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JULY 2008
V1.0
Pay attention to the last page
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CONTENTS
1 Product Description.................................................................................................................3
1.1 Features.............................................................................................................................3
1.2 Applied field .....................................................................................................................3
1.3 Basic Structure Description...............................................................................................3
2 LXY28161 Specification..........................................................................................................3
2.1 Block Diagram and Pin Configuration..............................................................................3
2.2 Maximum Rating..............................................................................................................5
2.3 Electrical Characteristics (V
DD
=5.0V)..............................................................................6
2.4 Switching Characteristics（V
DD
＝5V） ..........................................................................7
2.5 Test Circuit for Switching Characteristics........................................................................8
2.6 Timing Waveform.............................................................................................................9
2.6.1 Serial-Port Timing Waveform....................................................................................... 9
2.6.2 Output-Current Channel Timing Waveform.................................................................9
2.7 Constant Current.............................................................................................................10
2.8 Setting Output Current....................................................................................................10
2.9 Delay Time of Staggered Output....................................................................................10
2.10 Package Power Dissipation.............................................................................................10
2.11 Usage of Thermal Pad.....................................................................................................10
2.12 Thermal Protection Function...........................................................................................11
2.13 LED Supply Voltage.......................................................................................................11
2.14 Switching Noise Reduction.............................................................................................11
2.15 Equivalent Circuits of Inputs and Outputs......................................................................12
3 Package Outline.....................................................................................................................12
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4 Attention…………………………………………………………………………………… 14
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1 Product Description
LXY28161, the 16-channel constant
current LED Driver, is designed for LED video
applications using internal Wise Pulse Width
Modulation (W-PWM) control with selectable
16-bit color depth. LXY28161 saves the 60 Hz
images input data in the 8K RAM, then converts
into each pixel gray scale of output channel, all
output channels can be built with 65536 gray
scales and 4800 Hz refresh rate.
LXY28161 has 16 constant-current
output channels. Constant output current is
invariant to load voltage change. The output
current can be preset through an external
resistor. LXY28161 supports static and any scan
mode (within 16) led displays. The gray scales
and refresh rate is user adjustable.
1.1 Features
z Backward compatible with main trend 16-channel constant current IC in
package
z 16 constant-current output channels
z 16-bit color depth W-PWM control
z Refresh rate up to 4800Hz
z Schmitt trigger input
z Staggered output delay (reduce EMI)
z Over temperature protection
z Constant output current range: 5V, 5~60mA
z Output current accuracy: between channels: +
3%, between ICs: +6%
z Maximum data clock frequency: 25MHz
z 5V supply voltage
1.2 Applied field
z LED video applications
1.3 Basic Structure Description
LXY28161 mainly includes serial-data input, Wise Pulse Width Modulation, constant current
controlling circuit, constant current output.
2 LXY28161 Specification
2.1 Block Diagram and Pin Configuration
LXY28161 applies SOP－24 and TSSOP-24 in package outline, Block Diagram and Pin
Configuration are as following diagrams:
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Block Diagram
Pin Configuration
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Pin Name Pin No. Type Function
GND 1 Power Ground terminal for control
logic and current sink
SDI 2 Schmitt trigger
input
Serial-data input to the shift
register
CLK 3 Schmitt trigger
input
Clock input terminal for data
shift on rising edge
LE 4 Schmitt trigger
input
Data strobe terminal and
controlling command with DCLK
OUT0～15 5～20 Output Constant current output
terminal, 5-60mA
NC 21 - -
SDO 22 Controllable
staggered
output delay
10ns，20ns，30ns selectable.
