IS31BL3231 FLASH LED DRIVER January 2012 GENERAL DESCRIPTION FEATURES The IS31BL3231 is a current-regulated charge pump and ideal for powering high brightness LEDs for camera flash and torch applications. The charge pump can be set to regulate two current levels for FLASH and TORCH modes. The IS31BL3231 automatically switches between linear and boost modes ensuring that LED current does not depend on the LED forward voltage. IS31BL3231 provides low cost, space saving solution for driving LED. It also integrates thermal and short circuit protection function. IS31BL3231 is available in DFN-10 (3mm × 3mm). It operates from 2.7V to 5.5V over the temperature range of -40°C to +85°C. Operates from 2.7V to 5.5V Up to 90% efficiency in Torch Mode Output current up to 750mA Adjustable output current in Flash Mode Minimum external components, no external inductor required Automatic boost mode Less than 1µA shutdown current Low ripple and EMI Over voltage protection on output Short and over temperature protections Available in DFN-10 (3mm × 3mm) package APPLICATIONS White LED backlighting Cellular phones Generic lighting/flash/strobe applications TYPICAL APPLICATION CIRCUIT Figure 1 Typical Application Circuit 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, 01/03/2011 1 IS31BL3231 PIN CONFIGURATION Package Pin Configuration (Top View) DFN-10 PIN DESCRIPTION No. Pin Description 1 VCC Power supply. 2 CP Positive input for external flying cap. 3 CN Negative input for external flying cap. 4 FLASH Input pin to toggle operation between Flash Mode and Torch Mode. 5 EN Shutdown control input and Torch reference select pin. 6 RSET 7 FB 8 SGND Internal ground pin. 9 PGND Power ground pin. 10 VOUT Charge pump output voltage. Thermal Pad Connect to GND. Set the FB voltage in Flash Mode. VFB 1.25V / RSET 11 .2 k Feedback input for the current control loop. I LED VFB / RFB Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 01/03/2011 2 IS31BL3231 ORDERING INFORMATION Industrial Range: -40°C to +85°C Order Part No. Package QTY/Reel IS31BL3231-DLS2-TR DFN-10, Lead-free 2500 Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 01/03/2011 3 IS31BL3231 ABSOLUTE MAXIMUM RATINGS Supply voltage, VDD Voltage at EN pin Output current pulse (Flash Mode) Output current pulse (Torch Mode) Maximum junction temperature, TJMAX Storage temperature range, TSTG Operating temperature range, TA ESD (HBM) -0.3V ~ +6.0V 0V ~ 7V 1A 0.4A 150°C -65°C ~ +150°C −40°C ~ +85°C 7kV 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. DC CHARACTERISTICS TA = +25°C, VCC = 2.7V ~ 5.5V, unless otherwise stated. Typical value are TA = +25°C, VCC = 4.2V. Symbol Parameter Condition VCC Supply voltage ICC Quiescent current VCC = 4.2V，VFLASH = 0V ISD Shutdown current VCC = 5.5V，VEN = 0V tON Charge pump soft start time VFB FB reference voltage TOVP Over temperature protection Min. Typ. 2.7 Max. Unit 5.5 0.6 mA 1 550 VFLASH = VCC，RSET = 88.7kΩ 150 VFLASH = 0V 50 V µA µs mV 160 °C VIH Input logic high 1.4 V VIL Input logic low tLO EN low time (Note 1) tHI EN high time (Note 1) tOFF EN shutdown timeout (Note 1) 500 µs tLAT EN latch timeout (Note 1) 500 µs 0.4 V 0.3 75 µs 0.1 75 µs Note 1: Guaranteed by design. Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 01/03/2011 4 IS31BL3231 TYPICAL PERFORMANCE CHARACTERISTICS 250 800 Flash Mode ILED = 700mA VOUT = 3.73V 700 Output Current(mA) Output Current(mA) 200 150 100 600 500 400 300 200 50 Torch Mode ILED = 200mA VOUT = 3.45V 0 3 100 3. 