IZ1937

IZ1937 White LED Step-Up Converter (Functional equvalent of LT1937 Linear Technology Corporation) Description The IZ1937 is a step-up DC/DC converter specifically designed to drive white LEDs with a constant current. The device can drive two, three or four LEDs in series from a Li-Ion battery. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminating the need for ballast resistors. The IZ1937 operates at 1.2MHz, allowing the use of tiny external components. The output capacitor can be as small as 0.22uF, saving space and cost versus alternative solutions. A low 95mV feedback voltage minimizes power loss in the current setting resistor for better efficiency. The device can used in mobile phones, PDAs, Handheld Computers, calculators, digital cameras, MP3-players, GPS-receivers. Features Internally determined LED current High Efficiency: 84% Typical Drives Up to 4 LEDs from a 3.2V Supply Drives Up to 6 LEDs from a 5V Supply 36V rugged bipolar switch Fast 1.2MHz switching frequency Uses tiny 1mm Tall Inductors Requires only 0.22uF output capacitor ICs are available for shipment in chip form on unsawn wafers Tab 1. Contact Pad Description Contact pad number Symbol Description 01 SW Switch pad (Pin) 02 GND Common pad (pin) 03 VIN Input supply pad (pin) 04 SHDN Shutdown pad (pin) 05 GND Common pad (pin) 06 FB Feedback pad (pin) 1 Ver.1.0/9.02.2008 IZ1937-TSe.doc IZ1937 VIN 03 Reference voltage s...