[hpsdr] [OZY] Schematic Update for 12 May 2006

[Ahti Aintila]

Phil,

Your selection of Littlefuse PGB Series ESD suppressor is good against
short transients. If you want a RoHS compliant component, you may take
PGB102ST23WR. Whichever, but a better place would be next to the
connector.
On the other hand, this type of component is good only for short ESD
transients, they clamp only to 150V (plus or minus). They cannot
protect against longer lasting overvoltage surges of DC power.

My recommendation is Bourns CDSOT23-SR724. It protects 4 lines, it is
USB 2.0 compatible (Cj 3 pF), RoHS compliant and can handle both ESD
transients and overvoltage surges. See :
<http://www.bourns.com/pdfs/CDSOT23-SR724.pdf>. Best place for this
component is between the common mode coil and the USB chip.

73, Ahti OH2RZ

On 12/05/06, Philip Covington <p.covington at gmail.com> wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi group,
>
> Here's today's update to the OZY schematic:
>
> <http://www.philcovington.com/HPSDR/OZY/REVXA.1/>
>
> or
>
> <http://www.hamsdr.com/personaldirectory.aspx?id=235>
>
> or committed to HPSDR SVN.
>
> Changes:
>
> 1. Configuration jumpers changed to through hole 1x3 headers.
>
> 2. EMC protection on USB changed to Littlefuse PGB002ST23WR.
>
> 3. Schottky diodes added in series with 3.3V supply on 2X10 Logic
> Analyzer/Debug port header pin 1.
>
> 4. FX2 INT4 (active high) routed optionally to FPGA (selected by making jumper).
>
> 5. PCA9555 16 bit I2C IO expander added for local IO.  Interrupt line
> from PCA9555 routed to FX2 INT5 (active low).  ULN2003A added to seven
> bits of PCA9555A for high voltage open collector outputs.  There are
> now 8 inputs/8 outputs of optional local IO on OZY.
>
> What has not been added:
>
> A. 1-Wire bus support... still researching options...
>
> B. RS-232 connectors...depends on A above since if we use the DS2480B
> we will steal one of the FX2's serial ports.  That will leave use with
> one RS-232 serial port originating from the FX2 and one RS-232 serial
> port originating from the FPGA.
>
> 73 de Phil N8VB
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