Monthly Archives: August 2007

IC Friday: Intersil’s X9250


This week we have the X9250 from Intersil. This is a SPI-programmable quad potentiometer. The one imaged is 100kOhm total resistance. This unit is responsible for the gain and offset control in my digitally-programmable amplifiers and has done a fairly good job so far. It should be noted that the device can read out the wiper positions and has non-volatile storage. Finally, visit
the maximum current limit for the device is 15mA through the wiper which may be lower than a comparable mechanical potentiometer.


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( x9250ts.pdf )

Out to lunch


I am going to Yalta, no rx Ukraine for two weeks to visit my parents and to enjoy the beaches. The obvious result is that there won’t be too many posts until I return on the 27th of August. I have already imaged the next three chips for IC Friday and will queue them up with WordPress for routine publication. The chips will be the INA132, dosage TLV2374 and X9250TC. These are a diff amp, visit quad op amp and a programmable potentiometer respectively. Otherwise, there may be a few pictures posted since I may have limited internet access. If anyone wants postcards from Yalta, send me an email with “Postcard” somewhere in the title and your address somewhere in the body.

Sun Microsystems to release their UltraSparc T2 design


Jonathan Schwartz recently made a post in his blog about Sun entering the “commodity silicon” market. He also mentioned that the design for the UltraSparc T2 (Niagara 2) will be released to the open source community under the GPL. Although this is a step in a good direction, medications there are some potential dangers. The key to success in such a strategy is to provide a truly good product since everybody can see the details of the design. It would be unfortunate if there was some bug which allowed privilege escalation at a hardware level (remember having to run the older UltraSparcs in 32-bit mode to prevent some security problems?). Over all, site this move puts Sun in a stronger position and I hope they do well. I can’t wait to see the actual design files.

How to duplicate certain RF proximity cards


With RFID-type devices becoming more and more ubiquitous in our society, treatment it is good to know some of the advances being made in the security research fields so as to avoid a false sense of security. I came across Jonathan Westhues‘ site which outlines his experiences duplicating certain identification devices. It is important to note that the duplicated devices are of the identification-only type and do not have any built in security mechanisms, however, these are accessible initial steps. Hopefully this will motivate me to do something with the TMS3705A-based RFID reader I built following a sample design.