.1.
With Brown-In / Brown-Out
Function
When BR pin voltage is more than VBR(DIS) = 0.6 V
and less than VBR(IN) = 5.60 V, the Bias Assist Function
(see 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
Startup Operation
Figure 9-1 shows the circuit around IC.
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) = 47 V, the
startup circuit starts operation.
During the startup process, the constant current,
ICC(ST) = −2.50 mA, charges C2 at VCC pin. When VCC
pin voltage increases to VCC(ON) = 15.0 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.
T1
VAC
C1
7､8
D/ST
U1
VCC
5
D2
C2
GND
BR
2
P
R2
D
VD
3
Figure 9-1 VCC pin peripheral circuit
(Without Brown-In / Brown-Out)
VCC pin
voltage
VCC(ON)
tSTART
Drain current,
ID
⇒
(1)
The oscillation start timing of IC depends on
Brown-In / Brown-Out Function (See Section 9.10).
9.1.1.
Without Brown-In / Brown-Out
Function (BR pin voltage is
VBR(DIS) = 0.6 V or less)
VCC pin
voltage
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:
(2)
where,
tSTART : Startup time of IC (s)
VCC(INT): Initial voltage on VCC pin (V)
Figure 9-2 Startup operation
(Without Brown-In / Brown-Out)
tSTART
VCC(ON)
VCC(OFF)
BR pin
voltage
VBR(IN)
Drain current,
ID
Figure 9-3 Startup operation
(With Brown-In / Brown-Out)
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
11
STR6A100HZ Series
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) = 8.5 V, the control circuit stops operation by
Undervoltage Lockout (UVLO) circuit, and reverts to
the state before startup.
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 VCC pin voltage decreases.
When VCC pin voltage decreases to VCC(BIAS), the Bias
Assist Function is activated and the startup failure is
prevented.
Circuit current, ICC
VCC pin
voltage
Stop
Start
Startup success
IC starts operation
Target operating
voltage
Increase with rising of
output voltage
VCC(ON)
VCC(BIAS)
Bias assist period
VCC(OFF)
Startup failure
VCC（OFF）
VCC（ON） VCC pin
voltage
Figure 9-4 Relationship between
VCC pin voltage and ICC
Time
Figure 9-5
9.4.
9.3.
Bias Assist Function
By the Bias Assist Function, the startup failure is
prevented. The Bias Assist Function is activated, in both
of following condition:
the FB pin voltage is FB/OLP Pin Oscillation Stop
Threshold Voltage, VFB(OFF)= 1.77 V or less
and the VCC voltage decreases to the Startup Current
Biasing Threshold Voltage, VCC(BIAS) = 9.6 V.
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
VCC(OFF).
Since the startup failure is prevented by the Bias
Assist Function, the value of C2 connected to VCC pin
can be small. Thus, the startup time and the response
time of the 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 9-5 shows VCC pin voltage behavior during
the startup period.
After VCC pin voltage increases to VCC(ON) = 15.0 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.
When 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
VCC pin voltage during startup period
Soft Start Function
Figure 9-6 shows the behavior of VCC pin voltage
and drain current during the startup period.
VCC pin
voltage
Startup of IC Startup of SMPS
Normal opertion
tSTART
VCC(ON)
VCC(OFF)
Time
D/ST pin
current, ID
Soft start period
approximately 8.75 ms (fixed)
Limited by OCP operation
tLIM < tOLP (min.)
Time
Figure 9-6
VCC and ID behavior during startup
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, over current threshold is
increased step-wisely (7 steps). This function reduces
the voltage and the current stress of MOSFET and
secondary side rectifier diode.
Since the Leading Edge Blanking Function (see
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.
After the soft start period, D/ST pin current, ID, is
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
12
STR6A100HZ Series
limited by the Overcurrent Protection (OCP), until the
output voltage increases to the target operating voltage.
This period is given as tLIM.
When tLIM is longer than the OLP Delay Time, tOLP,
the output power is limited by the Overload Protection
(OLP).
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.).
9.5.
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 (see Section
4.Functionnal Block Diagram), and the target voltage,
VSC, is generated. The IC compares the voltage, V ROCP,
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 9-7 and Figure 9-8.
