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WS3252 Product Description
High Precision CC/CV Primary-Side PWM Controller
Features
General Description
■ 5uA ultra-low startup current
■ 2mA Low operating current
■ ±5% Constant Voltage Regulation at Universal AC input
■ Primary-side Sensing and Regulation Without TL431 and
Opto-coupler
■ Programmable CV and CC Regulation
■ Built-in Primary winding inductance compensation
■ Programmable cable drop compensation
■ Built-in soft start
■ Built-in Leading-edge blanking
■ Cycle by cycle over current protection (OCP)
■ VCC over voltage clamp & under voltage lockout( UVLO)
■ Maximum Gate output voltage clamped at 12V
■ Frequency jittering
■ Ultra low standby power (<100mW)
WS3252 is a high-integrated offline PWM controller, optimized
for high performance low power AC/DC charger and adapter
adapter application.
WS3252 operates in primary-side sensing and regulation.
Consequently, opto-coupler and TL431 could be eliminated,
thus reduce the cost. It can achieve ±5% constant voltage
precision in full input voltage range. CC/CV Control as shown
in fig.1.In CC Control, the current and output power setting can
be adjusted externally by the sense resistor Rs at CS pin. In
CV control, multi-mode operations are utilized to achieve high
performance and high efficiency. In addition, good load
regulation is achieved by the built-in cable drop compensation.
Device operates in PFM in CC mode as well at large load
condition and it operates in PWM with frequency reduction at
light/medium load.
Vo
5%
Io
Applications
Low power AC/DC offline SMPS for
■ Cell Phone Charger
■ Digital Cameras Charger
■ Small Power Adapter
■ Auxiliary Power for PC, TV etc.
■ Linear Regulator/RCC Replacement
Icc
Fig.1 Typical CC/CV Curve
WS3252 offers power on soft start control and protection
coverage with auto-recovery features including Cycle-by-Cycle
current limiting, VCC OVP,VCC clamp and UVLO. The
gate-driven output is clamped to maximum 12V to protect the
internal MOSFET. Excellent EMI performance is achieved by
using the soft-switching and frequency jittering at the
totem-pole-gate-drive output. The WS3252 is the ideal substitute
of the linear power supply or the RCC-mod e power, for a better
performance of the whole switch power system and a lower cost.
WS3252 is available in SOT23-6 and DIP-8 package.
Typical Application Circuit
VO
NS
CO
NP
AC
NA U X
VCC
GND
C O M P G AT E
IN V
C S
RS
WS 3252
W/T-Y008-Rev.A/3 May.2014
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WS3252 Product Description
Pin Definition and Device Marking
6
1 GND
VCC 6
52: WS3252;
Y: Year 2=2012，
52 YM F
2 G AT E C O M P 5
M: Month 1,2…A=10,B=11,C=12
F: Factory No.
3 CS
IN V 4
1
S OT23-6
SOT23-6
1 GND
NC 8
2 VCC
G AT E 7
3 COMP
CS
6
4 IN V
NC
5
WS3252D8P
D8P：DIP8，Pb free
A: Product Code
2D8P
WS325
WS3252
A1a
2C
X：Internal Code
B：Area Code
YM：Year, Month
D IP - 8
Pin Function Description
Pin
Pin Num
Name
SOT23-6/DIP-8
GND
1/1
GATE
2/7
CS
3/6
Pin Type
Function Description
GND
Ground.
Gate-driven
Totem-pole gate driver output for power MOSFET.
output
Current
Current sense input.
Monitoring
The voltage feedback from auxiliary winding. Connected to resistor
INV
4/4
Feedback Input
divider from auxiliary winding reflecting output voltage. PWM duty
cycle is determined by EA output and current sense signal at pin3.
