Driving a white LED from 1.5V


A small DC-DC converter to drive a bright white LED from a 1.5V battery.

TODO
Test setup
The film canister contains the battery
Prototype

[white_led.png]

T1 is 20+20 windings on a small ferrite core. The prototype used a purple coated binocular core measuring 6x6x4 mm. See the references for construction hints.

Prototype data:
  • Total peak current, Ipeak: 82 mA @ 1.6V
  • Ipeak through LED: 82 mA @ 1.6V
  • Switching frequency: ~100KHz
  • ton: 2.6 usec
  • toff: 7.1 usec

Currents are measured by inserting 10 ohm resistors at the marked points. The currents look like this:

[led_currents.png]

Archive containing the Xcircuit files (encapsulated postscript).

References: