| 摘要 |
An internal precision oscillator (IPO) is trimmed within a microcontroller integrated circuit. The microcontroller integrated circuit receives a test program into flash memory on the microcontroller integrated circuit from a tester. The microcontroller integrated circuit also receives a reference signal from the tester. The IPO generates a clock signal having a frequency that depends upon a trim value. A general purpose timer on the microcontroller integrated circuit counts the number of cycles of the clock signal during a time period defined by the reference signal and outputs a digital value. A processor on the microcontroller integrated circuit executes the test program, reads the digital output, and adjusts the trim value such that the frequency of the clock signal is calibrated with respect to the reference signal. Test-time on the tester is reduced because the decision making during the frequency trimming process is made by the processor instead of the tester.
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