WS9841 Datasheet PDF - Winsemi
| Part Number | WS9841 | |
| Description | High Efficiency TRIAC dimmable LED | |
| Manufacturers | Winsemi | |
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WS9841 Product Description
WS9841 High Efficiency TRIAC dimmable LED
Features
TRIAC dimmable
Internal 300V Power MOSFET
Critical Conduction Mode Operation
Ultra Low Operating Current
±5% LED Output Current Accuracy
LED Open Protection
LED Short Protection
Current Sensing Resistor Short Protection
VCC Under Voltage Protection
Thermal Regulation Function
Available in SOP-8 Package
Typical Appliction
LED Candle Light
LED Bulb
Other LED Lighting
Driver
Description
The WS9841 is a high efficiency TRIAC dimmable LED
driver. The device operates in critical conduction mode and is
suitable for buck, buck-boost or fly-back LED lighting.
The WS9841 integrates a 300V power MOSFET. It
utilizes patent pending MOSFET driving technique and
current sensing method. The operating current of the IC is
very low. With very few external components count, it can
achieve excellent constant current performance, so the
system cost and size are greatly reduced.
The WS9841 offers rich protection functions to improve
the system reliability, including LED open circuit protection,
LED short circuit protection, VCC under voltage protection,
CS resistor short circuit protection and thermal regulation
function.
The WS9841 is available in a SOP-8 Package.
Typical Application Circuit
WINSEMI MICROELECTRONICS
WINSEMI MICROELECTRONICS
WINSEMI MICROELECTRONICS
Copyright@Winsemi Microelectronics Co., Ltd., All right reserved.
WINSEMI MICROELECTRONICS
WINSEMI MICROELECTRONICS
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WS9841 Product Description
Function Description
The WS9841 is a high efficiency TRIAC dimmable LED
driver IC, specially designed for Buck, Buck-boost or
Fly-back LED lighting. The WS9841 integrates a 300V power
MOSFET. Utilizing patent pending MOSFET source driving
technique, it can achieve excellent constant current
performance with very few external components count, so
the system cost and size are greatly reduced.
Start Up
After system powered up, 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 WS9841 integrates an 18.8V zener
diode to clamp the VCC voltage. After the output voltage is
established, VCC is supplied by the output voltage.
Constant Current Control
Cycle by Cycle current sense is adopted in WS9841, 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 peak inductor current is given by:
I PK
400
R CS
(mA)
Where, RCS is the current sense resistor value. The CS
comparator includes a 350ns leading edge blanking time.
The VLN pin detects the TRIAC dimmer conducting
angle to adjust the LED driver output current. The application
circuit of the VLN pin is shown in Figure 4. When the VLN pin
voltage is higher than 3V, the threshold for peak current limit
VCS_TH decreases linearly as shown in Figure 5. When the
VLN pin is not used, it can be grounded or floated.
Figure 5. Relationship of VLN voltage and VCS_TH
Inductor Selection
The WS9841 works under inductor current critical
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:
t on
L IPK
VIN VLED
Where,
L is the inductance value.
VIN is the DC bus voltage after the rectifier bridge.
VLED is the voltage on the LED.
The maximum on time of the MOSFET is set to 10us
internally.
After the power MOSFET is switched off, 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:
t off
L IPK
VLED
The inductance can be calculated by the equation:
L
VLED
f
(VIN VLED )
IPK VIN
Figure 4. VLN pin application circuit
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.
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Part DetailsOn this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for WS9841 electronic component. |
| Information | Total 8 Pages | |
| Link URL | [ Copy URL to Clipboard ] | |
| Download | [ WS9841.PDF Datasheet ] | |
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