ssc3s900 ds en

LLC Current-Resonant Off-Line Switching Controller
SSC3S900 Series
Data Sheet
Description
Package
The SSC3S900 series is a controller with SMZ*
method for LLC current resonant switching power
supplies, incorporating a floating drive circuit for a
high-side power MOSFET.
The product includes useful functions such as Standby
mode change, Overload Protection with input voltage
compensation, Automatic Dead Time Adjustment, and
Capacitive Mode Detection. The product realizes high
performance-to-cost power supply system, downsized by
high efficiency and low noise.
*SMZ: Soft-switched Multi-resonant Zero Current
switch, achieved soft switching operation during all
switching periods
SOP18
Not to scale
Lineup
Features
Product
● Standby Mode Change Function
▫ Output Power at Light Load: PO = 100 mW
(PIN = 0.27 W, as a reference with discharge resistor
of 1MΩ for across the line capacitor)
▫ Burst operation in standby mode
▫ Soft-on/Soft-off function: reduces audible noise
● Realizing power supply with universal mains input
voltage
● Floating Drive Circuit: drives a high-side power
MOSFET directly
● Soft-start Function
● Capacitive Mode Detection Function
● Reset Detection Function
● Automatic Dead Time Adjustment Function
● Brown-In and Brown-Out Function
● Built-in Startup Circuit
● Input Electrolytic Capacitor Discharge Function
● Protections
▫ High-side Driver UVLO
▫ Overcurrent Protection (OCP): Peak drain current
detection, 2-step detection
▫ Overload Protection (OLP) with Input Voltage
Compensation
▫ Overvoltage Protection (OVP)
▫ Thermal Shutdown (TSD)
Protection Operation
UVLO / OCP
OLP / OVP / TSD
SSC3S901
Auto Restart
Auto Restart
SSC3S902
Auto Restart
Latch Shutdown
Application
Switching power supplies for electronic devices such as:
● Digital appliances: LCD television and so forth
● Office automation (OA) equipment: server, multifunction printer, and so forth
● Industrial apparatus
● Communication facilities
Typical Application
VAC
T1
VOUT1
1
18
VCC
2
17
NC
FB
3
16
VGH
VSPL
4
15
VS
CSS
5
CL
6
RC
7
PL
8
SB
9
U1
SSC3S900
VSEN
ST
14
VB
13
NC
12
REG
11
VGL
10
GND
PC1
GND
VOUT2
PC2
Standby
PC1
PC2
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
1
SSC3S900 Series
CONTENTS
Description ------------------------------------------------------------------------------------------------------ 1
CONTENTS ---------------------------------------------------------------------------------------------------- 2
1. Absolute Maximum Ratings ----------------------------------------------------------------------------- 3
2. Electrical Characteristics -------------------------------------------------------------------------------- 4
3. Block Diagram --------------------------------------------------------------------------------------------- 7
4. Pin Configuration Definitions --------------------------------------------------------------------------- 7
5. Typical Application --------------------------------------------------------------------------------------- 8
6. External Dimensions -------------------------------------------------------------------------------------- 9
7. Marking Diagram ----------------------------------------------------------------------------------------- 9
8. Operational Description ------------------------------------------------------------------------------- 10
8.1 Resonant Circuit Operation --------------------------------------------------------------------- 10
8.2 Startup Operation --------------------------------------------------------------------------------- 13
8.3 Undervoltage Lockout (UVLO) ---------------------------------------------------------------- 13
8.4 Bias Assist Function------------------------------------------------------------------------------- 13
8.5 Soft Start Function -------------------------------------------------------------------------------- 14
8.6 Minimum and Maximum Switching Frequency Setting ----------------------------------- 14
8.7 High-side Driver ----------------------------------------------------------------------------------- 14
8.8 Constant Voltage Control Operation ---------------------------------------------------------- 15
8.9 Standby Function ---------------------------------------------------------------------------------- 15
8.9.1
Standby Mode Changed by External Signal ------------------------------------------- 16
8.9.2
Burst Oscillation Operation --------------------------------------------------------------- 16
8.10 Automatic Dead Time Adjustment Function ------------------------------------------------ 17
8.11 Brown-In and Brown-Out Function ----------------------------------------------------------- 17
8.12 Capacitive Mode Detection Function ---------------------------------------------------------- 18
8.13 Input Electrolytic Capacitor Discharge Function ------------------------------------------- 19
8.14 Reset Detection Function ------------------------------------------------------------------------ 19
8.15 Overvoltage Protection (OVP) ------------------------------------------------------------------ 21
8.16 Overcurrent Protection (OCP) ----------------------------------------------------------------- 21
8.17 Overload Protection (OLP) with Input Voltage Compensation -------------------------- 22
8.17.1 Overload Protection (OLP) ---------------------------------------------------------------- 22
8.17.2 OLP Input Voltage Compensation Function ------------------------------------------- 24
8.18 Thermal Shutdown (TSD) ----------------------------------------------------------------------- 25
9. Design Notes ---------------------------------------------------------------------------------------------- 26
9.1 External Components ---------------------------------------------------------------------------- 26
9.1.1
Input and output electrolytic capacitors ------------------------------------------------ 26
9.1.2
Resonant transformer ---------------------------------------------------------------------- 26
9.1.3
Current detection resistor, ROCP---------------------------------------------------------- 26
9.1.4
Current resonant capacitor, Ci ----------------------------------------------------------- 26
9.1.5
Gate Pin Peripheral Circuit --------------------------------------------------------------- 26
9.2 PCB Trace Layout and Component Placement --------------------------------------------- 26
10. Pattern Layout Example ------------------------------------------------------------------------------- 28
11. Reference Design of Power Supply ------------------------------------------------------------------ 29
IMPORTANT NOTES ------------------------------------------------------------------------------------- 32
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
2
SSC3S900 Series
1.
Absolute Maximum Ratings
● The polarity value for current specifies a sink as "+," and a source as "−," referencing the IC.
● Unless otherwise specified, TA is 25°C
Symbol
Pins
Rating
Unit
VSEN Pin Sink Current
ISEN
1 − 10
1.0
mA
Control Part Input Voltage
VCC
2 − 10
−0.3 to 35
V
FB Pin Voltage
VFB
3 − 10
−0.3 to 6
V
VSPL Pin Sink Current
ISPL
4 − 10
1.0
mA
CSS Pin Voltage
VCSS
5 − 10
−0.3 to 6
V
CL Pin Voltage
VCL
6 − 10
−0.3 to 6
V
RC Pin Voltage
VRC
7 − 10
−6 to 6
V
PL Pin Voltage
VPL
8 − 10
−0.3 to 6
V
SB Pin Sink Current
ISB
9 − 10
100
μA
VGL pin Voltage
VGL
11 − 10
−0.3 to VREG+0.3
V
REG pin Source Current
IREG
12 − 10
−10.0
mA
VB−VS
14 − 15
−0.3 to 19.2
V
VS Pin Voltage
VS
15 − 10
− 1 to 600
V
VGH Pin Voltage
VGH
16 − 10
VS−0.3 to VB+0.3
V
ST Pin Voltage
VST
18 − 10
−0.3 to 600
V
Operating Ambient Temperature
TOP
−
−40 to 85
°C
Storage Temperature
Tstg
−
−40 to 125
°C
Characteristic
Voltage Between VB Pin and VS Pin
Junction Temperature
TJ
−
150
°C
* Surge voltage withstand (Human body model) of No.14, 15, 16 and 18 is guaranteed 1000V. Other pins are
guaranteed 2000V.
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
3
SSC3S900 Series
2.
Electrical Characteristics
● The polarity value for current specifies a sink as "+," and a source as "−," referencing the IC.
● Unless otherwise specified, TA is 25 °C, VCC is 19 V
Characteristic
Symbol
Conditions
Pins
Min.
Typ.
Max.
Unit
Notes
Start Circuit and Circuit Current
Operation Start Voltage
VCC(ON)
2 − 10
12.9
14.0
15.1
V
Operation Stop Voltage
Startup Current Biasing Threshold
Voltage*
Circuit Current in Operation
VCC(OFF)
2 − 10
9.0
9.8
10.6
V
VCC(BIAS)
2 − 10
10.1
11.0
11.9
V
ICC(ON)
2 − 10
−
−
10.0
mA
Circuit Current in Non-Operation
ICC(OFF)
2 − 10
－
1.0
2.0
mA
Startup Current
VCC Pin Protection Circuit Release
Threshold Voltage (1)
VCC Pin Latch Protection Circuit
Release Threshold Voltage (2)
Circuit Current in Protection
ICC(ST)
2 − 10
3.0
6.0
9.0
mA
VCC(P.OFF)
2 − 10
9.0
9.8
10.6
V
SSC3S901
VCC(L.OFF)
2 − 10
6.5
7.8
9.0
V
SSC3S902
2 − 10
−
1.0
2.0
mA
28.5
32.0
35.5
kHz
230
300
380
kHz
0.20
0.35
0.50
µs
1.20
1.65
2.10
µs
70.0
74.0
78.0
kHz
ICC(P)
VCC = 9V
VCC = 11V
Oscillator
f(MIN)ADJ
11 – 10
16 − 15
11 – 10
16 − 15
11 – 10
16 − 15
11 – 10
16 − 15
11 – 10
RCSS = 30kΩ
16 − 15
VFB(ON)
3 – 10
0.15
0.30
0.45
V
VFB(OFF)
3 – 10
0.05
0.20
0.35
V
3 – 10
− 300
− 195
− 100
µA
5 – 10
− 120
− 105
− 90
µA
1.2
1.8
2.4
mA
f(MAX)SS
5 – 10
11 – 10
16 − 15
400
500
600
kHz
VSB(STB)
9 – 10
4.5
5.0
5.5
V
VSB(ON)
9 – 10
0.5
0.6
0.7
V
Minimum Frequency
f(MIN)
Maximum Frequency
f(MAX)
Minimum Dead-Time
td(MIN)
Maximum Dead-Time
td(MAX)
Externally Adjusted Minimum
Frequency
Feedback Control
FB Pin Oscillation Start Threshold
Voltage
FB Pin Oscillation Stop Threshold
Voltage
FB Pin Maximum Source Current
IFB(MAX)
VFB = 0V
Soft-start
CSS Pin Charging Current
ICSS(C)
CSS Pin Reset Current
ICSS(R)
Maximum Frequency in Soft-start
VCC = 9V
Standby
SB Pin Standby Threshold Voltage
SB Pin Oscillation Start Threshold
Voltage
(1)
(2)
VCC(P.OFF) = VCC(OFF) < VCC(BIAS) always.
