TECHNICAL DATA
HIGH-POWER LED DRIVER
IK2802
FEATURES
2 constant-current output channels
Constant output current invariant to load voltage
change
Maximum output constant current per channel:
360 mA
Thermal protection and flag
Output current adjusted through an external resistor
Schmitt trigger input
5V supply voltage
Package type: Pb-free package with thermal pad
Small Outline Package
SOP8
ORDERING INFORMATION
Device
IK2802DT
Operating Temperature Range
ТА = - 40 ... + 85 С
Current Accuracy
Between Channels
Between ICs
<±3%
<±6%
Package
Shipping
SOP-8
Tape& Reel
Conditions
IOUT = 40mA ~ 360 mA
@ VDS= 0.6V
PRODUCT DESCRIPTION
IK2802 is an instant On/Off LED driver for high power LED applications and exploits to enhance its
output characteristics.
IK2802 provides users with 2-channel constant current ports. Users may adjust the output current up
to 360 mA through an external resistor, Rext, which gives users flexibility in controlling the light intensity of
LEDs. Also, users can precisely adjust LED brightness from 0% to 100% via output control with Pulse Width
Modulation. Alternatively, IK2802 provides one-step current adjustment to make 25% of the output current
via enabling the quarter pin (QT) as “Low”.
Additionally, to ensure the system reliability, IK2802 is built with Thermal Protection (TP) function and
thermal pad. The TP function protects IC from over temperature (165°C). Also, the thermal pad enhances
the power dissipation. As a result, a large amount of current can be sunk safely in one package.
APPLICATIONS
High-flux LED lighting
Automotive interior lighting
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2011, February Ver. 03
IK2802
TYPICAL APPLICATION CIRCUIT
Figure 1
FUNCTIONAL DIAGRAM
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2011, February Ver. 03
IK2802
PIN CONFIGURATION
PIN DESCRIPTION
Pin No.
Pin Name
1
GND
2
R-EXT
3
QT
4,5
OUT0~OUT1
6
ERR
7
OE
8
VDD
-
Thermal Pad
Function
Ground terminal for control logic and current sink
Terminal used to connect an external resistor (Rext) for setting up output
current for all output channels
Set all the output current to 25% of the
Default value is high.
pre-set current when QT is low.
Constant current output terminals
Open drain thermal error flag, when junction temperature is over 165 ºC,
ERR is going to low.
Output enable terminal
when OE is active (low), the output pins are enabled; when OE is inactive
(high), all output pins are turned OFF (blanked).
5V supply voltage terminal
Power dissipation terminals connected to GND*
*To eliminate the noise influence, the thermal pad is suggested to be connected to GND on PCB.
In addition, desired thermal conductivity will be improved, if a heat-conducting copper foil on PCB is soldered with
thermal pad.
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2011, February Ver. 03
IK2802
MAXIMUM RATINGS
Characteristic
Symbol
Rating
Unit
Supply Voltage
VDD
0~7.0
V
Input Voltage
VIN
-0.4~VDD + 0.4
V
Output Current
IOUT
360*
mA
Sustaining Voltage
VDS
-0.5~+27
V
GND Terminal Current
IGND
720
mA
PD
0.8
W
Power Dissipation*
(On PCB, Ta=25 ºC)
Thermal Resistance**
(By simulation)
Empirical Thermal Resistance*
(On PCB, Ta=25 ºC)
SOP8
33.39
Rth(j-a)
Operating Junction Temperature
ºC/W
125
Tj,max
125
ºC
Operating Temperature
Topr
-40~+85
ºC
Storage Temperature
Tstg
-55~+150
ºC
*Users must notice that the power dissipation (almost equaling to IOUT x VDS) should be within the Safe Operation
Area shown in Figure 7.
** Provided by factory.
*** Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device.
These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated
under “recommended operating conditions” is not implied.
Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
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2011, February Ver. 03
IK2802
Electrical Characteristics
Characteristics
Symbol
Condition
Min.
Typ.
Max.
Unit
Supply Voltage
VDD
-
4.5
5.0
5.5
V
Sustaining Voltage at OUT pin
VDS
OUT0~OUT1
-
-
27.0
V
Output Current
IOUT
DC Test Circuit
40
-
360.0
mA
“H” level
VIH
Ta=-40~85 ºC
1.6
-
VDD
V
“L” level
VIL
Ta=-40~85 ºC
GND
-
0.6
V
Output Leakage Current
IOH
VOH=27V
-
-
0.5
uA
ERR Output Voltage
VOL
IOL=+1.0mA
-
-
0.5
V
ERR Turn On Impedance
RDS,(ON),ERR
Refer to the “Test Circuit for
Electrical Characteristics”
300
600
800
Ohm
Output Current 1
IOUT1
Rext=1.8kOhm
-
340
-
mA
Current Skew 1
dIOUT/IOUT
Rext=1.8kOhm
-
±1
±3
%
Output Current 2
IOUT2
Rext=2.4kOhm
-
240
-
mA
Current Skew 2
dIOUT/IOUT
Rext=2.4kOhm
-
±1
±3
%
Input Voltage
for OE, QT
VDS=0.8V
IOL=340mA
VDS=0.8V
VDS=0.6V
IOL=240mA
VDS=0.6V
Regulation of Output Current vs.
Sustaining Voltage
Regulation of Output Current vs.
