IS31LT3117 53V, 350MA, 4-CHANNEL CONSTANT CURRENT REGULATOR WITH OTP July 2021 GENERAL DESCRIPTION FEATURES The IS31LT3117 is a 4-channel, linear regulated, 6V to 53V input supply voltage range constant current LED driver which can provide 4 equal Up to 1.4A total output current currents outputs of up to 350mA per channel to drive Over temperature protections high brightness LEDs over an input voltage range of Thermal current regulation above 130C 6V to 53V, while maintaining an output leakage current 3% output current matching between channels of less than 1A. The output current is easily PWM dimming and shutdown control input programmed using a single, tiny external resistor. The outputs of the IS31LT3117 can be connected in Optional 2.5V output to drive external standoff BJTs parallel to allow greater than 350mA output current. Very few external components The IS31LT3117 also features a PWM input to enable simple dimming control using a digital control signal. APPLICATIONS The recommended frequency range of the PWM signal Industrial LED lighting is 4kHz ~ 100kHz. Low EMI lighting applications The IS31LT3117 provides a unique over temperature Low-side constant current regulator protection scheme. A hard shutdown which turns off all LED currents occurs if the die junction temperature exceeds the maximum value of 160C. However, as the die junction temperature rises up to over 130C (Typ.), the output current will begin to roll off at a rate of -2.22%/C (Typ.). If the die temperature continues to rise above the hard shutdown temperature threshold, the LED currents will drop to zero. When temperature returns to 140C (Typ.) or below, the hard shutdown protection is released and the chip will function again. The IS31LT3117 also has an optional 2.5V reference voltage output which is able to supply up to 10mA (typ.) output current. This voltage may be used to drive the base of the external BJTs for higher current applications in such case, driving for a wide varying input voltage is needed. The IS31LT3117 is offered in eTSSOP-16 package with operating temperature range of -40C to +125C. TYPICAL APPLICATION CIRCUIT Figure 1 IS31LT3117 Directly Driving 4 LED Strings Lumissil Microsystems www.lumissil.com 1 Rev. C, 07/15/2021 IS31LT3117 V CC 6V ~ 53VDC C OUT 33F R5 Q 5 V 3 9 b VCC VREF 8 ISET 1F Q R V Q R V Q R V Q R V 1 1 b 2 2 b 3 3 b 4 4 b CIN IS31LT3117 R ISET 6 16 10F 100nF 100nF 100nF 100nF GND VLED1 2,5 14 PGND VLED2 12 C PWM VLED3 1nF 1 10 PWM PWM VLED4 R PWM 1k Optional Figure 2 IS31LT3117 With Optional 2.5V Output Driving 4 External Standoff BJTs Note 1: The 33F output capacitor should be placed as close to the LED array as possible in order to minimize the parasitic inductor effect due to the output wiring. Note 2: The resistor R should be place as close to ISET and GND pins as possible. ISET Note 3: If you want less than four channels, the unused channel should be connected to GND. Note 4: RPWM and CPWM are optional to optimize PWM pin ESD performance. But a RC filter will degrade PWM dimming contrast ratio. Lumissil Microsystems www.lumissil.com 2 Rev. C, 07/15/2021