WS9254 [ETC]
High Precision PSR Constant Current LED Driver;![WS9254](http://pdffile.icpdf.com/pdf2/p00338/img/icpdf/WS9254_2078925_icpdf.jpg)
型号: | WS9254 |
厂家: | ![]() |
描述: | High Precision PSR Constant Current LED Driver |
文件: | 总8页 (文件大小:598K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
WS9254ProductDescription
High Precision PSR Constant Current LED Driver
Features
Description
Built-in600V Power MOSFET
The WS9254 is a high precision primary-side
Constant current control without secondary sense and
feedback circuit.
feedback and regulation controller for LED lighting, it
operates in constant current control mode and is designed
to work in inductor current discontinuous conduction mode
and extremely suitable for flyback convertor under
universal input, the output power of system should be less
than 12W.
±3% LED current accuracy
Ultra low operating current to improve efficiency
High resistance feedback resistor to improve efficiency
Universal input voltage
LED short and open circuit protection
VCC under-voltage protection
The WS9254integrates 600V power MOSFET. Since
adopting primary sense and feedback control technology,
the secondary sense and feedback circuit is eliminated.
The loop compensation components are also removed
while maintaining stability overall operating conditions. The
low component counts and low BOM cost are realized.
Since using the proprietary high accurate current
sense method, theWS9254 realizes ±3% accuracy of LED
current along with excellent line regulation and load
regulation.
Feedback loop short circuit protection
Current sense resistor open circuit protection
Over temperature protection
No external loop compensation component required
Available in DIP-7 package
Applications
LED bulb, spot light
OtherLED lighting
The WS9254 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
WINSEMI MICROELECTRONICS
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Copyright@WinsemiMicroelectronics Co.,Ltd.,All rightreserved.
WS9254ProductDescription
Pin Configuration and Marking Information
WS9254is offered in DIP7 package, as bellows:
WS9254D7P
A:Product Code
X:Internal Code
BCY:Internal Code For QC
YMX:D/C
Pin Definition
Pin No.
Pin Name
GND
Function Description
1
2
3
Ground.
Feedback. This pin detects the output information from auxiliary winding.
Power suppl.
FB
VCC
CS
Current sense. This pin connects a current sense resistor to GND to detect
the primary current of transformer.
4
5,6
7
Drain
NC
Internal high voltage MOSFET drain.
No connection, must be floated.
Internal Block Diagram
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WS9254ProductDescription
Ordering Information
Package
Marking
Part Number
7-Pin DIP-7, Pb-free
WS9254D7P
WS9254D7P
Recommended Operation Conditions
Symbol
Parameter
Maximumworking frequency
Value
Unit
Fmax
TA
100
-20~85
10~17.5
<18
khz
℃
V
Operation temperature
Power supply voltage
VCC
POUT1
POUT2
Output power(Input voltage230V±15%)
Output power(Input voltage85V~265V)
W
W
<12
Absolute Maximum Ratings (Note1)
Symbol
Paramete
Limites
Unit
V
VCC
VCC pin input voltage
-0.3~20
-0.3~6
-0.3~600
-0.3~6
0.9
FB
Drain
CS
Feedback pin input voltage
Internal MOSFET drain voltage
Current sense pin input voltage
Power dissipation (note2)
V
V
V
PDMAX
Tjo
W
Operating junction temperature
Thermal resistance (Junction to Ambient)
Storage temperature range
-40~150
80
℃
θJA
℃/W
℃
TSTG
-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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Tel : +86-755-8250 6288
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WS9254ProductDescription
Electrical Characteristics (Unless otherwise specified, VCC=8V and TA =25 ℃)
Symbol
Parameter
Test condition
Min
Typ
Max
Units
Supply Voltage Section
VDD_CLAMP
UVLO_on
VDD Clamping Voltage
VDD Power Supply
4mA
17.4
16.1
18.3
17.1
19.4
18.1
V
V
VDD Under Voltage
Lockout
UVLO_off
VCC_OVP
8.5
9
9 .5
V
V
VCCover voltage
protection level
Start up current
Operating current
17.9
18.9
19.9
Ist
35
uA
uA
Iop
152
Current Sense Section
Ipp
Primary Peak Current
484
508
500
200
42
531
mV
ns
ns
%
TLEB
Lead Edge Blanking
Shutdown Delay
TDELAY
D_max
Maximum Duty Cycle
FeedbackInputSection
MaximumDemagnetization
Toff_max
420
4
us
us
time
MinimumDemagnetizationt
ime
Toff_min
Ton_max
MaxmiumON time
100
1
us
V
Vfb
FB voltage sense level
Power MOSFET
Drain-source leakage
current
Idss
Vgs=0V,Vds=600V
10
uA
V
Drain-source breakdown
voltage
BVdss
Ron
600
Static drain-source
on-resistance
6.8
8.5
Ω
Over TemperatureProtection
Thermal Regulation
Temperature
T_comp
147
℃
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WS9254ProductDescription
Application Information
The ratio of FB upper resistor to lower resistor is
recommended to about 4.0. The FB upper resistor can be
set to 300KΩ~750KΩ to improve efficiency of convertor.
