DS2251T Datasheet, PDF (2/19 Pages) Dallas Semiconductor – 128K Soft Microcontroller Module

DS2251T
mapped peripherals. This leaves the 32 I/O port pins
free for application use.
The DS2251T provides high–reliability operation in por-
table systems or systems with unreliable power. These
features include the ability to save the operating state,
Power–fail Reset, Power–fail Interrupt, and Watchdog
Timer. All nonvolatile memory and resources are main-
tained for over 10 years at room temperature in the
absence of power.
A user loads programs into the DS2251T via its on–chip
Serial Bootstrap Loader. This function supervises the
loading of software into NVRAM, validates it, then
becomes transparent to the user. Software is stored in
on–board CMOS SRAM. Using its internal Partitioning,
the DS2251T can divide a common RAM into user
selectable program and data segments. This Partition
can be selected at program loading time, but can be
modified anytime later. The microprocessor will decode
memory access to the SRAM, access memory via its
Byte–wide bus and write–protect the memory portion
designated as program (ROM).
ORDERING INFORMATION
PART NUMBER
DS2251T–32–16
DS2251T–64–16
DS2251T–128–16
RAM SIZE
32K bytes
64K bytes
128K bytes
MAX CRYSTAL SPEED
16 MHz
16 MHz
16 MHz
TIMEKEEPING?
Yes
Yes
Yes
Operating information is contained in the User’s Guide section of the Secure Microcontroller Data Book. This data
sheet provides ordering information, pinout, and electrical specifications.
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