In SX Microcontrollers, SX/B Compiler and SX-Key Tool, g_daubach wrote:

William,

I left an SX-Key USB connected to a USB port for about 30 minutes. It got moderately warm around the SX20 chip and the coil (about 40° C = 104° F). I don't think the coil is producing much heat. Most of it is generated by the SX 20 running at a 32 MHz clock, and the clock generator chip with a 20 MHz master clock.

You are right, Vpp is generated continuously but not fed through to the OSC1 pin, thus almost no current is drawn from the Vpp source when the Key is idle, so the coil should not heat up normally.

Nice to hear that you like the blue LED. It is turned on as long as comminication is established between the SX-Key USB and the SX-Key IDE. In a former firmware version, I had the LED flicker while programming a chip was in progress. Maybe, this additional gimmic will be re-introduced in a later firmware version.

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