Loop
Loop Compensation for CV Stability
COMP
5/3
VCC
6/2
Power
NC
5/8
Not Connected
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Power supply
Floating
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WS3252 Product Description
Block Diagram
GND
1
6 VCC
Vc c _ O VP
G a te
2
regulator
UVLO
Inter supply
POR
CLK
Generation
L o g ic
Driver
CC
Controller
LEB
OCP
5 COMP
PW M
+& S S Drop Comp
CS
-
3
EA
+
Sampler
4 IN V
2V
Sampling
Controller
Ordering Information
Package
6-Pin SOT23-6,
IC Marking Information
Pb-free
8-Pin DIP-8, Pb-free
Purchasing Device Name
52 YMF
WS3252YP
WS3252D8P
WS3252D8P
Recommended Operating Condition
Symbol
Parameter
Value
Unit
VCC
VCC supply voltage
10~30
V
TA
Operating temperature
-20~85
℃
Absolute Maximum Ratings
Symbol
Parameter
Value
Unit
VCC
DC supply voltage
30
V
VINV
INV input voltage
-0.3~7
V
VCS
CS input voltage
-0.3~7
V
COMP input voltage
-0.3~7
V
150
℃
VCOMP
TJ
Max. Operating junction temperature
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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WS3252 Product Description
Electrical Characteristics (TA=25℃，VCC=16V, if not otherwise noted)
Supply Voltage (VCC)
symbol
parameter
Test condition
Min
Typ
Max
Unit
I_VCC_ST
Start up current
VCC=13V
5
20
uA
I_VCC_OP
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
27
28.3
30
V
1.938
1.975
2.012
V
OVP
Over voltage protection Threshold Ramp VCC until gate shut down
Error Amplifier Section
Vref_EA
Gain
Reference voltage for EA
DC gain of EA
I_comp_max
Max. Cable compensation current INV=2V,COMP=0V
60
dB
37.5
uA
625
ns
Current Sense Section
TLEB
Leading edge Blanking Time
Zsense
Input impedance
50
TD_OC
OCP control delay
VTH_OC
OCP threshold
T_ss
Soft start time
kΩ
110
0.88
0.91
ns
0.94
17
V
ms
Oscillator Section
Freq_Max1
IC Maximum frequency
Freq_Nom
System nominal switch frequency
60
Freq_startup
∆f/Freq
INV=0V,COMP=5V
Frequency shuffling range
67.5
75
khz
50
khz
14
khz
±6
%
Gate Driver Output Section
VOL
Output Low Level
Io=20mA
VOH
Output High Level
Io=20mA
V_clamp
1
6
Output Clamp Voltage Level
V
V
12
V
T_r
Output Rising Time
CL=0.5nF
650
ns
T_f
Output Falling Time
CL=0.5nF
40
ns
Note
Note: 1. Freq_Max indicates IC internal maximum clock frequency. In system application, the maximum operation frequency of
60kHz nominal occurs at maximum output power or the transition point from CV to CC.
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WS3252 Product Description
Typical Operating Characteristics
UVLO ( OFF ) ( V ) vs Temperature ( C )
UVLO ( ON ) ( V ) vs Temperature ( C )
O
O
UV LO ( OF F )( V )
UVLO ( ON ) ( V)
1 0 .5
1 0 .0
9 .5
9 .0
8 .5
8 .0
7 .5
-4 0
20
-1 0
50
80
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
-1 0
20
50
80
11 0
Temperature ( C )
O
Temperature ( C )
O
Istarup ( uA ) vs Temperature ( C )
O
Freq_Max ( kHz )vs Temperature ( C )
7 0 .0
Istarup ( uA )
Freq_Max ( kHz)
O
6 5 .0
6 0 .0
5 5 .0
3 .0
2 .5
2 .0
1 .5
1 .0
5 0 .0
-4 0
20
-1 0
50
80
-40
11 0
-10
20
50
80
11 0
Temperature ( C )
O
Temperature ( C )
O
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WS3252 Product Description
Function Description
WS3252 is a high-integrated offline PWM controller,
V AUX =
optemized for high poformance low power AC/DC charger
and adapter adapter application. WS3252 operates in
primary-side
sensing
and
regulation.
Consequently,
N AUX
* (Vo + ∆V )
NS
Where △V indicates the drop voltage of the output Diode.
opto-coupler and TL431 could be eliminated, thus reduce
Via a resistor divider connectrd between the auxiliary
the cost. High presicion CC/CV control can meet most
winding and INV, the auxiliary voltage is sampled at the end
adapter and charger application requirements.
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
Startup Current and Startup Control
Startup current of WS3252 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.
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
frequency is controlled by the sampled voltage thus the
output voltage to regulate the output current, thus the
constant output current can be achieved.
Operating Current
The operating current of WS3252 is low at 2mA. Excellent
Adjustable CC point and Output Power
efficiency is achieved with low operating current together
In WS3252, the CC point and maximum output power can
and multi-mode control circuit.
be externally adjusted by eaternal current sense resistor Rs
at CS pin. The output power is adjusted through CC point
change. The larger Rs, the smaller CC point is, and the
CC/CV Operation
WS3252 is designed to produce good CC/CV control
smaller output power becomes, and vice versa.
characteristic as shown in the fig.1. In charger applications,
Vo
a discharged battery charging starts in the CC portion of the
curve until it is nearly full charged and smoothly switches to
Large R s
operate in CV portion of the curve. In an AC/DC adapter, the
Small R s
normal operation occurs only on the CV portion of the curve.
