EUP2538

EUP2538 10X2 Strings WLED Boost Converter DESCRIPTION The EUP2538 is a constant current step-up converter specifically designed to drive white LEDs. The Step-up converter topology allows series connection of the white LEDs so the LED currents are identical for uniform brightness. The EUP2538 switches at 1MHz, allowing the use of tiny external components. The output capacitor can be as small as 0.47µF, saving space and cost versus alternative solutions. A low 0.3V feedback voltage minimizes power loss in the current setting resistor for better efficiency. The EUP2538 high-voltage output stage is perfect for driving mid-size and large panel displays containing up to ten white LEDs in series. The 1.2A current limit and 0.65Ω RDSON allows the part using for up to 10 × 2 string WLED lighting. LED dimming can be done by using a DC voltage, a logic signal, or a pulse width modulation(PWM) signal. The enable input pin allows the device to be placed in shutdown mode with “zero” quiescent current. The EUP2538 is available in low profile 8pin 3mm × 3mm TDFN package. FEATURES 2.6V to 5.5V Input Range 38V Output with Over Voltage Protection Internal Soft-Start PWM Dimming Control Internal High Power 40V MOSFET Switch Fast 1MHz Switching Frequency Using Low-Profile Inductors and Capacitors Available in 3mm × 3mm TDFN-8 Package RoHS Compliant and 100% Lead (Pb)-Free APPLICATIONS GPS Navigation Systems Portable Media Players Handheld Devices, Digital Camera Portable Game Machines Typical Application Circuit Figure 1. White LED Application DS2538 Ver1.3 Nov. 2008 1 EUP2538 Pin Configurations Package Type Pin Configurations TDFN-8 Pin Description PIN PGND IN EN GND FB LX TDFN-8 1,2 3 4 5 6 7,8 Input Supply Voltage Chip Enable Pin. Connect to 1.4V or higher to enable device, 0.3V or less to disable device. Common Ground. Connect the pin to the ground plane. Feedback Pin. Reference voltage is 0.3V. Connect cathode of lowest LED and resistor here. Calculate resistor value according to the formula: RFB=0.3/ILED Switch Pin. This is the drain of the internal power switch. Connect inductor/diode here. Minimize trace area at this pin to reduce EMI. DESCRIPTION Power Ground. Connect to GND and the exposed pad directly under the IC. DS2538 Ver1.3 Nov. 2008 2 EUP2538 Ordering Information Order Number EUP2538JIR1 Package Type TDFN-8 Marking Operating Temperature Range -40 °C to +85°C xxxxx P2538 EUP2538 □ □ □ □ Lead Free Code 1: Lead Free 0: Lead Packing R: Tape & Reel Operating temperature range I: Industry Standard Package Type J: TDFN Block Diagram Figure 2. DS2538 Ver1.3 Nov. 2008 3 EUP2538 Absolute Maximum Ratings (1) Supply Voltage ,VIN ----------------------------------------------------------------SW ----------------------------------------------------------------------------------The Other Pins ---------------------------------------------------------------------Package Thermal Resistance TDFN-8,θJA ------------------------------------------------------------------------Maximum Junction Temperature --------------------------------------------------Lead Temperature (Soldering, 10sec.) --------------------------------------------Storage Temperature Range ---------------------------------------------------------0.3V to 6V -0.3V to 40V -0.3V to 6V 39.1°C/W 125°C 260°C -65°C to +150°C Recommend Operating Conditions (2) Junction Temperature Range ------------------------------------------------------- -40°C to +85°C Supply Voltage , VIN----------------------------------------------------------------- 2.6V to 5.5V Note (1): Stress beyond those listed under “Absolute Maximum Ratings” may damage the device. Note (2): The device is not guaranteed to function outside the recommended operating conditions. Electrical Characteristics (VIN =3.6V, VOUT=34V, COUT=0.22µF, CIN=2.2µF, L1=22µH, RFB=15Ω,TA=-40°C to +85°C. Unless otherwise noted. Typical values are at TA= +25°C) Symbol UVLO ICC1 ICC2 ICC3 Oscillator Fosc Dmax VFB MOSFET Parameter Under Voltage Lock Out Maximum Output Voltage Supply Current Quiescent Current Shutdown current Operation Frequency Maximum Duty Cycle Feedback Voltage Conditions Rising No Switching VCC=5.5V, Continuous Switching VCC=5.5V, FB=1.3V, No Switching VCC=5.5V, VEN