ds2251 Maxim Integrated Products, Inc., ds2251 Datasheet - Page 8

• Manufacturer Part Number: ds2251
• Description: 128k Soft Microcontroller Module
• Manufacturer: Maxim Integrated Products, Inc.

DS2251T
DS2251T MEMORY MAP WITH (PES=1) Figure 4
POWER MANAGEMENT
The DS2251T monitors V
to provide Power-fail Reset, early warning Power-fail Interrupt, and switch-
CC
over to lithium backup. It uses an internal band-gap reference in determining the switch points. These are
called V
, V
, and V
respectively. When V
drops below V
, the DS2251T will perform an
PFW
CCMIN
LI
CC
PFW
interrupt vector to location 2Bh if the power-fail warning is enabled. Full processor operation continues
regardless. When power falls further to V
, the DS2251T invokes a reset state. No further code
CCMIN
execution will be performed unless power rises back above V
. All decoded chip enables and the
CCMIN
R/
signal go to an inactive (logic 1) state. The
signal will be driven to a logic 0. V
is still the
W
VRST
CC
power source at this time. When V
drops further to below V
, internal circuitry will switch to the built-
CC
LI
in lithium cell for power. The majority of internal circuits will be disabled and the remaining nonvolatile
states will be retained.
will be driven to a logic 0. The User’s Guide has more information on this
PF
topic. The trip points V
and V
are listed in the electrical specifications.
CCMIN
PFW
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