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WS3221 Product Description
WS3221 High Precision PSR Constant Current LED Driver
Features
■ Built-in 650V Power MOSFET
regulation controller for LED lighting, it operates in constant
■ ±5% LED Current Accuracy
current control mode and is designed to work in inductor
■ Primary-side Sensing and Regulation Without TL431
current discontinuous
and Opto-coupler
suitable for
■ No Auxiliary Winding For Sensing And Supplying
output power of system is recommended to less than 7W.
■ Ultra low operating current
WS3221 integrates 650V power MOSFET. Since adopting
■ LED Open/Short Circuit Protection
primary
■ External programmable LED Open voltage
secondary sense and feedback circuit is eliminated. And it
■ CS Resistor Short Circuit Protection
does not need the auxiliary winding for sensing the output
■ VCC Clamp & under voltage lockout( UVLO)
current and supplying the chip. The low component counts
■ Over Temperature Protection
and small system size are realized.
■ Temperature compensation technology
Since using the high accurate current sense method, WS3221
conduction mode and especially
flyback convertor under universal input. The
sense
and
feedback
control
technology,
the
realizes ±5% accuracy of LED current along with excellent line
Applications
and load regulation.
■ GU10 LED driver
Advanced temperature compensation is applied to eliminate
■ LED spot light
flicker of LED at high temperature
■ Other LED lighting
WS3221
offers
comprehensive
protection
including
Cycle-by-Cycle current limiting (OCP), LED open/short circuit
protection, CS resistor short circuit protection, VCC UVLO and
General Description
Clamp, and over temperature protection.
WS3221 is a high precision primary-side feedback and
WS3221 is available in SOP8 package.
Typical Application Circuit
Np
Ns
AC
2 VCC
4
RO VP
NC
5
NC
6
1 CS
D ra in 7
3 GND
D ra in 8
W/T-S042-Rev.A/0 Mar.2014
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WS3221 Product Description
Pin Definition and Device Marking
WS3221 is offered in SOP-8 packages，as shown below：
1
VCC
2
GND
3
ROVP
4
WS3221S8P
AXB YM
CS
8
WS3221S8P: Product code
D ra in
A: Die Code
7 D ra in
X: Internal Code
6
NC
5
NC
B: Area Code
YM:Year, Month
Pin Function Description
Pin
Pin
Name
Number
CS
1
Current Sense
VCC
2
Power Supply
GND
3
Ground
Ground.
ROVP
4
Input
Setting
NC
5,6
NC
Drain
7,8
Drain
Pin Type
Function Description
Current sense. This pin connects a current sense resistor to GND to
detect the primary current of transformer.
Power supply.
LED open voltage by connect a resistor to GND。
No connection, must be floated
Internal high voltage MOSFET drain.
Block Diagram
VCC
D r a in
650V
Pow erMOS
O CP
B ia s &
internal supply
OTP
Temperat ure
compensation
D emagnetiz
a tio n
detected
8 .1 V
5 .1 V 7 .4 5 V
CC loop & Logic control
LEB
0 .5 V
LED Open
protection
OCP
CS
Line - comp
UVLO
ROVP
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WS3221 Product Description
Ordering Information
Package
SOP8,
IC Marking Information
Purchasing Device Name
WS3221S8P
WS3221S8P
Pb-free
Recommended Operating Condition
symbol
parameter
value
unit
Pout1
Output power (Vin=230V±15%)
<7
W
Pout2
Output power (Vin=85V～265V)
<5
W
Fmax
Max switching frequency
120
KHz
-20~85
℃
TA
Operation temperature
Absolute Maximum Ratings
Symbol
Parameter
Icc_max
VCC pin maximum sink current
Drain
Internal HV MOSFET drain voltage
Value
Unit
5
mA
-0.3~650
V
-0.3~7
V
CS
CS pin input voltage
TJ
Operating junction temperature
-40~150
℃
TSTG
Min./Max. Storage temperature
-55~150
℃
Note
Note: Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are
stress ratings only, functional operation of the device at these or any other conditions beyond those indicated in the
Recommended Operating Conditions section are not implied. Exposure to absolute maximum-rated conditions for extended
periods may affect device reliability.