Serial-data output to the
receiver-end SDI of next
driver IC
R-EXT 23 Controlling Input terminal used to connect
an external resistor for
setting up output current for
all output channels
VDD 24 Power 5V supply voltage terminal
2.2 Maximum Rating
Characteristic Symbol Rating Unit
Supply Voltage VDD 7 V
Input Pin Voltage (SDI) VIN
-0.4～
VDD+0.4
V
Output Current I
OUT
+60
mA
Sustaining Voltage at OUT Port VDS 7 V
Data Clock Frequency DCLK +25 MHz
GND Terminal Current I
GND
+1000 mA
L Type PD 2.12 W Power Dissipation
(On PCB, Ta=25°C)
S Type PD 1.73 W
L Type R
th(j-a
) 59.1
Thermal Resistance
(On PCB, Ta=25°C)
S Type
72.43
°C/W
Operating Temperature T
opr
-40～+85 °C
Storage Temperature T
stg
-55～+150 °C
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2.3 Electrical Characteristics (VDD=5.0V)
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Characteristics
Sym
bol
Condition Min. Typ. Max. Unit
Supply Voltage VDD - 3.3 5.0 5.5 V
Sustaining Voltage
at OUT Ports
V
DS
OUT0 ~ OUT15 - - VDD+0.4 V
I
OUT
Refer to “Test Circuit for
Electrical Characteristics”
5 - 60 mA
IOH SDO - - -6.0 mA
Output Current
I
OL
SDO - - 6.0 mA
”H” level VIH Ta=-40~85ºC 0.7*VDD - VDD V
Input
Voltage
”L” level V
IL
Ta=-40~85ºC GND - 0.3*VDD V
Output Leakage
Current
I
OH
VDS=7.0V - - 0.5
μA
VOL IOL=+6.0mA - - 0.4 V
Output
Voltage
SDO
VOH IOH=-6.0mA 4.6 - - V
Current Skew
(Channel)
ΔI
OUT
1
I
OUT
=10.8mA
V
DS
=1.0V
R
ext
=1800 - ±1.5 ±3.0 %
Current Skew (IC)
ΔI
OUT
2
I
OUT
=10.8mA
V
DS
=1.0V
R
ext
=1800 - ±3.0 ±6.0 %
Output Current vs.
Output Voltage
Regulation
%/ΔV
DS
V
DS
＝ 1.0V and 3.0V,
R
ext
=910@21mA
- ±0.1 ±0.5 % / V
Output Current vs.
Output Voltage
Regulation
%/dV
DD
V
DD
＝ 4.5V and 5.5V
- ±1.0 ±5.0 % / V
Pull-down Resistor
R
IN
(d
own)
LE 250 500 800 K
IDD(of
f) 1 R
ext
=Open
OUT0 ~ OUT15
=Off
- 11.4 12.5
IDD(of
f) 2
R
ext
=1800
OUT0 ~ OUT15
=Off
- 12.3 13.5
”Off”
I
DD
(of
f) 3 R
ext
=910
OUT0 ~ OUT15
=Off
- 13.7 15.0
IDD(o
n) 1 R
ext
=1800
OUT0 ~ OUT15
=On
- 14.2 15.7
Supply
Current
”On”
I
DD
(o
n) 2
R
ext
=91
OUT0 ~ OUT15
=On
- 16.3 18.5
mA
Thermal Flag
Temperature
TTF Junction Temperature 135 150 165
°C
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2.4 Switching Characteristics（VDD＝5V）
Characteristics Symbol Condition Min. Typ. Max Unit
SDI - DCLK t
SU0
1 - - ns
LE –
DCLK
t
SU1
1 - - ns
Setup Time
LE –
DCLK
t
SU2
5 - - ns
DCLK - SDI tH0 3 - - ns
Hold Time
DCLK - LE t
H1
7 - - ns
5 10 20 ns
15 20 30 ns
25 30 40 ns
DCLK -SDO
(adjustable)
t
PD0
VDD=5.0V
VIH=VDD
VIL=GND
DCLK output to the
receiver-end SDI of next
driver IC
-
Propagation
Delay Time
GCLK –
OUT4n
t
PD1
* 75 - ns
OUT4n + 1*
t
DL1
- 25 - ns
OUT4n + 2 *
t
DL2
- 50 - ns
Stagger
Delay Time
OUT4n + 3 *
t
DL3
- 75 - ns
LE tw(L) 5 - - ns
Pulse Width
DCLK
t
w
(DCLK) 20 - - ns
Output Rise Time of Output
Ports
tOR - 10 20 ns
Output Fall Time of Output
Ports
tOF
RL=152
CL=10pF
C1=100nF
C2=10F
- 10 20 ns
* Refer to the Timing Waveform, when n=0, 1, 2, 3.
