SAB80C517A-N18 Siemens Semiconductor Group, SAB80C517A-N18 Datasheet - Page 50

• Manufacturer Part Number: SAB80C517A-N18
• Description: 8-Bit CMOS Single-Chip Microcontroller
• Manufacturer: Siemens Semiconductor Group

Power Saving Modes
The SAB 80C517A provides – due to Siemens ACMOS technology – four modes in which pow-
er consumption can be significantly reduced.
– The Slow Down Mode
– The Idle Mode
– The Power Down Mode
– The Hardware Power Down Mode
Hardware Enable for Software controlled Power Saving Modes
A dedicated Pin PE/SWD) of the SAB 80C517A allows to block the Software controlled power
saving modes. Since this pin is mostly used in noise-critical application it is combined with an
automatic start of the Watchdog Timer.
PE/SWD = V
PE/SWD = V
When left unconnected, Pin /PE/SWD is pulled high by a weak internal pullup. This is done to
provide system protection on default.
The logic-level applied to pin PE/SWD can be changed during program execution to allow or to
block the use of the power saving modes without any effect on the on-chip watchdog circuitry.
Semiconductor Group
The controller keeps up the full operating functionality, but is driven with one eighth
of its normal operating frequency. Slowing down the frequency remarkable reduces
power consumption.
The CPU is gated off from the oscillator, but all peripherals are still supplied with the
clock and continue working.
Operation of the SAB 80C517A is stopped, the on-chip oscillator and the RC-oscillator
are turned off. This mode is used to save the contents of the internal RAM with a very
low standby current.
Operation of the SAB 80C517A is stopped, the on-chip oscillator and the RC-Oscillator
are turned off. The pin HWPD controls this mode. Port pins and several control lines
enter a floating state. The Hardware Power Down Mode is independent of the state of
pin PE/SWD.
IH
IL
(logic high level):
(logic low level):
Using of the power saving modes is not possible.
The watchdog timer starts immediately after reset.
The instruction sequences used for entering of
power saving modes will not affect the normal operation
of the device.
All power saving modes can be activated by software.
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SAB 80C517A/83C517A-5
1994-05-01