Super Low Power Microcomputer

We will present several segments describing the specific power reduction technologies and unique functions of SLP. The first segment will focus on the " oscillation stabilizer time reduction function"

[Part 1] Oscillation Stabilizer Time Reduction Function (featured in all product groups)

When users are looking for low power microcomputers, they will most likely first look in the product manual for the power consumption current specifications. Of course the manual will show the specifications for the various operation modes such as active and sub-active mode, but there are no provisions for indicating the consumption current present during oscillation stabilization 3/4 a current equivalent to that during active mode 3/4 in product manuals. (There are current losses in areas that do not show up in spec sheets.)

In any microcomputer, there is a considerable flow of consumption current during oscillation stabilization. And this of course means:
"The shorter the period of oscillation stabilization, the less current is consumed!"
SLP has focused on this principle.

Here, we will present a simple explanation of this "oscillation stabilization period."

There are two types of oscillation circuits built into the SLP: a system clock oscillation circuit for high-speed CPU operations, and a sub-clock oscillation circuit for clock functions and low-power operations. The system clock shuts down in low power mode(*1). When the status shifts from low power mode to high-speed operation ("active mode"), the system clock that had been shut down until that time begins to oscillate. In order to ensure that the microcomputer runs normally, the amplitude of the system clock oscillation must be large and stable. The time required for this system clock oscillation to stabilize is called the oscillation stabilization period.

The oscillation stabilization period is normally several milliseconds long, but in the case of SLP is only a few microseconds?a ratio of 1/1000. But how does this difference in the length of the oscillation stabilization period affect the consumption current?

Let us take as an example repeated actions once each second in active mode and watch mode. These status transitions occur 60 times a minute, or 3,600 times each hour; which means 31,536,000 times per year. Each time a status transition occurs, there is a corresponding oscillation stabilization period, which results in excess current consumption (31,536,000 x the power consumption during each oscillation stabilization period; i.e., the needless current consumption that is not indicated in the manual).

The number of status transitions differs for each application, but there are thought to be an extremely large number of repeated status transitions in the case of flow meters and other similar applications, so we believe that the effects of oscillation stabilization period reduction function will be particularly significant here.

The oscillation stabilization period reduction function described in this first segment is just one of the ways that the Super Low Power microcomputer offers unique advantages that are not necessarily visible in product manuals.

(*1) Among the various types of Low Power Mode are: "sub-active," sub-sleep," and "watch" modes during 32Hz operations; "standby mode," the mode with the lowest current consumption, when all functions are at rest; and "active mid-speed," "sleep high-speed,' and "sleep mid-speed" during operations in system lock mode.

In the second segment, we will discuss "asynchronous counters".