IL2802 IKSEMICON | Alldatasheet
Document overview
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Technical content
1 2011, February Ver. 03 Small Outline Package SOP8 HIGH-POWER LED DRIVER
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 resis- tor Schmitt trigger input 5V supply voltage Package type: Pb-free package with thermal pad
ORDERING INFORMATION
ture Range Package Shipping IK2802DT ТА = - 40 ... + 85 С SOP-8 Tape& Reel Current Accuracy Conditions Between Channels Between ICs <±3% <±6% 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 IK2802
2 2011, February Ver. 03 TYPICAL APPLICATION CIRCUIT Figure 1 FUNCTIONAL DIAGRAM
3 2011, February Ver. 03 PIN CONFIGURATION PIN DESCRIPTION Pin No. Pin Name Function
1 GND Ground terminal for control logic and current sink
2 R-EXT Terminal used to connect an external resistor (Rext) for setting up output
current for all output channels QT Set all the output current to 25% of the pre-set current when QT is low. Default value is high. 4,5 OUT0~OUT1 Constant current output terminals ERR Open drain thermal error flag, when junction temperature is over 165 ºC, ERR is going to low. 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).
8 VDD 5V supply voltage terminal
- Thermal Pad 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.
4 2011, February Ver. 03 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 Power Dissipation* (On PCB, Ta=25 ºC) SOP8 PD 0.8 W Thermal Resistance** (By simulation) Rth(j-a) 33.39 ºC/W Empirical Thermal Resistance* (On PCB, Ta=25 ºC) 125 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.
5 2011, February Ver. 03
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 Input Voltage for OE, QT “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 VDS=0.8V Rext=1.8kOhm - 340 - mA Current Skew 1 dIOUT/IOUT IOL=340mA VDS=0.8V Rext=1.8kOhm - ±1 ±3 % Output Current 2 IOUT2 VDS=0.6V Rext=2.4kOhm - 240 - mA Current Skew 2 dIOUT/IOUT IOL=240mA VDS=0.6V Rext=2.4kOhm - ±1 ±3 % Regulation of Output Current vs. Sustaining Voltage %/dVDS VDS within 1.0V and 3.0V - ±0.1 - %/V Regulation of Output Current vs. Supply Voltage %/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 Supply Current “OFF” IDD(off) 1 Rext=Open,OUT0~OUT1=Off - 4 9 mA IDD(off) 2 Rext=2.4kOhm, OUT0~OUT1=Off - 6 10 IDD(off) 3 Rext=1.8kOhm, OUT0~OUT1=Off - 7 12 “ON” IDD(on) 1 Rext=2.4kOhm, OUT0~OUT1=On - 5 10 IDD(on) 2 Rext=1.8kOhm, OUT0~OUT1=On - 6 10 TEST CIRCUIT FOR ELECTRICAL CHARACTERISTICS
7 2011, February Ver. 03 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
8 2011, February Ver. 03 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. Figure 5 Iout versus Vds 120 160 200 240 280 320 360 400 0 1 2 3 4 Vds (V) Iout (mA) 16,1k 4,9k 2,9k 2,1k 1,6k
9 2011, February Ver. 03 Setting Output Current The output current of each channel (I OUT) is set by an externa l resistor, Rext. The relationship between I OUT and Rext is shown in the following Figure 6 and Table1. Figure 6 Iout(mA) Rext(kohm) 360 1.60 280 2.07 200 2.89 120 4.88 40 16.14 Table1 Iout versusu Rext 120 160 200 240 280 320 360 400 0 2,5 5 7,5 10 12,5 15 17,5 Rext (kOHM) Iout (mA)
10 2011, February Ver. 03 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) = (T j,max – Ta) / R th(j-a). When 2 output channels are turned on simultaneously, the actual package power dissipation is P D(act) = (I DD 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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12 2011, February Ver. 03 TP Function (Thermal Protection) Thermal protection turns off the output current when the junction temper ature rises to approximately 165 °C, al- lowing the device to cool and the thermal error flag, goes low simultaneously. W hen the junction tem pera- ture cools to approximately 155°C, the output current is turned on again. Depending on power dissi pation, ther- mal resistance, and ambient tempe rature, the thermal protection circuit may cycle on and off. This limits the dis- sipation of the driver, protecting it from damage due to overheating. Load Supply Voltage (VLED) IK2802 is designed to operate with adequate V DS to achieve constant current. V DS together with I OUT should not exceed the package power dissipation limit, PD(max). As in Figure 8, V DS = VLED – VF, and VLED is the load supply voltage. P D(act) will be greater than P D(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
13 2011, February Ver. 03 PACKAGE DIMENSIONS SOP 8 Note: The unit for the outline drawing is mm.