VCC(L.OFF) < VCC(OFF) < VCC(BIAS) always.
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
4
SSC3S900 Series
Characteristic
SB Pin Oscillation Stop Threshold
Voltage
SB Pin Clamp Voltage
Symbol
Conditions
Pins
Min.
Typ.
Max.
Unit
VSB(OFF)
9 – 10
0.4
0.5
0.6
V
VSB(CLAMP)
9 – 10
6.1
6.7
7.4
V
SB Pin Source Current
ISB(SRC)
9 – 10
− 20
− 10
−4
µA
SB Pin Sink Current
ISB(SNK)
9 – 10
4
10
20
µA
Notes
Overload Protection (OLP) with Input Voltage Compensation
CL Pin Threshold Voltage (1)
VCL1
VSPL = 1V
6 – 10
4.40
4.69
4.88
V
CL Pin Threshold Voltage (2)
VCL2
VSPL = 2V
6 – 10
3.05
3.43
3.65
V
CL Pin Threshold Voltage (3)
VCL3
VSPL = 4V
6 – 10
1.60
1.83
2.05
V
CL Pin Threshold Voltage (4)
VCL4
VSPL = 5V
6 – 10
1.05
1.29
1.55
V
ICL
6 – 10
− 29
− 17
−5
μA
VSEN Pin Threshold Voltage (On)
VSEN(ON)
1 – 10
1.248
1.300
1.352
V
VSEN Pin Threshold Voltage (Off)
VSEN(OFF)
1 – 10
1.070
1.115
1.160
V
VSEN Pin Clamp Voltage
VSEN (CLAMP)
1 – 10
10.0
–
–
V
VSPL Pin Clamp Voltage
VSPL (CLAMP)
4 – 10
10.0
–
–
V
tRST(MAX)
11 – 10
16 − 15
4.0
5.0
6.0
µs
VREG
12 – 10
9.6
10.4
11.2
V
VBUV(ON)
14 – 15
6.3
7.3
8.3
V
VBUV(OFF)
14 – 15
5.5
6.4
7.2
V
11 – 10
16 − 15
–
– 540
–
A
11 – 10
16 − 15
–
1.50
–
A
11 – 10
− 140
16 − 15
− 90
− 40
mA
11 – 10
16 − 15
140
250
360
mA
0.02
0.10
0.18
V
CL Pin Source Current
Brown-In and Brown-Out
Reset Detection
Maximum Reset Time
Driver Circuit Power Supply
VREG Pin Output Voltage
High-side Driver
High-side Driver Operation Start
Voltage
High-side Driver Operation Stop
Voltage
Driver Circuit
VGL,VGH Pin Source Current 1
IGL(SRC)1
IGH(SRC)1
VGL,VGH Pin Sink Current 1
IGL(SNK)1
IGH(SNK)1
VGL,VGH Pin Source Current 2
IGL(SRC)2
IGH(SRC)2
VGL,VGH Pin Sink Current 2
IGL(SNK)2
IGH(SNK)2
VREG = 10.5V
VB = 10.5V
VGL = 0V
VGH = 0V
VREG = 10.5V
VB = 10.5V
VGL = 10.5V
VGH = 10.5V
VREG = 12V
VB = 12V
VGL = 10.5V
VGH = 10.5V
VREG = 12V
VB = 12V
VGL = 1.5V
VGH = 1.5V
Current Resonant and Overcurrent Protection(OCP)
Capacitive Mode Detection Voltage 1
VRC1
7 – 10
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
− 0.18 − 0.10 − 0.02
V
5
SSC3S900 Series
Characteristic
Symbol
Conditions
Pins
Min.
Typ.
Max.
Unit
0.35
0.50
0.65
V
Capacitive Mode Detection Voltage 2
VRC2
7 – 10
RC Pin Threshold Voltage (Low)
VRC(L)
7 – 10
RC Pin Threshold Voltage
(High speed)
VRC(S)
7 – 10
ICSS(L)
5 – 10
1.2
1.8
2.4
mA
ICSS(S)
5 – 10
13.0
20.5
28.0
mA
VCC(OVP)
2 – 10
29.5
32.0
34.5
V
Tj(TSD)
−
140
–
–
°C
θj-A
−
−
−
95
°C/W
CSS Pin Sink Current (Low)
CSS Pin Sink Current
(High speed)
− 0.65 − 0.50 − 0.35
1.42
1.50
1.58
− 1.58 − 1.50 − 1.42
2.15
2.30
2.45
− 2.45 − 2.30 − 2.15
Notes
V
V
V
V
V
Overvoltage Protection (OVP)
VCC Pin OVP Threshold Voltage
Thermal Shutdown (TSD)
Thermal Shutdown Temperature
Thermal Resistance
Junction to Ambient Thermal
Resistance
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
6
SSC3S900 Series
3.
Block Diagram
ST
18
High Side Driver
STARTUP
14
VB
UVLO
VCC
GND
VSEN
SB
FB
CSS
2
START/STOP/
REG/BIAS/
OVP
16
LEVEL
SHIFT
15
10
VCC
GND
1
9
3
5
VGH
VS
INPUT
SENSE
12
11
MAIN
STANDBY
CONTROL
RC DETECTOR
DEAD
TIME
FREQ.
CONTROL
FB CONTROL
FREQ.
MAX
SOFT-START/
OC/FMINADJ
7
REG
VGL
RC
dv/dt
DETECTOR
OC DETECTOR
6
PL DETECTOR/
OLP
8
4
CL
PL
VSPL
BD_SSC3S900_R2
4.
Pin Configuration Definitions
Number
1
Name
VSEN
ST 18
2
VCC
3
FB
4
VSPL
5
CSS
6
CL
7
RC
8
PL
9
10
11
12
13
14
15
16
17
18
SB
GND
VGL
REG
(NC)
VB
VS
VGH
(NC)
ST
1
VSEN
2
VCC
(NC) 17
3
FB
VGH 16
4
VSPL
VS 15
5
CSS
VB 14
6
CL
(NC) 13
7
RC
REG 12
8
PL
VGL 11
9
SB
GND 10
Function
The mains input voltage detection signal input
Supply voltage input for the IC, and Overvoltage
Protection (OVP) signal input
Feedback signal input for constant voltage control
The input voltage detection signal input for OLP
Input Voltage Compensation
Soft-start capacitor connection
OLP Input Voltage Compensation capacitor
connection
Resonant current detection signal input, and
Overcurrent Protection (OCP) signal input
Resonant current detection signal input for OLP
Input Voltage Compensation
Standby mode change signal input
Ground
Low-side gate drive output
Supply voltage output for gate drive circuit
−
Supply voltage input for high-side driver
Floating ground for high-side driver
High-side gate drive output
−
Startup current input
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
7
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
C9
PC1
R7
R3
C10
SB
PL
RC
CL
CSS
VSPL
FB
VCC
VSEN
R15
R2
R16
Q1R17
9
8
7
6
5
4
3
2
1
U1
SSC3S900
R8
R6
ROCP
C8
C7
C6
R5
C5
R4
C4
C1
BR1
PC2
10
11
12
13
14
15
16
17
18
R15 D5
C11
GND
VGL
R13
C2
R14
R11
D4
R12
NC
D3
REG R16
D6
VB
VGH
C12 R10
VS
NC
ST
Q(L)
Q(H)
R1
Ci
CV
D1
C3
T1
D54
D52
D51
D53
C51
C52
PC1
Q51
PC2
R59
R58
R57
R55
R56
C53
C55
R53
C54
R51
R52
R54
Standby
VOUT2
GND
VOUT1
5.
Main Input
VAC
SSC3S900 Series
Typical Application
8
SSC3S900 Series
6.
External Dimensions
● SOP18
NOTES:
● Dimension is in millimeters
● Pb-free. Device composition compliant with the RoHS directive
7.
Marking Diagram
18
SSC3S90×
Part Number
SKYMD
XXXX
1
Lot Number
Y is the last digit of the year (0~9)
M is the month (1~9, O, N or D)
D is a period of days (1 ~ 3):
1 : 1st ~ 10th
2 : 11th ~ 20th
3 : 21th ~ 31st
Sanken Control Number
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
9
SSC3S900 Series
8.
Operational Description
All of the parameter values used in these descriptions
are typical values, unless they are specified as minimum
or maximum. With regard to current direction, "+"
indicates sink current (toward the IC) and "–" indicates
source current (from the IC).
Q(H) and Q(L) indicate a high-side power MOSFET and
a low-side power MOSFET respectively. Ci, and CV
indicate a current resonant capacitor and a voltage
resonant capacitor respectively.
8.1
Resonant Circuit Operation
Figure 8-1 shows a basic RLC series resonant circuit.
R
Figure 8-1
L
C
RLC series resonant circuit
The impedance of the circuit, Ż, is as the following
Equation.
(1)
The frequency in which Ż becomes minimum value is
the resonant frequency, f0. The higher frequency area
than f0 is the inductance area, and the lower frequency
area than f0 is the capacitance area.
From Equation (3), f0 is as follows;
(4)
Figure 8-3 shows the circuit of a current resonant
power supply. The basic configuration of the current
resonant power supply is a half-bridge converter. The
switching device Q(H) and Q(L) are connected in series
with VIN. The series resonant circuit and the voltage
resonant capacitor CV are connected in parallel with Q(L).
The series resonant circuit is comprised of a resonant
inductor LR, a primary winding P of a transformer T1
and a current resonant capacitor Ci.
In the resonant transformer T1, the coupling between
primary winding and secondary winding is designed to
be poor so that the leakage inductance increases. By
using it as LR, the series resonant circuit can be down
sized. The dotted mark in T1 shows the winding polarity,
the secondary windings S1 and S2 are connected so that
the polarities are set to the same position shown in
Figure 8-3, and the winding numbers of each other are
equal.
From Equation (1), the impedance of current resonant
power supply is calculated by Equation (5). From
Equation (4), the resonant frequency, f0, is calculated by
Equation (6).
where, ω is angular frequency and ω = 2πf.
