20160401090410 7105

WS9442 Product Description
Non-isolated Buck Offline LED Driver
Features
 Critical Conduction Mode Operation

Internal 500V Power MOSFET

Gate Drive and No Auxiliary Winding

±3% LED Current Accuracy

Efficiency up to 93%

LED Short Circuit Protection

LED Open Circuit Protection


Current Sense Resistor Short Protection
Description
The WS9442 is a high precision buck constant current
LED driver and is applied to non-isolated buck LED power
system with AC input voltage of 85VAC-265VAC. The
WS9442 integrates a 500V power MOSFET, and can
achieve excellent constant current performance with very
few external components, so the system cost and size are
minimized. The driver operates in critical conduction mode,
and the output current does not change with the inductance
Thermal Regulation Function
and LED output voltage. The operating current of the IC is
200uA, so it doesn’t need the auxiliary winding for supplying
the chip, thus simplifying design and reducing cost.
Applications

LED Bulb Lights

LED Panel Lights
thoroughly solves the problem of light flashing at high

LED Strings
temperatures. The WS9442P offers full protection functions
The WS9442 adopts intelligent temperature control and
to improve the system reliability, including LED open circuit
protection, LED short circuit protection, CS resistor short
circuit protection and thermal regulation function.
The WS9442 is available in DIP-7 Package.
Typical Application Circuit
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WS9442 Product Description
Pin Configuration and Marking Information
The WS9442 is available in DIP-7 Package. The top marking is shown as below:
WS9442D7P:Product Code
A:Product Code
X:Internal Code
BCY:Internal Code For QC
YMX:D/C
Pin Definition
Pin No.
Name
1
GND
2
ROVP
3
NC
4
VCC
5,6
DRAIN
7
CS
Description
Ground
Over Voltage Protection Setting Pin. Connect a resistor to GND
No Connection.Should be hanged out.
Power Supply Pin
Internal HV Power MOSFET Drain
Current Sense Pin. Connect a sense resistor between this pin and GND
pin.
Block Diagram
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WS9442 Product Description
Ordering Information
Package
Marking
Part Number
7-Pin DIP-7, Pb-free
WS9442D7P
WS9442D7P
Recommended Operation Conditions
Part Number
Package
Input voltage
Maximum output power
120V/280mA
175VAC-264VAC
WS9442D7P
160V/220mA
DIP7
90VAC-264VAC
80V/300mA
Absolute Maximum Ratings
Symbol
Parameter
Range
Unit
VDS
Internal HV MOSFET drain voltage
-0.3~500
V
ICC_MAX
VCC pin maximum sink current
10
mA
VROVP
LED open circuit protection voltage regulation
-0.3~7
V
VCS
Current sense pin input voltage
-0.3~7
V
PDMAX
Power dissipation DIP7
0.9
W
TJ
Maximum operating junction temperature
150
℃
TSTG
Minimum/Maximum Storage temperature
-55~150
℃
Note:Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device
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WS9442 Product Description
Electrical Characteristics (Unless otherwise specified, VCC=15V and TA =25 ℃)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
17.8
18.8
19.8
V
14
15
16.2
V
9
9.5
10
V
Supply Voltage Section
VCC_CLAMP
VCC Clamp Voltage
UVLO_on
Chip Startup Voltage
10mA
VDD Under voltage
UVLO_off
protection
Ist
Startup Current
VCC= 13V
150
220
300
uA
Iop
Operating Current
Fop=70KHz
100
170
250
uA
390
400
410
mV
Current Sense Section
Threshold Voltage for
Vcs_th
Peak Current Limit
Leading Edge Blanking
TLEB
Time for Current Sense
TDELAY
Switch Off Delay Time
350
ns
200
ns
310
us
4.5
us
100
us
6.8
Ω
Internal Time Control Section
Toff_max
Minimum OFF Time
Toff_min
Maximum OFF Time
Ton_max
Maximum On Time
Rovp=70k
MOSFET Section
Static Drain-source
Rds_on
Vgs=15V,Ids=0.5A
On-State Resistance
Drain-Source Breakdown
BVdss
Voltage
Drain-Source Leakage
Idss
Vgs=0V,Ids=250uA
500
V
Vgs=0V,Vds=500V
Current
10
uA
Thermal Regulation Section
Thermal Regulation
TREG
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150
Temperature
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WS9442 Product Description
Function Description
comparator, and the voltage on CS pin is compared with the
The WS9442 is a high performance non-isolated buck
internal 400mV reference voltage. The MOSFET will be
converter specially designed for LED lighting. The device
switched off when the voltage on CS pin reaches the threshold.
integrates a 500V power MOSFET. With the help of
advanced constant current control and gate drive technology,
The CS comparator includes a 350ns leading edge blanking
the
time.
converter
achieves
excellent
constant
current
performance with very few external components. It does not
The peak inductor current is calculated by the equation:
need auxiliary winding for powering the IC or voltage sensing,
I PK 
hence the system size and cost is greatly reduced.
Start Up
400
(mA)
RCS
Where, RCS is the current sense resistor value.
After system powered on, the VCC pin capacitor is
The current in LED can be calculated by the equation:
charged up by the start up resistor. When the VCC pin
voltage reaches the turn on threshold, the internal circuits
I LED 
start operating. The WS9442 integrates a 17V ZENER diode
I PK
(mA)
2
to clamp the VCC voltage. Due to the ultra-low operating
Where, IPK is the peak current of the inductor.
current, the auxiliary winding is not needed to supply the IC.
The typical value of the start-up current is 200uA (the
maximum value is 300uA). For the application of 176VAC—
Freewheeling Diode
264VAC, the start-up resistor can be calculated by the
equation:
RST 
The diode will bear the reverse voltage equal to the input
voltage when the MOSFET is on. A 600V diode was
VIN _ MIN  1.414
I ST _ MAX
176  1.414

