IS31BL3506A 1.0MHZ BOOST CONVERTER WITH 35V INTERNAL MOSFET SWITCH January 2014 GENERAL DESCRIPTION FEATURES IS31BL3506A is a boost converter featuring an Supply voltage: 2.7V~5.5V integrated MOSFET switch designed for driving series Built-in soft start strings of LED or other device. Input operating voltage Drive series strings of range is 2.7V~5.5V. The device regulates the LED load -9 LEDs (DFN-8) current is set using an external, low value sensing -8 LEDs (TSOT-23-6, SOT-23-6) resistor. The device adjusts the PWM duty cycle of the PWM or DC voltage dimming switch to maintain the voltage at the FB pin at a value Frequency of PWM is 500Hz ~ 500kHz of 0.3V. The IS31BL3506A operates at a constant switching frequency of 1.0MHz to allow for small 1.0MHz high speed switching frequency component size. IS31BL3506A features an over 300mV feedback voltage voltage shutdown pin which prevents the output Integrated high power MOSFET voltage from exceeding 35V (typ.) in the case of an Over voltage protection open circuit condition. The device is offered in a tiny -40C ~ +85C working temperature range TSOT-23-6, SOT-23-6 and DFN-8 (2mm2mm) TSOT-23-6, SOT-23-6 and DFN-8 (2mm2mm) package and a temperature rating from -40C ~ +85C. package APPLICATIONS Small LCD Backlights Notebook PC GPS TYPICAL APPLICATION CIRCUIT Figure 1 Constant current white LED driver using PWM at the EN pin to control intensity Note 1: C must be rated for 50V. Smaller values of output capacitance will cause the LED current ripple to increase. OUT Note 2: The resistor R should be placed as close as possible to the FB pin to prevent the EMI. EST Note 3: Because of the different packages, V is not the same (Page 6). 9 LEDs can be driven by DFN-8 package and 8 LEDs can be driven OVP by TSOT-23-6 and SOT-23-6 package most. Note 4: The high level of PWM signal for EN pin should last at least 200ns when power on, or the IC wont start up. Lumissil Microsystems www.lumissil.com 1 Rev. C, 01/09/2014 IS31BL3506A VBattery L1 D1 2.7~5.5V 10 H 2.2 F 0.1 F COUT VCC LX 1 F (50V) (4~8)2 PWM Signal OUT LEDs Micro IS31BL3506A EN Controller FB 100k RSET GND 7.5 Figure 2 Constant current white LED driver using PWM at the EN pin to control intensity (4~8)2 LEDs VBattery L1 D1 2.7~5.5V 10 H VOUT =VFB (R1 +RSET)/RSET 2.2 F 0.1 F COUT VCC LX 1 F (50V) Load R1 OUT IS31BL3506A Micro EN Controller FB 100k RSET GND Figure 3 Constant output voltage for general purpose use Figure 4 Constant output current with DC dimming input Lumissil Microsystems www.lumissil.com 2 Rev. C, 01/09/2014