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Four Channel Constant Current LED Driver
EC4101 FEATURES
Cost Effective LED driver Constant current output ideal for Driving Led strings Four Channel LED Driver provides matched LED current Current adjusted via an external resistor PWM dimming possible by using either the ENABLE Small SOP-8 package Outputs can be connected in parallel to increase drive Constant current for wide cathode voltage range (4.5V to 18V) Highly integrated design, minimal components Thermal shutdown protects the driver Package type SOP-8
APPLICATIONS
Next Generation Mobile Phones PDA, DSC, MP3 Players Handheld Computers LCD Display Modules Keyboard Backlight LED Displays
DESCRIPTION
The EC4101 is a linear constant current driver designed to drive multiple LEDs in series from a high input voltage rail. The driver acts as a high current matched four channel current source ensuring constant LED current for a range of input voltage. The EC4101 allows implementing the lowest cost LED driver for a variety of applications. Internal circuitry maintains the pre-set constant current output for a wide voltage range at the LED outputs (LED1,2,3,4). LED current can be adjusted up to 125mA per string with an external resistor. The dimming can be achieved by controlling the ISET input or by feeding a PWM signal to the EN pin. Fast EN turn-on and turn-off time allows for very fast PWM dimming frequencies completely eliminating flickering. The built-in thermal protection automatically adjusts LED current to prevent overheating.
P1/6
DR18EC070105-VER1.0
Four Channel Constant Current LED Driver
EC4101 ABSOLUTE MAXIMUM RATINGS
Vcc, VLED1, VLED2, VLED3, VLED4 Voltage to GND 0.3V to 18V
ISET and EN Voltage to GND..................................... 6V
Output Current per LED (IOUT) ............................. 125mA Power Dissipation per Package 8-pin SOP at TA = 85 ......................... 1.1W Junction Temperature ..........................................+150C Storage Temperature ........................... -55C to +150C ESD Level. ....................................................... 1.5kV HBM These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.
ELECTRICAL CHARACTERISTICS
4.5V < VCC <18V , VEN = 5V, VLED1 =VLED2 =VLED3 =VLED4 =1.0V, RSET =10k or ISET=125uA, -40 < TA < 85C, Unless otherwise noted.
PARAMETER Supply Voltage Quiescent Supply Current Output/ISET Current Multiplication Ratio LED Current (per diode ) CH to CH Current Matching LED Current Line Voltage Regulation LED Current Load Voltage Regulation LED Current Thermal Regulation ISET Pin Voltage Thermal Shutdown Threshold Thermal Shutdown Hysteresis Current OFF Mode Min. ENABLE " ON Voltage " (Note1) Max. ENABLE " OFF Voltage " (Note2)
MIN. 4.5
TYP. 5 0.4
MAX. UNITS CONDITIONS 18 0.5 1400 V mA
ILED1=ILED2=ILED3=ILED4
VCH = 1V
1000
1200
125 -5% 0.15 9 0.1 1.4 1.5 130 20 0.5 1.6 0.4 1.6 +5% 0.6
mA % %/V %/V
IOUT change per volt Vcc change
1.0V < VLED <5V, ILED = 125mA
%/ ILED =125mA V mA V V VEN = 0V
Note 1. ENABLE "ON" is VEN for which ILED > 80mA Note 2. ENABLE "OFF" is VEN for which ILED < 1uA@ VLED1 > 1.0V
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DR18EC070105-VER1.0
Four Channel Constant Current LED Driver
EC4101 BLOCK DIAGRAM
THEORY OF OPERATION
Introduction
The EC4101 is a four channel constant current source LED driver with programmable output current level. The design consists of a regulator bandgap, voltage to current converter, and output mirror drivers. The bandgap ensures good performance over voltage and temperature. The four outputs are tightly coupled allowing for excellent channel matching.
Thermal Shutdown
The EC4101 uses a thermal comparator to monitor the system temperature shutting the device down if the internal temperature reaches 150C. The device will remain off until the internal temperature drops below 130C.
Enable
The device has an enable function that is designed for TTL level inputs. This input will also track the VCC pin so levels up to VCC are acceptable. The enable pin can also be used to control the LED brightness with a pulse width modulated control signal. Duty Cycle or PWM control of the LED current maintains constant LED color while brightness is changing. The EC4101 responds in less than 10us to PWM signals applied to this pin.
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DR18EC070105-VER1.0
Four Channel Constant Current LED Driver
EC4101
ISET Pin
The ISET pin is the servo point of an amplifier configured as a voltage to current converter. The voltage at this pins servos to the internal bandgap potential. A set resistor can be connected from the Iset pin to ground to generate a reference current for the following current gain stages. A current could alternately be applied to this pin in the form of a current source or current output DAC. This pin can also have a PWM signal applied to control the LED brightness.
The RSET value may be determined as RSET = 1.5 * 1200/IOUT, k where 1.5 is a typical ISET pin voltage, 1200 is a typical current multiplication ratio, and IOUT is a required LED current in mA.
Cathode Voltage, Supply Voltage and Power Dissipation The voltage applied to the cathode of each LED determines the overall efficiency of the EC4101 circuit. The EC4101 is designed to be able to sink 125mA at each of its four outputs; LED1 - 4. The EC4101 is also designed to be able to handle up to 18V on these pins. This voltage handling capability assumes the total power can be dissipated by the EC4101. The power dissipation inside the EC4101 will de directly related to the voltage and current applied to these pins. For example, the typical operating cathode voltage is 500mV. At maximum current the power dissipated by one LED driver output is 125mA * 500mV = 62.5mW. The following charts show the power dissipation of the EC4101 under various conditions. The power dissipation should be kept below 1.3W for safe operation and long term reliability at room P4/6 DR18EC070105-VER1.0
Four Channel Constant Current LED Driver
EC4101
temperature and dartle to 530mW at 85C. While the above operating conditions are recommended, the part cannot be damaged due to internal temperature control as described above in the thermal shutdown section.
ORDERING INFORMATION
PART NUMBER EC4101N-F EC4101N-G TOP MARK EC4101-F EC4101-G PACKAGE Lead free 8-pin SOP Green Mode 8-pin SOP
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DR18EC070105-VER1.0
Four Channel Constant Current LED Driver
EC4101 PACKAGE TYPE SOP8 :
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DR18EC070105-VER1.0

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