WS9441P [ETC]
Non-isolated BuckOffline LED Driver;型号: | WS9441P |
厂家: | ETC |
描述: | Non-isolated BuckOffline LED Driver |
文件: | 总9页 (文件大小:825K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
WS9441P Product Description
Non-isolated BuckOffline LED Driver
Features
Description
Critical Conduction Mode Operation
Internal 500V Power MOSFET
Gate Drive and No Auxiliary Winding
±3% LED Current Accuracy
Efficiency up to 93%
The WS9441P 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 WS9441P 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 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.
LED Short Circuit Protection
LED Open Circuit Protection
Current Sense Resistor Short Protection
Thermal Regulation Function
External PWM Dimming
The WS9441P adopts intelligent temperature control and
thoroughly solves the problem of light flashing at high
temperatures. It integrates an external dimming pin which inputs
PWM signal and can dim by changing the duty cycle of the PWM
signal. The WS9441P offers full protection functions to improve
the system reliability, including LED open circuit protection, LED
short circuit protection, CS resistor short circuit protection and
Applications
LED Bulb Lights
LED Panel Lights
LED Strings
thermal regulation function.
The WS9441P is available in SOP-7 Package.
Typical Application Circuit
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WS9441P Product Description
Pin Configuration and Marking Information
The WS9441P is available in SOP-7 Package. The top marking is shown as below:
WS9441PS7P:Product Code
A:Product Code
X:Internal Code
BCY:Internal Code For QC
YMX:D/C
Pin Definition
Pin No.
Description
Name
1
GND
Ground
2
3
ROVP
DIM
Over Voltage Protection Setting Pin. Connect a resistor to GND
Dinmming Pin.Must be floated when not in use.
Power Supply Pin
4
VCC
5,6
DRAIN
Internal HV Power MOSFET Drain
Current Sense Pin. Connect a sense resistor between this pin and the GND
pin.
7
CS
Block Diagram
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WS9441P Product Description
Ordering Information
Package
Marking
Part Number
7-Pin DIP-7, Pb-free
WS9441PS7P
WS9441PS7P
Recommended Operation Conditions
Part Number
Package
Input voltage
Maximum output power
150V/120mA
80V/200mA
WS9441PS7P
SOP7
175VAC-264VAC
Absolute Maximum Ratings
Symbol
VDS
Parameter
Range
-0.3~500
2.5
Unit
V
Internal HV MOSFET drain voltage
VCC pin maximum sink current
ICC_MAX
mA
V
VROVP
VCS
LED open circuit protection voltage regulation
Current sense pin input voltage
-0.3~7
-0.3~8
-0.3~7
0.9
V
PDMAX
TJ
Power dissipation SOP7
V
Maximum operating junction temperature
Minimum/Maximum Storage temperature
W
℃
TSTG
150
Note:Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device
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WS9441P Product Description
Electrical Characteristics (Unless otherwise specified, VCC=15V and TA =25 ℃)
Symbol
Parameter
Conditions
Min
Typ
Max
Units
Supply Voltage Section
VCC_CLAMP
UVLO_on
VCC Clamp Voltage
Chip Startup Voltage
VDD Under voltage
protection
10mA
17.8
14
18.8
15
19.8
16.2
V
V
UVLO_off
9
9.5
10
V
Ist
Startup Current
VCC= 13V
150
100
220
170
300
250
uA
uA
Iop
Operating Current
Fop=70KHz
Current Sense Section
Threshold Voltage for
Vcs_th
390
400
410
mV
Peak Current Limit
Leading Edge Blanking
Time for Current Sense
TLEB
350
200
ns
ns
TDELAY
Switch Off Delay Time
Internal Time Control Section
Toff_max
Toff_min
Ton_max
Minimum OFF Time
310
4.5
us
us
us
Maximum OFF Time
Maximum On Time
Rovp=70k
100
DIM Dimming Section
DIM Square Wave High
VH_DIM
1
3
0
5
400
5
V
Level
DIM Square Wave Low
Level
VL_DIM
-300
0.1
mV
KHZ
DIM Square Signal
Frequency
f_DIM
0.5
MOSFET Section
Rds_on
Static Drain-source
On-State Resistance
Drain-Source Breakdown
Voltage
Vgs=15V,Ids=0.5A
Vgs=0V,Ids=250uA
Vgs=0V,Vds=500V
9
11
10
Ω
V
BVdss
Idss
500
Drain-Source Leakage
Current
uA
Thermal Regulation Section
Thermal Regulation
TREG
150
℃
Temperature
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WS9441P Product Description
Function Description
The WS9441P is a high performance non-isolated buck
converter specially designed for LED lighting. The device
adopted in WS9441P, the CS pin is connected to the current
sense comparator, and the voltage on CS pin is compared
with the internal 400mV reference voltage. The MOSFET will
be switched off when the voltage on CS pin reaches the
threshold. The CS comparator includes a 350ns leading edge
integrates
a 500V power MOSFET. With the help of
advanced constant current control and gate drive technology,
the converter achieves excellent constant current
performance with very few external components. It does not
need auxiliary winding for powering the IC or voltage sensing,
hence the system size and cost is greatly reduced.
blanking time.
The peak inductor current is calculated by the equation:
400
IPK
(mA)
RCS
Start Up
After system powered on, the VCC pin capacitor is
charged up by the start up resistor. When the VCC pin
voltage reaches the turn on threshold, the internal circuits
start operating. The WS9441P integrates a 17V ZENER
diode to clamp the VCC voltage. Due to the ultra-low
operating current, the auxiliary winding is not needed to
supply the IC.
