PARKZ is an input early warning signal that must alert the controller at least 32 µs before DC supply voltages drop below specifications. Typically, the PARKZ signal is provided by the DLPAxxxx interrupt output signal. PARKZ must be deasserted (set high) prior to releasing RESETZ (that is, prior to the low-to-high transition on the RESETZ input) for normal operation. When PARKZ is asserted (set low) the controller performs a Fast Park operation on the DMD which assists in maintaining the lifetime of the DMD. The reference clock must continue running and RESETZ must remain deactivated for at least 32 µs after PARKZ has been asserted (set low) to allow the park operation to complete.
Fast Park operation is only intended for use when loss of power is imminent and beyond the control of the host processor (for example, when the external power source has been disconnected or the battery has dropped below a minimum level). The longest lifetime of the DMD may not be achieved with Fast Park operation. The longest lifetime is achieved with a Normal Park operation (initiated through GPIO_08). Hence, PARKZ is typically only used instead of a Normal Park request if there is not enough time for a Normal Park. A Normal Park operation takes much longer than 32 µs to park the mirrors. During a Normal Park operation, the DLPAxxxx keeps on all power supplies, and keeps RESETZ high, until the longer mirror parking has completed. Additionally, the DLPAxxxx may hold the supplies on for a period of time after the parking has been completed. View the relevant DLPAxxxx datasheet for more information. The longer mirror parking time ensures the longest DMD lifetime and reliability.DMD Parking Switching Characteristics specifies the park timings.