TLC5927 driver max voltage.

Q: TLC5927 driver max voltage. by 1621419

Hello,

 

Customer has been  looking at our TLC5927 driver. They have been able to successfully implement it as an LED digit driver. Since they have many different size digits, the number of LEDs that need to be driven by each output varies. The datasheet for the TLC5927 driver states that outputs are rated to for maximum voltage of 20V (recommended 17V).

 

The question is: Is this the maximum voltage the driver can handle AFTER the voltage drop through LEDs? In other words, lets say I have 10 LEDS driven by one of the outputs. LED supply voltage is 28V. The voltage drop across the LEDs is about 21V. So the remaining voltage that the driver should see is only 7V? Is this setup OK?

 


A: Re: TLC5927 driver max voltage. by 10449

The TLC5927 maximum voltage rating is independent of the LED supply voltage, the number of LEDs, their current, etc.  You must ensure the OUTx voltage is below 20V under all conditions.  If you can guarantee OUTx is less than 20V with a 28V LED voltage, this is an acceptable design.  Note that the the voltage drop across the LEDs drop significantly when there is no forward current.  You must ensure that the OUTx voltage is does not rise above 28V when the LEDs are turned off.