IS31LT3515 HIGH VOLTAGE LED LIGHTING DRIVER BOOST OR BUCK-BOOST TOPOLOGY Advanced Information March 2015 GENERAL DESCRIPTION FEATURES The IS31LT3515 is a current mode PWM controller designed to drive an external MOSFET for high current LED applications. With a current sense amplifier threshold of 250mV, the LED current is programmable with one external current sense resistor. The IS31LT3515 is ideal for boost or buck-boost operation. With 250kHz operating frequency (typical, and this frequency can be set up by external resistor), the external inductor and capacitors can be small while maintaining high efficiency. Dimming can be either analog or PWM digital. Input DC voltage from LD pin for analog dimming. Input PWM signal from PWM pin can get either analog dimming or PWM dimming. The IS31LT3515 is available in SOP-16 package and TSSOP-16 package. Wide input voltage from 5V to 35V Boost or buck-boost operation Easy dimming: Analog, PWM or PWM converting to analog with an external capacitor Output over voltage protection (OVP) Internal soft start to avoid inrush current Current mode PWM with an 250kHz operating frequency (Typical, RSET = 150kΩ) Output short circuit protection VCC under voltage lock out and over temperature protection (OTP) APPLICATIONS General industrial high power LED lighting Desk lights and room lighting, street lighting Display backlight TYPICAL APPLICATION CIRCUIT Figure 1 Typical Application Circuit (Boost Configuration) Integrated Silicon Solution, Inc. – www.issi.com Rev. 00A, 03/09/2015 1 IS31LT3515 VCC 5V ~ 35V L1 22 H D1 VOUT RO1 1 VCC GATE CIN 10 F CS 15 13 M1 COUT 10 F RO2 RCS 2 Micro Controller 3 6 5.1k 4.7nF 16 CDD CLD 1 F 10nF 4 5 12 PWM EN OVP IS31LT3515 ISN COMP FAULT VDD FSET LD SENSE GND Figure 2 ISP 9 11 RIS 10 14 7 RFSET 8 RS Typical Application Circuit (Buck-Boost Configuration) Integrated Silicon Solution, Inc. – www.issi.com Rev. 00A, 03/09/2015 2