Microcontroller or DSP circuit controls on/off function

摘要

IN MANY APPLICATIONS, a single on/off button switches the power supply on or off. Usually, the system switches off regardless of the processing function or workload the microcontroller or DSP circuit is currently handling. The small circuit in Figure 1 is intended to make the microcontroller or DSP circuit the master over this on/off function. The circuit allows the microcontroller or DSP circuit to take ownership over the on/off function. Thus, the system can do whatever has to be done, such as processing data, storing data, and so forth, before it issues the command to shut down the supply. Figure 2 shows the timing diagram. The switch connects directly to the dc supply or battery, though the end application is disconnected from the supply. Thus, all the capacitors discharge. The most difficult task is to get the two D flip-flops in Figure 1 into the desired "off" configuration.