Regulation

TECHNICAL DATA
CONSTANT–CURRENT LED DRIVER
IK2816
FEATURES
 16 constant-current output channels
 Constant output current invariant to load voltage change
 Excellent output current accuracy:
between channels: <±3% (max.), and
between ICs: <±6% (max.)
 Output current adjusted through an external resistor
 Constant output current range per channel: 5-60 mA
 Schmitt trigger input
 5V supply voltage
 Package Type: Pb-free package with thermal pad
Thin Shrink SOP
TSSOP20
ORDERING INFORMATION
Device
IK2816TSDT
Operating
Temperature Range
ТА = - 40 ... + 85 С
Package
Shipping
TSSOP-20
Tape& Reel
Current Accuracy
Between Channels
Between ICs
<±3%
<±6%
Conditions
IOUT = 5~ 60 mA
PRODUCT DESCRIPTION
IK2816 is an instant On/Off LED driver for lighting applications and exploits to enhance its
output characteristics. At IK2816 output stage, sixteen regulated current ports are designed to
provide uniform and constant current sinks for driving LEDs within a large range of VF
variations.
IK2816 provides users 16-channel constant current ports to match LEDs with equal current.
Users may adjust the output current from 5 mA to 60 mA through an external resistor, Rext,
which gives users flexibility in controlling the light intensity of LEDs. In addition, users can
precisely adjust LED brightness from 0% to 100% via output enable
with Pulse Width Modulation.
Additionally, to ensure the system reliability, IK2816 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
handled safely in one package.
APPLICATIONS



Automotive interior lighting
Channel letter
Decoration lighting
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2011, February Ver. 03
IK2816
TYPICAL APPLICATION CIRCUIT
Figure 1
FUNCTIONAL DIAGRAM
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2011, February Ver. 03
IK2816
PIN CONFIGURATION
PIN DESCRIPTION
Pin Name
GND
OUT0~OUT15
Function
Ground terminal for control logic and current sink
Constant current output terminals
OE
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).
R-EXT
Terminal used to connected an external resistor (Rext) for setting
up output current for all output channels
VDD
Thermal Pad
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
IK2816
ABSOLUTE 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
80*
mA
Sustaining Voltage
VDS
27.0
V
GND Terminal Current
IGND
1000
mA
PD
0.85
W
Power Dissipation*
(On PCB, Ta=25 ºC)
Thermal Resistance**
(By simulation)
Empirical Thermal Resistance*
(On PCB, Ta=25 ºC)
TSSOP20
31.99
ºC/W
Rth(j-a)
117
Operating Junction Temperature
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 I OUT 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
IK2816
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~OUT15
·
·
27.0
V
Output Current
IOUT
DC Test Circuit
5
·
60*
mA
“H” level
VIH
Ta=-40~85 ºC
0.7*VDD
VDD
V
“L” level
VIL
Ta=-40~85 ºC
GND
0.3*VDD
V
IOH
VOH=27V
·
·
0.5
µA
Input Voltage
Output Leakage Current
Output Current 1
IOUT1
VDS=0.6V
Rext=2.4kOhm
·
30.5
·
mA
Current Skew 1
dIOUT/IOUT
IOL=30.5mA
VDS=0.6V
Rext=2.4kOhm
·
±1
±3
%
Output Current 2
IOUT2
VDS=0.8V
Rext=1.3kOhm
·
56.0
·
mA
Current Skew 2
dIOUT/IOUT
IOL=56mA
VDS=0.8V
Rext=1.3kOhm
·
±1
±3
%
Regulation of Output Current
vs. Sustaining Voltage
Regulation of Output Current
vs. Supply Voltage
Pull-up Resistor
Thermal
temperature
Shutdown
“OFF”
Supply Current
“ON”
%/dVDS
VDS within 1.0V and 3.0V
·
±0.1
·
%/V
%/dVDD
VDD within 4.5V and 5.5V
·
±1
·
%/V
RN(up)
__
OE
250
500
800
kΩ
TXI
Shutdown
Temp.increasing
·
165
·
ºC
TXD
Reset
Temp.decreasing
·
145
·
ºC
IDD(off) 1
Rext=Open, OUT0~OUT15=Off
·
5
9
IDD(off) 2
Rext=2.4kOhm,OUT0~OUT15=Off
·
6
10
IDD(off) 3
Rext=1.3kOhm,OUT0~OUT15=Off
·
8
12
IDD(on) 1
Rext=2.4kOhm,OUT0~OUT15=On
·
6
10
IDD(on) 2
Rext=1.3kOhm,OUT0~OUT15=On
·
7
10
mA
Each output current, IOUT, can be driven up to 80mA, but the total output current should be smaller than 1A.
