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WS3411 Product Description
WS3411 Active PFC Non-isolated Buck LED Driver
Features
�
High
General Description
Power
Factor
Correction,
Low
Total
The WS3411 is designed for active PFC non-isolated buck
Harmonic Distortion
LED driver. It operates at valley switching mode with high
�
Dynamic Temperature Compensation
efficiency, low EMI and High PF. The output current
�
500V Power MOSFET Integrated
automatically adapt to the variation of the inductance and the
�
No Auxiliary Winding For Supplying
output voltage. The truly constant current LED is realized.
�
SOP8 Package, Up To 260mA Output Current
The WS3411 integrates 500V power MOSFET, using SOP8
�
Valley Switching, High efficiency, Low EMI
package,
�
Automatic Compensate the Inductance Variation
It can achieve excellent constant current performance with
�
Automatic Adapt to the Change of Output Voltage
very few external components.
�
LED Short Circuit Protection
The WS3411 offers rich protection functions, including over
�
Over Voltage Protection
voltage protection, LED short circuit protection, cycle by
�
Over Temperature Protection
cycle current limiting, dynamic temperature compensation,
�
Open Circuit Protection
over temperature protection and soft start.
�
Few External Components
WS3411 consumes very low start current and operation
current,
producing
driving
LED
up
to
260mA
efficiently
output
under
current.
universal
AC
input(85VAC~265VAC).
WS3411 is available in SOP8 package.
Applications
�
LED Driver Supply
Typical Application Circuit
5
6
3
AC
2
8
D
CS
D
CS 7
VCC
FB
GND
CO MP
4
LE D +
1
LE D-
W/T-D046-Rev.A/ 0 May.2014
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WS3411 Product Description
Pin Definition and Device Marking
WS3411 is available in SOP-8 package.
COMP
3
FB
4
WS3411S8P
VCC
AXB YM
GND
2
CS
8
1
WS3411S8P: Product code
7
CS
A: Product Code
6
D
X：Internal Code
5
D
B：Area Code
YM：Year, Month
Pin Function Description
Pin Name
Pin NO.
Description
COMP
1
Loop compensation, with a cap to GND.
GND
2
Ground
VCC
3
Power supply
FB
4
Feedback signal input.
D
5
Internal HV power MOSFET drain
D
6
Internal HV power MOSFET drain
CS
7
Current sense input, connect to internal HV power MOSFET source
CS
8
Current sense input, connect to internal HV power MOSFET source
Block Diagram
VCC
FB
GND
3
4
2
8 .5 V
OVP
UVLO
Inter
supply
Zero-Current
Detect
Temperature
control
5 ,6
D
L o g ic
&
driver
PFC
control
7 ,8 C S
OTP
200m V
CO MP 1
1V
EA
Current
sense
1 .5 V
low-clamp
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WS3411 Product Description
Ordering Information
Package
8-Pin SOP-8,
Pb-free
Part Number
Marking
WS3411S8P
WS3411S8P
Recommended Operating Condition
symbol
parameter
value
units
ILED
Output LED current
< 260
mA
Absolute Maximum Ratings
symbol
parameter
VDS
VCC
Range
Units
Internal HV MOSFET drain voltage
-0.3~500
V
Power Supply
-0.3~8.5
V
VCS
Current sense pin input voltage
-0.3~7
V
VFB
Feedback voltage input
-0.3~7
V
VCOMP
Loop Compensation Pin voltage
-0.3~7
V
PDMAX
Power dissipation
0.5
W
TJ
Max. Operating junction temperature
150
℃
TSTG
Max./Min. Storage temperature range
-55~150
℃
Note: Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. Under
“recommended operating conditions” the device operation is assured, but some particular parameter may not be achieved.
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WS3411 Product Description
Electrical Characteristics (Unless otherwise specified，TA=25℃，VCC=8V)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
7.8
8.5
9.3
V
5
mA
Supply Voltage Section
Vcc_clamp
VCC Clamping Voltage
Icc_clamp
VCC Clamping Current
VCC_ST
VCC Start Up Voltage
VCC Under Voltage
Vuvlo_HYS
Latch Out Hysteresis
Ist
Start Up Current
Iop
Operation Current
VCC Rise
7.5
V
VCC Falling
1.5
V
VCC<VCC_ST-0.5V
70
100
uA
400
uA
1
V
Current Sensor Section
Vocp
Current Sensor Voltage Threshold
TLEB
Leading Edge Blanking
350
ns
TDELAY
Turn Off Delay Time
200
ns
Loop Compensation Section
VREF
Internal Reference Voltage
VCL
Comp Low Clamp Voltage
194
VCH
200
206
mV
1.5
V
4
V
Internal Driver Secion
Toff_min
Min. Demagnetization Time
3
us
Ton_max
Max. On Time
20
us
Feedback input Section
VFB
OVP Threshold Voltage
1.6
V
VZCD
Zero Crossing Checking Threshold
0.2
V
Internal HV MOSFET
RDSON
HV MOS ON Resistance
VDS
Drain to Source voltage
10
500
ohm
V
Over Temperature Section
TSD
Thermal Shut Down Temperature
160
℃
TSD_HYS
Thermal Shut Down Hysteresis
30
℃
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WS3411 Product Description
Function Description
The WS3411 is designed for active PFC non-isolated buck
Sence Resistor
LED driver, which integrates 500V power MOSFET and
The WS3411 is designed for active PFC non-isolated buck
using SOP8 package, producing up to 260mA output current.
It operates under
valley switching mode, automatically
adapting to the variation of the inductance and the output
voltage.
It
can
achieve
excellent
constant
current
performance with very few external components.
