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WS3441 Product Description
Constant Current Controller for Non-isolated Buck LED Driver
General Description
Features
�
Inductor
Current
Critical
Mode,
No
Need
The WS3441 is a high precision constant current controller，
to
designed for non-isolated buck LED driver. It can operate
Compensate the Inductance Variation
under universal AC input or 12V~500V DC input.
�
500V MOSFET integrated
�
Source Driver Structure, Not Need the Auxiliary
The WS3441 integrates 500V power MOSFET, so it can
achieve excellent constant current performance with very few
Winding for VCC
external components.
�
±3% LED Current Accuracy
�
Up to 93% System Efficiency
�
LED Open/Short Circuit Protection
�
Current Sense Resistor Short Circuit Protection
�
Over Temperature Protection
�
Programmable LED open protection
�
Temperature compensation technology
The WS3441 uses high precision current sense circuit and
patent method for constant current control, to achieve high
precision output current and excellent line regulation. The
WS3441 operates in inductor current critical mode. The LED
current is constant over wide range of inductance variation
and the LED output voltage, so the load regulation is
excellent.
Applications
The WS3441 uses patent source driver architecture. The
�
LED Bulb
operation current is 200uA only, so the auxiliary winding is not
�
LED Candle light
needed. It can simplify the system design and reduce the
�
LED Spot light
system cost.
�
Decorative LED lighting
WS3441
�
T5/T8 Lamp
technology , can easily solve the problem of lights flashing at
�
Ceiling Lamp
high temperature
�
Flat Lamp
The WS3441 offers rich protection functions, including LED
applies
intelligent
temperature
compensation
open/short circuit protection, current sense resistor short
Typical Application Circuit
circuit protection and over temperature protection.
AC
1 GND
CS
8
2 RO VP
CS
7
3 NC
D R A IN 6
4 VCC
D R A IN 5
Note:
Note:Rovp resistor in parallel around a 20pF capacitor helps to strengthen anti-jamming capability; VCC to ground with a resistor
in parallel to solve the problem of power-down flashback .
W/T-D034-Rev.A/1 May.2014
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WS3441 Product Description
Pin Definition and Device Marking
WS3441 is available in DIP-8 and SOP-8 package.
ROVP
2
NC
3
VCC
4
8
CS
GND
1
7
CS
ROVP
2
6
D R A IN
NC
3
5
D R A IN
VCC
4
WS3441 S8 P
AXB YM
1
WS3441 D8 P
AXB YM
GND
8
CS
7
CS
WS3441: Product code
A: Product Code
X：Internal Code
6
D R A IN
5
D R A IN
B：Area Code
YM：Year, Month
Pin Function Description
Pin Name
Pin NO.
Description
GND
1
Ground
ROVP
2
Programmable LED open protection pin，connect a resistor to GND
NC
3
floating
VCC
4
Power supply
DRAIN
5,6
Internal HV power MOSFET drain
CS
7,8
Current sense input, the sense resistor is connected from CS to ground
Block Diagram
VCC
D R A IN
4
5 ,6
Soft-Driver
GND 1
Inter
supply
UVLO
Zero-Current
Detect
L o g ic
&
driver
400m V
OCP
L in e
co mp e n sa tio n
3 N C
LED Short
CS Short
RO VP 2
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WS3441 Product Description
Ordering Information
Package
Part Number
Marking
8-Pin DIP-8, Pb-free
WS3441D8P
WS3441D8P
8-Pin SOP-8,
WS3441S8P
WS3441S8P
Pb-free
Recommended Operating Condition
symbol
symbol
parameter
value
units
WS3441D8P
P
output power
< 14
W
WS3441S8P
P
output power
<9
W
Absolute Maximum Ratings
symbol
parameter
VDS
Range
Units
-0.3~500
V
2.5
mA
-0.3~7
V
-0.3~8
V
-0.3~7
V
Power dissipation
0.9
W
Operating junction temperature
150
℃
-55~150
℃
Internal HV MOSFET drain voltage
ICC_MAX
VCC pin maximum sink current
VROVP
ROVP input voltage
The source voltage of the internal high voltage
VSOURCE
MOSFET
VCS
Current sense pin input voltage
PDMAX
TJ
TSTG
Storage temperature range
Note: 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.