U1
S/OCP
GND
3
1
FB/OLP
4
PC1
ROCP
VROCP
Figure 9-7
C3
IFB
FB/OLP pin peripheral circuit
● 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 I D 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
9-9. 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 V SC, 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.
Target voltage including
Slope Compensation
-
VSC
+
VROCP
FB Comparator
Target voltage
without Slope Compensation
Voltage on both
sides of ROCP
tON1
Drain current,
ID
Figure 9-8
Drain current, ID, and FB comparator
operation in steady operation
T
tON2
T
T
Figure 9-9 Drain current, ID, waveform
in subharmonic oscillation
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
13
STR6A100HZ Series
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 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 = 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 (see
Section 9.11).
9.7.
Step Drive Control
Figure 9-10 shows a flyback control circuit. The both
end of secondary rectification diode (D51) is generated
surge voltage when a power MOSFET turns on. Thus,
VRM of D51 should be set in consideration of the surge.
The IC optimally controls the gate drive of the
internal power MOSFET (Step drive control) depending
on the load condition. The step drive control reduces the
surge voltage of D51 when the power MOSFET turns on
(See Figure 9-11). Since VRM of D51 can be set to lower
value than usual, the price reduction and the increasing
circuit efficiency are achieved by using a diode of low
VF.
VAC
VD51
BR1
T1
D51
P1
C1
S1
C51
ID
5-8
U1 D/ST
S/OCP
1
ROCP
Figure 9-10
Time
Flyback control circuit
Time
Reducing surge voltage
VD51
Time
Without step drive
control
Figure 9-11
9.9.
Random Switching Function
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.
9.8.
ID
Time
With step drive
control
ID and VD51 waveforms
Operation Mode
As shown in Figure 9-12, when the output power is
decreasing, together with the decrease of the drain
current ID of the internal power MOSFET, the operation
mode is automatically changed to the fixed switching
frequency mode (100 kHz), to the Green mode
controlled the switching frequency (25 kHz to 100 kHz),
and to the burst oscillation mode controlled by an
internal oscillator. In the Green mode, the number of
switching is reduced. In the burst oscillation mode, the
switching operation is stopped during a constant period.
Thus, the switching loss is reduced, and the power
efficiency is improved.
When the output load becomes lower, FB/OLP pin
voltage decreases. When FB/OLP pin voltage decreases
to VFB(FDS) = 3.60 V or less, the green mode is activated
and the oscillation frequency starts decreasing. When
FB/OLP pin voltage becomes VFB(FDE) = 3.10 V, the
oscillation frequency stops decreasing. At this point, the
oscillation frequency becomes fOSC(MIN) = 25 kHz.
When FB/OLP pin voltage further decreases and
becomes the standby operation point, the burst
oscillation mode is activated. As shown in Figure 9-13,
the burst oscillation mode consists of switching period
and non-switching period. The oscillation frequency
during switching period is the Minimum Frequency,
fOSC(MIN) = 25 kHz.
Generally, to improve efficiency under light load
conditions, the frequency of the burst mode becomes
just a few kilohertz. Because the IC suppresses the peak
drain current well during burst mode, audible noises can
be reduced.
The OCP detection usually has some detection delay
time. The higher the AC input voltage is, the steeper the
slope of ID is. Thus, the peak drain current at the burst
oscillation mode becomes high at a high AC input
voltage.
It is necessary to consider that the burst frequency
becomes low at a high AC input.
If the VCC pin voltage decreases to VCC(BIAS) = 9.6 V
during the transition to the burst mode, the Bias Assist
function is activated and stabilizes the standby mode,
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
14
STR6A100HZ Series
because the Startup Current, ICC(ST), 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-side winding and/or reducing the
value of R2 (see Section 10.1).
VBR(IN)
VBR(OUT)
Normal
operation
fOSC(MIN)
Burst oscillation
Green mode
Standby power
Figure 9-12
BR pin voltage and drain current
waveforms
There are two types of detection method as follows:
9.10.1. DC Line Detection
Output power, PO
Relationship between PO and fOSC
Switching period
Non-switching period
fOSC(MIN)
tOLP
Drain current,
ID
Figure 9-14
Switching
frequency
fOSC
fOSC(AVG)
ID
BR pin voltage
Figure 9-15 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.