LED driver. It operates under
valley switching mode and
can achieve high accuracy constant current performance
with very few external components. The peak current of
inductor is continuous detected. CS terminal is connected
internal of the chip, and compared with the internal 200mV.
Internal Amplifier’s output COMP adjust the on-time, making
the average value so CS equal to 200mV after the system is
stable. In addition, a 1V cycle-by-cycle over current
Start up
The start current is very low, Typ. 70uA(Max. 100uA). Under
protection is set up inside CS pin.
LED output current:
the design system of 85VAC, the startup resistor is:
I LED =
85 * 2
R=
= 1.2 M
100
0.2V
RCS
FB Voltage Detection
Chip Supply
After startup, the output voltage should supply the chip,
rectifier diodes D6 need to use fast recovery diodes.Current
FB voltage determines the working status of the system,
when
FB
is
greater
then
1.6V(typ.),
WS3411
will
automatically considered as output over voltage protection.
limiting resistor R4 is calculated as:
The system will enter extremely energy efficient hiccup
R4 = (1 − D ) *
VLED − 9
400uA
mode. Output over voltage protection voltage as follows:
VOVP = 1.6 *
Where, D is duty cycle, 400uA is the normal operation
R2 + R3
R3
current of the chip, Vled is output load voltage. The
R2,R3,please refer to the typical application diagram, in
consumption of R4 is:
which R3=1k(no more than 2k). use 1.3 instead of constant
PR 4 =
(VLED − 9)
2
R4
1.6 in the above formula in the design of system. Assuming
* (1 − D)
Vovp=90V, we got R2=56k from the above formula,
For example:
choosing 60k for R2 (larger as far as possible).
Requirements:180~260V input voltage, 36~80V output,
Because VFB2 is between 1.3 and 1.9, choose 1.9 to
240mA output current.
calculate the withstand voltage of C4,
Vovp=1.9*(1+60)/1=116V
The R4 design of above program should be met:
1. Supply Problem when Min. input AC voltage 180V and
The withstand voltage of C4 shoule larger than the above
Min. output voltage 36V(which is the weakest power supply):
value, 200V capacitor could be used.
D=36/180/1.414=0.141,R4=(1-0.141)*(36-9)/400uA=58k
The WS3411 uses the patent source driver structure. The
2.Power consumption problem of R4 when Max. input AC
typical operation current is as low as 200uA, the auxiliary
voltage 260V and Max. output voltage 80V(which is the
winding is not need. So the system design is simple and the
strongest power supply):
cost is low.
D=80/260/1.414=0.218
WS3411 will automatic detect the output voltage when
The power consumption of R4:
enters hiccup mode; and will re-enter the normal working
state when the output voltage is lower than Vovp.
P=(80-9)*(80-9)/58*(1-0.218)=68mW
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WS3411 Product Description
Output Open(Short) protection
Power Factor Correction
Output open/short protection is integrated inside WS3411.
Active PFC control circuit is integrated in WS3411, which
Once output open/short circuit is detected, the system will
can get high PF value and low THD.
automatic enter hiccup mode until the protection signal
PCB Design
disappear.
The following guidelines should be followed in WS3411 PCB
Over Temperature Automatic adjustment of output
layout:
current
Bypass Capacitor: The bypass capacitor on VCC pin should
WS3411 has over temperature regulating function, gradually
be as close as possible to the VCC and GND pins.
reducing the output current when the power is over
Ground Path: The power ground path for current sense
temperature, so as to control the output power and the
should be short, and the power ground path should be
temperature rise, keeping the power temperature in a setting
separated from small signal ground path before the negative
value in order to improving the reliability of the system. The
node of the bulk capacitor.
starting regulation temperature is 135℃.
The Area of Power Loop: The area of power loop should be
as small as possible to reduce EMI radiation.
Input Filter Capacitor
And the controller should be placed away from the heat
In order to obtain high PF value, the input capacitor can not
be too large. 10-100nF is recommended.
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generator, such as the power diode.
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WS3411 Product Description
Package Information
SOP-8 Package Outline Dimensions
B2
A1
A2
D
D1
B
B1
A
C4
A3
0 . 5 * 0.125± 0. 05
球形标记
R2
C
C1
θ4
θ2
C2
θ1
C3
θ3
R1
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Dimensions in Millimeters
Symbol
Dimensions in Inches
Min
Max
Min
Max
A
4.70
5.10
0.185
0.201
B
3.70
4.10
0.146
0.161
C
1.30
1.50
0.051
0.059
A1
0.35
0.48
0.014
0.019
A2
1.27TYP
0.05TYP
A3
0.345TYP
0.014TYP
B1
5.80
B2
6.20
0.228
5.00TYP
0.244
0.197TYP
C1
0.55
0.70
0.022
0.028
C2
0.55
0.70
0.022
0.028
C3
0.05
0.225
0.002
0.009
C4
0.203TYP
0.008TYP
D
1.05TYP
0.041TYP
D1
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0.016
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WS3411 Product Description
NOTE:
1.We strongly recommend customers check carefully on the trademark when buying our product, if there is
any question, please don't be hesitate to contact us.
2.Please do not exceed the absolute maximum ratings of the device when circuit designing.
3.Winsemi Microelectronics Co., Ltd reserved the right to make changes in this specification sheet and is
subject to change without prior notice.
CONTACT:
Winsemi Microelectronics Co., Ltd.
ADD:Futian District, ShenZhen Tian An Cyber Tech Plaza two East Wing 1002
Post Code : 518040
Tel : +86-755-8250 6288
FAX : +86-755-8250 6299
Web Site : www.winsemi.com
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