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WS3253 Product Description
High Precision Primary-Side Off-line PWM Power Switch
Features
� 5uA ultra-low startup current
� 2mA Low operating current
� ±5% Constant Voltage Regulation at Universal AC
Primary-side Sensing and Regulation Without
current and output power setting can be adjusted externally
operations are utilized to achieve high performance and high
efficiency. In addition, good load regulation is achieved by
TL431 and Opto-coupler
�
�
�
�
�
�
�
Control as shown in fig.1.In CC Control, the
by the sense resistor Rs at CS pin. In CV control, multi-mode
input
�
constant voltage precision in full input voltage range. CC/CV
the built-in cable drop compensation. Device operates in
Programmable CV and CC Regulation
Built-in Primary winding inductance compensation
PFM in CC mode as well at large load condition and it
operates in PWM with frequency reduction at light/medium
Programmable cable drop compensation
load.
Built-in soft start
Vo
Built-in Leading-edge blanking
Cycle by cycle over current protection (OCP)
5%
VCC over voltage clamp & under voltage
lockout( UVLO)
�
�
�
Maximum Gate output voltage clamped at 12V
Frequency jittering
Ultra low standby power (<100mW)
Io
Icc
Applications
Low power AC/DC offline SMPS for
Fig.1 Typical CC/CV Curve
�
Cell Phones/Cordless phones Charger
WS3253 offers power on soft start control and protection
�
Digital Cameras Charger
coverage with auto-recovery features
�
Small Power Adapter
including Cycle-by-Cycle current limiting, VCC
�
Auxiliary Power for PC, TV etc.
OVP, VCC clamp and UVLO. The gate-driven output is
�
Linear Regulator/RCC Replacement
clamped to maximum 12V to protect the internal MOSFET.
Excellent EMI performance is achieved by using the
soft-switching
and
frequency
jittering
at
the
General Description
totem-pole-gate-drive output. The WS3253 is the ideal
WS3253 is a high-integrated offline PWM power switch,
substitute of the linear power supply or the RCC-mod e
optimized for high performance low power AC/DC
power, for a better performance of the whole switch power
charger and adapter application.
system and a lower cost.
WS3253
operates
in
primary-side
sensing
and
WS3253 is available in DIP8 and SOP8 package.
regulation. Consequently, optocoupler and TL431 could
be eliminated, thus reduce the cost. It can achieve ±5%
W/T-DS011-Rev.A/2 May.2014
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WS3253 Product Description
Typical Application Circuit
VO
CO
NS
NP
AC
NA U X
VCC
GND
COMP
GND
IN V
CS
RS
G ra in
G ra in
W S3 2 5 3
Pin Definition and Device Marking
WS3253 is available in DIP8 and SOP8 package:
VCC
COMP
IN V
1
8
2
7
3
D IP 8
GND
GND
WS3253D8P
6
D R A IN
4
5
CS
A1a
2C
D: DIP8 S: SOP P: no Pb
A:wafer information;
D R A IN
1:Ver.; a: Package Code
2C:Y+M(2=2012 C=12 Month
VCC
COMP
IN V
1
8
2
7
3
SOP8
(1,2…A=10,B=11,C=12)
GND
GND
WS3253S8P
6
A1a
D R A IN
4
5
CS
2C
D R A IN
Pin Function Description
Pin
Name
VCC
COMP
Pin
Number
1
2
INV
3
CS
DRAIN
GND
4
5/6
7/8
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Function Description
Power
Loop Compensation
Feedback Input
Current Monitoring
Power transistor drain
GND
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Power supply
Loop Compensation for CV Stability
The voltage feedback from auxiliary winding. Connected to resistor
divider from auxiliary winding reflecting output voltage. PWM duty cycle is
determined by EA output and current sense signal at pin4.
Current sense input.
This pin connects directly to the primary lead of the transformer.
Ground
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WS3253 Product Description
Block Diagram
vcc
1
5V
POR
UVLO
D R A IN
Insernal
S u p p ly
5 /6
G a te
Driver
Po we r
M O SF ET
CC
Controller
Soft start
PW M
Generator
D ro p
Com p
OCP
2V
CLK
Genterator
EA
IN V
Sampler
3
CS
4
LEB
Sa mp lin g
Co n tro lle r
Frequency
Shuffling
2
GND
7 /8
COMP
Output Power Table
230VAC±15%
85-264VAC
Adapter1
Adapter1
8W
5W
Product
WS3253
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
Purchasing Device Name
8-Pin DIP-8, Pb-free
WS3253D8P
WS3253D8P
8-SOP8, Pb-free
WS3253S8P
WS3253S8P
Recommended Operating Condition
Symbol
Parameter
Value
Unit
VCC
VCC supply voltage
10~30
V
TA
Operating temperature
-20~85
℃
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WS3253 Product Description
Absolute Maximum Ratings
Symbol
Parameter
Value
Drain voltage(off-state)
Drain Voltage (off state)
VCC
Unit
-0.3~600
V
DC supply voltage
30
V
VINV
INV input voltage
-0.3~7
V
VCS
CS input voltage
-0.3~7
V
VCOMP
COMP input voltage
-0.3~7
V
TJ
Max. Operating junction temperature
150
℃
TSTG
Min./Max. Storage temperature
-55~150
℃
ICC
VCC Clamp Continuous 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.