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WS3441 Product Description
Electrical Characteristics (Unless otherwise specified，TA=25℃，VCC=7V)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
Ivcc=1mA
7.0
7.3
7.6
V
-
-
2.5
mA
6.6
6.9
7.2
V
VCC Falling
-
1.5
-
V
VCC<VCC_ST-0.5V
-
45
60
uA
-
200
-
uA
390
400
410
mV
Leading Edge Blanking
-
350
-
ns
Turn Off Delay Time
-
300
-
ns
Supply Voltage Section
Vcc_clamp
VCC Clamping Voltage
Icc_clamp
VCC Clamping Current
VCC_ST
VCC Start Up Voltage
Vuvlo_HYS
VCC Rise
VCC Under Voltage
Latch Out Hysteresis
Ist
Start Up Current
Iop
Operation Current
Current Sensor Section
Current Sensor Voltage
Vcs_th
Threshold
TLEB
TDELAY
Internal Driver Section
TOFF_MIN
Minimum Demagnetization Time
-
4
-
us
TOFF_Max
Maximum Demagnetization Time
-
240
-
us
TON_MAX
Maximum Turn On Time
-
40
-
us
-
12
-
ohm
-
-
V
10
uA
Internal HV MOSFET
RDSON
Switch ON Resistance
Vcc=7V/Id=0.5A
VDS_BD
Drain to Source voltage
Vgs=0V/Id=250uA
500
Power tube leakage current
Vgs=0V/Vds=500V
-
Idss
ROVP part
VROVP
Internal reference voltage
-
0.5
-
V
Thermal Shut Down Temperature
-
160
-
℃
Thermal Shut Down Hysteresis
-
20
-
℃
Over Temperature Section
TSD
TSD_HYS
T_comp
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function
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WS3441 Product Description
Function Description
constant current.
WS3441 is a constant current controller, designed for driving
non-isolated buck LED power supply. WS3441 integrates
Source Driver Structure
500V power MOSFET, and it uses advanced constant
The WS3441 uses the advanced source driver structure.
current control method and source driver structure, excellent
The typical operation current is as low as 200uA, the
constant current characteristic is achieved with low counts
auxiliary winding is not need. So the system design is simple
components. Low cost and high efficiency of system is
and the cost is low.
realized.
intelligent temperature compensation technology
Start up
WS3441 applies intelligent temperature compensation
The Vcc will be charged through the startup resistor when
technology, when the temperature of the chip is higher than
the system is powered on. When the voltage on Vcc reaches
140 ℃, the output current will start to be reduced, so that the
the startup voltage threshold, the controller starts to
temperature will achieve a new balance
switching. The Vcc voltage of WS3441 is clamped to 7.3V
Inductance Calculation
by internal Zener diode.
The WS3441 is designed to work in inductor current critical
Constant Current Control and Output Current Setting
mode, the energy will be stored in the inductor when the
The WS3441 uses patent constant current control method,
MOSFET is turned on. The turn on time is given by:
excellent constant current is achieved with low counts
ton =
components. The WS3441 senses the peak current in
L × I PK
VIN − VLED
inductor cycle by cycle. The CS Pin is connected to the input
of internal current comparator, and compared with the
internal 400mV reference voltage. The external power
MOSFET will be turned off when the CS pin voltage reaches
the voltage threshold. The comparator has a 350ns LEB
inductor. The VIN is the input rectified voltage. The VLED is
the voltage on LED.
