20160322025707 7936

WS9252ProductDescription
High Precision PSR Constant Current LED Driver
Features

Description
Constant current control without secondary sense and
The WS9252 is a high precision primary-side
feedback circuit.
feedback and regulation controller for LED lighting, it

±3% LED current accuracy
operates in constant current control mode and is designed

Ultra low operating current to improve efficiency
to work in inductor current discontinuous conduction mode

High resistance feedback resistor to improve efficiency
and extremely suitable for buckboost/flyback convertor

Universal input voltage
under universal input.

LED short and open circuit protection

VCC under-voltage protection
technology, the secondary sense and feedback circuit is

Feedback loop short circuit protection
eliminated. The loop compensation components are also

Current sense resistor open circuit protection
removed while maintaining stability overall operating

Over temperature protection
conditions. The low component counts and low BOM cost

No external loop compensation component required
are realized.

Available in SOT23-5 package
Since adopting primary sense and feedback control
Since using the proprietary high accurate current
sense method, theWS9252 realizes ±3% accuracy of LED
current along with excellent line regulation and load
Applications
regulation.

GU10/E27 LED bulb, spot light

Other LED lighting
The WS9252 offers rich protection functions including
LED short circuit protection, LED open circuit protection,
die
over-temperature
protection,
VCC
over
voltage
protection, VCC under voltage protection and FB short
circuit
protection.
All
the
protection
features
are
auto-recovery.
Typical Application
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WS9252ProductDescription
Pin Configuration and Marking Information
WS9252 is offered in SOT23-5 package, as bellows:
9252:Product Code
X:Product Code
YM:Production Date
XX:Internal Code For QC
Pin Definition
Pin No.
Pin Name
Function Description
1
VCC
Power supply
2
GND
Ground
3
GATE
Gate Driver Pin. Connect it to the gate of external power MOSFET.
4
CS
5
FB
Current sense. This pin connects a current sense resistor to GND to detect
the primary current of transformer.
Feedback Pin. This pin detects the output information from auxiliary winding.
Internal Block Diagram
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WS9252ProductDescription
Ordering Information
Package
Marking
Part Number
5-Pin SOT23-5, Pb-free
WS9252YP
WS9252YP
Recommended Operation Conditions
Symbol
Parameter
Value
Unit
TA
Operation temperature
-20~85
℃
Fmax
Maximumworking frequency
100
khz
VCC
Power supply voltage
10~17.5
V
POUT1
Output power(Input voltage230V±15%)
<50
W
POUT2
Output power(Input voltage85V~265V)
<36
W
Absolute Maximum Ratings (Note1)
symbol
paramete
limites
unit
VCC
VCC pin input voltage
-0.3~20
V
FB
Feedback pin input voltage
-0.3~6
V
Gate
Gate driver of external power MOSFET
-0.3~20
V
CS
Current sense pin input voltage
-0.3~6
V
PDMAX
Power dissipation (note2)
0.3
W
Tjo
Operating junction temperature
-40~150
℃
θJA
Thermal resistance (Junction to Ambient)
300
℃/W
TSTG
Storage temperature range
-55~150
℃
Note 1: 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.
The electrical characteristics table defines the operation range of the device, the electrical characteristics is assured on DC and
AC voltage by test program. For the parameters without minimum and maximum value in the EC table, the typical value defines
the operation range, the accuracy is not guaranteed by spec.
Note 2: The maximum power dissipation decrease if temperature rise, it is decided by TJMAX, θ JA, and environment
temperature (TA). The maximum power dissipation is the lower one between PDMAX = (TJMAX - TA)/ θJA and the number
listed in the maximum table.
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WS9252ProductDescription
Electrical Characteristics (Unless otherwise specified, VCC=8V and TA =25 ℃)
Symbol
Parameter
Test condition
Min
Typ
Max
Units
VDD Clamping Voltage
4mA
17.4
18.3
19.4
V
16.1
17.1
18.1
V
8.5
9
9 .5
V
17.9
18.9
19.9
V
Supply Voltage Section
VDD_CLAMP
UVLO_on
VDD Power Supply
VDD Under Voltage
UVLO_off
Lockout
VCCover voltage
VCC_OVP
protection level
Ist
Start up current
35
uA
Iop
Operating current
152
uA
Current Sense Section
Ipp
Primary Peak Current
TLEB
TDELAY
D_max
484
508
531
mV
Lead Edge Blanking
500
ns
Shutdown Delay
200
ns
Maximum Duty Cycle
42
%
420
us
4
us
MaxmiumON time
100
us
FB voltage sense level
1
V
100
mA
20
Ω
147
℃
FeedbackInputSection
MaximumDemagnetization
Toff_max
time
MinimumDemagnetizationt
Toff_min
ime
Ton_max
Vfb
Power MOSFET
Isource
Rds_off
GATE Pin Sourcing
Current
Resistor Of Gate
Driver(OFF)
Over TemperatureProtection
T_comp
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Thermal Regulation
Temperature
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WS9252ProductDescription
Application Information
recommended to about 4.0. The FB upper resistor can be
The WS9252 is a high performance power switch
set to 300KΩ~750KΩ to improve efficiency of convertor.
specially designed for LED lighting, it uses the patent
constant current control technology of WINSEMI. The
Operation Switching Frequency
accurate LED current can be realized without opto-coupler
The WS9252 is designed to work in discontinuous
and TL431 feedback circuit while minimizing the external
conduction mode and no external loop compensation
component count, lowering the total bill of material cost.
component is required while maintaining stability. The
maximum duty cycle is limited to 42%. The maximum
Start Up
switching frequency should be set to less than 100KHz and
The VCC capacitor will be charged through the start-up
the minimum switching frequency should be set to more
resistor when the system is powered on, once the voltage
than 20KHz. The maximum and minimum switching
on VCC reaches the start-up threshold, the WS9252 will
frequency is limited in WS9252 to ensure the stability of
start to operate, and then the VCC is supplied by the
system.
auxiliary winding.
The switching frequency can be set by the formula:
f 
Constant Current Control
Np 2  VLED
8  Ns 2  Lp  I LED
Cycle-by-Cycle current sense is offered in WS9252, the
Where, LP is the primary winding inductance of
CS is connected to the current sense comparator, and the
voltage on CS will be compared with the internal 508mV
reference voltage, the MOSFET will be switched off when
the voltage on CS reaches the threshold. The output of the
transformer.
Protection Function
The WS9252 has several protection functions. The
comparator also includes a 500nS leading edge blanking
internal MOSFET will be shut down immediately when the
time
voltage on VCC reaches the threshold of OVP and the
The primary peak current is given by:
I P_PK
device will not recover until the protection condition is
508