(5)
(2)
(6)
When the frequency, f, changes, the impedance of
resonant circuit will change as shown in Figure 8-2
Inductance area
Impedance
Capacitance area
where,
R: the equivalent resistance of load
LR: the inductance of the resonant inductor
LP: the inductance of the primary winding P
Ci: the capacitance of current resonant capacitor
ID(H)
R
Q(H)
f0
Frequency
Series resonant circuit
VDS(H)
VGH
LR
T1
IS1
VIN
Figure 8-2
ID(L)
Impedance of resonant circuit
Q(L)
Cv
P
VOUT
(+)
S1
LP
In Equation (2), Ż becomes minimum value (= R) at
2πfL = 1/2πfC, and then ω is calculated by Equation
(3) .
VGL
VDS(L)
VCi
ICi
(3)
Figure 8-3
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
S2
Ci
(−)
IS2
Current resonant power supply circuit
10
SSC3S900 Series
In the current resonant power supply, Q(H) and Q(L) are
alternatively turned on and off. The on time and off time
of them are equal. There is a dead time between Q(H) on
period and Q(L) on period. During the dead time, both
Q(H) and Q(L) are in off status.
The current resonant power supply is controlled by
the frequency control. When the output voltage
decreases, the IC makes the switching frequency low so
that the output power is increased and the output voltage
is kept constant. This control must operate in the
inductance area (fSW > f0). Since the winding current is
delayed from the winding voltage in the inductance area,
the turn-on operation is ZCS (Zero Current Switching)
and the turn-off operation is ZVS (Zero Voltage
Switching). Thus, the switching loss of Q(H) and Q(L) is
nearly zero,
In the capacitance area (fSW < f0), the current resonant
power supply operates as follows. When the output
voltage decreases, the switching frequency is decreased,
and then the output power is more decreased. Thus, the
output voltage cannot be kept constant. Since the
winding current goes ahead of the winding voltage in the
capacitance area, the operation with hard switching
occurs in Q(H) and Q(L). Thus, the power loss increases.
This operation in the capacitance area is called the
capacitive mode operation. The current resonant power
supply must be operated without the capacitive mode
operation (refer to Section 8.12 about details of it).
Figure 8-4 shows the basic operation waveform of
current resonant power supply (see Figure 8-3 about the
symbol in Figure 8-4). The current resonant waveforms
in normal operation are divided a period A to a period F.
The current resonant power supply operates in the each
period as follows.
In following description,
ID(H) is the current of Q(H),
ID(L) is the current of Q(L),
VF(H) is the forwerd voltage of Q(H),
VF(L) is the forwerd voltage of Q(L),
IL is the current of LR,
VIN is an input voltage,
VCi is Ci voltage, and
VCV is CV voltage.
1) Period A
When Q(H) is ON, energy is stored into the series
resonant circuit by ID(H) flowing through the resonant
circuit and the transformer as shown in Figure 8-5. At
the same time, the energy is transferred to the
secondary circuit. When the primary winding voltage
can not keep the secondary rectifier ON, the energy to
the secondary circuit is stopped.
2) Period B
After the secondary side current becomes zero, the
resonant current flows to the primary side only as
shown in Figure 8-6 and Ci is charged by it.
VGH
VGL
VDS(H)
VIN+VF(H)
ID(H)
VDS(L)
ID(L)
ICi
VCi
VIN
IS1
IS2
A
B
D
E
C
Figure 8-4
F
The basic operation waveforms of current
resonant power supply
Q(H)
ID(H)
ON
LR
LP
VIN
S1
Q(L)
IS1
Cv
VCV
OFF
S2
Ci
VCi
Figure 8-5
Operation in period A
Q(H)
ID(H)
ON
LR
LP
VIN
S1
Q(L)
Cv
OFF
S2
Ci
Figure 8-6
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
Operation in period B
11
SSC3S900 Series
3) Period C
Pireod C is the dead-time. Both Q(H) and Q(L) are in
off-state.
When Q(H) turns off, IL is flowed by the energy stored
in the series resonant circuit as shown in Figure 8-7,
and CV is discharged. When VCV decreases to VF(L),
−ID(L) flows through the body diode of Q(L) and VCV is
clamped to VF(L).
After that, Q(L) turns on. Since VDS(L) is nearly zero at
the point, Q(L) operates in ZVS and ZCS. Thus,
switching loss is nearly zero.
Q(H)
LR
OFF
LP
VIN
IL
Q(L)
Cv
VCV
OFF
-ID(L)
Ci
Figure 8-7
4) Period D
When Q(L) turns on, ID(L) flows as shown in Figure 8-8
and the primary winding voltage of the transformer
adds VCi. At the same time, energy is transferred to
the secondary circuit. When the primary winding
voltage can not keep the secondary rectifier ON, the
energy to the secondary circuit is stopped.
Q(H)
LR
OFF
LP
VIN
ID(L)
Q(L)
S1
Cv
ON
5) Period E
After the secondary side current becomes zero, the
resonant current flows to the primary side only as
shown in Figure 8-9 and Ci is charged by it.
S2
IS2
Ci
VCi
Figure 8-8
6) Period F
This pireod is the dead-time. Both Q(H) and Q(L) are in
off-state.
When Q(L) turns off, − IL is flowed by the energy
stored in the series resonant circuit as shown in Figure
8-10. CV is discharged. When VCV decreases to VIN +
VF(H), − ID(H) flows through body diode of Q(H) and
VCV is clamped to VIN + VF(H).
After that, Q(H) turns on. Since VDS(H) is nearly zero at
the point, Q(H) operates in ZVS and ZCS. Thus, the
switching loss is nearly zero.
Operation in period C
Operation in period D
Q(H)
LR
OFF
LP
VIN
ID(L)
Q(L)
S1
Cv
ON
S2
Ci
Figure 8-9
7) After the Period F
Then, ID(H) flows and the operation returns to the
period A.
Operation in period E
Q(H)
The above operation is repeated, the energy is
transferred to the secondary side from the resonant
circuit.
-ID(H)
LR
OFF
LP
VIN
-IL
Q(L)
VCV
OFF
Cv
Ci
Figure 8-10
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
Operation in period F
12
SSC3S900 Series
8.2
Startup Operation
8.3
Figure 8-11 shows the VCC pin peripheral circuit.
When the following all conditions are fulfilled, the IC
starts the startup operation:
● The mains input voltage is provided, and the VSEN
pin voltage increases to the on-threshold voltage,
VSEN(ON) = 1.300 V, or more.
● The startup current, ICC(ST), which is a constant current
of 6.0 mA, is provided from the IC to capacitor C2
connected to the VCC pin, C2 is charged, and the
VCC pin voltage increases to the operation start
voltage, VCC(ON) = 14.0 V, or more.
● The FB pin voltage increases to the oscillation start
threshold voltage, VFB(ON) = 0.30 V, or more.
Undervoltage Lockout (UVLO)
Figure 8-12 shows the relationship of VCC and ICC.
After the IC starts operation, when the VCC pin
voltage decreases to VCC(OFF) = 9.8 V, the IC stops
switching operation by the Undervoltage Lockout
(UVLO) Function and reverts to the state before startup
again.
ICC
Stop
Start
After that, the startup circuit stops automatically, in
order to eliminate its own power consumption.
VCC（OFF）
R2
1
C1
18
ST
VSEN
R3
U1
VCC
VSPL
CSS
GND
5
10
R4 R5
C6
2
R1 D1
Figure 8-12
VCC（ON） VCC pin
voltage
VCC versus ICC
4
C4
VD
8.4
C2
Bias Assist Function
Figure 8-13 shows the VCC pin voltage behavior
during the startup period.
Figure 8-11
VCC pin peripheral circuit
VCC pin voltage
IC startup
During the IC operation, the rectified voltage from the
auxiliary winding voltage, VD, of Figure 8-11 is a power
source to the VCC pin.
The winding turns of the winding D should be
adjusted so that the VCC pin voltage is applied to
equation (7) within the specification of the mains input
voltage range and output load range of the power supply.
The target voltage of the winding D is about 19 V.
VCC(ON)
VCC(BIAS)
VCC(OFF)
Startup success
Target
operating
voltage
Increasing by output
voltage rising
Bias Assist period
Startup failure
Time
Figure 8-13
⇒11.0 (V) < VCC < 32.0 (V)
VCC pin voltage during startup period
(7)
The startup time, tSTART, is determined by the value of
C2 and C6 connected to the CSS pin. Since the startup
time for C6 is much smaller than that for C2, the startup
time is approximately given as below:
(8)
where:
tSTART is the startup time in s,
VCC(INT) is the initial voltage of the VCC pin in V, and
ICC(ST) is the startup current, 6.0 mA
When the conditions of Section 8.2 are fulfilled, the
IC starts operation. Thus, the circuit current, ICC,
increases, and the VCC pin voltage begins dropping. At
the same time, the auxiliary winding voltage, VD,
increases in proportion to the output voltage rise. Thus,
the VCC pin voltage is set by the balance between
dropping due to the increase of ICC and rising due to the
increase of the auxiliary winding voltage, VD. When the
VCC pin voltage decreases to VCC(OFF) = 9.8 V, the IC
stops switching operation and a startup failure occurs.
In order to prevent this, when the VCC pin voltage
decreases to the startup current threshold biasing voltage,
VCC(BIAS) = 11.0 V, the Bias Assist Function is activated.
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
13
SSC3S900 Series
While the Bias Assist Function is activated, any
decrease of the VCC pin voltage is counteracted by
providing the startup current, ICC(ST), from the startup
circuit. It is necessary to check the startup process based
on actual operation in the application, and adjust the
VCC pin voltage, so that the startup failure does not
occur. If VCC pin voltage decreases to VCC(BIAS) and the
Bias Assist Function is activated, the power loss
increases.
Thus, VCC pin voltage in normal operation should be
set more than VCC(BIAS) by the following adjustments.
When the IC becomes any of the following conditions,
C6 is discharged by the CSS Pin Reset Current,
ICSS(R) = 1.8 mA.
● The turns ratio of the auxiliary winding to the
secondary-side winding is increased.
● The value of C2 in Figure 8-11 is increased and/or the
value of R1 is reduced.
8.6
During all protection operation, the Bias Assist
Function is disabled.
8.5
Soft Start Function
Figure
8-14
waveforms.
CSS pin
voltage
shows
the
Soft-start
operation
Frequency control
by feedback signal
OCP operation
● The VCC pin voltage decreases to the operation stop
voltage, VCC(OFF) = 9.8 V, or less.