When the power MOSFET is turned off, the inductor current
will decrease from the peak current to zero. The turn off time
timer to avoid mis-trigger.
is given by:
The peak current in the inductor is given by:
I PK
The L is the inductance. The Ipk is the peak current in
toff =
400
=
(mA)
RCS
L × I PK
VLED
The Rcs is the resistance of current sense resistor The
The MOSFET will be turned on again when it detects the
current in LED can be calculated by the following equation:
inductor current goes to zero. The inductance can be
I LED =
I PK
2
calculated by the following equation:
L=
The IPK is the peak current in inductor.
VLED × (VIN − VLED )
f × I PK × VIN
The f is the system switching frequency, which is
Line Compensation
proportional to the input voltage. So the minimum switching
The WS3441 integrates line compensation function. LED
frequency is set at lowest input voltage, and maximum
current can keep consistent in the whole voltage range, has
switching frequency is set at highest input voltage.
a very small linear regulation, to ensure high precision of
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WS3441 Product Description
The WS3441 internally set the minimum off time to 4us and
temperature protection circuitry in the WS3441 monitors the
maximum off time to 240us. When the inductance is very
die
small, the toff may goes below the minimum off time and the
temperature rises to 160℃, the power MOSFET will be shut
inductor current becomes discontinuous. So the output LED
down immediately and maintains at switch off condition until
current will be smaller than the setting value. If the
the temperature on die falls 20℃ below the thermal
inductance is too large, the toff may goes beyond the
protection trigger point.
junction
temperature
after
start
up.
When
the
maximum off time and the inductor current becomes
continuous. And the output LED current will be larger than
PCB Layout
the setting value. So it’s very important to select a right
The following guidelines should be followed in WS3441 PCB
inductance.
layout:
The WS3441 also internally set the maximum on time to
Bypass Capacitor
40us. When the input voltage is very low or LED output
The bypass capacitor on VCC pin should be as close as
voltage is very high, the ton may goes beyond the maximum
possible to the VCC and GND pins.
on time. The power MOSFET will be turned off even the
Ground Path
inductor current still below the setting value. So the output
The power ground path for current sense should be short,
LED current will be smaller than the setting value.
and separated from the other power ground path and small
signal ground path before the negative node of the bus
Set open protection
capacitor.
The LED open protection voltage can be set by adjusting the
The Area of Power Loop
value of the resistor connecting from ROVP to GND. Rovp
The area of main current loop should be as small as
voltage is 0.5V.
possible to reduce EMI radiation. And the controller should
In the LED open condition, the output voltage will raise
be placed away from the heat generator, such as the power
graduate, and the demagnetize time will shorten as well, the
diode.
demagnetize time Tovp can be calculator as below:
IC reference ground together with IC supply capacitor,
Tovp =
ROVP resistor and interference capacitor in parallel ROVP
L × V CS
R CS × V OVP
and VCC discharge resistor connected to the input
individually lead to the end of a large capacitor to reduce
In which the Vcs is the OCP threshold (0.4V) ,the Vovp is
interference from other signals
the new target output protection voltage. And the value of
Pin3 is floating, no electrical properties, which can be
the resistor Rovp is as below:
connected to PIN 1 to form a ground shield to strengthen the
anti-jamming capability, but the shield can not form a closed
Rovp = 15 * Tovp * 10
6
（KΩ）
loop; to prevent the effect of the eddy current signal.
In order to increase the cooling effect of the IC can be
Protection Functions
relatively increased IC drain pin copper area; Also
The WS3441 has many protection functions, including LED
open/short circuit protection, current sense resistor short
circuit protection and over temperature protection. All of the
recommend staying away from low voltage CS / VCC and
ROVP pin. If the distance is not enough, you can increase
the creepage distance slotted.
protection functions are designed to auto-recover. The over
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WS3441 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
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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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WS3441 Product Description
SOP-8 Package Information
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
θ1
C3
θ3
R1
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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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WS3441 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
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FAX : +86-755-8250 6299
Web Site : www.winsemi.com
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