Hello,
We have an offline LED driver IC which is of the switched linear regulator type. The IC has a thermal pad on it. However, its datasheet does not say to which pin the thermal pad should be connected. If we connect the thermal pad to a bottom layer copper pour on the PCB, then we can’t leave this pad floating. –Because as you know, floating copper pours on PCBs generate all kinds of noise problems?
Do you agree that leaving the copper pour which connects to the thermal pad ‘floating’ will invite all manner of noise problems…specially since on our tiny PCB, this ‘floating’ pad will be near the microcontroller and all the PCB traces leading to the microcontroller.
The LED Driver IC is DT3007B by Seoul semiconductor, and we have requested the datasheet from info.europe@seoulsemicon.com but get no reply. The datasheet is nowhere to be found on the web.
A piece of copper does not generate noise. Maybe thermal noise. "all kinds of noise must include rap-music" lol
The copper might conduct noise from one place like your micro to another place.
Most likely this floating pad is not connected to anything inside the IC. Does not mead you can't connect it to ground, or supply. It probably does not say you have to leave it floating. (they left it floating)
Yes, our Far Eastern buyer contact got us 1000 of them.
We put them on PCBs......some of them work some dont.....its the micro that doesnt respond to dali signals that worries us...though some do , some dont...we wonder if its noise from the DT3007Bs thermal pad which we left floating.
Page 21 of the DT3001B datasheet says that the thermal pad should not be connected to any electrical node. Ive just found the DT3001B datasheet. DT3001B looks to be a sister chip of DT3007B.
Thanks,,problem is we've already had 1000 PCBs made up with it floating...and the thermal copper is on the base of the PCB...we cannot add a wire there as it would rise the PCB off the heatsink on to which it is mounted.
I think this "NC heatsink" is just like "NC pins". In most cases they are really not connected inside. Many people do not connect the pins because they are "NC". I found I can connect the NC pins to ground to help the ground plane.
What happens when you connect the heat sink to ground?
..Knowing our luck, probably nothing at first, but then two weeks after shipment, the entire batch of 1000 comes back failed-in-field due to some leakage current flowing from pin to themal pad.