Supply Voltage
%/dVDS
VDS within 1.0V and 3.0V
-
±0.1
-
%/V
%/dVDD
VDD within 4.5V and 5.5V
-
±1
-
%/V
Pull-up Resistor
RN(up)
OE, QT
300
600
800
kOhm
Thermal Shutdown temperature
TXI
Shutdown
Temp.increasing
-
165
-
ºC
TXD
Reset
Temp.decreasing
-
155
-
ºC
Rext=Open,OUT0~OUT1=Off
-
4
9
Rext=2.4kOhm,
OUT0~OUT1=Off
Rext=1.8kOhm,
OUT0~OUT1=Off
Rext=2.4kOhm,
OUT0~OUT1=On
-
6
10
-
7
12
-
5
10
Rext=1.8kOhm,
OUT0~OUT1=On
-
6
10
IDD(off) 1
“OFF”
IDD(off) 2
IDD(off) 3
Supply Current
“ON”
IDD(on) 1
IDD(on) 2
mA
TEST CIRCUIT FOR ELECTRICAL CHARACTERISTICS
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2011, February Ver. 03
IK2802
Figure 2
SWITCHING CHARACTERISTICS
Characteristics
Propagation Delay
Time(“L” to “H”)
Propagation Delay
Time(“L” to “H”)
Pulse width
Symbol
Condition
Min.
Typ.
Max.
Unit
OE-OUTn
tpLH
0.3
0.5
1
us
OE-OUTn
tpHL
VDD=5.0V
VDS=1.0V
VIH=VDD
VIL=GND
Rext=1630Ohm
0.3
0.5
1
us
1
-
-
us
OE
tw(OE)
Output Rise Time of OUT (turn off)
tor
(IOUTn=360mA)
VL=4.0V
RL=8.5Ohm
0.3
0.5
1
us
Output Rise Time of OUT (turn on)
tof
CL=10pF
0.3
0.5
1
us
TEST CIRCUIT FOR SWITCHING CHARACTERISTICS
Figure 3
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2011, February Ver. 03
IK2802
APPLICATION CIRCUITS
(a) IK2802 application circuit, where VLED and VDD share a single voltage source.
(b) IK2802 Application Circuit with dimming control by PWM signal, where VLED and VDD use voltage sources
separately.
Figure 4
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2011, February Ver. 03
IK2802
Constant Current
In LED lighting applications, IK2802 provides nearly no variation in current from channel to channel and from IC
to IC. This can be achieved by:
1) The maximum current variation between channels is less than ±3%, and that between ICs is less than ±6%.
2) In addition, the current characteristic of output stage is flat and users can refer to the figure as shown below.
The output current can be kept constant regardless of the variations of LED forward voltages (VF). This guarantee
s LED to be performed on the same brightness as user’s specification.
Iout (mA)
Iout versus Vds
400
360
320
280
240
200
160
120
80
40
0
16,1k
4,9k
2,9k
2,1k
1,6k
0
1
2
3
4
Vds (V)
Figure 5
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2011, February Ver. 03
IK2802
Setting Output Current
The output current of each channel (IOUT) is set by an external resistor, Rext. The relationship between IOUT and
Rext is shown in the following Figure 6 and Table1.
Iout (mA)
Iout versusu Rext
400
360
320
280
240
200
160
120
80
40
0
0
2,5
5
7,5
10
12,5
15
17,5
Rext (kOHM)
Figure 6
Iout(mA)
360
280
200
120
40
Rext(kohm)
1.60
2.07
2.89
4.88
16.14
Table1
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2011, February Ver. 03
IK2802
Package Power Dissipation (PD)
The maximum power dissipation, PD(max) = (Tj,max – Ta) / Rth(j-a), decreases as the ambient temperature increases.
Figure 7
The maximum allowable package power dissipation is determined as PD(max) = (Tj,max – Ta) / Rth(j-a). When 2
output channels are turned on simultaneously, the actual package power dissipation is P D(act) = (IDD x VDD) +
(IOUT x Duty x VDS x 2). Therefore, to keep PD(act) ≤ PD(max), the allowable maximum output current as a function
of duty cycle is:
IOUT = { [ (Tj – Ta) / Rth(j-a) ] – (IDD x VDD) } / VDS / Duty / 2,
where Tj = 125°C;
Duty= tON / T;
tON: the time of LEDs turning on; T:
signal period
*Note: The empirical thermal resistor Rth(j-a) =125 °C/W is based on the following structure.
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2011, February Ver. 03
IK2802
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2011, February Ver. 03
IK2802
TP Function (Thermal Protection)
Thermal protection turns off the output current when the junction temperature rises to approximately 165°C, allowing the device to cool and the thermal error flag,
goes low simultaneously. When the junction temperature cools to approximately 155°C, the output current is turned on again. Depending on power dissipation, thermal resistance, and ambient temperature, the thermal protection circuit may cycle on and off. This limits the dissipation of the driver, protecting it from damage due to overheating.
Load Supply Voltage (VLED)
IK2802 is designed to operate with adequate VDS to achieve constant current. VDS together with IOUT should not
exceed the package power dissipation limit, PD(max).
As in Figure 8, VDS = VLED – VF, and VLED is the load supply voltage. PD(act) will be greater than PD(max), if VDS drops
too much voltage on the driver. 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 can be used in the applications as shown in Figure 8.
Figure 8
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2011, February Ver. 03
IK2802
PACKAGE DIMENSIONS
SOP 8
Note: The unit for the outline drawing is mm.
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2011, February Ver. 03