The LT®1937 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 cell. Series connection of the LEDs provides identical
LED currents resulting in uniform brightness and
eliminating the need for ballast resistors. The LT1937
switches at 1.2MHz, allowing the use of tiny external
components. The output capacitor can be as small as
0.22mF, saving space and cost versus alternative solutions.
A low 95mV feedback voltage minimizes power loss
in the current setting resistor for better efficiency.
The LT1937 is available in low profile SC70 and ThinSOT
packages.