FT232R Ferrite Bead

Lightfoot

I am planning on building the circuit in figure 12 in the datasheet to power two SX chips and two optoisolaters (load around 26ma max). What frequency should that ferrite bead be?

Datasheet link:

www.ftdichip.com/Documents/DataSheets/DS_FT232R.pdf

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔

Chris Savage

Hello,

The Ferrite Bead is not necessarily required in all given circuits. Most likely you won’t need it. You can see examples of the FT232R using in our designs by looking at the schematics for such devices as the Prop Clip or Prop Plug. The schematic is listed in the documentation on the website. Take care.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support

kjennejohn

Lightfoot, you are giving us apples-and-oranges. The data sheet is for the USB IC, not a switching supply IC. Yes? No? Your post suggests you are designing a supply.

Later!
kenjj

Mike Green

Lightfoot,
Pretty much any small ferrite beads will do. You've got frequencies from about 50MHz down that you would like to keep off the USB cable. Clearly, Parallax doesn't feel the need for them. A lot depends on how quiet you want things to be.

Chris Savage

From the datasheet:

A Ferrite Bead is connected in series with USB power to prevent noise from the device and associated circuitry (EMI) being radiated down the USB cable to the Host. The value of the Ferrite Bead depends on the total current required by the circuit – a suitable range of Ferrite Beads is available from Steward (www.steward.com) for example Steward Part # MI0805K400R-00.

So this gives you an example if you want to put one in your circuit. Take care.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support

Lightfoot

Will pulling the #RESET input high be at all beneficial? If so what value should i use.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