Hi,
I am looking to replace the LM3409HV chip we use in a design with a multi-channel LED driver. The product has 90 separate high voltage (29-38V) LED strings that need to be controlled separately. The strings are for LED's in an individual colour and we have up to 20 strings of a singe colour. The design requires that each colour is able to be dimmed separately via an LED driver that can control from 0-500mA. It is possible for us to group these so a single chip could drive multiple strings of the same colour if that helps with the driver selection.
I have been looking for some potential replacement LED drivers and the best I have been able to find so far are:
LM3463:
LM3463 data sheet, product information and support | TI.com
This a 6 channel (two channels are tied together which we can work around) by making the output of all 6 channels the same colour strings. The limitation with this chip is that there is a common DC bus driving all of the LED strings. The DHC circuit that is used to limit the supply voltage to keep it as close to the sum of forward voltages in the string will have limitations when it comes to the LED strings that have smaller forward voltages.
We have noticed that with the smaller forward voltage strings the FET's used in the development board get very hot due to the excess voltage in the string.
TPS92830
TPS92830-Q1 data sheet, product information and support | TI.com
This is a three channel LED driver that can control three channels to the same dimming control. It looks relatively simple and has the benefit of a high side switch FET so my understanding is it will fare better when the supply voltage is higher than the string voltage.
I am looking for devices with high channel counts to reduce the number of chips required for the design. We need to be able to maintain a dimming control between 0-500mA. The supply voltage is 50-55Vdc.
Thank you.