Offline Emergency led sign and battery charger

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eem2am

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Hello,

We are doing an emergency LED signage system.

The LEDs to be driven are two series strings of six leds (330mA current in each led)

The sign is supplied by the mains…

….but when the mains fails it must be supplied by the on-board Ni-MH battery.
–the voltage of this battery is 2 to 6.4V
-when the battery is supplying the leds, the led current only has to be 150mA.

When the mains is present it must charge up the batteries and make sure they stay charged.

Do you know of any IC’s for use in this?
 

Once you get mains regulated to a useable DC voltage, you can take a look at the LT1510 from Linear. They also have some good chipsets for input power muxing (LTC2952 might be good to look at?)
 

Hi

Use linear LTC4412 to switch between battery and mains voltage - application circuit is included in the DS

use any battery charger IC (lot of manufacture) to charge the battery( the easy one i use came from "monolithic power"

Also you will need to use a boost circuit to drive the LED when main power go off

Depend on product cost you can use logic gate or a small controller to control the charger led intensity power consumption etc

All the best

Bobi
 

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