The CC portion provides output current limiting. In CV
operation, the output voltage is regulated through the
primary side control. In CC operation mode, WS3252 will
Io
regulate the output current constant regardless of the output
voltage drop.
Fig.2 Adjustable output power by changing Rs
Principle of Operation
To achieve high precision CC/CV control, system needs
Operation switching frequency
to be designed in DCM mode for flyback system. In DCM
The switching frequency of WS3252 is adaptively controlled
mode, the output voltage can be sensed via the auxiliary
according to the load conditions and the operation modes.
The operation switching frequency at maximum output
winding. During MOSFET turn-on time, the load current is
power is set to 60KHz internally. In DCM mode, the
supplied from the output filter capacitor Co. The current in
maximum output power is given by
the primary winding ramps up. When MOSFET turns off, the
PoMAX =
primary current transfers to the secondary at the amplitude
of
Where Lp indicate the inductance of primary winding and Ip
N
Is = P * I p
Ns
is peak current of primary winding.
The change of the primary winding inductance results in the
The auxiliary voltage reflects the output voltage, given by
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2
LP FSW I P
2
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WS3252 Product Description
current in CC mode. To compensate the change from
Cable drop compensation is implemented to achieve good
viariations of primary winding inductance, the switching
load regulation in WS3252. An offset voltage is generated at
frequency is locked by an internal loop such that the
INV by an internal current flowing into the resister divider.
switching frequency is
The current is inversely proportional to the voltage across
FSW =
pin COMP, as a result, it is inversely proportional to the
1
output load current, thus the drop due to the cable loss can
2TDemag
be compensated. As the load current decreases from
Since TDemag is inversely proportional to the inductance,
full-load to no-load, the offset voltage at INV will increase. It
as a result, the product Lp and Fsw is constant, thus the
can also be programmed by adjusting the resistance of the
maximum output power and constant current in CC mode
divider to compensate the drop for various cable lines used.
will not change as primary winding inductance changes. Up
to ±10% variation of the primary winding inductance can be
Gate Drive
compensation.
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
Frequency Shuffling
output strength and dead time control is achieved through
Excellent EMI performance is achieved by using frequency
the design of the built-in totem pole gate. The low standby
jittering in WS3252
dissipation and good EMI system design is easier to achieve
through this dedicated devise. For MOSFET gate protection,
Current Sensing and Leading Edge Blanking
an internal 12V clamp is added at higher than expected VCC
Cycle-by-Cycle current limiting is offered in WS3252. The
input.
switch current is detected by a sense resistor into the sense
pin. An internal leading edge blanking circuit chops off the
Protection Controls
sense voltage spike at initial MOSFET on state due to
Excellent system stability is achieved by the comprehensive
snubber diode reverse recovery so that the external RC
protection of WS3252. Including Cycle-by-Cycle current
filtering on sense input is no longer required. The current
limiting (OCP), VCC Clamp, Under Voltage Lockout on VCC
limit comparator is disabled and thus cannot turn off the
(UVLO).
internal MOSFET during the blanking period. PWM duty
Device restarts when VCC voltage drops below UVLO limit.
cycle is determined by the current sense input voltage and
It is clamped when VCC is higher than threshold value. The
the EA output voltage.
power MOSFET is shut down when VCC drops below UVLO
limit and device enters power on start-up sequence
Programmable Cable Drop Compensation
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WS3252 Product Description
SOT-23-6L Package Dimension
U n it:m m
A
C2
B1
B
θ1
θ
B2
A2
R
C
D
R1
θ2
C1
θ3
R2
D1
D3
D2
A1
Winsemi
Dimensions in Millimeters
Symbol
Dimensions in Inches
Min
Max
Min
Max
A
2.72
3.12
0.107
0.123
B
1.40
1.80
0.055
0.071
C
1.00
1.20
0.039
0.047
A1
0.90
1.00
0.035
0.039
A2
0.30
0.50
0.012
0.020
B1
2.60
3.00
0.102
0.118
B2
0.119
0.135
0.005
0.005
C1
0.03
0.15
0.001
0.006
C2
0.55
0.75
0.022
0.030
D
0.03
0.13
0.001
0.005
D1
0.30
0.60
0.012
0.024
D2
0.25TYP
D3
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0.60
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0.024
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WS3252 Product Description
DIP-8 Package Dimension
D2
θ1
C1
C
C4
θ2
C2
C3
θ3
D1
A2
A5
A3
A1
D
A4
B
A
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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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WS3252 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
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FAX : +86-755-8250 6299
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