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WS3221 Product Description
Electrical Characteristics (TA=25℃，VCC=8V, if not otherwise noted)
symbol
parameter
Test condition
Min
Typ
Max
Unit
8.7
V
Supply Voltage (VCC)
VCC_Clamp
VCC Clamp voltage
Icc=1mA
8.1
UVLO_ON
Turn on threshold Voltage
VCC rising
7.45
V
UVLO_OFF
Turn-off threshold Voltage
VCC falling
5.1
V
I_OP
Operation Current
Fop=50Khz
150
250
uA
IST
starting current
VCC=UVLO_on-1V
60
100
uA
Current Sense Section
TLEB
Leading edge Blanking Time
VTH_OC
OCP threshold
500
485
500
ns
515
mV
OCP threshold @ output short
VTH_short
300
mV
100
ns
circuit
Tdelay
Switch off delay time
Frequency Section
Fmin
Minimum operation frequency
3
Khz
Dmax
Maximum duty cycle
42
%
Fmax
Max switching frequency
120
KHz
VROVP
ROVP voltage
0.5
V
15
Ω
MOSFET Section
Rds_on
Static drain-source on-resistance
Vgs=14V/Ids=0.5A
BVdss
Drain-source breakdown voltage
Vgs=0V/Ids=250uA
Idss
Drain-source leakage current
Vgs=0V/Vds=650V
650
V
10
uA
Over Temperature Protection
Tsd
Thermal shutdown threshold
160
℃
Tsd_hys
Thermal shutdown hysteresis
25
℃
Tcomp
Temp comp start point
140
℃
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WS3221 Product Description
Typical Operating Characteristics
V C C欠 压 保 护 阈 值
VCC 启动电压 （V）
5.16
7.33
5.13
7.30
5.10
5.07
7.27
5.04
7.24
5.01
4.98
7.21
4.95
7.18
4.92
-40 -20 0
10
20
40
60
80 100 120 140 150
-40 -20 0
10
20
40
60
8 0 100 120 140 150
I_startup（uA） vs temperature
OCP 阈值电压
100.00
0.501
90.00
0.501
80.00
0.501
70.00
0.501
60.00
0.501
50.00
0.501
40.00
0.501
30.00
0.501
20.00
0.501
10.00
0.501
0.00
-40 -20 -10
-40-20-10 0 10 20 40 60 80 90 100120130140150
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10
20
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40
60
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80 100 120 140 150
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WS3221 Product Description
Function Description
Power MOSFET
WS3221 is a high performance power witch specially
The WS3221 integrates a 650V power N-MOSFET. It Can
designed for LED lighting, with constant current control
minimize the external component count and reduce the
technology. WS3221 integrates a 650V power MOSFET.
BOM cost and PCB size. The WS3221 uses SOP-8 package.
The accurate LED current can be realized without
Mainly used for LED lamp below 7W.
opto-coupler, TL431 feedback circuit and auxiliary winding
while minimizing the external component count, lowering the
Operation switching frequency
total bill of material cost.
The WS3221 is designed to work in discontinuous
conduction mode and no external loop compensation
Startup Current
component is required while maintaining stability,The
The start-up current in WS3221 is designed to as low as
maximum duty cycle is limited to 42%. The maximum
60uA. The VCC capacitor will be charged through the
switching frequency at normal operation is suggested to set
start-up resistor when the system is powered on. Once the
around 100KHz. If the maximum frequency is set too high, it
VCC voltage reaches the start-up threshold, the WS3221
will affect the number of maximum series LED lamps. If set
will start to switch. WS3221 integrates a 8.1V zener for VCC
too low, the LED open circuit voltage will be too high. The
clamping. Due to the ultra-low operating current, the
maximum and minimum switching frequency is limited in
auxiliary winding is not needed to supply the IC.