Time
BR1
VAC
Figure 9-13
Switching waveform at burst oscillation
RA
VDC
9.10. 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) = 0.6 V, this function is activated.
Figure 9-14 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) = 4.80 V or less for the OLP
Delay Time, tOLP = 75 ms, the IC stops switching
operation.
When the AC input voltage increases and the BR pin
voltage reaches VBR(IN) = 5.60 V or more in the operating
state that the VCC pin voltage is VCC(OFF) or more, the IC
starts switching operation.
When 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.
U1
C1
RB
2
RC
Figure 9-15
BR
C4
GND
3
DC line detection
<< 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
● C4 is 470 pF to 2200 pF for high frequency noise
reduction
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
15
STR6A100HZ Series
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:
(3)
where,
VDC(OP): C1 voltage when Brown-In and Brown-Out
Function is activated
VBR(TH): Any one of threshold voltage of BR pin
(see Table 9-1)
Table 9-1 BR pin threshold voltage
Parameter
Symbol
Brown-In Threshold Voltage
VBR(IN)
Value
(Typ.)
5.60 V
VBR(OUT)
4.80 V
Brown-Out Threshold Voltage
VDC(OP) can be expressed as the effective value of AC
input voltage using Equation (4).
(4)
RA, RB, RC and C4 should be selected based on actual
operation in the application.
<< 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
● RS must be adjusted so that the BR pin voltage is
more than VBR(DIS) = 0.6 V when the VCC pin
voltage is VCC(OFF) = 8.5 V
● C4 is 0.22 μF to 1 μF for averaging AC input voltage
and high frequency noise reduction
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:
(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.
9.10.2. AC Line Detection
Figure 9-16 shows BR pin peripheral circuit of AC
line detection. In order to detect the AC input voltage
(after half-wave rectification), 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.
VAC
BR1
RA
5
VCC
RS
VDC
RB
C1
2
RC
Figure 9-16
BR
C4
U1
GND
3
AC line detection (after half-wave
rectification)
9.11. Overcurrent Protection (OCP)
9.11.1. Overcurrent Protection Operation
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 9-17. 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 power MOSFET turns on, the surge voltage
width of S/OCP pin should be less than tBW, as shown in
Figure 9-17. In order to prevent surge voltage, pay extra
attention to ROCP trace layout (see Section 10.2).
In addition, if a C (RC) damper snubber of Figure
9-18 is used, reduce the capacitor value of damper
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
16
STR6A100HZ Series
snubber.
tBW
VOCP(LEB)
VOCP’
(6)
Surge pulse voltage width at turning-on
S/OCP pin voltage
C（RC）
Damper snubber
T1
D51
C1
C51
7, 8
D/ST
U1
C（RC）
Damper snubber
S/OCP
1
1.0
OCP Threshold Voltage after
compensation, VOCP'
Figure 9-17
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
VOCP(H)
VOCP(L)
DDPC=36%
0.5
ROCP
0
50
DMAX=75%
100
ON Duty (%)
Figure 9-18
Damper snubber
9.11.2. 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 9-19.
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) = 0.888 V
Figure 9-19 Relationship between ON Duty and Drain
Current Limit after compensation
9.12. Overload Protection (OLP)
Figure 9-20 shows the FB/OLP pin peripheral circuit,
and Figure 9-21 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) = 7.3 V or more for the OLP delay
time, tOLP = 75 ms or more, the OLP function is
activated, the IC stops switching operation.
During OLP operation, the intermittent operation by
VCC pin voltage repeats and reduces the stress of parts
such as the power MOSFET and secondary side rectifier
diode.
When the OLP function is activated, the IC stops
switching operation, and the VCC pin voltage decreases.
During OLP operation, the Bias Assist Function is
disabled. When the VCC pin voltage decreases to
VCC(OFF)SKP (about 9 V), the startup current flows, and
the VCC pin voltage increases. When the VCC pin
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
17
STR6A100HZ Series
voltage increases to VCC(ON), the IC starts operation, and
the circuit current increases. After that, the VCC pin
voltage decreases. When the VCC pin voltage decreases
to VCC(OFF) = 8.5 V, the control circuit stops operation.
Skipping the UVLO operation of VCC(OFF) (see Section
9.2), the intermittent operation makes the non-switching
interval longer and restricts the temperature rise of the
power MOSFET.
