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PDF WS2803 Data sheet ( Hoja de datos )
| Número de pieza | WS2803 | |
| Descripción | 18-Channel Constant Current LED Driver | |
| Fabricantes | Worldsemi | |
| Logotipo |  |
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Preliminary WS2803
18-Channel Constant Current LED Driver
With Programmable PWM Outputs
Features
●Supports both constant voltage and constant current drive mode
Constant output current range
-5-30mA@5V supply voltage
[email protected] supply voltage
●18 constant current driving channels
● 30V high voltage output channels
● 8bit PWM gray level control
● Precision output driving current
Between channels in a chip: ±2 %
Between chips: ±4%
● Maximum clock frequency up to 25MHz.
● Free run ability
● Over temperature protection
Applications
● LED decorative lighting
● Indoor/Outdoor LED video or massage display
General Description
The WS2803 is a constant current LED driver. It is designed for indoor/ outdoor LED displays and decorative LED
lighting system. It is suitable for LED cascading applications. The WS2803 ownes 18 output channels, each channel can
drive a constant current up to 30mA. WS2081 contains serial shift registers, data latches, output registers, band gap
reference voltage generator, internal oscillator, and programmable constant output current drivers. The serial data is read
into the shift registers at the rise edge of the external clock. The data and clock output buffers are designed for cascading
another chip. The output current can be set by connect a resistor at IREF pin to set the output current of each channel. The
over temperature protection is built in to protect the chip from thermal damage, if the core temperature level rise over 120℃,
the output current will be decreased to stable the core temperature within a safe level. The 2-wire control scheme can
reduce the system cost; it is very suitable for low cost LED decorative LED lighting systems.
WS2803 is available in both SOP-28 and DIP-28 package, the operating temperature is -40~85℃
Absolute Maximum Ratings
Parameter
Symbol
Ratings
Unit
Power Supply Voltage
VCC
-0.3 to 6V
V
Input Voltage
Output Voltage
Output Pin Voltage
Output Current
Constant Current Drive Mode
Output Current Deviation
Between output channels
Between chips
Input Clock Frequency
Maximum Power Dissipation
Operating Junction Temperature
VIN
VOUT
VXOUT
VXOUT
IOUTCC
DIOI
DIOE
FCLK
PD
Topr
-0.3 to VCC+0.3V
-0.4 to 45V
-0.3 to 30V，IOUT off
-0.3 to 10V，
5 to 30
±2
±4
25
2600
-40 to + 150
V
V
V
V
mA
%
MHz
mW
Storage Temperature Range
Tstg -55 to + 150
℃
Lead Temperature (Soldering, 10 seconds)
Tsolder
300
ESD susceptibility
2000
V
Note: If the voltage on the pins exceeds the maximum ratings may cause permanent damage to the device.
1/8
WS-Preliminary-V0.1
http://www.world-semi.com
1 page  
Preliminary WS2803
18-Channel Constant Current LED Driver
With Programmable PWM Outputs
VREXT=1.25V. To set the output current at 20mA, a resistor with 1.25Kohm resistance should be connected from REXT to
GND. The relationship between IOUT and REXT is shown in the following figure.
Package Power Dissipation (PD)
The maximum allowable package power dissipation is determined as PD(max)=(Tj-Ta)/Rth(j-a), when all 18 output
channels are turned on simultaneously, the actual package power dissipation is:
PD (act ) = (IDD ×VDD ) + (IOUT × Duty ×VDS ×18)
Therefore, to keep PD(act)≤PD(MAX), the maximum output current as a function of duty cycle is:
I OUT
=
T
(
j
Ta
R th ( j a )
ICC × VCC ) /VDS / Duty / 18
The maximum power dissipation PD(MAX)=(Tj-Ta)/Rth(j-a), decreases as the ambient temperature increases.
Load Supply Voltage (VLED)
WS2803 is designed to operate VDS ranging from 0.4 to 1.0V, considering the package power dissipating limits. VDS
maybe high enough to ensure PD(ACT)>PD(MAX), when VLED=24V and VDS=VLED-VF, in which VLED is the load
supply voltage. In case it is recommended to use the lowest possible supply voltage or to set an external voltage reducer,
VDROP, to dissipate the excessive power.
A voltage reducer lets VDS=(VLED-VF)-VDROP.
Resistors or zener diode can be used in the applications as shown in the following figures.
Fig 3 power reducer of WS2803
2-wire Control Mode
When MS pin is connected to VCC, WS2803 operates in 2-wire control mode, at this mode, only 2 wires are needed to
transmit the grayscale data. It is a low cost solution. Only 2 ports of MCU are needed to control over thousand WS2803
chips.At this mode, CKI pin keeps LOW more than 600us, the internal logic control circuitry will be reset. Once reset, the
internal circuitry wait for the positive pulse on the CKI pin, at this state, the signal on SDI pin is shifted in to the internal data
registers, once total 144 pulses are detected, WS2803 will latch the signal from the shift registers, and the WS2803
operates as a signal relay, at this state, the CKO and SDO are enabled. If the CKI keeps LOW for more than 600us, all the
internal data control circuit will back to the original states, wait for next data transmi
WS-Preliminary-V0.1
5/8
http://www.world-semi.com
5 Page | ||
| Páginas | Total 8 Páginas | |
| PDF Descargar | [ Datasheet WS2803.PDF ] | |
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