IS31LT3177/78 10-TO-200MA CONSTANT-CURRENT LED DRIVER September 2020 GENERAL DESCRIPTION FEATURES The IS31LT3177 and IS31LT3178 are adjustable Low-side current sink linear current devices with excellent temperature - Adjustable from 10mA to 150mA (SOT23- stability. A single resistor is all that is required to set 6)/200mA (SOP-8-EP) with external resistor the operating current from 10mA to 200mA. The selection devices can operate from an input voltage from 2.9V Wide input voltage range from to 40V with a minimal voltage headroom of 1.0V - 2.9V to 40V (IS31LT3178) (Typ.) at 150mA. Designed with a low dropout - 5V to 40V (IS31LT3177) voltage the device can drive LED strings close to with a low dropout of typical 1.0V at 150mA the supply voltage without switch capacitors or Up to 1kHz PWM input (IS31LT3178 only) inductors. 5% current accuracy Protection features: The IS31LT3177/78 simplifies designs by - 0.6%/K current roll off at high temp over 145C providing a stable current without the additional for thermal protection requirement of inductors, FETs or diodes. The - Output current limit complete constant current driver requires only a - Thermal shutdown current set resistor and a small PCB area making Up to 0.77W (SOT23-6)/2.32W (SOP-8-EP) designs both efficient and cost effective. power dissipation in a small package The EN Pin of the IS31LT3177 can be tied to V BAT RoHS compliant (Pb-free) package or PSM (Power Supply Modulation) signal for high side dimming. The EN Pin of the IS31LT3178 can APPLICATIONS function as the PWM signal input used for MCU General lighting PWM dimming. Architectural LED lighting As a current sink it is ideal for LED lighting Channel letters for advertising, LED strips for applications or current limiter for power supplies. decorative lighting Retail lighting in fridge, freezer case and vending The device is provided in a lead (Pb) free, SOT23-6 machines and SOP-8-EP packages. Emergency lighting (e.g. steps lighting, exit way sign etc.) Lumissil Microsystems www.lumissil.com 1 Rev. B, 09/09/2020IS31LT3177/78 TYPICAL APPLICATION CIRCUIT V BAT V C or IN BAT 0.1F C IN 2.9V~5.5V 1 2, 4, 5 1 2, 4, 5 0.1F or PSM EN GND EN GND IS31LT3177 IS31LT3178 PWM (SOT23-6) (SOT23-6) 6 6 ISET ISET 3 3 R OUT R OUT ISET ISET Optional Optional C C OUT OUT 1nF 1nF V BAT or V C BAT IN 0.1F C 2.9V~5.5V IN 35~8 35~8 0.1F or PSM EN GND EN GND IS31LT3177 IS31LT3178 PWM (SOP-8-EP) (SOP-8-EP) 4 4 ISET ISET 1,2 1,2 R R ISET OUT ISET OUT Optional Optional C OUT C OUT 1nF 1nF Figure 1 Typical Application Circuit Note 1: All GND pins must be connected to ground. Note 2: C must be placed close to IC. If no PSM dimming requirement, please use larger value for C . IN IN Note 3: C is optional. When the LED connection wire is long, the C should be placed close to OUT pin to avoid EMI interference. OUT OUT Note 4: R MUST be placed close to ISET and GND pins to improve the Electro-Magnetic Susceptibility (EMS) performance. ISET Lumissil Microsystems www.lumissil.com 2 Rev. B, 09/09/2020