20160322025901 8353

WS3410 ProductDescription
Non-isolated Buck APFC Offline LED Driver
Features
Description

Active PFC for High Power Factor and Low THD

Critical Conduction Mode Operation

System Efficiency up to 95%
with active PFC, specially designed for universal input offline

Without auxiliary winding
constant current LED lighting. The driver with on-chip PFC

Excellent Line and Load Regulation
circuit achieves high power factor and low THD. Operating in

±3% LED Output Current Accuracy
critical conduction mode, the power MOSFET switching loss

Thermal Regulation Function
is reduced and the inductor is fully utilized.

LED Short/Open Protection

Current Sensing Resistor Open Protection

Auto Fault Recovery

Available in SOT23-6 Package
The WS3410 is a high precision non-isolated buck driver
With few external components, the LED output current
can be precisely controlled.
The WS3410 offers rich protection functions to improve
the system reliability, including LED open circuit protection,
LED short circuit protection, CS resistor open circuit
protection and cycle by cycle current limit. All the protection
Applications
functions are auto-recovery. The system reliability is further

E27 LED Bulb, Spot Light
improved by the thermal regulation function. The output

PAR30, PAR38 Lamp
current is reduced when the driver is over temperature.

T8/T10 LED String

Other LED Lighting
The WS3410 has ultra low start up current and ultra low
operating current.
The WS3410 is available in SOT23-6 Package
Typical Application
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WS3410 ProductDescription
Pin Configuration and Marking Information
The WS3410 is available in SOT23-6 Package,the top marking is shown as below:
3410:Product Code
X:Product Code
YM:Production Date
XX:Internal Code For QC
Pin Definition
Name
Pin No.
Description
VCC
1
Power Supply Pin. Connect a bypass capacitor from this pin to GND.
GND
2
Ground.
COMP
3
GATE
4
Gate Driver Pin. Connect this pin to the gate of external power MOSFET.
CS
5
Current Sense Pin. Connect a resistor to GND to sense the inductor current.
FB
6
Loop Compensation Node. This pin connects a capacitor to GND for stabilization of the
control loop, achieving accurate LED current, high Power Factor and low THD.
Feedback Voltage Input Pin. This pin detects the inductor demagnetization signal and the
output voltage.
Internal Block Diagram
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WS3410 ProductDescription
Ordering Information
Package
6-Pin SOT23-6,
Pb-free
Marking
Part Number
WS3410YP
WS3410YP
Recommended Operation Conditions
Part Number
Package
WS3410YP
SOT23-6
Input voltage
Maximum output
power
175VAC-264VAC
120V/450mA
90VAC-264VAC
80V/450mA
Absolute Maximum Ratings
symbol
paramete
Range
unit
VCC
Vcc pin voltage
-0.3~8
V
Vgate
Gate driver pin voltage
-0.3~8
V
VCS
Current sense pin input voltage
-0.3~7
V
VFB
Feedback pin input voltage
-0.3~7
V
VCOMP
Compensation pin voltage
-0.3~7
V
PDMAX
Power dissipation
0.2
W
TJ
Operating junction temperature
165
℃
TSTG
Storage temperature range
-55~165
℃
Note : Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device.
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WS3410 ProductDescription
Electrical Characteristics (Unless otherwise specified, VCC=8V and TA =25 ℃)
Symbol
Parameter
Conditions
Min
Typ
Max
7.5
8.0
8.5
Units
Supply Voltage Section
Vcc_clamp
VCC Clamp Voltage
Icc_clamp
VCC Clamp Current
VCC_ST
VCC Turn On Threshold
VCC Rising
Vuvlo_HYS
VCC Turn Off hysteresis
VCC Falling
1.32
Ist
VCC Startup Current
VCC<VCC_ST-0.5V
70
Iop
VCC Operating Current
5
7.07
V
mA
7.57
8.07
V
V
100
uA
400
uA
1
V
350
ns
200
ns
Current Sense Section
Over current
Vocp
TLEB
Protectionthreshold
Leading Edge Blanking Time
for Current Sense
Td
Switch off Delay Time
Compensation Section
VREF
Internal Reference Voltage
194
200
206
mV
VCL
COMP Low Clamp Voltage
1.5
V
VCH
COMP High Clamp Voltage
4
V
Internal driver
TOFF_MIN
Minimum Off Time
3
us
TON_MAX
Maximum On Time
20
us
1.6
V
0.2
V
Feedback Section
VFB
VZCD
FB Over Voltage Protection
Threshold
FB Falling Edge
Threshold Voltage
Thermal Regulation Section
TREG
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Thermal Regulation
Temperature
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150
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WS3410 ProductDescription
Application Information
RFBL
1.6V

