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WS2287 Product Description
WS2287 Current Mode PWM Controller
Features
General Description
■ Burst Mode Control
■ 5uA ultra-low startup current
■ 1.8mA Low operating current
■ Built-in Leading-edge blanking
■ Built-in synchronous slope compensation circuit
■ Built-in Soft-Start
■ 65kHz fixed switch frequency
■ Cycle by cycle over current protection (OCP)
■ VDD over voltage clamp & under voltage lockout( UVLO)
■ Over load protection (OLP)
■ OVP shut down latch
■ Maximum Gate output voltage clamped at 12V
■ Frequency jittering
■ Adjustable OVP through external Zener
WS2287 is a high performance current mode PWM controller,
optimized for low power power switch equipment.
For lower the standby power and higher RoHS compliant, the
IC offers a Burst Mode control feature and ultra-low start-up
current and operating current, that is, at the condition of no
load or light load, WS2287 can reduce the switch frequency
linearly which minimize the switching power loss; the ultra-low
startup current and operating current make a reliable power
for startup design, and also large resistor can be used in the
startup circuit to improve switching efficiency. The internal
synchronous slope compensation circuit reduces the possible
subharmonic oscillation at high PWM duty cycle output.
Leading-edge blanking on current sense(CS) input removes
the signal glitch due to snubber diode circuit reverse recovery
and thus greatly reduces the external component count and
system cost in the design.
WS2287 offers comprehensive protection coverage with
automatic self-recovery feature, including cycle by cycle over
current protection (OCP), over load protection (OLP), VCC
Clamp, under voltage lockout (UVLO), OTP and OVP shut
down latch. The gate-driven output is clamped to maximum
12V to protect the internal MOSFET.
■ Ultra low standby power (<100mW)
Applications
Universal switch power supply equipment and offline
AC/DC flyback power converter
■ Power Adapter
■ Set-Top Box Power Supplies
■ Open-frame SMPS
■ Battery Charger
Typical Application Circuit
V+
L
EMI
Filter
N
V-
1
2
3
4
N C
GND
VDD
GND
FB
D R A IN
CS
D R A IN
8
7
6
5
W/T-D020-Rev.A/2 Jul.2014
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WS2287 Product Description
Pin Definition and Device Marking
WS2287 is available in DIP8 package:
NC
VDD
1
8
2
7
D IP 8
3
FB
CS
4
6
D: DIP8
GND
P: no Pb
A:wafer information;
GND
1:Ver.; a: Package Code
WS2287D8P
A1a
2C
D ra in
5
2C:Y+M(2=2012 C=12 Month
(1,2…A=10,B=11,C=12)
D ra in
Pin Function Description
Pin
Pin
Name
Number
NC
1
NC
VDD
2
Power
Pin Type
Function Description
Floating pin
Power supply
Feedback input pin. The PWM duty cycle is determined by voltage level
FB
3
Feedback
into this pin and the current-sense signal at Pin 4. The internal protection
Input
circuit will automatically shutdown when the FB voltage level exceeds a
preset threshold voltage.
CS
Current
4
Current sense input.
Monitoring
Power
DRIAN
5/6
This pin connects directly to the primary lead of the transformer and is
transistor
capable of switching a maximum of 650V
drain
GND
7/8
GND
Ground
Block Diagram
GND
OSC
Trigger
and
L o g ic
VDD
Clamper
Soft switch
Control
OCP
Com p
VDD
PWM Comparator
Driver
Output
D R A IN
Soft start
CS
LEB
Slope
Com p
UVLO
Vo lta g e
Divider
OLP
Internal
su p p ly
FB
Burst
M ode
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WS2287 Product Description
Output Power Table
230VAC±15%
85-265VAC
Adapter1
Adapter1
25W
18W
Product
WS2287
Note
Note: Maximum practical continuous power in an Adapter design with sufficient drain pattern as a heat sink, at 50℃ ambient.
Ordering Information
Package
IC Marking Information
8-DIP8, Pb-free
Purchasing Device Name
WS2287D8P
WS2287D8P
Recommended Operating Condition
Symbol
Parameter
Value
Unit
VCC
VCC 供电电压
10~30
V
TA
操作温度
-20~85
℃
Absolute Maximum Ratings
Symbol
Parameter
Value
Unit
Drain voltage(off-state)
Drain Input Voltage
-0.3~650
V
VDD
DC supply voltage
30
V
VFB
FB input voltage
-0.3~7
V
VCS
CS input voltage
-0.3~7
V
TJ
Operating junction temperature
-20~150
℃
TSTG
Storage temperature
-40~150
℃
VCV
VDD clamp voltage
28
V
ICC
VDD DC clamp current
10
mA
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.