● The VSEN pin voltage decreases to the off-threshold
voltage, VSEN(OFF) = 1.0 V, or less.
● Any of protection operations in protection mode
(OVP, OLP or TSD) is activated.
Minimum and Maximum Switching
Frequency Setting
The minimum switching frequency is adjustable by
the value of R5 (RCSS) connected to the CSS pin. The
relationship of R5 (RCSS) and the externally adjusted
minimum frequency, f(MIN)ADJ, is shown in Figure
8-15.
The f(MIN)ADJ should be adjusted to more than the
resonant frequency, f0, under the condition of the
minimum mains input voltage and the maximum output
power. The maximum switching frequency, fMAX, is
determined by the inductance and the capacitance of the
resonant circuit. The fMAX should be adjusted to less than
the maximum frequency, f(MAX) = 300 kHz.
peropd
90
Soft-start
period
0
Time
Primary-side
winding current
OCP limit
0
Figure
f(M(N)ADJ (kHz)
80
C6 is charged by ICSS(C)
Time
1 The maximum frequency during normal operation is
f(MAX) = 300 kHz.
60
50
40
8-14 Soft-start operation
The IC has Soft Start Function to reduce stress of
peripheral component and prevent the capacitive mode
operation. During the soft start operation, C6 connected
to the CSS pin is charged by the CSS Pin Charge
Current, ICSS(C) = − 105 μA. The oscillation frequency is
varied by the CSS pin voltage. The switching frequency
gradually decreases from f(MAX)SS1 = 500 kHz at most,
according to the CSS pin voltage rise. At same time,
output power increases. When the output voltage
increases, the IC is operated with an oscillation
frequency controlled by feedback.
70
8.7
20
30
40
50
RCSS (kΩ)
60
Figure
8-15 R5 (RCSS) versus f(MIN)ADJ
70
High-side Driver
Figure 8-16 shows a bootstrap circuit. The bootstrap
circuit is for driving to Q(H) and is made by D3, R12 and
C12 between the REG pin and the VS pin. When Q(H) is
OFF state and Q(L) is ON state, the VS pin voltage
becomes about ground level and C12 is charged from
the REG pin.
When the voltage of between the VB pin and the VS
pin, VB-S, increases to VBUV(ON) = 7.3 V or more, an
internal high-side drive circuit starts operation. When
VB-S decreases to VBUV(OFF) = 6.4 V or less, its drive
circuit stops operation. In case the both ends of C12 and
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
14
SSC3S900 Series
D4 are short, the IC is protected by VBUV(OFF). D4 for
protection against negative voltage of the VS pin
● D3
D3 should be an ultrafast recovery diode of short
recovery time and low reverse current. As for
Sanken’s diode lineup, AG01A (VRM = 600 V) of
UFRD series is recommended for the specification
that the maximum mains input voltage is 265VAC.
● C11, C12, and R12
The values of C11, C12, and R12 are determined by
total gate charge, Qg, of external MOSFET and
voltage dip amount between the VB pin and the VS
pin in the burst mode of the standby mode change.
C11, C12, and R12 should be adjusted so that the
voltage between the VB pin and the VS is more than
VBUV(ON) = 7.3 V by measuring the voltage with a
high-voltage differential probe.
The reference value of C11 is 0.47μF to 1 μF.
The time constant of C12 and R12 should be less than
500 ns. The values of C12 and R22 are 0.047μF to 0.1
μF, and 2.2 Ω to 10 Ω.
C11 and C12 should be a film type or ceramic
capacitor of low ESR and low leakage current.
inductance area).
The feedback current increases under slight load
condition, and thus the FB pin voltage decreases. While
the FB pin voltage decreases to the oscillation stop
threshold voltage, VFB(OFF) = 0.20 V, or less, the IC stops
switching operation. This operation reduces switching
loss, and prevents the increasing of the secondary output
voltage.
In Figure
8-17, R8 and C9 are for phase
compensation adjustment, and C5 is for high frequency
noise rejection. The secondary-side circuit should be
designed so that the collector current of PC1 is more
than 195 μA which is the absolute value of the
maximum source current, IFB(MAX). Especially the current
transfer ratio, CTR, of the photo coupler should be taken
aging degradation into consideration.
U1
FB
3
C9
Figure
8.9
VS
16
Q(H)
T1
15
C12
D4
VB 14
Cv
R12
U1
REG
VGL
GND
12
D3
Q(L)
11
10
Ci
C11
Bootstrap circuit
Figure 8-16
8.8
Bootstrap circuit
Constant Voltage Control Operation
Figure 8-17 shows the FB pin peripheral circuit. The
FB pin is sunk the feedback current by the photo-coupler,
PC1, connected to FB pin. As a result, since the
oscillation frequency is controlled by the FB pin, the
output voltage is controlled to constant voltage (in
R8
C5
● D4
D4 should be a Schottky diode of low forward voltage,
VF, so that the voltage between the VB pin and the VS
pin must not decrease to the absolute maximum
ratings of −0.3 V or less.
VGH
GND
10
PC1
8-17 FB pin peripheral circuit
Standby Function
The IC has the Standby Function in order to increase
circuit efficiency in light load.
When the Standby Function is activated, the IC
operates in the burst oscillation mode as shown in Figure
8-18.The burst oscillation has periodic non-switching
intervals. Thus, the burst mode reduces switching losses.
Generally, to improve efficiency under light load
conditions, the frequency of the burst mode becomes
just a few kilohertz. In addition, the IC has the Soft-on
and the Soft-off Function in order to suppress rapid and
sharp fluctuation of the drain current during the burst
mode. thus, the audible noises can be reduced (refer to
Section 8.9.2).
The operation of the IC changes to the standby
operation by the external signal (refer to Section 8.9.1).
Primary-side main
winding current
Switching period
Non-switching period
Soft-on
Time
Soft-off
Figure 8-18
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
Standby waveform
15
SSC3S900 Series
8.9.1
Standby Mode Changed by External
Signal
Figure 8-19 shows the standby mode change circuit
with external signal. Figure 8-20 shows the standby
change operation waveforms. When the standby
terminal of Figure 8-19 is provided with the L signal, Q1
turns off, C10 connected to the SB pin is discharged by
the sink current, ISB(SNK) = 10 µA, and the SB pin voltage
decreases. When the SB pin voltage decrease to the SB
Pin Oscillation Stop Threshold Voltage, VSB(OFF) = 0.5 V,
the operation of the IC is changed to the standby mode.
When SB pin voltage is VSB(OFF) = 0.5 V or less and FB
pin voltage is Oscillation Stop Threshold Voltage
VFB(OFF) = 0.20 V or less, the IC stops switching
operation.
When the standby terminal is provided with the H
signal and the SB pin voltage increases to Standby
Threshold Voltage VSB(STB) = 5.0 V or more, the IC
returns to normal operation.
8.9.2
Burst Oscillation Operation
In standby operation, the IC operates burst oscillation
where the peak drain current is suppressed by Soft-on
/Soft-off Function in order to reduce audible noise from
transformer. During burst oscillation operation, the
switching oscillation is controlled by SB pin voltage.
Figure 8-21 shows the burst oscillation operation
waveforms.
Output current
0
Output voltage
0
FB pin voltage
VFB(ON)
VFB(OFF)
0
Charged
by ISB(SRC)
SB pin voltage
REG
12
Discharged
by ISB(SNK)
VSB(ON)
C11
U1
VSB(OFF)
0
FB
SB
3 R8
9
R58
R16
Q1
R15
PC2
R17
C5
Primary-side
main winding
current
C10
0
Standby
Soft-on
Soft-off
Time
Q51
R59
C9
PC1
PC2
Figure 8-19
Standby
Standby mode change circuit
H
0
SB pin voltage
GND
H
L
Standby operation
Discharging
by ISB(SNK)
VSB(OFF)
VSB(STB)
0
FB pin voltage
VFB(OFF)
0
Primary-side
main winding
current
0
Switching stop
Figure 8-20
Time
Standby change operation waveforms
Figure 8-21
Burst oscillation operation waveforms
When the SB pin voltage decreases to VSB(OFF) = 0.5 V
or less and the FB pin voltage decreases to
VFB(OFF) = 0.20 V or less, the IC stops switching
operation and the output voltage decreases.
Since the output voltage decreases, the FB pin voltage
increases. When the FB pin voltage increases to the
oscillation start threshold voltage, VFB(ON) = 0.30 V, C10
is charged by ISB(SRC) = − 10 µA, and the SB pin voltage
gradually increases.
When the SB pin voltage increases to the oscillation
start threshold voltage, VSB(ON) = 0.6 V, the IC resumes
switching operation, controlling the frequency control
by the SB pin voltage. Thus, the output voltage increases
(Soft-on). After that, when FB pin voltage decrease to
oscillation stop threshold voltage, VFB(OFF) = 0.20 V, C10
is discharged by ISB(SNK) = 10 µA and SB pin voltage
decreases. When the SB pin voltage decreases to
VSB(OFF) again, the IC stops switching operation. Thus,
the output voltage decreases (Soft-off).
The SB pin discharge time in the Soft-on and Soft-off
Function depends on C10. When the value of C10
increases, the Soft-on/Soft-off Function makes the peak
drain current suppressed, and makes the burst period
longer. Thus, the output ripple voltage may increase
and/or the VCC pin voltage may decrease.
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
16
SSC3S900 Series
If the VCC pin voltage decreases to VCC(BIAS) = 11.0 V,
the Bias Assist Function is always activated, and it
results in the increase of power loss (refer to Section
8.4).
Thus, it is necessary to adjust the value of C10 while
checking the input power, the output ripple voltage, and
the VCC pin voltage. The reference value of C10 is
about 0.001 μF to 0.1 μF.
actual operation in the application.
U1
VGH
RV
DETECTOR
VS 15
VGL
Main
T1
16
VDS(L)
Cv
11
GND
10
8.10 Automatic Dead Time Adjustment
Function
The dead time is the period when both the high-side
and the low-side power MOSFETs are off.
As shown in Figure 8-22, if the dead time is shorter
than the voltage resonant period, the power MOSFET is
turned on and off during the voltage resonant operation.
