PCM In-System Programming Solutions

Onboard programming of firmware onto Flash memory during PCB manufacture is a common practice. It allows customers to integrate programming and testing into a single step, eliminating the need to outsource the pre-programming function. In-system programming (ISP) also allows manufacturers to make code changes during the production run.

Because PCM is a thermally activated technology, data retention is linked to temperature. At standard solder reflow temperatures (235º C), PCM data retention time is measured in microseconds. For this reason, PCM requires an in-system programming usage model.

Customers can take advantage of PCM’s fast write speeds with in-system programming solutions to load firmware or system data within the manufacturing environment, while maintaining fast manufacturing beat rates.

PCM has very fast write times when writing a 0, and after a 235ºC solder flow, all PCM bits will be a 1 (i.e., pre-erased like a Flash device). Because a PCM device can write a 0 approximately 100 times faster than a NOR Flash device, PCM programming rates will be much faster than those for Flash memory.

Micron Documentation:

In-System Programming with Micron Phase Change Memory white paper – outlines different ISP solutions.

Third-party ISP solutions:

• JTAG – Technique that checks the structural integrity between the device and the PCB.
  XJTAG Case Study
  
• Agilent – In-circuit tester (ICT) used during the PCB function test; via test points.
  
• DediProg – Direct programming of the PCM without the chipset. Programming PCM through the chipset.