Z8F0113HJ005EG Datasheet, PDF (45/245 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F0823 Series
Product Specification
30
Low-Power Modes
Z8 Encore! XP F0823 Series products contain power-saving features. The highest level of
power reduction is provided by the STOP Mode, in which nearly all device functions are
powered down. The next lower level of power reduction is provided by the HALT Mode,
in which the CPU is powered down.
Further power savings can be implemented by disabling individual peripheral blocks
while in ACTIVE mode (defined as being in neither STOP nor HALT Mode).
STOP Mode
Executing the eZ8 CPU’s Stop instruction places the device into STOP Mode, powering
down all peripherals except the Voltage Brown-Out detector, and the Watchdog Timer.
These two blocks may also be disabled for additional power savings. In STOP Mode, the
operating characteristics are:
• Primary crystal oscillator and internal precision oscillator are stopped; X_IN and X_OUT
(if previously enabled) are disabled, and PA0/PA1 revert to the states programmed by
the GPIO registers
• System clock is stopped
• eZ8 CPU is stopped
• Program counter (PC) stops incrementing
• Watchdog Timer’s internal RC oscillator continues to operate if enabled by the Oscil-
lator Control Register
• If enabled, the Watchdog Timer logic continues to operate
• If enabled for operation in STOP Mode by the associated Flash Option Bit, the Voltage
Brown-Out protection circuit continues to operate
• All other on-chip peripherals are idle
To minimize current in STOP Mode, all GPIO pins that are configured as digital inputs
must be driven to one of the supply rails (V_CC or GND). Additionally, any GPIOs config-
ured as outputs must also be driven to one of the supply rails. The device can be brought
out of STOP Mode using Stop Mode Recovery. For more information about Stop Mode
Recovery, see the Reset and Stop Mode Recovery chapter on page 21.
PS024315-1011
PRELIMINARY
Low-Power Modes