RFBL  RFBH VOVP
The WS3410 is a high precision Active PFC driver,
specially designed for non-isolated buck offline constant
current LED lighting. Operating in critical conduction mode,
Where,
the driver achieves high power factor, low THD and high
RFBL: The lower resistor of the feedback network
efficiency.
RFBH: The upper resistor of the feedback network
VOVP: Output over voltage setting point
Start Up
The minimum VOVP should be set about 1.3Vo.It is
After system powered up, the VCC pin capacitor is
charged up by the start up resistor. When the VCC pin
recommended that the FB lower resistor is set to
3.3KΩ—5.1KΩparalleled with a 22pF ceramic capacitor.
voltage reaches the turn on threshold, the internal circuits
start working. The COMP pin voltage is pulled up to 1.5V
Protection Functions
quickly. Then the WS3410 starts switching. The system
works at 10k Hz frequency at the beginning, the COMP
The WS3410 offers rich protection functions to improve
the system reliability.
voltage rises up gradually, and the inductor peak current
When the LED is open circuit, the output voltage will
also rises up. The LED current hence achieves a soft start
gradually rise up. The output voltage is sensed by the FB pin
without overshoot. After the output voltage is built up, the
when power MOSFET is turned off. When FB voltage
VCC power is supplied by the output voltage through a
reaches the OVP threshold, it will trigger fault logic and the
diode.
system stops switching.
The maximum value of the startup current is 100uA. For
When the LED is shorted circuit, the system will work
the application of 85VAC—264VAC, the startup resistor can
under 10k Hz switching frequency. Meanwhile, the output
be calculated by the equation:
voltage is low and the VCC pin cannot be charged up by the
Rst 
Vin _ min
I st _ max
output voltage, so the VCC pin voltage will gradually
85V

 850 KΩ
100uA
decrease and finally reaches the UVLO threshold.
After the system enters into fault condition, the VCC
voltage will decrease until it reaches UVLO threshold. Then
the system will re-start again. If the fault condition is
Constant Current Control
The WS3410 utilizes floating ground structure. The
removed, the system will resume normal operation.
inductor current is sensed during the whole switching cycle,
When the output is short circuit or the inductor is
thus it achieves high precision output current control and
saturated, the CS peak voltage will be relatively high. When
also excellent line and load regulation.
CS voltage reaches the internal limitation (1V), the power
The current in LED can be calculated by the equation:
MOSFET will be turned off instantaneously. This cycle by
cycle current limitation can help protecting the power
V
200mV
I O  CS 
RCS
Rcs
MOSFET, the inductor and the output diode.
Thermal Regulation
Rcs is the current sensing resistor.
The WS3410 integrates thermal regulation function.
When the system is over temperature, the output current is
Feedback Network
gradually reduced; the output power and thermal dissipation
The WS3410 senses the output current zero crossing
information through the feedback network, the FB falling
threshold voltage is set to 0.2V with 0.15V hysteresis. The
are also reduced. The system temperature is regulated and
the system reliability is improved. The thermal regulation
temperature is set to 150℃ internally.
FB pin is also used to detect output OVP, the threshold
voltage is 1.6V. The ratio of FB upper resistor to lower
resistor can be set as:
PCB Layouts
The following guidelines should be followed in WS3410
PCB layout:
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WS3410 ProductDescription
Bypass Capacitor
FB Pin
The bypass capacitor on VCC pin should be as close as
The feedback resistor divider should be as close as
possible to the VCC and GND pins.
possible to the FB pin, and the trace must keeps away from
Ground Path
dynamic node of the inductor (DRAIN pin trace、the positive
The power ground path for current sense resistor
pin and the negative pin of Vo trace), otherwise the FB pin
should be short and wide, and it should be as close as
OVP function might have risk to be mis-triggered by the
possible to the IC ground (pin 2), otherwise the LED output
system noise.
current accuracy maybe affected. The IC signal ground for
DRAIN Pin
COMP and FB components should be connected to the IC
To increase the copper area of DRAIN pin for better
GND pin with short traces and should be away from the
thermal dissipation. However, too large copper area may
power ground path.
compromise EMI performance.
The Area of Power Loop
The material of PCB
The area of main current loop should be as small as
Avoid choosing the material that is easy to absorb the
possible to reduce EMI radiation.
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moisture, just like paper copper-clad laminates.
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WS3410 ProductDescription
Package Information
SOT23-6Package Outline Dimensions
Unit:mm
A
C2
B1
B
θ1
θ
B2
A2
R
θ3
C
D
R1
θ2
C1
R2
D1
D3
D2
A1
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Symbol
Dimensions in Millimeters
Dimensions in Inches
Min
Max
Min
Max
A
2.72
3.12
0.107
0.123
B
1.40
1.80
0.055
0.071
C
1.00
1.20
0.039
0.047
A1
0.90
1.00
0.035
0.039
A2
0.30
0.50
0.012
0.020
B1
2.60
3.00
0.102
0.118
B2
0.119
0.135
0.005
0.005
C1
0.03
0.15
0.001
0.006
C2
0.55
0.75
0.022
0.030
D
0.03
0.13
0.001
0.005
D1
0.30
0.60
0.012
0.024
D2
D3
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0.25TYP
0.01TYP
0.60
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0.024
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0.028
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WS3410 ProductDescription
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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