In this case, the power MOSFET turned on and off in
hard switching operation, and the switching loss
increases. The Automatic Dead Time Adjustment
Function is the function that the ZVS (Zero Voltage
Switching) operation of Q(H) and Q(L) is controlled
automatically by the voltage resonant period detection of
IC. The voltage resonant period is varied by the power
supply specifications (input voltage and output power,
etc.). However, the power supply with this function is
unnecessary to adjust the dead time for each power
supply specification.
VGL
VGH
Q(H) D-S voltage,
VDS(H)
Dead time
Loss increase by hard
switching operation
Low-side, VDS(L) On
Ci
dv Off
dt
dt
On
Dead time period
Figure 8-23
VS pin and dead time period
Q(H) drain current,
ID(H)
Flows through body
diode about 1μs
Figure 8-24
ZCS check point
8.11 Brown-In and Brown-Out Function
Figure 8-25 shows the VSEN pin peripheral circuit.
This function detects the mains input voltage, and stops
switching operation during low mains input voltage, to
prevent exceeding input current and overheating.
R2 to R4 set the detection voltage of this function.
When the VCC pin voltage is higher than VCC(ON), this
function operates depending on the VSEN pin voltage as
follows:
● When the VSEN pin voltage is more than V SEN
(ON) = 1.300 V, the IC starts.
Voltage resonant period
Figure 8-22
ZVS failure operation waveform
As shown in Figure 8-23, the VS pin detects the dv/dt
period of rising and falling of the voltage between drain
and source of the low-side power MOSFET, VDS(L), and
the IC sets its dead time to that period. This function
controls so that the high-side and the low-side power
MOSFETs are automatically switched to Zero Voltage
Switching (ZVS) operation. This function operates in the
period from td(MIN) = 0.35 µs to td(MAX) = 1.65 µs.
In minimum output power at maximum input voltage
and maximum output power at minimum input voltage,
the ZCS (Zero Current Switching) operation of IC (the
drain current flows through the body diode is about 1 μs
as shown in Figure 8-24), should be checked based on
When the VSEN pin voltage is less than VSEN
1.0 V, the IC stops switching operation.
(OFF) =
VAC
R2
1
VDC
C1
R3
U1
4
C4
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
VSPL
R4
10
Figure 8-25
VSEN
GND
VSEN pin peripheral circuit
17
SSC3S900 Series
Capacitance area
Inductance area
Impedance
Given, the DC input voltage when the IC starts as
VIN(ON), the DC input voltage when the switching
operation of the IC stops as VIN(OFF). VIN(ON) is calculated
by Equation (9). VIN(OFF) is calculated by Equation (10).
Thus, the relationship between VIN(ON) and VIN(OFF) is
Equation (11).
Operating area
(9)
f0
Resonant fresuency
Hard switching
Sift switching
(10)
(11)
Uncontrollable operation
The detection resistance is calculated from Equation
(9) as follows:
(12)
Because R2 and R3 are applied high DC voltage and
are high resistance, the following should be considered:
● Select a resistor designed against electromigration
according to the requirement of the application, or
● Use a combination of resistors in series for that to
reduce each applied voltage
The reference value of R2 is about 10 MΩ.
C4 shown in Figure 8-25 is for reducing ripple
voltage of detection voltage and making delay time. The
value is 0.1 µF or more, and the reference value is about
0.47 µF.
The value of R2, R3 and R4 and C4 should be
selected based on actual operation in the application.
8.12 Capacitive Mode Detection Function
The resonant power supply is operated in the
inductance area shown in Figure 8-26. In the capacitance
area, the power supply becomes the capacitive mode
operation (refer to Section 8.1). In order to prevent the
operation, the minimum oscillation frequency is needed
to be set higher than f0 on each power supply
specification.
However, the IC has the capacitive mode operation
Detection Function kept the frequency higher than f0.
Thus, the minimum oscillation frequency setting is
unnecessary and the power supply design is easier. In
addition, the ability of transformer is improved because
the operating frequency can operate close to the resonant
frequency, f0.
Figure 8-26
Operating area of resonant power supply
The resonant current is detected by the RC pin, and
the IC prevents the capacitive mode operation.
When the capacitive mode is detected, the C7
connected to CL pin is charged by ICL(SRC) = − 17 μA.
When the CL pin voltage increases to VCL(OLP), the OLP
is activated and the switching operation stops. During
the OLP operation, the intermittent operation by UVLO
is repeated (refer to Section 8.17). The detection voltage
is changed to VRC1 = ±0.10 V or VRC2 = ±0.50 V
depending on the load as shown in Figure 8-28 and
Figure 8-29. The Capacitive Mode Operation Detection
Function operations as follows:
● Period in which the Q(H) is ON
Figure 8-27 shows the RC pin waveform in the
inductance area, and Figure 8-28 and Figure 8-29
shows the RC pin waveform in the capacitance area.
In the inductance area, the RC pin voltage doesn’t
cross the plus side detection voltage in the downward
direction during the on period of Q(H) as shown in
Figure 8-27.
On the contrary, in the capacitance area, the RC pin
voltage crosses the plus side detection voltage in the
downward direction. At this point, the capacitive
mode operation is detected. Thus, Q(H) is turned off,
and Q(L) is turned on, as shown in Figure 8-28 and
Figure 8-29.
● Period in which the Q(L) is on
Contrary to the above of Q(H), in the capacitance area,
the RC pin voltage crosses the minus side detection
voltage in the upward directiont during the on period
of Q(L) At this point, the capacitive mode operation is
detected. Thus, Q(L) is turned off and Q(H) is turned on.
As above, since the capacitive mode operation is
detected by pulse-by-pulse and the operating frequency
is synchronized with the frequency of the capacitive
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
18
SSC3S900 Series
mode operation, and the capacitive mode operation is
prevented. In addition to the adjusting method of ROCP,
C3, and R6 in Section 8.16, ROCP, C3, and R6 should be
adjusted so that the absolute value of the RC pin voltage
increases to more than |VRC2| = 0.50 V under the
condition caused the capacitive mode operation easily,
such as startup, turning off the mains input voltage, or
output shorted. The RC pin voltage must be within the
absolute maximum ratings of −6 to 6 V
the equivalent to ICC(ST) = 6.0 mA.
D7
6 mA
(ICC(ST))
R2
Main input→Off
D8
C1
1
R3
VDS(H)
OFF
4
ON
RC pin
voltage
R4
18
ST
VSEN
U1
VSPL
GND
10
+VRC
0
Figure 8-27
Figure 8-30
RC pin voltage in inductance area
VDS(H)
0
OFF
ON
Capacitive mode
operation detection
RC pin
voltage +VRC2
+VRC1
0
Figure 8-28
High side capacitive mode detection in
light load
VDS(H)
0
RC pin
voltage +VRC2
+VRC1
0
OFF
ON
Capacitive mode
operation detection
Input capacitor discharge
8.14 Reset Detection Function
The magnetizing current means the circulating current
applied for resonant operation, and that flows only into
the primary-side circuit. During the startup period when
the feedback control for the output voltage is inactive, if
the magnetizing current cannot be reset in the on-period
because of unbalanced operation, negative current may
flows just before a power MOSFET turns off, and hard
switching may occur, and stresses of power MOSFET
may increase. To prevent this hard switching, the IC
incorporates the Reset Detection Function.
Figure 8-32 shows the high-side operation and drain
current waveform examples in normal resonant
operation and reset failure operation. Figure 8-31 shows
the reset detection operation example at the high-side
on-period.
VGH pin
voltage Low
High
VGL pin High
voltage
Low
Turning-on
in negative drain current
ID(H)
Figure 8-29
High side capacitive mode detection in
heavy load
Reset failure waveform
VRC= +0.1V
0
8.13 Input Electrolytic Capacitor
Discharge Function
Figure 8-30 shows an application that residual voltage
of the input capacitor, C1, is reduced after turning off
the mains input voltage. R2 is connected to the AC input
lines through D7 and D8. Just after turning off the mains
input voltage, the VSEN pin voltage decreases to
VSEN(OFF) = 1.0 V according to a short time of the time
constant with R2 to R4 and C4, and C1 is discharged by
Expanded
on-period
Normal on-period
tRST(MAX) = 5μs
Figure 8-31 Reset detection operation example
at high-side on-period
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
19
SSC3S900 Series
The Reset Detection Function extends the on-period
until the absolute value of RC pin voltage, |VRC1|,
increases to 0.10 V or more. Thus, this function prevents
the hard switching operation. When the on-period
reaches the maximum reset time, tRST(MAX) = 5.0 μs, the
on-period expires at that moment, and the power
MOSFET turns off (refer to Figure 8-31).
○ Normal resonant operation
B
ID(H)
C
● Reset failure operation
ID(H)
Magnetizing
current
Point D
VDS(H)=0V
A
Point A
VDS(H)=0V
Q(H)
Lr
Q(L)
Lr
Q(L)
Cv
Off
Ci
Lp
ID(H)
Cv
Ci
Point E
VDS(H)=0V
Q(H)
Q(H)
Lr
On
Q(L)
Q(L)
Cv
Off
Ci
Q(H)
Off
Lp
Q(L)
Lp
ID(H)
Cv
Ci
Point F
Q(H)
Lr
Lr
On
Lp
ID(H)
Point C
Off
E
D
Off
Lp
ID(H)
Point B
VDS(H)=0V
Off
0
Q(H)
Off
Off
F
Recovery current
of body diode
ID(H)
Off
Lr
Lp
Q(L)
Cv
Ci
Turning on at VDS(L)= 0V results in　soft-switching
On
Cv
Ci
Turning on at VDS(L) >> 0V results in hard-switching
Figure 8-32 High-side operation and drain current waveform examples in normal resonant operation
and in reset failure operation
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
20
SSC3S900 Series
8.15 Overvoltage Protection (OVP)
When the voltage between the VCC pin and the GND
pin is applied to the OVP threshold voltage,
VCC(OVP) = 32.0 V, or more, the Overvoltage Protection
(OVP) is activated.
The IC has two operation types of OVP. One is the
auto restart. The other is latched shutdown.
When the auxiliary winding supplies the VCC pin
voltage, the OVP is able to detect an excessive output
voltage, such as when the detection circuit for output
control is open in the secondary-side circuit because the
VCC pin voltage is proportional to the output voltage.
The output voltage of the secondary-side circuit at
OVP operation, VOUT(OVP), is approximately given as
below:
(13)
decreases.
