C515C Datasheet, PDF (52/69 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

C515C
Figure 24
Block Diagram of the Oscillator Watchdog
Power Saving Modes
The C515C provides two basic power saving modes, the idle mode and the power down mode.
Additionally, a slow down mode is available. This power saving mode reduces the internal clock
rate in normal operating mode and it can be also used for further power reduction in idle mode.
– Idle mode
The CPU is gated off from the oscillator. All peripherals are still provided with the clock and
are able to work. Idle mode is entered by software and can be left by an interrupt or reset.
– Power down mode
The operation of the C515C is completely stopped and the oscillator is turned off. This mode
is used to save the contents of the internal RAM with a very low standby current.
Software power down mode : Software power down mode is entered by software and can
be left by reset or by a short low pulse at pin P3.2/INT0.
Hardware power down mode : Hardware power down mode is entered when the pin HWPD
is put to low level.
Semiconductor Group
52
1997-07-01