Electrical Characteristics(VDD=16V，TA=25℃if not otherwise noted)
Supply Voltage (VCC)
symbol
parameter
Test condition
Min
Typ
Max
Unit
30
V
VCC_OP
Operation voltage
UVLO_ON
Turn on threshold Voltage
6.8
7.5
8.5
V
UVLO_OFF
Turn-off threshold Voltage
12.5
13.5
14.5
V
I_VCC_ST
Start up current
VCC=13V
5
20
uA
I_VCC_OP
Operation Current
VFB=3V
1.8
2.5
mA
Vpull_up
Pull-up PMOS active
VDD_Clamp
VDD Zener Clamp Voltage
OVP(ON)
Over voltage protection voltage
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IVDD=10mA
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CS=0.3V,FB=3V,
Ramp up VCC until
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30
32
34
V
26
28
30
V
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WS2287 Product Description
gate clock is off
Vlatch_release
Latch release voltage
5
V
4.2
V
2
V/V
Feedback Input Section
VFB_Open
VFB Open Loop Voltage
3.9
Avcs
PWM input gain ΔVfb/ΔVcs
Vref_green
The threshold enter green mode
2.1
V
Vref_burst_H
The threshold exit burst mode
1.3
V
Vref_burst_L
The threshold enter burst mode
1.2
V
IFB_Short
FB Pin Short Current
0.4
mA
VTH_PL
Power limiting FB Threshold
3.7
V
TD_PL
Power limiting Debounce
ZFB_IN
Input Impedance
Max_Duty
Maximum duty cycle
FB Shorted to GND
80
88
96
ms
16
75
80
kΩ
85
%
Current CS Section
SST
Soft Start time
4
ms
TLEB
Leading edge Blanking Time
220
ns
ZCS
Input impedance
40
kΩ
TD_OC
OCP control delay
120
ns
VTH_OC
OCP threshold
0.75
V
0.9
V
FB＝3V
Vocp_clamping
Oscillator Section
Fosc
Normal Oscillation Frequency
Fosc_BM
Burst mode frequency
Frequency
∆f_temp
variation
versus
temp. Deviation
Frequency variation
∆f_VDD
versus VDD
VCC=14V,FB=3V,
57
CS=0.3V
65
71
khz
22
khz
TEMP = -20 to 85℃
1
%
VDD = 12 to 25V
1
%
F_shuffling
Shuffling Frequency
32
Hz
∆f_OSC
Frequency Jittering
±4
%
MOSFET Section
MOSFET Drain-Source
BVdss
650
breakdown voltage
V
Static Drain to Source on
Ron
2.5
resistance
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WS2287 Product Description
Typical Operating Characteristics
UVLO(OFF)(V) vs Temperature( 。
C )
UVLO(ON)(V)vs Temperature( 。
C )
1 3 .8 0
UVLO(OFF)(V)
UVLO(ON)(V)
8 .5 0
8 .3 0
8 .1 0
7 .9 0
1 3 .6 0
1 3 .4 0
1 3 .2 0
1 3 .0 0
7 .7 0
-4 0
0
40
80
120
-4 0
80
120
。
Fose(KHz)vs Temperature( C )
V th _ O C ( V ) v s d u ty ( % )
0 .9 5
6 4 .0
0 .9 0
6 3 .8
Fo s e(K Hz )
Vth_OC(V)
40
。
Temperature( C )
。
Temperature( C )
0 .8 5
0 .8 0
6 3 .5
6 3 .3
6 3 .0
0 .7 5
0
14
28
42
56
70
-4 0
D u ty ( % )
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40
120
80
。
Temperature( C )
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WS2287 Product Description
Function Description
the switching power supply comes from the MOSFET
WS2287 is a high performance current mode PWM
controller, optimized for low power AC/DC application. Ultra
low startup current and operating current together with burst
mode feature minimize the standby power consumption and
improve the switching efficiency. In addition to reduce the
external component count, the internal synchronous slope
compensation combines with the leading-edge blanking
improves system large stability and reduces the possible
subharmonic oscillation. WS2287 also have multiform
general recovery protection mode. The main function is
described as below:
switching loss, the core loss of the transformer and the loss
on the snubber circuit. The magnitude of power loss is in
proportion to the number of switching events within a period
of time. Therefore reducing the switch event leads to
reduction on the power loss and thus saving the energy.