2 3. 4 3. 6 3. 8 4 0 4. 2 3 3. 2 3. 4 Supply Voltage(V) Figure 2 EN Pin 5V/Div Supply Voltage vs. Output Current (Torch Mode) VCC = 3.6V Torch Mode ILED = 200mA RFB = 0.22Ω 3. 6 3. 8 4 4. 2 Supply Voltage(V) Figure 3 EN Pin 5V/Div Supply Voltage vs. Output Current (Flash Mode) VCC = 3.6V Flash Mode ILED = 700mA VOUT 1V/Div VOUT 1V/Div IIN 500mA/Div IIN 500mA/Div Figure 4 Figure 5 EN On (Torch Mode) EN On (Flash Mode) FLASH Pin VCC = 3.6V Torch Mode to Flash Mode 5V/Div FLASH Pin VCC = 4.2V Torch Mode to Flash Mode 5V/Div VOUT 1V/Div VOUT 1V/Div VFB 0.2V/Div VFB 0.2V/Div IOUT 1A/Div IOUT 1A/Div Figure 6 Torch Mode to Flash Mode Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 01/03/2011 Figure 7 Torch Mode to Flash Mode 5 IS31BL3231 APPLICATION INFORMATION GENERAL DESCRIPTION TORCH MODE The IS31BL3231 is a current-regulated charge pump and ideal for powering high brightness LEDs for camera flash and torch applications. By pulling the FLASH pin to low, IS31BL3231 operates in the Torch Mode. The VFB is controlled by Pulse Count Control (PCC wire) serial interface. The interface records rising edges of the EN pin and decodes them into 8 different states. The 8 voltage level settings available are indicated in Table 1. CHARGE PUMP The charge pump converter boosts input supply voltage (VCC) up to a higher output voltage (VOUT) to drive LED. The charge pump converter only requires three external components: supply decoupling capacitor, output bypass capacitor and flying capacitor. Choose low ESR capacitors to ensure the best operating performance and place the capacitors as close as possible to the IS31BL3231. Table 1 VFB Control (RFB = 0.22Ω) Pulse VFB (Typ.) ILED (Typ.) 1 50mV 227mA 2 60mV 273mA 3 70mV 318mA 4 85mV 386mA The charge pump will start up automatically to offer a higher output voltage when VFB is lower than the setting value. 5 100mV 455mA 6 120mV 545mA CURRENT SETTING 7 140mV 636mA ≥8 170mV 773mA The LED current is set by the external resister, RFB, following the Equation (1) below. I LED VFB / RFB TIMING CONTROL (1) VFB is calculated by the Equation (2) when IS31BL3231 operates in the Flash Mode. VFB is set in the Table 1 when IS31BL3231 operates in the Torch Mode. The EN pin should be configured as the Figure 8. tLAT is the latch time. High level should be at last tLAT to active the pulse signal. tOFF is the shutdown time. EN pin is pulled low at last tOFF the IC will be shutdown. OPERATING MODE FLASH MODE By pulling the FLASH pin to high, IS31BL3231 operates in the Flash Mode. VFB is set by the RSET. VFB 1.25V / RSET 11.2 k (2) For example, in Figure 1, RFB = 0.22Ω, RSET = 88.7kΩ, So, VFB 1.25V / 88 .7 k 11 .2 k 158 mV I LED 158mV / 0.22 718mA Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 01/03/2011 Figure 8 EN pin timing THERMAL PROTECTION The IS31BL3231 has a thermal protection circuit that will shut down the chip if the die temperature rises above the thermal limit until the temperature falls down. 6 IS31BL3231 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 9 Classification Profile Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 01/03/2011 7 IS31BL3231 TAPE AND REEL INFORMATION Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 01/03/2011 8 IS31BL3231 PACKAGE INFORMATION DFN-10 Note: All dimensions in millimeters unless otherwise stated. Integrated Silicon Solution, Inc. – www.issi.com Rev. A, 01/03/2011 9