Scan Clocking

A method, comprising:

• writing a test sequence into a first plurality of storage elements on clock pulses of a first clock signal at a first frequency;
• producing a second clock signal based on the first clock signal, the second clock signal having a second frequency that is greater than the first frequency;
• writing the test sequence into a second plurality of storage elements on clock pulses of the second clock signal;
• producing a third clock signal based on the first clock signal, the third clock signal having a third frequency that is less than the second frequency;
• writing the test sequence into a third plurality of storage elements on clock pulses of the third clock signal;
• and
• performing a built-in-self-test using the test sequence in the third plurality of storage elements.

A device, comprising:

• a clock circuit configurable to output a clock signal;
• a first storage element coupled to the clock circuit;
• a logic circuit coupled to the clock circuit and configurable to read data from the first storage element to perform a built-in-self-test;
• and
• a controller coupled to the clock circuit, the first storage element, and the logic circuit, the controller configurable to:
• instruct the clock circuit to output the clock signal at a first frequency;
• write a first portion of a test sequence to the first storage element on clock pulses of the clock signal at the first frequency;
• instruct the clock circuit to output the clock signal at a second frequency;
• write a second portion of the test sequence to the first storage element on clock pulses of the clock signal at the second frequency, the second frequency being greater than the first frequency;
• instruct the clock circuit to output the clock signal at a third frequency;
• write a third portion of the test sequence to the first storage element on clock pulses of the clock signal at the third frequency, the third frequency being less than the second frequency;
• and
• enable the logic circuit to read one of the first, second, or third portions of the test sequence from the first storage element to perform the built-in-self-test.