When the abnormal condition is removed, the IC
returns to normal operation automatically.
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).
(7)
where,
VOUT(NORMAL): Output voltage in normal operation
VCC(NORMAL): VCC pin voltage in normal operation
U1
GND
FB/OLP
4
3
VCC
9.14. Thermal Shutdown (TSD)
5
PC1
C3
D2 R2
C2
D
Figure 9-20
VCC pin voltage
FB/OLP pin peripheral circuit
Non-switching
interval
When the temperature of control circuit increases to
Tj(TSD) = 145 °C or more, Thermal Shutdown (TSD) is
activated, and 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).
Non-switching
interval
VCC(ON)
10. Design Notes
VCC(OFF)SKP
VCC(OFF)
FB/OLP pin voltage
tOLP
tOLP
tOLP
VFB(OLP)
10.1. External Components
Take care to use properly rated, including derating as
necessary and proper type of components.
Drain current,
ID
CRD clamp snubber
BR1
T1
VAC
R1
C6
RA
C1
Figure 9-21
OLP operational waveforms
P
D1
RB
D2
8
9.13. Overvoltage Protection (OVP)
When a voltage between VCC pin and GND terminal
increases to VCC(OVP) = 29.1 V or more, Overvoltage
Protection (OVP) is activated and 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).
When the VCC pin voltage is provided by using
auxiliary winding of transformer, the overvoltage
conditions such as output voltage detection circuit open
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
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
2
3
4
C4
C3
PC1
ROCP
The IC peripheral circuit
18
STR6A100HZ Series
10.1.1. Input and Output Electrolytic
Capacitor
because the variation of the auxiliary winding voltage is
affected by the transformer structural design。
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.
Without R2
VCC pin voltage
With R2
10.1.2. S/OCP Pin Peripheral Circuit
Output current, IOUT
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.
10.1.3. 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
Figure 10-2
Variation of VCC pin voltage and power
10.1.6. Snubber Circuit
If 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-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. When the
damper snubber circuit is added, this components
should be connected near D/ST pin and S/OCP pin.
See the section 9.10 about the AC input voltage
detection function and the components around BR pin.
10.1.7. Phase Compensation
10.1.4. 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 0.01 µF, and should be selected based on actual
operation in the application.
A typical phase compensation circuit with a
secondary shunt regulator (U51) is shown in Figure
10-3.
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.
10.1.5. VCC Pin Peripheral Circuit
L51
T1
The value of C2 is generally recommended to be 10
µF to 47 μF (see 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,
VOUT
(+)
D51
PC1
R55
C51
S
R54
R51
R52
C53
C52 R53
U51
R56
(-)
Figure 10-3
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
Peripheral circuit around secondary shunt
regulator (U51)
19
STR6A100HZ Series
10.1.8. Transformer
Margin tape
Bobbin
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:
Margin tape
Winding structural example (a)
Bobbin
Margin tape
● Increase the number of wires in parallel.
● Use litz wires.
● Thicken the wire gauge.
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 (OVP) may be activated. In transformer
design, the following should be considered;
● 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.
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.
P1 S1 P2 S2 D
P1 S1 D S2 S1 P2
Margin tape
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.
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.
(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.
(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.
(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.
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
20
STR6A100HZ Series
(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.
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.
(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.
(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,
carrying the switching current, and thus it should be
(1) Main trace should be wide
trace and small loop
(4)ROCP should be as close to S/OCP pin
as possible.
(6) Main trace of secondary side should
be wide trace and small loop
T1
C1
(7)Trace of D/ST pin should be
wide for heat release
RA
D51
R1
C6
P
C5
RB
A
ROCP
C4
1
S/OCP
D/ST
2
BR
D/ST
7
D2
(5)The components
connected to the IC
should be as close to
the IC as possible, and
should be connected as
short as possible
GND
5
4
FB/OLP
PC1 C3
R2
NC
3
S
8
RC
(2) Control GND trace
should be connected at
a single point as close
to the ROCP as possible
C51
D1
U1
VCC
C2
D
CY
(3) Loop of the power supply should be small
Figure 10-5
Peripheral circuit example around the IC
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
21
STR6A100HZ Series
11. Pattern Layout Example
The following show the PCB pattern layout example and the schematic of circuit using STR6A100HZ series.
Figure 11-1
1
L1
C1
PCB circuit trace layout example
P2
BR1
T1
D51
JP3
R1
2
C2
F1
R51
C54
C4
C3
P1
D1
C52
D2
D/ST
JP2
NC
VCC
U1
C9
U2
R2
5
D/ST
R6
C8
STR6A100
S/OCP
BR
1
2
R53
R56
D
C7
GND FB/OLP
3
4
JP5
R7
C53
C51
JP1
7
VOUT(-)
PC1
JP4
8
2
R55
R52
R5
VOUT(+)
S
P1
R4
1
R54
R3
C5
Figure 11-2
C6
PC1
JP6
C10
PSA50123 rev.1.0
Circuit schematic for PCB circuit trace layout
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
22
STR6A100HZ 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.
● Circuit schematic
使用 IC
入力電圧
最大出力電力
出力電圧
出力電流
STR6A163HZ
AC85V～AC265V
21 W
14 V
1.5 A (max.)
● Circuit schematic
See Figure 11-2.
● Transformer specification
▫ Primary inductance, LP
▫ Core size
▫ Al-value
▫ Winding specification
：700 μH
：EI-22
：231 nH/N2 (Center gap of about 0.23 mm)
Winding
Symbol
Number of
turns (T)
Primary winding 1
P1
30
2UEW-φ0.23
Primary winding 2
P2
25
2UEW-φ0.23
Auxiliary winding
D
10
2UEW-φ0.23
Output winding 1
S1
9
TEX-φ0.0.26 × 2
Output winding 2
S2
9
TEX-φ0.0.26 × 2
Wire diameter(mm)
VDC
P1
S2
D
S1
P2
Bobbin
Cross-section view
Construction
Single-layer,
solenoid winding
Single-layer,
solenoid winding
Space winding
Single-layer,
solenoid winding
Single-layer,
solenoid winding
(+) 14V
P1
S1
P2
(-)
D/ST
VCC
D
VOUT
S2
GND
● Start at this pin
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
23
STR6A100HZ Series
 Bill of materials
Symbol
BR1
C1
(2)
Part type
Ratings(1)
Recommended
Sanken Parts
Ratings(1)
Symbol
Part type
(2)
CM inductor
10 mH
Photo-coupler
PC123 相当
Metal oxide
470 kΩ, 1 W
Diode bridge
600 V, 1 A
L1
Film, X2
0.1 μF, 275 V
PC1
(3)
C2
Electrolytic
82 μF, 400 V
R1
C3
Electrolytic
Open
R2
General
4.7 Ω
C4
Ceramic
1000 pF, 630 V
R3
General
1 Ω, 1 W
R4
(3)
General
2.2 MΩ
C5
C6
Ceramic
(2)
C7
1000 pF
Ceramic
0.01 μF
R5
(3)
General
2.2 MΩ
Electrolytic
22 μF, 50 V
R6
(3)
General
Short
(3)
General
330 kΩ
C8
(2)
Ceramic
Open
R7
C9
(2)
Ceramic
Open
R51
General
2.2 kΩ
Ceramic, Y1
2200 pF, 250 VAC
R52
General
1.5 kΩ
General
10 kΩ
C10
(2)
C51
Electrolytic
1000 μF, 25V
R53
C52
Ceramic
0.22 μF, 50V
R54
General, 1%
6.8 kΩ
C53
Electrolytic
Open
R55
General, 1%
39 kΩ
C54
Ceramic
Open
R56
General, 1%
D1
Fast recovery
1000V, 0.5A
EG01C
T1
Transformer
D2
Fast recovery
200 V, 1 A
AL01Z
U1
IC
D51
Schottky
100 V, 10 A
FMEN-210A
U2
Shunt regulator
10 kΩ
See the
specification
－
VREF=2.5V
TL431or equiv
Recommended
Sanken Parts
STR6A163HZ
F1
Fuse
AC250V, 2 A
(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.
(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.
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
24
STR6A100HZ Series
IMPORTANT NOTES
● All data, illustrations, graphs, tables and any other information included in this document as to Sanken’s products listed herein (the
“Sanken Products”) are current as of the date this document is issued. All contents in this document are subject to any change
without notice due to improvement, etc. Please make sure that the contents set forth in this document reflect the latest revisions
before use.
