What is the “functionality test” referred to on page 4 of the LM628/LM629 Programming Guide (AN-693)?
The functionality test referred to under Software Reset Considerations in AN-693, “LM628 Programming Guide”, is the code represented by the section of Flow Diagram 2 that starts at Reset interrupts. There is a small chance (1/500,000) the LM628/9 will not reset properly even though a valid hardware reset signal has been applied. This is due to the asynchronicity between the hardware reset signal and the clock. The “functionality test” is simply a way of catching this 1 in 500,000 miss and looping back to execute another hardware reset to correct the problem. See Flow Diagram 2. While it may seem likely that there would be a hidden test mode for the LM628 and LM629, in reality there are no undocumented commands for these devices.