For the burst mode control circuit, WS2287 self adjusts the
switching mode according to the loading condition. At the
condition of no load or light/medium load, the FB input
voltage drops below burst mode threshold level. Device
enters Burst Mode control on the basis of the judgment. The
gate drive output switches only when VCC voltage drops
below a preset level and FB input is active. Otherwise the
Startup Current and Startup Control
gate drive remains at off to minimize the switching loss and
Startup current of WS2287 is designed to be extremely low
power consumption to the greatest extend. The frequency
at 5uA, so that VCC could be charged up above UVLO
control also eliminates the audio noise at any loading
threshold level and device starts up quickly. A large value
conditions.
startup resistor can therefore be used to minimize the power
loss, predigest the design of startup circuit and provides
Oscillator Operation
reliable startup in application. For the design of AC/DC
The switching frequency is internally fixed at 65kHz. No
adaptor with universal input range, a startup resistor of 2 MΩ,
external frequency setting components are required for PCB
1/8 W could be used together with a VCC capacitor to
design simplification.
provide a fast startup and low power dissipation solution.
Current Sensing and Leading Edge Blanking
Operating Current
Cycle-by-Cycle current limiting is offered in WS2287. The
The operating current of WS2287 is low at 1.8mA. Excellent
switch current is detected by a sense resistor into the sense
efficiency is achieved with low operating current together
pin. An internal leading edge blanking circuit chops off the
and extended burst mode control circuit.
sense voltage spike at initial MOSFET on state due to
snubber diode reverse recovery so that the external RC
Soft Start
filtering on sense input is no longer required.
WS2287 features an internal 4ms soft start to soften the
The current limit comparator is disabled and thus cannot
electrical stress occurring in the power supply during startup.
turn off the internal MOSFET during the blanking period.
It is activated during the power on sequence. As soon as
PWM duty cycle is determined by the current sense input
VCC reaches UVLO （ OFF ）， the CS peak voltage is
voltage and the FB input voltage.
gradually increaced from 0.15V to the maximum level. Every
restart up is followed by a soft start.
Internal Synchronized Slope Compensation
Built-in slope compensation circuit adds slope voltage onto
Extended Burst Mode Operation
the current sense input voltage for PWM generation. This
At zero load or light load, most of the power dissipation of
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WS2287 Product Description
greatly enhances the close loop stability at CCM and
Protection Controls
prevents possible subharmonic oscillation and thus reduces
Excellent system stability is achieved by the comprehensive
the output ripple voltage.
protection of WS2287. Including Cycle-by-Cycle current
limiting (OCP), Over Load Protection (OLP) and over
Gate Drive
voltage clamp, VCC Clamp, Under Voltage Lockout on VCC
The gate drive strength which is too weak leads to over
(UVLO), OTP and OVP shut down latch. At overload
switch loss of MOSFET while too strong gate drive output
condition when FB input voltage exceeds power limit
compromises in the over EMI. A good tradeoff between
threshold value for more than TD_PL, control circuit reacts
output strength and dead time control is achieved through
to shut down the output power MOSFET. Device restarts
the design of the built-in totem pole gate. The low standby
when VCC voltage drops below UVLO limit. It is clamped
dissipation and good EMI system design is easier to achieve
when VCC is higher than threshold value. The power
through this dedicated devise. For MOSFET gate protection,
MOSFET is shut down when VCC drops below UVLO limit
an internal 12V clamp is added at higher than expected VCC
and device enters power on start-up sequence thereafter.
input.
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WS2287 Product Description
Package Information
DIP8 Package Outline Dimensions
D2
θ1
C1
C
C4
θ2
C2
C3
θ3
D1
A2
A5
A3
A1
D
A4
B
A
Winsemi
Dimensions in Millimeters
Symbol
Dimensions in Inches
Min
Max
Min
Max
A
9.00
9.50
0.354
0.374
B
6.10
6.60
0.240
0.260
C
3.0
3.4
0.118
0.134
A1
1.474
1.574
0.058
0.062
A2
0.41
0.53
0.016
0.021
A3
2.44
2.64
0.096
0.104
A4
0.51TYP
0.02TYP
A5
0.99TYP
0.04TYP
C1
6.6
C2
7.30
0.260
0.50TYP
0.287
0.02TYP
C3
3.00
3.40
0.118
0.134
C4
1.47
1.65
0.058
0.065
D
7.62
9.3
0.300
0.366
D1
0.24
0.32
0.009
0.013
D2
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WS2287 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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