20160322025347 4052

WS9221ProductDescription
High Precision PSR Constant Current LED Driver
Features
Description

Built-in650V Power MOSFET

Constant current control without secondary sense and
The WS9221 is a high precision primary-side feedback
feedback circuit.
and regulation controller for LED lighting, it operates in

No Auxiliary winding for sensing and supplying
constant current control mode and is designed to work in

Ultra low operating current to improve efficiency
inductor

Universal input voltage
especially suitable for flyback convertor under universal input.

±5% LED current accuracy
The output power of system is recommended to less than 5W.

LED short and open circuit protection

CS resistor short circuit protection
adopting primary sense and feedback control technology, the

VCC under-voltage protection
secondary sense and feedback circuit is eliminated. The loop

Over temperature protection
compensation

Available in SOP-7 package
maintaining
current
discontinuous
conduction
mode
and
The WS9221integrates 650V power MOSFET. Since
components
stability
are
overall
also
removed
operating
conditions.
while
The
operating current is very low, and it doesn’t need the auxiliary
winding for sensing the output current and supplying the chip.
Applications
The

GU10/E27 LED bulb, spot light

Other LED lighting
low
component
counts
and
small
system
size
arerealized.
Since using the proprietary high accurate current sense
method, theWS9221 realizes ±5% accuracy of LED current
along with excellent line and load regulation.
The WS9221 offers rich protection functions including
LED open/short circuit protection, CS resistor short circuit
protection, over-temperature protection, VCC under voltage
protection.
Typical Application
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WS9221ProductDescription
Pin Configuration and Marking Information
The WS9221 is available in SOP7 Package,the top marking is shown as below:
Pin Definition
Name
Pin No.
Description
CS
1
GND
2
Ground
VCC
3
Power supply
NC
4
No connection, must be floated
DRAIN
5/6
Internal high voltage MOSFET Drain
NC
7
No connection, must be floated
Current sense. This pin connects a current sense resistor to GND to detect the primary
current of transformer.
Internal Block Diagram
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WS9221ProductDescription
Ordering Information
Package
7-Pin SOP-7,
Pb-free
Marking
Part Number
WS9221S7P
WS9221S7P
Recommended Operation Conditions
Part Number
Package
WS9221S7P
SOP7
Input voltage
Maximum output
power
175VAC-264VAC
≤7W
90VAC-264VAC
≤5W
Absolute Maximum Ratings
symbol
paramete
Range
unit
Icc_max
VCC pin maximum sink current
5
mA
Drain
Internal HV MOSFET drain voltage
-0.3~650
V
CS
Current sense pin input voltage
-0.3~7
V
OUT
Internal HV MOSFET Source voltage
-0.3~8
V
TJ
Operating junction temperature
-40~150
℃
TSTG
Storage temperature range
-55~150
℃
Note : Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device.
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WS9221ProductDescription
Electrical Characteristics (Unless otherwise specified, VCC=8V and TA =25 ℃)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
Supply Voltage Section
VCC_Clamp
VCC clamp voltage
1mA
7.3
7.9
8.5
V
VCC_ON
Turn on threshold voltage
VCC rising
6.7
7.4
8.0
V
V CC_UVLO
Turn off threshold voltage
VCC falling
5.1
IST
VCC startup current
VCC= VCC_ON - 1V
45
100
uA
IOP
VCCoperating current
Fop=50kHz
105
250
uA
500
515
mV
V
Current Sense Section
VCS_TH
TLEB
TDELAY
Threshold voltage for peak
485
current limit
Leading edge blanking time
for current sense
Switch off delay time
500
ns
100
ns
Switching Frequency
Fmax
Maximum working frequency
100
kHz
Max duty
Maximum duty cycle
42
%
Fmin
Minimum working frequency
3
kHz
Mininum OFF time
4
us
Output OVP Threshold Time
5.1
us
Tons_mi
n
Tons_O
VP
MOSFET Section
RDS_ON
BVDSS
IDSS
Static drain-source
on-resistance
Drain-source breakdown
voltage
Drain-source leakage current
Vgs=14V/Ids=0.5A
Vgs=0V/Ids=250uA
13
16
650
Ω
V
Vgs=0V/Vds=650V
10
uA
Over Temperature Protection
T_comp
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Thermal Regulation
140
Temperature
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WS9221ProductDescription
Application Information
Operating Switching Frequency
The WS9221 is a high performance power switch
The WS9221 is designed to work in discontinuous
specially designed for LED lighting, with patent constant