( mA)
RCS
removed. A 18V zener diode is designed in the WS9252 to
prevent the chip damage from the abnormal situation.
The current in LED can be calculated by the equation:
I OUT 
I P_PK
4

The thermal protection circuitry in the WS9252 senses
the die temperature after start up, and the thermal protection
NP
NS
threshold is set to 147℃
The system will work in low consumption mode when
Where,
the output LED short circuit or open circuit is detected.
NP: primary winding turns of transformer
While the WS9252 continuous to detect output status until
NS: secondary winding turns of transformer
the LED recover to normal condition, and then the device
IP_PK: peak current in MOSFET
will be operate in normal mode.
Feedback Network
PCB Layout
The WS9252 senses the output information through the
feedback network and the FB threshold voltage is set to 1V.
The following rules should be followed in WS9252 PCB
layout:
The ratio of FB upper resistor to lower resistor is
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WS9252ProductDescription
Bypass Capacitor
The Area of Power Loop
The bypass capacitor on VCC should be as close as
The area of main current loop should be as small as
possible to the VCC pin
possible to reduce EMI radiation, such as the primary
Ground Path
current loop, the snubber circuit and the secondary
The power ground path for current sense should be
rectifying loop.
short, and the power ground path should be separated from
FB Pin
small signal ground path before the negative of the bulk
The feedback divider should be as close as possible to
capacitor.
FB Pin and the node must keep away from dynamic node of
transformer.
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WS9252ProductDescription
Package Information
SOT23-5 Package Outline Dimensions
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Dimensions in Millimeters
Symbol
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Min
Max
A
-
1.45
A1
0
0.15
A2
0.90
1.30
A3
0.60
0.70
b
0.39
0.49
b1
0.35
0.45
c
0.08
0.22
c1
0.08
0.20
D
2.80
3.00
E
2.60
3.00
E1
1.50
1.70
e
0.85
1.05
e1
1.80
2.00
L
0.35
0.60
L1
0.60REF
L2
0.25BSC
R
0.10
-
R1
0.10
0.25
θ
0°
8°
θ1
7°
11°
θ2
8°
12°
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WS9252ProductDescription
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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