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WS3253 Product Description
Electrical Characteristics (TA=25℃，VDD=16V, RI=26Kohm, if not otherwise noted)
Supply Voltage (VCC)
symbol
parameter
Test condition
I_VCC_ST
Start up current
I_VCC_OP
Typ
Max
VCC=13V
5
20
uA
Operation Current
VCC=18V,INV=2V,CS=0V
2
3
mA
UVLO_ON
Turn on threshold Voltage
VCC falling
8.2
9.0
10.5
V
UVLO_OFF
Turn-off threshold Voltage
VCC rising
13.5
14.8
16.0
V
VCC_Clamp
VCC Zener Clamp Voltage
IVCC=10mA
28
29
31
V
Ramp VCC until gate shut down
27
28.3
30
V
1.935
1.975
2.015
V
Over
voltage
Min
Unit
protection
OVP
Threshold
Error Amplifier Section
Vref_EA
Reference voltage for EA
Gain
DC gain of EA
Max.
Cable
60
dB
37.5
uA
625
ns
compensation
I_comp_max
INV=2V,COMP=0V
current
Current Sense Section
TLEB
Leading edge Blanking Time
Zsense
Input impedance
TD_OC
OCP control delay
VTH_OC
OCP threshold
T_ss
Soft start time
50
kΩ
110
0.895
0.91
ns
0.925
17
V
ms
Oscillator Section
Freq_Max
IC Maximum frequency
60
Freq_Nom
System nominal switch frequency
Freq_startup
∆f/Freq
INV=0V,COMP=5V
Frequency shuffling range
67.5
75
khz
60
khz
14
khz
±6
%
MOSFET Section
MOSFET Drain-Source
BVdss
600
breakdown voltage
Static Drain to Source on
Ron
V
Ω
12
resistance
Note
Note: 1. Freq_Max indicates IC internal maximum clock frequency. In system application, the maximum operation frequency of
70 kHz nominal occurs at maximum output power or the transition point from CV to CC.
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WS3253 Product Description
Typical Operating Characteristics(TA=25℃，VDD=16V, RI=26Kohm, if not otherwise noted)
UVLO( OFF)( V) vs Temperature( C)
UVLO( ON)( V) vs Temperature( C)
UVLO ( O FF )( V )
UVLO ( ON ) ( V)
1 0 .5
1 0 .0
9 .5
9 .0
8 .5
8 .0
7 .5
-4 0
-1 0
20
50
80
Temperature( C)
1 6 .5 0
1 5 .5 0
1 5 .0 0
1 4 .5 0
1 4 .0 0
1 3 .5 0
1 3 .0 0
-4 0
11 0
20
50
11 0
80
Temperature( C)
Istarup (uA )vs Temperature (C )
Freq_Max( kHz) vs Temperature( C)
7 0 .0
Istarup ( uA )
Freq_Max ( kHz )
-1 0
6 5 .0
6 0 .0
5 5 .0
3 .0
2 .5
2 .0
1 .5
1 .0
5 0 .0
-40
-4 0
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-1 0
20
11 0
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80
Temperature( C)
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-10
20
50
80
11 0
Temperature ( C )
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WS3253 Product Description
Function Description
WS3253 is a high-integrated offline PWM power switch,
Is =
optimized for high performance low power AC/DC charger
and adapter application. WS3253 operates in primary-side
NP
*Ip
Ns
The auxiliary voltage reflects the output voltage, given by
sensing and regulation. Consequently, opto-coupler and
TL431 could be eliminated, thus reduce the cost. High
V AUX =
precision CC/CV control can meet most adapter and charger
N AUX
* (Vo + ∆V )
NS
Where △V indicates the drop voltage of the output Diode.
application requirements.
Via a resistor divider connected between the auxiliary
winding and INV, the auxiliary voltage is sampled at the
Startup Current and Startup Control
Startup current of WS3253 is designed to be extremely low
at 5uA, so that VCC could be charged up above UVLO
threshold level and device starts up quickly. A large value
startup resistor can therefore be used to minimize the power
loss, predigest the design of startup circuit and provides
reliable startup in application.
end of the demagnetization and it is hold until the next
sampling. The sampled voltage is compared with Vref (2V)
and the error is amplified. The error amplifier output COMP
reflects the load condition and controls the PWM switching
frequency to regulate the output voltage, thus the constant
output current can be achieved.
