IS31PW3500 1.1MHZ BOOST CONVERTER WITH 30V INTERNAL FET SWITCH February 2012 GENERAL DESCRIPTION FEATURES The IS31PW3500 is a constant current step-up converter. The step-up converter topology allows series connection of the white LEDs so the LED currents are identical for uniform brightness as well as constant output voltage to drive other devices. The IS31PW3500 switches at 1.1MHz, allowing the use of tiny external components. The input and output capacitor can be as small as 1μF, saving space and cost versus alternative solutions. A low 0.25V feedback voltage minimizes power loss in the current setting resistor for better efficiency. The IS31PW3500 is available in small DFN-8, 2mm × 2mm package. 2.4V to 5.5V input range 26V output with over voltage protection High efficiency :85 % typical PWM dimming control Internal high power 30V MOSFET switch Fast 1.1MHz switching frequency Small, low-profile inductors and capacitors DFN-8, 2mm × 2mm package RoHS compliant and 100% lead (Pb)-free APPLICATIONS Mobile phone Digital still camera PDAs, handheld computers MP3 players GPS receivers TYPICAL APPLICATION CIRCUIT Figure 1 Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 12/30/2011 Typical Application Circiut 1 IS31PW3500 PIN CONFIGURATION Package Pin Configuration (Top View) DFN-8 PIN DESCRIPTION No. Pin 1 PGND 2 VIN Input supply voltage. 3 EN Chip enable pin. Connect to 1.4V or higher to enable device, 0.4V or less to disable device. 4 AIN Audio input.(note1) 5 AOUT 6 FB 7 GND 8 LX Description Signal ground, connect to ground. Audio output.(note1) Feedback pin. Reference voltage is 0.25V. Connect cathode of lowest LED and resistor here. Calculate resistor value according to the formula: RFB = 0.25/ILED, calculate output voltage according to the formula: VOUT = (R2+R1)×0.25V/R2. Common ground Switch pin. Connect inductor/diode here. Minimize trace area at this pin to reduce EMI. Thermal Pad Connect to GND. Note 1: See section constant output voltage for Class-G audio amplifier in application information. Copyright © 2011 Integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its products at any time without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products. Integrated Silicon Solution, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless Integrated Silicon Solution, Inc. receives written assurance to its satisfaction, that: a.) the risk of injury or damage has been minimized; b.) the user assume all such risks; and c.) potential liability of Integrated Silicon Solution, Inc is adequately protected under the circumstances Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 12/30/2011 2 IS31PW3500 ORDERING INFORMATION Industrial Range: -40°C to +85°C Order Part No. Package QTY/Reel IS31PW3500-DLS2-TR DFN-8, Lead-free 3000 Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 12/30/2011 3 IS31PW3500 ABSOLUTE MAXIMUM RATINGS Supply voltage, VIN Voltage at any input pin LX Maximum junction temperature, TJMAX Storage temperature range, TSTG Operating temperature range, TA -0.3V ~ +6.0V -0.3V ~ +6.0V -0.3V ~ +30V 150°C -65°C ~ +150°C −40°C ~ +85°C Note: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other condition beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS VIN =3.6V, TA = 25°C, unless otherwise specified. Symbol Parameter Condition Min. Typ. Max. Unit 6.0 V 2.6 V 29 V 1 mA 120 170 μA 0.1 1 μA 1.2 MHz System Supply Input VIN UVLO Supply voltage 2.4 Under voltage lock out 2.2 2.45 Maximum Output Voltage ICC1 Supply current VIN = 6V, continuously switching ICC2 Quiescent current VIN = 6V, VFB = 1.3V, no switching ICC3 Shutdown current VIN = 6V, VEN<0.4V 70 Oscillator Fosc Operation frequency 0.8 1.0 Dmax Maximum duty cycle 85 90 0.237 0.25 0.263 V On resistance of MOSFET 0.6 0.7 1.0 Ω Current limit 400 800 1450 mA 0.4 V % Reference Voltage VFB Feedback voltage MOSFET Rds(on) IX Control and Protection VENL Shutdown voltage VENH Enable voltage IEN EN pin pull low current Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 12/30/2011 1.4 V 0.1 μA 4 IS31PW3500 APPLICATION INFORMATION CONSTANT OUTPUT VOLTAGE Figure 3 is an application of IS31PW3500 for backlight of main panel and flashlight. Setting the divider-resistors (R1 & R2) is to get a constant output voltage that depends on the forward voltage and the numbers of series-LEDs. There are three kinds of mode controlled by the switches - backlight mode /flashlight mode /backlight + flashlight mode. It can turn on backlight or flashlight at one time or both at the same time. Applying different duty cycle of PWM signal above 22kHz to backlight's switch can also control the brightness. The following formula (2), (3) can determine R3. C1 10μF VOUT = (R2+R1×0.25V/R2 (1) R3 = VOUT - 3VFB - VDS /Ib (2) VDS = Ib×RDS(ON) (3) LX 10μH C2 1μF C1 10μF D1 VOUT=12V VFF VIN LX R1 239k Ib IS31PW3500 SN3500 PGND FB R3 EN GND R2 5.1k GPIO1 Dimming Control Figure 2 Constant Output Voltage for Backlight and Flashlight CONSTANT OUTPUT VOLTAGE FOR CLASS-G AUDIO AMPLIFIER Figure 4 is another application for driving Class G Audio Amplifier, IS31AP4915. Setting the divider-resistors (R1 & R2) is to get a higher constant output voltage that can drive audio amplifier intends to get larger audio power. The following formula (4) can determine the output voltage. Other applications for Audio amplifier, please contact us for more information. VOUT = (R2+R1)×0.25V/R2 (4) IS31AP4915 IS31PW3500 Figure 3 Constant Output Voltage for Class-G Audio Amplifier Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 12/30/2011 5 IS31PW3500 CLASSIFICATION REFLOW PROFILES Profile Feature Pb-Free Assembly Preheat & Soak Temperature min (Tsmin) Temperature max (Tsmax) Time (Tsmin to Tsmax) (ts) 150°C 200°C 60-120 seconds Average ramp-up rate (Tsmax to Tp) 3°C/second max. Liquidous temperature (TL) Time at liquidous (tL) 217°C 60-150 seconds Peak package body temperature (Tp)* Max 260°C Time (tp)** within 5°C of the specified classification temperature (Tc) Max 30 seconds Average ramp-down rate (Tp to Tsmax) 6°C/second max. Time 25°C to peak temperature 8 minutes max. Figure 4 Classification Profile Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 12/30/2011 6 IS31PW3500 TAPE AND REEL INFORMATION Note: All dimensions in millimeters unless otherwise stated. Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 12/30/2011 7 IS31PW3500 PACKAGE INFORMATION DFN-8 Note: All dimensions in millimeters unless otherwise stated. Integrated Silicon Solution, Inc. – www.issi.com Rev.A, 12/30/2011 8