1 Watt LED Driver Using a Single 1.5 Cell

The 1 watt LED driver circuit shown in this article can be used for illuminating a 1 watt LED for quite sometime from a source that may be as minimal as a 1.5 V AAA cell..

The circuit is obviously based on boost driver technology, other wise driving such a huge load w such minimal source is beyond imagination.

1 Watt LED and 1.5 AAA Cell

A 1 watt LED is relatively huge when compared to a 1.5 V AAA cell source.

A 1 watt LED needs minimum 3 volts supply which is double the above cell rating.

Secondly a 1 watt LED would require anywhere between 20 to 350 mA of current for operating, 100 mA being a respectable current for driving these light machines.

Therefore using a AAA penlight cell for the above operation looks very remote and out of question.

However the discussed circuit here proves all of us wrong and successfully drives a 1 watt LED without much complications.

THANKS TO ZETEX, for providing us with this wonderful little IC ZXSC310, which requires just a few ordinary passive components for making this feat possible.

Simulation and Working

The diagram shows a rather simple configuration, which is basically a boost converter set up.
The input DC of 1.5 volts is processed by the IC to generate a high frequency output.

The frequency is switched by the transistor and the schottky diode via the inductor.

The rapid switching of the inductor provides the required boost in the voltage which becomes just appropriate for driving the connected 1 watt LED.

Here, during the completion of each frequency, the equivalent stored energy inside the inductor is pumped back into the LED generating the required voltage boost, which keeps the LED illuminated for long hours even with a source that's as small as a 1.5 volt cell.



Need Help? Please send your queries through Comments for quick replies!


Sameera Viraj said…
I want to set 1W LEDs to a 12V car battery. so can you send me a 1W LED driver circuit for that. but really i want to connect more than 10 LEDs and all of them should have their maximum bright. thank you.
Swagatam said…
Please refer to the last circuit given in this link:


calculate the resistor values as per your requirements using the given formulas.
Swagatam said…
0.3/3 = 0.1A

4.2 - 3/0.1 = 12 ohms

use a 12 ohms 1/2watt resistor in series with 4.2V and connect with the LEd.

Sivanan said…
LT3490 from Linear technolgy will be a better alternative with less components..
Hello sir,
as you said 100 ma as the respectable current, you were perfectly right here.
i had 2 batt units, a 4v1ah and 6v4.5ah.
firstly i tried to light up a single 1w led(coolwhite) from a 4v batt, it lit perfectly with resistor value 10r,1w.(previously tried 15r) here dont know about current,
secondly, i used a 6v batt, with some trial and error assumed resistor value as 33r. i came down to 30r and used this resistor, i always used 1w resitors.
then with 6v,30r and 1w led the current draw was 100ma and were perfectly bright.

Actually i had built the led bulb unit using 3 of them and mounted them on a heatsink cover from an old laptop charger unit.........i were very happy.
i made the driver unit using resistors and caps soldered all on pcb
powered it from 6v total current draw was 300ma.
I were pleased with this and decided to share with you.
So in conclusion i made a 3w led bulb unit.

Swagatam said…
That's nice Sherwin, however now the maximum light would be = 3 x 100mA = 300mA x 3.3 = 0.99 watts that's equivalent to a single 1 watt LED but anyway the whole system would be stress free and last much longer

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