● The Sanken Products are intended for use as components of general purpose electronic equipment or apparatus (such as home
appliances, office equipment, telecommunication equipment, measuring equipment, etc.). Prior to use of the Sanken Products,
please put your signature, or affix your name and seal, on the specification documents of the Sanken Products and return them to
Sanken. If considering use of the Sanken Products for any applications that require higher reliability (transportation equipment and
its control systems, traffic signal control systems or equipment, disaster/crime alarm systems, various safety devices, etc.), you
must contact a Sanken sales representative to discuss the suitability of such use and put your signature, or affix your name and seal,
on the specification documents of the Sanken Products and return them to Sanken, prior to the use of the Sanken Products. Any use
of the Sanken Products without the prior written consent of Sanken in any applications where extremely high reliability is required
(aerospace equipment, nuclear power control systems, life support systems, etc.) is strictly prohibited.
● In the event of using the Sanken Products by either (i) combining other products or materials therewith or (ii) physically,
chemically or otherwise processing or treating the same, you must duly consider all possible risks that may result from all such
uses in advance and proceed therewith at your own responsibility.
● Although Sanken is making efforts to enhance the quality and reliability of its products, it is impossible to completely avoid the
occurrence of any failure or defect in semiconductor products at a certain rate. You must take, at your own responsibility,
preventative measures including using a sufficient safety design and confirming safety of any equipment or systems in/for which
the Sanken Products are used, upon due consideration of a failure occurrence rate or derating, etc., in order not to cause any human
injury or death, fire accident or social harm which may result from any failure or malfunction of the Sanken Products. Please refer
to the relevant specification documents and Sanken’s official website in relation to derating.
● No anti-radioactive ray design has been adopted for the Sanken Products.
● No contents in this document can be transcribed or copied without Sanken’s prior written consent.
● The circuit constant, operation examples, circuit examples, pattern layout examples, design examples, recommended examples and
evaluation results based thereon, etc., described in this document are presented for the sole purpose of reference of use of the
Sanken Products and Sanken assumes no responsibility whatsoever for any and all damages and losses that may be suffered by you,
users or any third party, or any possible infringement of any and all property rights including intellectual property rights and any
other rights of you, users or any third party, resulting from the foregoing.
● All technical information described in this document (the “Technical Information”) is presented for the sole purpose of reference
of use of the Sanken Products and no license, express, implied or otherwise, is granted hereby under any intellectual property
rights or any other rights of Sanken.
● Unless otherwise agreed in writing between Sanken and you, Sanken makes no warranty of any kind, whether express or implied,
as to the quality of the Sanken Products (including the merchantability, or fitness for a particular purpose or a special environment
thereof), and any information contained in this document (including its accuracy, usefulness, or reliability).
● In the event of using the Sanken Products, you must use the same after carefully examining all applicable environmental laws and
regulations that regulate the inclusion or use of any particular controlled substances, including, but not limited to, the EU RoHS
Directive, so as to be in strict compliance with such applicable laws and regulations.
● You must not use the Sanken Products or the Technical Information for the purpose of any military applications or use, including
but not limited to the development of weapons of mass destruction. In the event of exporting the Sanken Products or the Technical
Information, or providing them for non-residents, you must comply with all applicable export control laws and regulations in each
country including the U.S. Export Administration Regulations (EAR) and the Foreign Exchange and Foreign Trade Act of Japan,
and follow the procedures required by such applicable laws and regulations.
● Sanken assumes no responsibility for any troubles, which may occur during the transportation of the Sanken Products including
the falling thereof, out of Sanken’s distribution network.
● Although Sanken has prepared this document with its due care to pursue the accuracy thereof, Sanken does not warrant that it is
error free and Sanken assumes no liability whatsoever for any and all damages and losses which may be suffered by you resulting
from any possible errors or omissions in connection with the contents included herein.
● Please refer to the relevant specification documents in relation to particular precautions when using the Sanken Products, and refer
to our official website in relation to general instructions and directions for using the Sanken Products.
STR6A100HZ-DSJ Rev.1.0
SANKEN ELECTRIC CO.,LTD.
Mar. 25, 2016
http://www.sanken-ele.co.jp/en/
© SANKEN ELECTRIC CO.,LTD. 2014
25