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2.5 Test Circuit for Switching Characteristics
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2.6 Timing Waveform
2.6.1 Serial-Port Timing Waveform
2.6.2 Output-Current Channel Timing Waveform
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2.7 Constant Current
In LED display application, LXY28161 provides nearly no
variation in current from channel to channel and from IC to IC. This
can be achieved by:
1) The typical current variation between channels is less than ±3%,
and that between IC is less than ±6%.
2) In addition, the output current can be kept constant regardless of
LED forward voltages. This guarantees LED to be performed on the same
brightness as user’s specification.
2.8 Setting Output Current
The output current (I
OUT
) is set by an external resistor, R
ext.
The
default relationship between I
OUT
and R
ext
is:
V
R-EXT
=1.26V ;
I
OUT
=(V
R-EXT
/R
ext
) x 15.5
Rext is the resistance of the external connected to R-EXT
terminal
VR－EXT is its voltage
The output current is about 21mA when Rext=910Ω and 10.8mA
when Rext=1800Ω
2.9 Delay Time of Staggered Output
LXY28161 has a built-in staggered circuit to perform delay
mechanism. 16 channels are divided to four groups. Each output port
has 25nS delay time, so that the instant current from the power line
will be lowered.
2.10 Package Power Dissipation
The maximum allowable package power dissipation is determined as
PD(max)=(Tj–Ta)/Rth(j-a).
When 16 output channels are turned on simultaneously, the actual
package power dissipation is
PD(act)=(IDDxVDD)+(I
OUT
xDutyxVDSx16).
Therefore, to keep PD (act)≤PD (max), the allowable maximum output
current as a function of duty cycle is:
I
OUT
={[(Tj–Ta)/Rth(j-a)]–(IDDxVDD)}/ (DutyxVDSx16), （ Tj=150°C）
The maximum power dissipation, PD(max)=(Tj–Ta)/Rth(j-a), decreases
as the ambient temperature increases. So the LXY28161 must work in
Safe Operation Area.
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2.11 Usage of Thermal Pad
The PCB area L2xW2 is 4 times of the IC’s area L1xW1.
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2.12 Thermal Protection Function
The thermal protection function is enabled by default. The
output current will decrease to 25%. As soon as the temperature is
below 110℃ , the thermal error flag will return to 0 and the output
current will recover from the 25% current.
2.13 LED Supply Voltage
LXY28161 are designed to operate with VDS ranging from 0.4V to
0.8V (depending on IOUT=5 ～ 60mA), considering the package power
dissipating limits. VDS may be higher enough to make when VLED＝5V，
PD
(act)
< PD
(max)
when VLED=5V and VDS=VLED– VF, in which VLED is the
load supply voltage. In this case, it is recommended to use the
lowest possible supply voltage or to set an external voltage reducer,
VDROP. A voltage reducer lets VDS=(VLED – VF) – VDROP. Resistors or
Zener diode can be used in the applications as shown in the following
figures.
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2.14 Switching Noise Reduction
LED drivers are frequently used in switch-mode applications
which always behave with switching noise due to the parasitic
inductance on PCB. To eliminate switching noise, refer to Application
Note for 8-bit and 16-bit LED Drivers-Overshoot.
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2.15 Equivalent Circuits of Inputs and Outputs
Equivalent circuits of Inputs and Outputs
3 Package Outline
LXY2816 applies SOP－24 and TSSOP-24 package outline:
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SOP-24 Outline Drawing
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SSOP-24 Outline Drawing
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4. Attention
4.1 The Rt value should satisfy: Rt < ( Rf / N /9), besides, set the
value as small as possible. Otherwise, there will be current
difference between ICs, which will effect the color uniformity.
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4.2 In the Line-output, before connecting the GND, add a zener diode.
The voltage of the zener diode is between 3.0V and 3.6V. Test and
choose one that suit most. In out test, 3.3V is good.
4.3 For Electronic capacitors, please use Taiwan Lelon’s RXZ series
high frequency capacitors, or some other brand which is similar in
functions with the follow specifications:
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