When VCC pin voltage decreases to VCC(OFF) = 9.8 V,
the startup circuit is activated. When VCC pin voltage
is increased to VCC(ON) = 14.0 V by startup current, the
startup circuit is turned off and VCC pin voltage
decreases. During the OVP operation, the latch state is
kept by turning on/off of the startup circuit.
The latched state is released by following condition:
VCC pin voltage is decreased to VCC(L.OFF) = 7.8 V or
less by turning off the input voltage,
or VSEN pin voltage is decreased to VSEN(OFF) = 1.0 V
or less.
VCC pin voltage
VCC(OVP)
VCC(L.OFF)
where,
VOUT(NORMAL) : Output voltage in normal operation
VCC(NORMAL): VCC pin voltage in normal operation
VCC pin voltage
VCC(OVP)
VCC(ON)
VCC(P.OFF)
0
VGH/VGL
0
Figure 8-33 Auto restart type
OVP operation waveforms
● Latched Shutdown Type: SSC3S902
Figure 8-34 shows the OVP operation waveforms of
latched shutdown type.
When the OVP is activated, the IC stops switching
operation at the latched state and VCC pin voltage
Release
VCC(ON)
VCC(OFF)
0
VGH/VGL
● Auto Restart Type: SSC3S901
Figure 8-33 shows the OVP operation waveforms of
auto restart type.
When the OVP is activated, the IC stops switching
operation and VCC pin voltage decreases. When VCC
pin voltage decreases to VCC(P.OFF) = 9.8 V, the OVP
operation is released and the startup circuit is
activated. When VCC pin voltage is increased to
VCC(ON) = 14.0 V by startup current, the IC starts the
switching operation. During the OVP operation, the
intermittent operation by UVLO is repeated.
When the fault condition is removed, the IC returns to
normal operation automatically.
Input voltage
turn off
Latch mode
0
Figure 8-34 Latched shutdown type
OVP operation waveforms
8.16 Overcurrent Protection (OCP)
The Overcurrent Protection (OCP) detects the drain
current, ID, on pulse-by-pulse basis, and limits output
power. In Figure 8-35, this circuit enables the value of
C3 for shunt capacitor to be smaller than the value of Ci
for current resonant capacitor, and the detection current
through C3 is small. Thus, the loss of the detection
resistor, ROCP, is reduced, and ROCP is a small-sized one
available. There is no convenient method to calculate the
accurate resonant current value according to the mains
input and output conditions, and others. Thus, ROCP, C3,
and C6 should be adjusted based on actual operation in
the application. The following is a reference adjusting
method of ROCP, C3, R6, and C8:
● C3 and ROCP
C3 is 100pF to 330pF (around 1 % of Ci value).
ROCP is around 100 Ω.
Given the current of the high side power MOSFET at
ON state as ID(H). ROCP is calculated Equation (14).
The detection voltage of ROCP is used the detection of
the capacitive mode operation (refer to Section 8.12).
Therefore, setting of ROCP and C3 should be taken
account of both OCP and the capacitive mode
operation.
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
(14)
21
SSC3S900 Series
● R6 and C8 are for high frequency noise reduction.
R6 is 100 Ω to 470 Ω. C6 is 100 pF to 1000 pF.
8.17 Overload Protection (OLP) with Input
Voltage Compensation
Q(H)
VGH
VS
U1
T1
15
Q(L)
VGL
CSS RC
5 7
16
11
10
PL GND
8 R7
Cv
I(H)
Ci
C3
R6
R5
C6 C8 ROCP
Figure 8-35 RC pin peripheral circuit
The OCP operation has two-step threshold voltage as
follows:
● Step I, RC pin threshold voltage (Low), VRC(L):
This step is active first. When the absolute value of
the RC pin voltage increases to more than
|VOC(L)| = 1.50 V, C6 connected to the CSS pin is
discharged by ICSS(L) = 1.8 mA. Thus, the switching
frequency increases, and the output power is limited.
During discharging C6, when the absolute value of
the RC pin voltage decreases to |VRC(L)| or less, the
discharge stops.
● Step II, RC pin threshold voltage (High-speed),
VRC(S):
This step is active second. When the absolute value of
the RC pin voltage increases to more than |V RC(S)
| = 2.30 V, the high-speed OCP is activated, and
power MOSFETs reverse on and off. At the same
time, C6 is discharged by ICSS(S) = 20.5 mA. Thus, the
switching frequency quickly increases, and the output
power is quickly limited. This step operates as
protections for exceeding overcurrent, such as the
output shorted. When the absolute value of the RC pin
voltage decreases to |VRC(S)| or less, the operation is
changed to the above Step I.
When OLP Input Voltage Compensation is used, CL
pin voltage is needed to reach the threshold voltage of
Overload Protection (OLP), VCL(OLP), in the state that RC
pin voltage is less than VRC(L). Therefore, when output
power increases, the OLP is activated (refer to Section
8.17).
When the input voltage is constant like PFC output,
OLP Input Voltage Compensation is unnecessary.
Therefore, when output power increases, the above OCP
operation (Step I and Step II ) is activated.
8.17.1 Overload Protection (OLP)
When CL pin voltage becomes the threshold voltage
of Overload Protection (OLP), VCL(OLP), the OLP is
activated and the switching operation stops. VCL(OLP) is
depended on the input voltage by OLP Input Voltage
Compensation Function as shown in Section 0.
The trigger of OLP is different according to the case
with OLP Input Voltage Compensation Function or
without it.
● Without OLP Input Voltage Compensation
Function
Figure 8-36 shows the OLP operation waveforms.
When the absolute value of RC pin voltage increases
to |VRC(L)| = 1.50 V by increasing of output power, the
overcurrent protection (OCP) is activated. After that,
the C7 connected to CL pin is charged by ICL = − 17
μA. When the OCP state continues and CL pin
voltage increases to VCL(OLP), the OLP is activated.
● With OLP Input Voltage Compensation Function
CL pin voltage is needed to reach VCL(OLP) in the state
that RC pin voltage is less than VRC(L).
When CL pin voltage reaches VCL(OLP) in one of the
following condition, the OLP is activated as shown in
Figure 8-37.
1) The output power increases, CL pin voltage
increases to VCL(OLP) which is constant.
2) The input voltage increases, VCL(OLP) depending
on OLP Input Voltage Compensation decreases to
CL pin voltage.
RC pin voltage
VRC(L)
0
VRC(L)
CL pin voltage
VCL(OLP)
Charged by ICL
0
VGH/VGL
0
Figure 8-36 OLP operation waveform
without OLP Input Voltage Compensation Function
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
22
SSC3S900 Series
RC pin voltage
VRC(L)
0
Input voltage
VRC(L)
CL pin voltage
VCL(OLP)
0
RC pin voltage
VRC(L)
0
0
VRC(L)
VCL(OLP) decreases
to CL pin voltage.
CL pin voltage
VCL(OLP)
VCC pin voltage
VCC(ON)
VCC(P.OFF)
0
0
VGH/VGL
Case 1)
Case 2)
VGH/VGL
0
Figure 8-37 OLP operation waveform with OLP Input
Voltage Compensation Function
The IC series has two operation types of OLP. One is
the auto restart. The other is latched shutdown.
● Auto Restart Type: SSC3S901
Figure 8-38 shows the auto restart type OLP operation
waveforms in the case without OLP Input Voltage
Compensation Function.
When the OLP is activated, the IC stops switching
operation. During the OLP operation, the intermittent
operation by UVLO is repeated (refer to Section 8.15).
When the fault condition is removed, the IC returns to
normal operation automatically.
● Latched Shutdown Type: SSC3S902
Figure 8-39 shows the latched shutdown type OLP
operation waveforms in the case without OLP Input
Compensation Function.
When the OLP is activated, the IC stops switching
operation at the latched state. During the OLP
operation, the latch state is kept by turning on/off of
the startup circuit (refer to Section 0).
The latched state is released by following condition:
VCC pin voltage is decreased to VCC(L.OFF) = 7.8 V or
less by turning off the input voltage,
or VSEN pin voltage is decreased to VSEN(OFF) = 1.0 V
or less.
0
Figure 8-38 Auto restart type OLP waveform without
OLP Input Voltage Compensation Function
RC pin voltage
VRC(L)
0
VRC(L)
CL pin voltage
VCL(OLP)
0
VCC pin voltage
VCC(ON)
VCC(OFF)
VCC(L.OFF)
Input voltage
turn off
Release
0
VGH/VGL
Latch mode
0
Figure 8-39 Latched shutdown type OLP waveform
without OLP Input Voltage Compensation Function
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
23
SSC3S900 Series
8.17.2 OLP Input Voltage Compensation
Function
In the case without OLP Input Voltage Compensation
Function, when the absolute value of RC pin voltage
increases to |VRC(L)| = 1.50 V, the capacitor connected to
CS pin is charged. When CS pin voltage increases to
VCL(OLP), the OLP is activated (refer to Figure 8-36).
In the constant voltage control of current resonant
topology, when the input voltage increases, the resonant
frequency increases, and the peak drain current
decreases. Since |VRC(L)| is a fixed value, when output
power increases at the constant rate, there are the output
power difference at OLP operation in high and low input
voltages as shown in Figure 8-40.In the universal mains
input voltage, the output power at OLP operation is very
large in the maximum input voltage, and component
stresses are increased by heating.
Therefore, the IC has OLP Input Voltage
Compensation Function that the output power difference
at OLP operation is limited in input voltages, and can
realize power supply of universal mains input voltage
(85 VAC to 265VAC).
As shown in Figure 8-41, this function compensates
the OLP threshold voltage, VCL(OLP), depending on input
voltage, and is used so that CL pin voltage reaches
VCL(OLP) in the state that RC pin voltage is less than
VRC(L).
AC265V
Input voltage
AC85V
0
RC pin voltage
VRC(L)
OLP active
OLP active
0
VRC(L)
CL pin voltage
VCL(OLP)
0
VGH/VGL
0
Output power
Output power difference
that occurs by input voltage
AC265V
Input voltage
AC85V
0
RC pin voltage
VRC(L)
OLP active
OLP active
0
VRC(L)
CL pin voltage
VCL(OLP)
0
VGH/VGL
0
Output power difference
that occurs by input voltage
Output power
0
Figure 8-41 OLP operation waveforms according to
input voltage (with OLP Input Voltage Compensation)
● PL Pin and CL Pin Setup:
The primary-side winding current as shown in Figure
8-42 includes the magnetizing current not transferred
to the secondary-side circuit, and the load current
proportional to the output current.