 820 K 
300
Two resistors in 1206 size SMD can be used in series.
VCC Capacitor Selection
The Vcc capacitor is used to bypass noise to IC, so that
to assure its stable operation, and should be as close as
possible to the chip.
suggested to use. Besides, the operating frequency of
freewheeling diode is from 20K to 120 KHz, such ultra fast
recovery diodes as ES and ER whose Trr is less than 50ns are
good choice.
Input Electrolytic Capacitor
Input voltage should be considered in to the capacitor
pressure, and the common value is 400V.
In general, the capacity design can be calculated by the
A 1uF capacitor can be used in Vcc. If selecting MLCC,
following empirical equations:
90Vac~264Vac: 1W output uses1uF buck electrolytic
the material of X7R will be used to satisfy the stability of the
capacity under high temperatures. Due to external damage
capacitor;
176Vac~264Vac: 1W output uses 0.5uF buck electrolytic
resulted from small volume and brittle texture of MLCC, the
Vcc is easy to leakage currents, which will make the WS9442
capacitor.
unable to start. Strict control measures are taken in its layout
Output Capacitor
and productive process.
Electrolytic capacitor is recommended to be used. Its
Constant Current Control
stable capacitance can improve the efficiency of power supply,
The WS9442 utilizes proprietary current control method.
the LED ripple current and luminous efficiency.
Vovp voltage should be considered in output capacitor
It can achieve precise LED output current with a few external
components. Cycle by Cycle current sense is adopted in
WS9442, the CS pin is connected to the current sense
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pressure.
Inductor Selection
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WS9442 Product Description
The WS9442 works in a inductor critical current
dissipation are also reduced. The system temperature is
conduction mode. When the power MOFET is switched on,
regulated and the system reliability is improved. The thermal
the current in the inductor rises up from zero. The on time of
regulation temperature is set to 150℃ internally.
the MOSFET can be calculated by the equation:
t on 
Over Voltage Protection
L  I PK
VIN  VLED
The over voltage protection of the WS9442 can be
programmed by the ROVP pin resistor. The ROVP pin voltage
Where,
is 0.5V.
L is the inductance value,
When the LED is open circuit, the period of the output
IPK is the peak current of the inductor,
VIN is the DC bus voltage after the rectifier bridge,
VLED is the voltage on the LED.
After the power MOSFET is also switched off and the
current in the inductor decreases. When the inductor current
voltage increases gradually, the demagnetization time gets
shorter. The demagnetization time at OVP---- Tovp can be
calculated by the open circuit protection voltage by the
equation:
reaches zero, the power MOSFET is turned on again by IC
Tovp 
internal logic. The off time of the MOSFET is given by the
equation:
toff 
L  I PK
VLED
L  V CS
R CS  V OVP
Where,
Vcs is the CS pin turn off threshold (0.4V);
Vovp is the open circuit protection voltage.
The inductance can be calculated by the equation:
And then the Rovp resistor value can be calculated by the
V  (VIN  VLED )
L  LED
f  I PK  VIN
equation:
Rovp  120  7 . 67 * Tovp * 10 6 (KΩ)
Where, f is the maximum system switching frequency,
It is suggested that the open circuit protection voltage is
which is proportional to the input voltage. So the minimum
switching frequency is set at lowest input voltage, and the
set at or above 1.5 times maximum load voltage.
maximum switching frequency is set at highest input voltage.
The minimum and maximum off time of WS9442 is set at
Protection Function
The WS9442 offers rich protection functions to improve
4.5us and 310us, respectively. Referring to the equation of
Toff calculation, if the inductance is too small, the Toff may be
smaller than the minimum off time, the system will operate in
discontinuous conduction mode and the output current will
be smaller than the designed value. If the inductance is too
large, the Toff may be larger than the maximum off time, the
system will operate in continuous conduction mode and the
output current will be higher than the designed value. So it is
the system reliability, including LED open/short protection, CS
resistor short protection, VCC under voltage protection,
thermal regulation. When the LED is open circuit, the system
will trigger the over voltage protection and stop switching.
When the LED short circuit is detected, the system works at
low frequency and the CS pin turnoff threshold is reduced. So
the system power consumption is very low. At some abnormal
fault condition, such as CS resistor shorted or inductor
important to choose a proper inductance.
saturation, the internal fast fault detection circuit will be
Thermal Regulation
triggered, the system stops switching immediately.
The WS9442 integrates thermal regulation function.
After the system enters into faulty condition, the VCC
When the system is under higher temperature, the output
voltage will decrease until it reaches the UVLO threshold, then
current is gradually reduced; the output power and thermal
the system will restart again. If the fault condition is removed,
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WS9442 Product Description
Ground Path: The power ground path for current sense
the system will recover to normal operation.
resistor should be short, and the power ground path should be
separated from small signal ground path before connecting to
Line Voltage Compensation
The WS9442 integrates line voltage compensation
function, which makes LED current remain unchanged in the
range of full voltage with good line regulation and current
the negative node of the bulk capacitor.
The Area of Power Loop: The area of main current loop
should be as small as possible to reduce EMI radiation. And it
should be away from diodes and other heating components.
accuracy.
ROVP PIN: The ROVP resistor should be as close as
possible to the ROVP Pin to increase its resistance to prevent
PCB Layout
from the interference.
The following rules should be followed in WS9442 PCB
layout:
DRAIN PIN: The copper area of DRAIN pin can be
increased for better thermal dissipation. And it should be away
VCC Capacitor: The VCC capacitor should be as close
from CS/VCC and ROVP Pin.
as possible to the VCC Pin and GND pin.
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WS9442 Product Description
DIP7 Package Dimension
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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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WS9442 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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