Objective Development Forums

Hi, I am unable to get LE35CZ in my country, can you please tell me is there any other equivalent that can be used instead of this in powerSwitch hardware.

thanks.

Hi sidz -

I would expect any 100ma low drop out regulator of about 3.5 volts, so a 3.3v component should be fine I would have thought, try a LE33CZ or a TS2950CT-3.3.

Cheers,

Daniel

Hey Daniel thanks, i tried for the one you suggested but no luck though...
what least i can arrange are the 5V LM series here like
LM78L05 - 5V,100mA Positive Voltage Regulator
LM7805- 5V,1A Positive Voltage Regulator

will any of the above work on this?

Hi -

Not really, no. USB has 4 pins. +5V, Ground and 2 data pins. The two data pins need around 3.5V if I remember right. If you power the MCU at 5V you won't comply with the USB spec when it is driving the pins. I think I've read somewhere that most USB ports can deal with higher voltages on the data pins. See the examples with either a couple of zener diodes (to limit the voltage on the data lines) or a couple of signal diodes to drop the voltage of the supply, however I don't think you should try that here, you really want to use a regulator as the supply voltage is quite variable. Were are you from? Are you sure you cannot find the appropriate component?

One final point - I don't want to be a killjoy, but it does sound like you are a beginner. The chaps from obdev.at would need to comment on this but my reading of it is that this is a reference design and is incomplete in a number of respects. You should take care, it's designed to switch mains voltage, and mains as I'm sure you know should be treated with great respect. I'd suggest that you take a few precautions - use a plastic case for the finished build, or if you use a metal one then ensure its properly earthed, plug the mains supply into an RCD, and ensure the fuses are correct. If you can get someone experienced to check the build project over, that would be good.

Cheers,

Daniel

PowerSwitch happens to be (or have been) the reference design simply because it was the first project every done with the driver. We needed such a device to switch the supply for a couple of servers. We now recommend to start with the examples which ship with the driver. They require much less hardware complexity, have no dangerous "high" voltage parts and are kept up to date.

Regarding the voltage regulator: You need a low drop regulator, the standard 78L types won't work. But in this simple case, you should get away with two series diodes to drop the voltage from 5 V to around 3.5 V.