conduction mode and no external loop compensation
current control technology. The WS9221integrates a 650V
component is required while maintaining stability. The
power MOSFET. The accurate LED current can be realized
maximum duty cycle is limited to 42%. The maximum
without opto-coupler, TL431 feedback circuit and auxiliary
switching frequency at normal operation is suggested to set
winding while minimizing the external component count,
around 65KHz~70KHz. If the maximum frequency is set too
lowering the total bill of material cost.
high, it will affect the number of maximum series LED lamps.
If set too low, the LED open circuit voltage will be too high.
Start Up
The maximum and minimum switching frequency is
The start-up current in WS9221 is designed to as low as
limited in WS9221 to ensure the stability of system.
45uA. The VCC capacitor will be charged through the
The switching frequency can be set by the formula:
start-up resistor when the system is powered on. Once the
f 
VCC voltage reaches the start-up threshold, the WS9221
will start to switch. The WS9221 integrates a 8V zener for
VCC clamping. Due to the ultra-low operating current, the
Np 2  VLED
8  Ns 2  Lp  I LED
Where, LP is the primary winding inductance of
auxiliary winding is not needed to supply the IC.
transformer.
Constant Current Control
Protection Function
Cycle-by-Cycle current sense is adopted in WS9221,
The WS9221 has integrated rich protection functions,
the CS is connected to the current sense comparator, and
LED open/short protection, CS resistor short circuit
the voltage on CS will be compared with the internal 500mV
protection, VCC under voltage protection, over temperature
reference voltage, the MOSFET will be switched off when
protection, and so on. When the LED is open circuit, it will
the voltage on CS reaches the threshold. The output of the
trigger over-voltage protection logic and latch, the system
comparator includes a 500ns leading edge blanking time.
stops switching immediately.
The primary peak current is given by:
I P_PK 
When the LED short circuit is detected, the system
works at low frequency (Fop=3KHz), so the power
500
( mA)
RCS
consumption is low. At some catastrophic fault condition,
such as shorted CS resistor or flyback transformer
The current in LED can be calculatedby the equation:
I OUT 
saturation, the internal fast fault detection circuit will trigger
and latch, the system stops switching immediately.
I P_PK
N
 P
4
NS
After the system enters into fault latch condition, the
VCC voltage will fall until it reaches UVLO threshold. Then
Where,
the system will re-start again. If the fault condition is
NP: primary winding turns of transformer
removed, the system will recover to normal operation.
NS: secondary winding turns of transformer
PCB Layouts
IP_PK: peak current in MOSFET
The following rules should be followed in WS9221 PCB
layout:
Power MOSFET
Bypass Capacitor
The WS9221 integrates a 650V power N-MOSFET. It
can minimize the external component count and reduce the
BOM cost and PCB size.
The bypass capacitor on VCC should be as close as
possible to the VCC pin and GND pin.
Ground Path
The WS9221 uses SOP-7 package. The recommended
system output power is below 5W in universal input
(90Vac~265Vac) application.
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The power ground path for current sense should be
short, and the power ground path should be separated from
small signal ground path before the negative of the bulk
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WS9221ProductDescription
capacitor.
The Area of Power Loop
The area of main current loop should be as small as
possible to reduce EMI radiation, such as the primary
current loop, the snubber circuit and the secondary rectifying
loop.
NC Pin
The NC pin must be left floating to satisfy the
requirement of creepage distance.
Drain pin
To increasethe copper area of drain for thermal
consideration.
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WS9221ProductDescription
Package Information
SOP7Package Outline Dimensions
B2
0.5*0.125±0 . 05
球形标记
A1
A2
D
D1
B
B1
A
C4
A3
R2
θ4
C
C1
C2
θ2
C3
θ1
θ3
R1
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Symbol
Dimensions in Millimeters
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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WS9221ProductDescription
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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