The current separated from the primary-side winding
current by C3 flows to the PL pin. As shown in Figure
8-43, the primary-side winding current flows to the
C7 connected to CL pin during the high side power
MOSFET turning on. The magnetizing current
becomes zero by charging and discharging. Only the
load current is charged to C7. As a result, the CL pin
voltage is proportional to the output current.
On actual operation of the application, C7 connected
to the CL pin should be adjusted so that ripple voltage
of the CL pin reduces. R7 connected to the PL pin
should be adjusted so that the OLP at the minimum
mains input voltage is activated before the OCP
limited by the low threshold voltage of OCP, VRC(L).
The PL pin voltage and the CL pin voltage must be
within the absolute maximum ratings of −0.3 to 6 V,
by adjusting R7, in the OCP operation point at the
minimum mains input voltage.
0
Figure 8-40 OLP operation waveforms according to
input voltage
(without OLP Input Voltage Compensation)
● VSPL Pin Setup:
The VSPL pin detects the mains input voltage.
Both VSPL and the setting voltage in Section 8.11
Brown-In and Brown-Out Function are determined by
R2, R3, and R4. Both of them should be adjusted
based on actual operation in the application.
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
24
SSC3S900 Series
Mains Input
U1
VGH
16
R2
VS
1
15
VSEN
R3
Q(L)
VGL
11
4
VSPL
Cv
10
GND
CL RC PL
6 7
8
R7
VSPL
Load current
Magnetizing current
Output current
T1
Q(H)
C1
● Without OLP Input Voltage Compensation Function:
Figure 8-45 shows the circuit that OLP Input Voltage
Compensation Function is canceled. The resistance of
between PL pin and GND pin is about 100 kΩ. The
fixed VSPL pin voltage is about 3V, and should be
adjusted by checking the heating of component in
OLP operation.
Q(H)
Ci
C3
U1
VGH
R4
16
C7 C8
R6
T1
VS
ROCP
15
Q(L)
VGL
Figure 8-42 the peripheral circuit of VSPL, PL, CL pin
About
3V
VGH pin
voltage
ROCP voltage
Cv
CL
6
RC
7
GND 10
PL
8
About
100kΩ
Ci
C3
R6
Load current
Magnetizing
current
Proportional
voltage to
output current
CL pin voltage
0V
Figure 8-43 The waveforms of CL pin
5
4
3
2
1
0
1
2
3
4
VSPL (V)
5
C7
ROCP C8
Figure 8-45 The IC peripheral circuit without OLP Input
Voltage Compensation Function
8.18 Thermal Shutdown (TSD)
● Relationship Between VCL(OLP) and VSPL:
VCL(OLP) is OLP threshold voltage of CL pin. VSPL is
VSPL pin voltage. There are relationship between
VCL(OLP) and VSPL as shown in Figure 8-44.
0
11
VSPL
0V
CL pin source
current 0A
VCL(OLP) (V)
4
6
Figure 8-44 VSPL pin voltage versus typical OLP
threshold voltage, VCL(OLP)
When the junction temperature of the IC reach to the
Thermal Shutdown Temperature T j(TSD) = 140 °C (min.),
Thermal Shutdown (TSD) is activated.
● Auto Restart Type: SSC3S901
When the TSD is activated, the IC stops switching
operation. When the VCC pin voltage is decreased to
VCC(P.OFF) = 9.8 V or less and the junction temperature
of the IC is decreased to less than Tj(TSD), the IC
restarts. During the protection mode, restart and stop
are repeated. When the fault condition is removed, the
IC returns to normal operation automatically.
● Latched Shutdown Type: SSC3S902
When the TSD is activated, the IC stops switching
operation at the latched state. During the TSD
operation, the latch state is kept by turning on/off of
the startup circuit (refer to Section 0).
The latched state is released by following condition:
VCC pin voltage is decreased to VCC(L.OFF) = 7.8 V or
less by turning off the input voltage,
or VSEN pin voltage is decreased to VSEN(OFF) = 1.0 V
or less.
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
25
SSC3S900 Series
9.
9.1
Design Notes
When the gate resistances are adjusted, the gate
waveforms should be checked that the dead time is
ensured as shown in Figure 9-2.
External Components
RB
Take care to use the proper rating and proper type of
components.
DS
Drain
Gate
RA
9.1.1
Input and output electrolytic
capacitors
RGS
Apply proper derating to ripple current, voltage, and
temperature rise. The electrolytic capacitor of high
ripple current and low impedance types, designed for
switch mode power supplies, is recommended to use.
9.1.2
Source
Figure 9-1 Power MOSFET peripheral circuit
High-side
Gate
Resonant transformer
Vth(min.)
The resonant power supply uses the leakage
inductance of transformer. Therefore, in order to reduce
the effect of the eddy current and the skin effect, the
wire of transformer should be used a bundle of fine litz
wires.
Low-side
Gate
Dead time
Dead time
Vth(min.)
9.1.3
Current detection resistor, ROCP
Choose a type of low internal inductance because a
high frequency switching current flows to ROCP, and of
properly allowable dissipation.
9.1.4
Current resonant capacitor, Ci
Since large current flows into Ci, choose a capacitor
of low loss and high allowable ripple current, such as
polypropylene capacitor. In addition, Ci must be
considered its frequency characteristic in order to flow
high frequency current.
9.1.5
Figure 9-2 Dead time confirmation
9.2
PCB Trace Layout and Component
Placement
The switching power supply circuit has the high
frequency and high voltage traces. Since the PCB circuit
design and the component layout significantly affect the
power supply operation, EMI noise, and power
dissipation, the high frequency trace of PCB shown in
Figure 9-3 should be designed low impedance by small
loop and wide trace.
Gate Pin Peripheral Circuit
The VGH pin and the VGL pin are gate drive output
pins for external power MOSFETs.
The peak source current of both of them is – 540 mA,
and the peak sink current is 1.50 A.
DS of Figure 9-1 makes a turn-off speed faster.
RA, RB and Ds should be adjusted considering power
losses of power MOSFETs, gate waveforms (reduction
of ringing caused by pattern layout and others), and EMI
noise.
RA is about 33 Ω to 330 Ω. RB is about 10 Ω.
RGS prevents malfunctions caused by steep dv/dt at
turning off power MOSFET. RGS is recommended to be
a resistor of 10 k to 100 kΩ close to the Gate and the
Source of power MOSFET.
Figure 9-3 High frequency current loop (hatched areas)
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
26
SSC3S900 Series
In addition, the PCB circuit design should be taken
account as follows:
Figure 9-4 shows the circuit design example.
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 C3 and
the IC are distant from each other, placing a film
capacitor Cf (about 0.1 μF to 1.0 μF) close to the
VCC pin and the GND pin is recommended.
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.
4) Peripheral Components for the IC Control
These components should be placed close to the IC,
and be connected to the IC pin as short as possible.
2) Control Ground Trace Layout
When large current flows into the control ground
trace, the operation of IC might be affected by it.
The control ground trace should be separate from the
main circuit trace, and should be connected at a
single point grounding as close to the GND pin as
possible.
5) Bootstrap Circuit Components
These components should be connected to the IC pin
as short as possible, and the loop for these should be
as small as possible.
6) Secondary side 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.
(1)Main trace should
be wide and short
C1
PC1
R4
R5
VCC
FB
R8
R3
VSPL
CSS
C6
CL
C7
C8
RC
ROCP
(4)Peripheral
components for IC
control should place
near IC
R6
R7
PL
SB
C10
1
18
2
17
3
16
4
5
SSC3S900
VSEN
C4
Cf
C5
C9
(6)Main trace of
secondary side should
be wide and short
R2
6
15
14
13
U1
VAC
CY
BR1
7
8
9
12
11
10
ST
T1
NC
R15
D53
D5
VGH
C52
Q(H)
R10
R11
VS
VB
C12
NC
D4
CV
R12
D3
D54
REG
R16 D6
VGL
R13
(5)Boot strap trace should
be small loop
Q(L)
Ci
C3
GND
C11
R14
D1
R15
A
(2)GND trace for IC should be
connected at a single point
R1
C2
(3)Loop of VCC and C2 should be short
Figure 9-4 Peripheral circuit trace example around the IC
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
27
SSC3S900 Series
10. Pattern Layout Example
The following show the PCB pattern layout example and the schematic of circuit using SSC3S900. The above circuit
symbols correspond to these of Figure 10-1.
(1)Main trace should be
wide and short
(5)Boot strap trace should be
small loop
(6)Main trace of secondary side
should be wide and short
S2-1
S2-2
Lp
D
S1-1
S1-2
(2)GND trace for IC should be
connected at a single point
(4)Peripheral components for IC
control should placed near IC
(3)Loop of VCC and C2
should be short
Figure 10-1 PCB circuit trace layout example
CN1
F101
L102
L101
C102
R101
R103
C101
CX102
CX101
VR101
R102
TH101
J2
D303
R201
R202
R203
R204
J5//J7
IC201
SSC3S900
T1
Q201
J6
C203
1
R205
2
VCC
3
FB
NC
17
VGH
16
C205
4
VSPL
VS
15
5
CSS
VB
14
C206
13
REG
12
8
PL
VGL
11
9
SB
GND
10
J27
D204
R215
P
D203
R308
J24
J29
J33
J11
C212
D205
C218
3
C303
S1
C214
R302
J1
J24
6
J14
D
J33
Q204
D601
TR1
R217
C225
4
Q602
R601
R610
R307
POWER_ CN401
ON/OFF
C304
R604
J31
R303
Q301
R218
R609
R616
D206 R206
R216
D207
J18
C605
R306
PC201
J20,
J30,
J32
C215 C217
D302
R208
J28
J21
Q601
10
R207
R301
R602
C301 C308
S2
J12
J23
CN601
12V
7
8,9
J9
R309
D301
C211
R220
R221
R225
NC
RC
J26
D304
Q202
R211
R210
D201
S4
14
R230
C207
CL
7
C604
1
C201
6
C309
13
D202
R209
R613
C302
R213
J13
C103 C104
S3
18
R214
C204
R212
ST
VSEN
R219
J3//J8
CN602
24V
12
R606
C305
R310
R614
J15
Q606
D208
PC202
C208
C209
PC201 R200 C202 C210
C213
PC202
D602
R603
C601 R605 R305 R304
C606 R615
C216
PSA50112_Rev.1.1
Figure 10-2 Circuit schematic for PCB circuit trace layout
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
28
SSC3S900 Series
11. 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. The values in bill of materials are reference design. They are necessary to be adjusted based
on actual operation in the application.
