Worldsemi WS2801 Schematic [ru]
Preliminary WS2801
3-Channel Constant Current
LED Driver With Programmable
PWM Outputs
Features Applications
• Supports both constant voltage and constant current drive mode
• Programmable constant LED drive current
• Wide constant output current range 5~150mA
• Build in PWM dimming scheme for each output channel,
supports free-run, especially suitable for low cost controller
application
• PWM free-run capability(refresh rate(2.5KHz)
• Build in buffers to cascading data and clock to the next driver
• Output polarity reverse function
• Support hot swap
• Maximum input clock frequency 25MHz
• Power supply voltage 3.3~5.5V
General Description
The WS2801 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 WS2801ownes 3 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 polarity reverse function is
designed for driving high power LED by adapting the application circuitry. The WS2801 adopts the reliable 2-wire scheme, which
features low EMI transport, very strong anti-interference ability, and support hot-swap. The 2-wire control scheme can reduce the
system cost; it is very suitable for low cost LED decorative LED lighting systems.
WS2801 is available in both SOP-14 and DIP-14 packages, the operating temperature is -40~85℃
Pin Configurations
• LED decorative lighting
• Indoor/Outdoor LED video or massage display
• PWM signal generator
• LCD TV back lighting
Ty pical Application Circuit
Fig1.a SOP-14 package Fig1.b DIP-14 package
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WS-Preliminary-V0.3 http://www.world-semi.com
Preliminary WS2801
3-Channel Constant Current
LED Driver With Programmable
PWM Outputs
Absolute Maximum Ratings
Parameter Symbol Ratings Unit
Power Supply Voltage VCC -0.3 to 6V V
Input Voltage V
Output Voltage V
Output Pin Voltage V
Output Current
Constant Current Drive Mode
Constant Voltage Drive Mode
Output Current Deviation (Constant Current Driving Mode)
Between output channels
Between chips
Input Clock Frequency F
Maximum Power Dissipation P
OUT
XOUT
I
OUTCC
I
OUTCV
D
D
CLK
IN
IOI
IOE
D
Operating Junction Temperature Topr -40 to + 150
Storage Temperature Range Tstg -55 to + 150
Lead Temperature (Soldering, 10 seconds)
Tsolder 300
ESD susceptibility 4000 V
Note: If the voltage on the pins exceeds the maximum ratings may cause permanent damage to the device.
Electrical Characteristics (VCC=5V, TA= 25℃, unless otherwise specified.)
Parameter Symbol Conditions Min Typ Max Units
Power Supply Voltage Range V
Output Voltage VOUT IOUT=1uA -0.3 -- 7.0 V
I
outH
Output Current
Standby Supply Current
Minimum Constant Current Output Time I
I
outL
I
SOURCE
I
SINK
I
STB
OH
Input Current I
Input Voltage Level
V
V
Constant Current Feed Back Voltage V
Output Saturation Voltage V
XFB
SAT
3.3 -- 5.5 V
CC
Constant Current Output 5 -- 30 mA
Constant Voltage Output -- -- 50 mA
Output Cut Off -- 0.1 1 uA
Other Output -- 1 -- mA
Other Output -- -1 -- mA
B
R/G/BOUT Floating -- 1 1.5 mA
VIN＝V
I
OUT
or VIL,
IH
=20mA
PIN：CKI，SDI
＝VDD or GND
V
IN
IH
IL
IN
PIN：CKM，POL
＝VDD or GND
V
IN
TA＝-40～125℃
B R
R/G/BFB
=20Ω B
IOUT=20mA -- 0.4 0.6 V
-0.3 to VCC+0.3V V
-0.4 to 7V V
-0.3 to 7V V
0 to 50
mA
0 to 100
±1
%
±3
25 MHz
600 mW
℃
-- 14 -- uS
-- --
--
±10 ±20
±1
uA
uA
0.8*VDD -- VDD V
GND -- 0.2*VDD
0.582 0.6 0.618
V
V
2 /15
WS-Preliminary-V0.3 http://www.world-semi.com
Preliminary WS2801
3-Channel Constant Current
LED Driver With Programmable
PWM Outputs
Output Voltage Regulation %dV
Line Regulation %dV
Pull High Resistance R
OUTVOUT
CC
INHIGH
Switching Characteristics (VCC=5V, TA=25℃)
Parameter Symbol Conditions Min Typ Max Units
Propagation Delay
(‘L’ to ‘H’)
Propagation Delay
(‘L’ to ‘H’)
Output Current Rise Time
Maximum Turn ON and OFF time of Drive Current
Output Current Propagation
CKI-to-CKO
CKI-to-CKO
Switching Characteristics (VCC=3.3V, TA=25℃)
Parameter Symbol Conditions Min Typ Max Units
Propagation Delay
(‘L’ to ‘H’)
Propagation Delay
(‘L’ to ‘H’)
Output Current Rise Time
Output Current Fall Time
Output Current Propagation
CKI-to-CKO
CKI-to-CKO T
Circuit for Switching Characteristics Test
=0.9~4, R
VCC＝4～5.5V --
R
POL
T
T
①T
T
①T
pLH
pHL
T
or
T
of
OP
pLH
pHL
T
or
T
of
OP
VIH=VCC
V
R
RL=180Ω
CL=30pF
VIH=VCC
V
R
RL=180Ω
CL=30pF
RGBFB
, R
CKM
=GND
IL
XFBs
=GND
IL
XFBs
=30Ω
=30
=30Ω
--
±0.1
±0.1
-- 30 -- KΩ
-- 8 -- ns
-- 8.6 -- ns
-- 50 -- ns
-- 50 -- ns
-- -- 3.3 mS
-- 9.0 -- ns
-- 13 -- ns
-- 50 --
-- 50 -- ns
-- -- 3.3 mS
-- %/V
-- %/V
Fig2, Circuit for switching characteristics test
Note:
① Reload the gray scale data at each end of the PWM cycle
3 /15
WS-Preliminary-V0.3 http://www.world-semi.com
Preliminary WS2801
3-Channel Constant Current
LED Driver With Programmable
PWM Outputs
Typical Block Diagram
Fig3, Block Diagram of WS2801
4 /15
WS-Preliminary-V0.3 http://www.world-semi.com
Preliminary WS2801
3-Channel Constant Current
LED Driver With Programmable
PWM Outputs
Pin Description
Pin Port Pin Name Pin Description
1
2 SDI Serial gray scale data input
3 POL
4 RFB
5 GFB
6 BFB
7 GND Ground
8 BOUT The output of the B channel
9 GOUT The output of the G channel
10 ROUT The output of the R channel
11 NC None connection
12 SDO The output of the serial gray scale data.
13 CKO The output of the buffered clock
14 VCC
Application Information
CKI Data clock input
Output polarity control. When this pin is pull to GND, the driver output will be
reversed; when floating or pulled high, the output polarity will not be reversed.
The feed back of the R channel, a resistor connected to this pin can set the
output constant current of the R channel
The feed back of the G channel, a resistor connected to this pin can set the
output constant current of the G channel
The feed back of the B channel, a resistor connected to this pin can set the
output constant current of the B channel
Power supply input, a capacitor can be connected from this pin to GND to
enhance the noise immunity.
Fig4, The typical application circuit of WS2801
5 /15
WS-Preliminary-V0.3 http://www.world-semi.com
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