The DS2251T 128k soft microcontroller module is an 8051-compatible microcontroller module based on nonvolatile RAM technology. It is designed for systems that need large quantities of nonvolatile memory. Like other members of the secure microcontroller family, it provides full compatibility with the 8051 instruction set, timers, serial port, and parallel I/O ports. By using NV RAM instead of ROM, the user can program, then reprogram the microcontroller while in-system. The application software can even change its own operation. This allows frequent software upgrades, adaptive programs, customized systems, etc. In addition, by using NV RAM, the DS2251T is ideal for data logging applications. The powerful realtime clock includes interrupts for time stamp and date. It keeps time to one-hundredth of seconds using its on-board 32kHz crystal.
The DS2251T provides the benefits of NV RAM without using I/O resources. Between 32 kbytes and 128 kbytes of onboard NV RAM are available. A non-multiplexed Byte-wide address and data bus is used for memory access. This bus, which is available at the connector, can perform all memory access and also provide decoded chip enables for off-board memory mapped peripherals. This leaves the 32 I/O port pins free for application use.
The DS2251T provides high-reliability operation in portable 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 maintained 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 NV RAM, validates it, then becomes transparent to the user. Software is stored in onboard 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).
Operating information is contained in the Secure Microcontroller User's Guide. This data sheet provides ordering information, pinout, and electrical specifications.
* Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.
Devices:
1-4 of 4
DS2251T
Notes
Free Sample
Buy
Status
Recommended Replacement
Package:
TYPE PINS FOOTPRINT
DRAWING CODE/VAR *
Temp
RoHS/Lead-Free? Materials Analysis
DS2251T-128-12
N/A
No Longer Available
DS2251T-128-16
Land Pattern: Not Available
0°C to +70°C
See data sheet
DS2251T-32-12
N/A
No Longer Available
DS2251T-32-16
Land Pattern: Not Available
0°C to +70°C
See data sheet
DS2251T-64-12
N/A
No Longer Available
DS2251T-64-16
Land Pattern: Not Available
0°C to +70°C
See data sheet
DS2251T-128-16
16MHz w/RTC
Active
0 pin;0 mm²
Land Pattern: Not Available
Use pkgcode/variation: SS-5*
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