When sampled voltage is below Vref and error amplifier
output COMP reaches its maximum, the switching
Operating Current
frequency is controlled by the sampled voltage thus the
The operating current of WS3253 is low at 2mA. Excellent
output voltage to regulate the output current, thus the
efficiency is achieved with low operating current together
constant output current can be achieved.
and multi-mode control circuit.
Adjustable CC point and Output Power
CC/CV Operation
In WS3253, the CC point and maximum output power can
WS3253 is designed to produce good CC/CV control
be externally adjusted by external current sense resistor Rs
characteristic as shown in the fig.1. In charger applications,
at CS pin. The output power is adjusted through CC point
a discharged battery charging starts in the CC portion of
change. The larger Rs, the smaller CC point is, and the
the curve until it is nearly full charged and smoothly
smaller output power becomes, and vice versa.
switches to operate in CV portion of the curve. In an AC/DC
Vo
adapter, the normal operation occurs only on the CV
Large R s
portion of the curve. The CC portion provides output
current limiting. In CV operation, the output voltage is
Small R s
regulated through the primary side control. In CC operation
mode, WS3253 will regulate the output current constant
regardless of the output voltage drop.
Io
Principle of Operation
Fig.2 Adjustable output power by changing Rs
To achieve high precision CC/CV control, system needs to
be designed in DCM mode for flyback system. In DCM mode,
the output voltage can be sensed via the auxiliary winding.
During MOSFET turn-on time, the load current is supplied
Operation switching frequency
The switching frequency of WS3253 is adaptively controlled
according to the load conditions and the operation modes.
from the output filter capacitor Co. The current in
The operation switching frequency at maximum output
the primary winding ramps up. When MOSFET turns off, the
primary current transfers to the secondary at the amplitude
power is set to 67.5KHz internally. In DCM mode, the
maximum output power is given by
of
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WS3253 Product Description
PoMAX =
1
2
LP FSW I P
2
Programmable Cable Drop Compensation
Where Lp indicate the inductance of primary winding and Ip
is peak current of primary winding.
load regulation in WS3253. An offset voltage is generated at
The change of the primary winding inductance results in the
change of the maximum output power and constant output
current in CC mode.
INV by an internal current flowing into the resister divider.
The current is inversely proportional to the voltage across
pin COMP, as a result, it is inversely proportional to the
To compensate the change from variations of primary
winding inductance, the switching frequency is locked by an
internal loop such that the switching frequency is
FSW =
Cable drop compensation is implemented to achieve good
output load current, thus the drop due to the cable loss can
be compensated. As the load current decreases from
full-load to no-load, the offset voltage at INV will increase. It
1
can also be programmed by adjusting the resistance of the
2TDemag
divider to compensate the drop for various cable lines used.
Since TDemag is inversely proportional to the inductance, as a
result, the product Lp and Fsw is constant, thus the
maximum output power and constant current in CC mode
will not change as primary winding inductance changes. Up
to ±10% variation of the primary winding inductance can be
Gate Drive
The gate drive strength which is too weak leads to over
switch loss of MOSFET while too strong gate drive output
compromises in the over EMI. A good tradeoff between
output strength and dead time control is achieved through
compensation.
the design of the built-in totem pole gate. The low standby
dissipation and good EMI system design is easier to achieve
Frequency Shuffling
through this dedicated devise. For MOSFET gate protection,
Excellent EMI performance is achieved by using frequency
jittering in WS3253.
an internal 12V clamp is added at higher than expected VCC
input.
Current Sensing and Leading Edge Blanking
Protection Controls
Cycle-by-Cycle current limiting is offered in WS3253. The
switch current is detected by a sense resistor into the sense
pin. An internal leading edge blanking circuit chops off the
sense voltage spike at initial MOSFET on state due to
snubber diode reverse recovery so that the external RC
filtering on sense input is no longer required. The current
limit comparator is disabled and thus cannot turn off the
internal MOSFET during the blanking period. PWM duty
cycle is determined by the current sense input voltage and
Excellent system stability is achieved by the comprehensive
protection of WS3253. Including Cycle-by-Cycle current
limiting (OCP), VCC Clamp, Under Voltage Lockout on VCC
(UVLO).
Device restarts when VCC voltage drops below UVLO limit.
It is clamped when VCC is higher than threshold value. The
power MOSFET is shut down when VCC drops below UVLO
limit and device enters power on start-up sequence
thereafter.
the EA output voltage.
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WS3253 Product Description
Package Information
DIP-8 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
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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Dimensions in Inches
7.62TYP
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WS3253 Product Description
SOP-8 Package Dimension
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
Winsemi
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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0.016
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WS3253 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: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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