● Power supply specification
IC
Input voltage (Output of PFC)
Maximum output power
Output 1
Output 2
SSC3S901
DC 390 V
227.1 W
13 V / 6.7 A
100 V / 1.4A
● Circuit schematic
PFC OUT
D303
R202
R201
R203
R204
Q201
1
R212
2
VCC
3
FB
S3
NC
17
VGH
16
C302
R213
4
VSPL
VS
15
5
CSS
VB
14
C206
NC
13
RC
REG
12
D204
R215
VGL
11
SB
GND
10
P
D203
C212
D205
C218
J12
CN601
13V
3
C303
S1
S2
C214
Q601
R302
J1
C215 C217
J24
6
J14
R216
D206 R206
D
J33
Q204
J18
R218
J28
J21
D302
R208
R301
C225
R609
R307
J20,
J30,
J32
C304
R303
C305
R604
D601
4
Q602
R601
R610
R306
PC201
POWER_ CN401
ON/OFF
J31
R616
Q301
R217
C605
R602
C301 C308
10
J23
J29
7
8,9
J9
R308
J24
D301
C211
R220
R221
R225
PL
9
R309
J33
J11
8
J27
Q202
R211
R210
CL
7
J26
D304
14
R230
C207
6
C604
13
S4
C201
J13
C205
C309
1
D202
R209
R613
18
R214
C204
ST
VSEN
R219
R205
CN602
100V
12
J6
C203
J3//J8
C103 C104
T1
J5//J7
IC201
SSC3S900
R310
R614
Q606
PC202
C209
PC201 R200 C202 C210
PC202
C216
D602
R305 R304
C606 R615
● Bill of materials
Symbol
C103
C104
C201
C202
C203
C204
C205
C206
C207
C209
C210
C211
C212
C214
C215
C216
C217
C225
C301
C302
C303
Part type
Electrolytic
Electrolytic
Chip
Chip
Ceramic
Chip
Chip
Chip
Chip
Chip
Chip
Ceramic
Chip
Ceramic
Polypropylene Film
Ceramic, Y1
Polypropylene Film
Electrolytic
Electrolytic
Electrolytic
Chip
Rating
450 V, 120 μF
450 V, 120 μF
50 V, 0.1 μF, 2012
50 V, 1.0 nF, 2012
Open
50 V, 2.2 nF, 2012
50 V, 0.47 μF, 2012
50 V, 0.22 μF, 2012
50 V, 220 pF, 2012
50 V, 0.22 μF, 2012
50 V, 4.7 nF, 2012
1 kV, 100 pF
50 V, 1 μF, 2012
1 kV, 100 pF
630 V, 27 nF
AC300 V, 2200 pF
Open
50 V, 100 μF,
35 V, 2200 μF
200 V, 220 μF
Open
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
Recommended Sanken Parts
29
SSC3S900 Series
Symbol
C304
C305
C308
C309
C604
C605
C606
D202
D203
D204
D205
D206
D301
D302
D303
D304
D601
D602
IC201
PC201
PC202
Q201
Q202
Q204
Q301
Q601
Q602
Q606
R200
R201*
R202*
R203*
R204*
R205
R206
R208
R209
R210
R211
R212
R213
R214
R215
R216
R217
R218
R219
R220
R221
R225
R230
Part type
Chip
Chip
Electrolytic
Electrolytic
Electrolytic
Electrolytic
Chip
Schottky
Schottky
Fast recovery
Schottky
Fast recovery
Schottky
Schottky
Fast recovery
Fast recovery
Schottky
Chip
IC
Photo-coupler
Photo-coupler
Power MOSFET
Power MOSFET
PNP transistor
Shunt regulator
PNP transistor
NPN transistor
NPN transistor
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Rating
Open
50 V, 0.22 μF, 2012
35 V, 2200 μF
Open
Open
Open
Open
40 V, 1 A, SJP
40 V, 1 A, SJP
600 V, 0.5 A, Axial
40 V, 1 A, SJP
200 V, 1 A, Axial
150 V, 30 A, TO220F
150 V, 30 A, TO220F
200 V, 5 A, TO220F
200 V, 5 A, TO220F
40 V, 1 A, SJP
0Ω ± 5 %, 1/8 W, 2012
Recommended Sanken Parts
SJPB-D4
SJPB-D4
AG01A
SJPB-D4
AL01Z
FMEN-230A
FMEN-230A
FML-14S
FML-14S
SJPB-D4
SSC3S901
PC123 or equiv
PC123 or equiv
10 A, 600 V, TO220
10 A, 600 V, TO220
–600 mA, –60 V, SOT23
VREF = 2.50 V (TL431or equiv)
0.6A, – 60V, SOT23
0.6 A, 40 V, SOT23
0.8 A, 60 V SOT-23/TO-92
47 kΩ ± 5 %, 1/4 W, 3216
1.0 MΩ ± 5 %, 1/4 W, 3216
1.0 MΩ ± 5 %, 1/4 W, 3216
1.0 MΩ ± 5 %, 1/4 W, 3216
910 kΩ + 47 kΩ ± 5 %, 1/4 W, 3216
680 Ω ± 5 %, 1/8 W, 2012
0 Ω ± 5 %, 1/4 W, 3216
22 kΩ ± 5 %, 1/8 W, 2012
47 kΩ ± 5 %, 1/8 W, 2012
100 Ω ± 5 %, 1/8 W, 2012
2.2 Ω ± 5 %, 1/8 W, 2012
33 kΩ ± 5 %, 1/8 W, 2012
100 Ω ± 5 %, 1/8 W, 2012
10 kΩ ± 5 %, 1/8 W, 2012
2.2 Ω ± 5 %, 1/8 W, 2012
47 kΩ ± 5 %, 1/8 W, 2012
22 kΩ ± 5 %, 1/8 W, 2012
100 kΩ ± 5 %, 1/8 W, 2012
2.2 Ω ± 5 %, 1/8 W, 2012
10 kΩ ± 5 %, 1/8 W, 2012
100 kΩ ± 5 %, 1/8 W, 2012
150 Ω ± 5 %, 1/8 W, 2012
100 Ω ± 5 %, 1/8 W, 2012
KST2907A
* 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.
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
30
SSC3S900 Series
Symbol
R301
R302
R303
R304
R305
R306
R307
R308*
R309*
R310
R601
R602
R604
R609
R610
R613*
R614
R615
R616
T1
Part type
Rating
5.6 kΩ ± 5 %, 1/8 W, 2012
4.7 kΩ ± 5 %, 1/8 W, 2012
10 kΩ ± 5 %, 1/8 W, 2012
2.2 kΩ ± 5 %, 1/8 W, 2012
Open
22 kΩ ± 5 %, 1/8 W, 2012
20 kΩ ± 5 %, 1/8 W, 2012
Open
Open
15 kΩ ± 5 % , 1/8 W, 2012
1 kΩ ± 5 %, 1/10 W, 2012
2.2 kΩ ± 5 %, 1/8 W, 2012
4.7kΩ ± 5 %, 1/8 W, 2012
Open
Open
Open
22 kΩ+4.7 kΩ ± 5 %, 1/8 W, 2012
Open
0 Ω ± 5 %, 1/8 W, 2012
See the specification
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Chip
Recommended Sanken Parts
* 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.
● Transformer specification
Primary inductance, LP : 250 μH
Leakage inductance, Lr : 80 μH
Core size
: EER-42
● Winding specification
Winding
Primary winding
Auxiliary winding
Output winding 1-1
Output winding 1-2
Output winding 2-1
Output winding 2-2
Symbol
Lp
D
S1-1
S1-2
S2-1
S2-2
Number of turns (T)
33
3
2
2
15
15
Wire diameter (mm)
Litz φ0.1 mm 30 strands
TIW φ0.2 mm
Litz φ0.1 mm 70 strands
Litz φ0.1 mm 70 strands
Litz φ0.1 mm 30 strands
Litz φ0.1 mm 30 strands
Construction
Solenoid winding
Space winding
Bifilar winding
Bifilar winding
Bifilar winding
Bifilar winding
(12) VOUT2(+)
S2-1
VS (1)
(11) VOUT2(-)
Primary side
Secondary side
Lp
S2-2
C215//C217 (2)
D
(11) VOUT2(-)
(10) VOUT2(+)
Lp
Bobbin
S2-1, S2-2
S1-1, S1-2
Bobbin
Core side
Core side
GND (3)
D
(8)
VOUT1(+)
(7)
VOUT1(-)
(6)
VOUT1(-)
(5)
VOUT1(+)
S1-1
VCC (4)
S1-2
Cross-section view
: Start at this pin
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
31
SSC3S900 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 of the Sanken Products, etc. Please make sure to confirm with a Sanken sales representative
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. When considering use of the Sanken Products for any applications that require higher reliability (such as 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. The Sanken Products are not intended for use in any applications that require extremely high reliability such as:
aerospace equipment; nuclear power control systems; and medical equipment or systems, whose failure or malfunction may result
in death or serious injury to people, i.e., medical devices in Class III or a higher class as defined by relevant laws of Japan
(collectively, the “Specific Applications”). Sanken assumes no liability or responsibility whatsoever for any and all damages and
losses that may be suffered by you, users or any third party, resulting from the use of the Sanken Products in the Specific
Applications or in manner not in compliance with the instructions set forth herein.
● 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, all
information 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,
including, without limitation, any warranty (i) as to the quality or performance of the Sanken Products (such as implied warranty
of merchantability, or implied warranty of fitness for a particular purpose or special environment), (ii) that any Sanken Product is
delivered free of claims of third parties by way of infringement or the like, (iii) that may arise from course of performance, course
of dealing or usage of trade, and (iv) as to 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.
DSGN-CEZ-16001
SSC3S900 - DSJ Rev.2.4
SANKEN ELECTRIC CO.,LTD.
Apr. 01, 2016
http://www.sanken-ele.co.jp
© SANKEN ELECTRIC CO.,LTD. 2013
32