Where, RCS is the current sense resistor value.
The current in LED can be calculated by the equation:
IPK
ILED
(mA)
2
Where, IPK is the peak current of the inductor.
The typical value of the start-up current is 200uA (the
maximum value is 300uA). For the application of 176VAC—
264VAC, the start-up resistor can be calculated by the
equation:
Freewheeling Diode
The diode will bear the reverse voltage equal to the
input voltage when the MOSFET is on. A 600V diode was
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.
VIN _ MIN 1.414
1761.414
RST
910K
IST _ MAX
270
Two resistors in 1206 size SMD can be used in series.
VCC Capacitor Selection
Input Electrolytic Capacitor
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.
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
following empirical equations:
A 1uF or above capacitor can be used in Vcc. If
selecting MLCC, the material of X7R will be used to satisfy
the stability of the capacity under high temperatures. Due to
external damage resulted from small volume and brittle
texture of MLCC, the Vcc is easy to leakage currents, which
will make the WS9441P unable to start. Strict control
measures are taken in its layout and productive process.
90Vac~264Vac: 1W output uses1uF buck electrolytic
capacitor;
176Vac~264Vac: 1W output uses 0.5uF buck electrolytic
capacitor.
Output Capacitor
Electrolytic capacitor is recommended to be used. Its
stable capacitance can improve the efficiency of power supply,
the LED ripple current and luminous efficiency.
Vovp voltage should be considered in output capacitor
pressure.
Constant Current Control
The WS9441P utilizes proprietary current control
method. It can achieve precise LED output current with a few
external components. Cycle by Cycle current sense is
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WS9441P Product Description
VLED (VIN VLED
f IPK VIN
)
L
External PWM Dimming
The WS9441P integrates an external dimming pin
which inputs PWM signal and can dim by changing the duty
cycle of the PWM signal. The testing dimmable curve of a
80V/220mA driver under 175~264Vac application is shown
Where, f is the maximum system switching frequency,
which is proportional to the input voltage. So the minimum
switching frequency is set at lowest input voltage, and the
maximum switching frequency is set at highest input voltage.
The minimum and maximum off time of WS9441P is set at
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
important to choose a proper inductance.
The duty cycle of the PWM signal
Inductor Selection
Thermal Regulation
The WS9441P integrates thermal regulation function.
When the system is under higher temperature, the output
current is gradually reduced; the output power and thermal
dissipation are also reduced. The system temperature is
regulated and the system reliability is improved. The thermal
regulation temperature is set to 150℃ internally.
The WS9441P works in
a inductor critical current
conduction mode. When the power MOFET is switched on,
the current in the inductor rises up from zero. The on time of
the MOSFET can be calculated by the equation:
L IPK
ton
VIN VLED
Over Voltage Protection
Where,
The over voltage protection of the WS9441P can be
programmed by the ROVP pin resistor. The ROVP pin voltage
is 0.5V.
L is the inductance value,
IPK is the peak current of the inductor,
VIN is the DC bus voltage after the rectifier bridge,
When the LED is open circuit, the period of the output
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:
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
reaches zero, the power MOSFET is turned on again by IC
internal logic. The off time of the MOSFET is given by the
equation:
L VCS
Tovp
L IPK
VLED
RCS VOVP
toff
Where,
The inductance can be calculated by the equation:
Vcs is the CS pin turn off threshold (0.4V);
Vovp is the open circuit protection voltage.
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WS9441P Product Description
And then the Rovp resistor value can be calculated by
the equation:
Rovp 120 7.67 * Tovp *10 6 (KΩ)
PCB Layout
It is suggested that the open circuit protection voltage is
set at or above 1.5 times maximum load voltage.
The following rules should be followed in WS9441P PCB
layout:
VCC Capacitor: The VCC capacitor should be as close
Protection Function
as possible to the VCC Pin and GND pin.
The WS9441P offers rich protection functions to
improve 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 saturation, the internal fast fault detection circuit
will be triggered, the system stops switching immediately.
After the system enters into faulty condition, the VCC
voltage will decrease until it reaches the UVLO threshold,
then the system will restart again. If the fault condition is
removed, the system will recover to normal operation.
Ground Path: The power ground path for current sense
resistor should be short, and the power ground path should be
separated from small signal ground path before connecting to
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.
ROVP PIN: The ROVP resistor should be as close as
possible to the ROVP Pin to increase its resistance to prevent
from the interference.
DRAIN PIN: The copper area of DRAIN pin can be
increased for better thermal dissipation. And it should be away
from CS/VCC and ROVP Pin.
Line Voltage Compensation
The WS9441P integrates line voltage compensation
function, which makes LED current remain unchanged in the
range of full voltage with good line regulation and current
accuracy.
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WS9441P Product Description
SOP7 Package Dimension
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Dimensions in Millimeters
Dimensions in Inches
Min
Symbol
Min
4.70
3.70
1.30
0.35
Max
5.10
4.10
1.50
0.48
Max
0.201
0.161
0.059
0.019
A
0.185
0.146
0.051
0.014
B
C
A1
A2
A3
B1
B2
C1
C2
C3
C4
D
1.27TYP
0.05TYP
0.345TYP
0.014TYP
5.80
6.20
0.228
0.244
5.00TYP
0.197TYP
0.55
0.55
0.05
0.70
0.70
0.022
0.022
0.002
0.028
0.028
0.009
0.225
0.203TYP
1.05TYP
0.008TYP
0.041TYP
D1
0.40
0.80
0.016
0.031
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WS9441P 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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