TEST CIRCUIT FOR ELECTRICAL CHARACTERISTICS
Figure 2
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2011, February Ver. 03
IK2816
SWITCHING CHARACTERISTICS
Characteristics
Propagation Delay
Time(“L” to “H”)
Propagation Delay
Time(“L” to “H”)
Pulse width
___ _____
OE - OUTn
___ _____
OE - OUTn
___
OE
Symbol
Condition
Min.
Typ.
Max.
Unit
tpLH
VDD=5.0V
VDS=1.0V
VIH= VDD
VIL=GND
Rext=1229
(IOUTn=60mA)
VL=4.0V
RL=51
CL=10pF
0.05
0.1
0.2
us
0.05
0.1
0.2
us
1.0
-
-
us
0.05
0.1
0.2
us
0.1
0.2
0.4
us
tpHL
tw(OE)
Output Rise Time of Out (turn off)
tor
Output Rise Time of Out (turn on)
tof
TEST CIRCUIT FOR SWITCHING CHARACTERISTICS
Figure 3
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2011, February Ver. 03
IK2816
APPLICATION CIRCUITS
(a) IK2816 application circuit, where VLED and VDD share a single voltage source.
* VLED > VDS + VF,LED x n; VF,LED: Forward voltage of LED; n: LED count
** R1 = (VLED - 5.1V) / IDD; refer to Electrical Characteristics for IDD
*** R2~R17 = [VLED –VDS – (VF,LED x n)] / ILED
(b) IK2816 application circuit with dimming control by PWM signal, where V LED and VDD use voltage sources
separately.
*VLED = VDS + VF,LED x n; VF,LED: Forward voltage of LED; n: LED count
Figure 4
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2011, February Ver. 03
IK2816
Constant Current
In LED lighting applications, IK2816 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 ±5%, 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 (V F).
This guarantees LED to be performed on the same brightness as user’s specification.
Iout vs VDS
70
32K
60
9,65K
Iout (mA)
50
5.68K
40
4,0K
30
2,63K
20
1,93K
1,5K
1,25K
10
0
0
0,5
1
1,5
2
2,5
3
VDS (V)
Figure 5
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2011, February Ver. 03
IK2816
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 Table.
Iout vs Rext
70
60
Iout (mA)
50
40
30
20
10
0
0
5
10
15
20
25
30
35
Rext (kΩ)
Figure 6
Iout
(mA)
Rext
(kΩ)
60
1.25
50
1.5
40
1.93
30
2.63
20
4.0
10
9.65
5
32.0
The output current can be calculated from the equation:
VR-EXT = 1.24V;
Rext = (VR-EXT / Iout) × 59 = (1.24V / Iout) × 59,
Iout = (VR-EXR / Rext) × 59 = (1.24V / Rext) × 59 within ± 6% chip skew
Where Rext is the resistance of the external resistor connected to R-EXT terminal and VR-EXT is the voltage of R
-EXT terminal. The magnitude of current (as a function of Rext) is around 56mA at 1.3kΩ and 30.5mA at 2.4kΩ.
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2011, February Ver. 03
IK2816
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 16
output channels are turned on simultaneously, the actual package power dissipation is P D(act) = (IDD x VDD) + (IOUT
x Duty x VDS x 16). 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 / 16,
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) =117 °C/W; it is based on the following structure.
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2011, February Ver. 03
IK2816
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. When the junction temperature cools to approximately 145°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)
IK2816 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
IK2816
PACKAGE DIMENSIONS
TSSOP 20
Note: The unit for the outline drawing is mm.
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2011, February Ver. 03