WS3221 to ensure the stability of system. The switching
frequency can be set by the formula:
f=Np2*Vled/ (8*Ns2*Lp*Io)
CC Operation
Cycle-by-Cycle current sense is adopted in WS3221 CS is
Where, LP is the primary winding inductance of transformer.
connected to the current sense comparator, and the voltage
on CS will be compared with the internal 500mV reference
Current Limiting and Leading Edge Blanking
voltage, the MOSFET will be switched off when the voltage
Cycle-by-Cycle current limiting is offered in WS3221. The
on CS reaches the threshold. The output of the comparator
switch current is detected by a sense resistor into the sense
includes a 500ns leading edge blanking time. The primary
pin. An internal leading edge blanking circuit chops off the
peak current is given by:
sense voltage spike at initial MOSFET on state due to
I_pk=0.5/Rcs（A）
snubber diode reverse recovery so that the external RC
The current in LED can be calculated by the equation:
filtering on sense input is no longer required. The current
Io=0.5*I_pk*Np/Ns*Tons/T
limit comparator is disabled and thus cannot turn off the
=0.25*I_pk*Np/Ns
internal MOSFET during the blanking period.
=0.125/Rcs* Np/Ns
Where,
Set open protection
NP: primary winding turns of transformer
The LED open protection voltage can be set by adjusting the
NS: secondary winding turns of transformer
value of the resistor connecting from ROVP to GND.
Rcs：The value of the sense resistance
In the LED open condition, the output voltage will raise
I_pk: peak current in MOSFET
graduate, and the demagnetize time will shorten as well, the
And the output current can be set by adjusting the current
demagnetize time Tovp can be calculator as below:
sense resistor Rcs.
Tovp =
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L s × V CS × Nps
R CS × V OVP
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WS3221 Product Description
In which the Vcs is the OCP threshold (0.5V) ,the Vovp is the
target output protection voltage. And the value of the resistor
Protection Controls
Excellent system stability is achieved by the comprehensive
protection of WS3221. Including Cycle-by-Cycle current
Rovp is as below:
limiting (OCP), LED open/short circuit protection, CS
Rovp = 15 * Tovp * 10 6
resistor short circuit protection, VCC UVLO and Clamp, over
（KΩ）
temperature protection, and so on.
Short circuit protection
When the LED is open circuit, it will trigger over-voltage
When output LED is shorted, WS3221 will operate at 3KHz ,
and the current limited threshold will decrease form 500mv
to 300mv to keep low power dissipation.
protection logic and latch, the system stops switching
immediately; When the LED short circuit is detected, the
system works at low frequency(Fop=3Khz), so the power
loss is low. At some catastrophic fault condition, such as
Temperature compensation and OTP
shorted CS resistor or flyback transformer saturation, the
When the temperature of WS3221 is high than 140℃, the
output current will start to decrease while the temperature
rising. And finally the temperature will reached an
equilibrium point.
internal fast fault detection circuit will trigger and latch, the
system stops switching immediately.
After the system enters into fault latch condition, the VCC
voltage will fall until it reaches UVLO threshold. Then the
Once the temperature reach 160℃, Over temperature
protection will be triggered, and the WS3221 will shut down
system will re-start again. If the fault condition is removed,
the system will recover to normal operation.
until the temperature decrease below 135℃
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WS3221 Product Description
SOP-8 Package Information
B2
A1
A2
0 . 5 * 0.125± 0. 05
球形标记
D
D1
B
B1
A
C4
A3
R2
C
C1
θ4
C2
θ2
R1
θ1
C3
θ3
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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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WS3221 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:Room 1002, East, Phase 2, HighTech Plaza,Tian-An Cyber Park,Chegongmiao, FuTian, Shenzhen, P.R.
China
Post Code : 518040
Tel : +86-755-8250 6288
FAX : +86-755-8250 6299
Web Site : www.winsemi.com
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