The WS9254 is a high performance power switch
specially designed for LED lighting, it uses the patent
constant current control technology of WINSEMI. The
WS9254 integrates a 600V power MOSFET. The accurate
LED current can be realized without opto-coupler and TL431
feedback circuit while minimizing the external component
count, lowering the total bill of material cost.
Operation Switching Frequency
The WS9254 is designed to work in discontinuous
conduction mode and no external loop compensation
component is required while maintaining stability. The
maximum duty cycle is limited to 42%. The maximum
switching frequency should be set to less than 100KHz and
the minimum switching frequency should be set to more
than 20KHz. The maximum and minimum switching
frequency is limited in WS9254 to ensure the stability of
system.
Start Up
The VCC capacitor will be charged through the
start-up resistor when the system is powered on, once the
voltage on VCC reaches the start-up threshold, the WS9254
will start to operate, and then the VCC is supplied by the
auxiliary winding.
The switching frequency can be set by the formula:
Np2 VLED
f
8 Ns2 Lp ILED
Constant Current Control
Cycle-by-Cycle current sense is offered in WS9254, the
CS is connected to the current sense comparator, and the
voltage on CS will be compared with the internal 500mV
reference voltage, the MOSFET will be switched off when
the voltage on CS reaches the threshold. The output of the
comparator also includes a 500nS leading edge blanking
time
Where, LP is the primary winding inductance of
transformer.
Protection Function
The WS9254 has several protection functions. The
internal MOSFET will be shut down immediately when the
voltage on VCC reaches the threshold of OVP and the
device will not recover until the protection condition is
removed. A 18V zener diode is designed in the WS9254 to
prevent the chip damage from the abnormal situation.
The thermal protection circuitry in the WS9254 senses
the die temperature after start up, and the thermal protection
threshold is set to 147℃
The primary peak current is given by:
508
IP_PK
(mA)
RCS
The current in LED can be calculated by the equation:
IP_PK
NP
NS
IOUT
4
The system will work in low consumption mode when
the output LED short circuit or open circuit is detected.
While the WS9254 continuous to detect output status until
the LED recover to normal condition, and then the device
will be operate in normal mode.
Where,
NP: primary winding turns of transformer
NS: secondary winding turns of transformer
IP_PK: peak current in MOSFET
Feedback Network
PCB Layout
The WS9254 senses the output information through the
feedback network and the FB threshold voltage is set to 1V.
The following rules should be followed in WS9254 PCB
layout:
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WS9254ProductDescription
Bypass Capacitor
NC Pin
The bypass capacitor on VCC should be as close as
possible to the VCC pin
The NC pin must be left floating to satisfy the
requirement of creepage distance.
Ground Path
Drain pin
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
capacitor.
To increase the copper area of drain for thermal
consideration.
FB Pin
The feedback divider should be as close as possible to
FB Pin and the node must keep away from dynamic node of
transformer.
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.
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WS9254ProductDescription
Package Information
DIP7 Package Outline Dimensions
Winsemi
Dimensions in Millimeters
Dimensions in Inches
Symbol
Min
9.00
6.10
3.0
Max
9.50
6.60
3.4
Min
Max
A
0.354
0.240
0.118
0.058
0.016
0.096
0.374
0.260
0.134
0.062
0.021
0.104
B
C
A1
A2
A3
A4
A5
C1
C2
C3
C4
D
1.474
0.41
2.44
1.574
0.53
2.64
0.51TYP
0.99TYP
0.02TYP
0.04TYP
6.6
7.30
0.260
0.287
0.50TYP
0.02TYP
3.00
1.47
7.62
0.24
3.40
1.65
9.3
0.118
0.058
0.300
0.009
0.134
0.065
0.366
0.013
D1
D2
0.32
7.62TYP
0.3TYP
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WS9254ProductDescription
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
WINSEMI MICROELECTRONICS
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