[time-nuts] RS485/422/232 Chip

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sat Apr 26 09:51:19 EDT 2008

Didier Juges wrote:
> I am using the LTC1535 in an application right now, and if you need RS-485,
> it is pretty neat. It includes the hardware to drive a small transformer
> that will provide you with an isolated 5V floating supply too.
> However, I am MUCH more impressed with the Analog Devices ADuM5241ARZ which
> not only has two isolated digital channels, but also the power transformer
> is built-in, and the whole device fits in an SO-8 package. You can get 5V at
> 10mA out of it. Analog calls this series "Digital Isolators"
> This is absolutely truly amazing. I am using one in one of my products right
> now. The Analog Device part is not RS-485 compatible, it is just a digital
> isolator (TTL in, TTL out), but with the built-in 5V power supply, you can
> drive any RS-485 driver. For RS-485, you will need the 4 port version of the
> chip (for the Tx Enable)
> The app note says it runs at 300 MHz. I have not checked the device with the
> spectrum analyzer yet, but with a 100 MHz scope, I can't see anything.
> They now have special versions for I2C and even a new one that provides
> isolated gate drive to power MOSFETs.
> Both devices are specified to sustain 2500VAC for one minute (UL
> requirement).
> Didier KO4BB

Any idea of the jitter of the Analog Devices transformer coupled isolators?


More information about the time-nuts mailing list