L6920 dc-dc converter

gawade · ‎2010-04-15

Posted on April 15, 2010 at 10:13

We are using the L6920 to drive a 1 watt LED.

We are trying to implement the under voltage cut off (lock out) too. We chose the values of the voltage bridge connected to the LBI pin such that the value comes to say 3V. However, the IC did not shut off at 3V.

We then tried connecting the LBO to Vout with a 200K resistor in between. Even this did not work.

Can someone help implement this circuit?

Thanks!

Ashish

#led-backlighting-power-supply

Vipin BOTHRA · ‎2010-04-19

Posted on April 19, 2010 at 18:30

Hi Ashish,

If you look into the block diagram of L6920 in its datasheet, you would notice that LBI input is connected to LBO output and that is the only purpose of this input. LBI input does not shut down the output!!

If you require to shut down the output, you need to use LBO output to shut down accordingly.

Vipin

balmukund66 · ‎2011-12-23

Posted on December 23, 2011 at 18:29

LBI pin is not for shutdown purpose.

It is only for the setting threshold,set it to around 1.23V. & use the LBO pin to shutdown.

I suggest connect it to SHDN pin. Do not forget to pull up the LBO Pin.