Analog Devices Inc./Maxim Integrated DS2250T-64-16

Overview

DS2250T-64-16 from Maxim Integrated is an 8-bit 8051-compatible soft microcontroller module featuring 64kB nonvolatile SRAM for program/data storage, integrated real-time clock (RTC) with on-board crystal, and operation up to 16MHz. It maintains full memory and register state for over 10 years without power and supports in-system serial programming-ideal for secure, battery-free industrial logging and tamper-resistant embedded control.

For engineers reviewing the DS2250T-64-16 datasheet, DS2250T-64-16 pinout, DS2250T-64-16 application, or DS2250T-64-16 equivalent, key selection considerations include nonvolatile RAM size, RTC integration, 40-pin SIMM package compatibility, 8051 instruction set compliance, and power-fail interrupt capability.

Technical Context

The DS2250T-64-16 implements a fully 8051-compatible CPU core with dual memory spaces: 64kB addressable program memory and 64kB data memory, both accessible via MOVX/MOVC instructions. Its nonvolatile SRAM retains contents without VCC, enabled by internal charge-pump circuitry and low-leakage CMOS design.

Real-time clock access is gated through SFR bit MCON.2 (ECE2), enabling alternate memory-mapped I/O space for serial RTC register access. The device supports two programming modes-serial bootstrap loader (9600/2400/1200/300 bps) and parallel load compatible with 87C51H timing-and includes hardware-level security features including encrypted software execution and programmable security lock.

Key Specifications

Pinout & Package

DS2250T-64-16 is housed in a 40-pin SIMM package with 0.050" lead pitch and standard memory-module footprint. Pin assignments follow industry-standard 8051 mapping with expanded bus support (ALE, PSEN, RD, WR) and dedicated RTC crystal connections (XTAL1/XTAL2).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar soft microcontroller applications.

Compared with DS2250T-32-16, DS2250T-64-16 doubles program/data capacity for complex firmware or extended logging; compared with DS5000T-64-16, it provides identical memory and RTC functionality in a plug-compatible SIMM format-critical for memory-module-based legacy systems.

Availability

DS2250T-64-16 is available at Aetrix Electronics and suitable for industrial data loggers, secure access controllers, energy meter firmware hosts, and legacy system upgrade modules requiring stable component supply and long-term obsolescence management.

Supply support for DS2250T-64-16 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) is a U.S.-based semiconductor company specializing in analog, mixed-signal, and secure microcontroller solutions for industrial, medical, and communications markets.

The DS2250(T) product line was designed as a "soft" microcontroller family emphasizing nonvolatile operation, in-system programmability, and hardware security-targeting applications where firmware persistence, tamper resistance, and battery-free RTC are mandatory.

FAQ

What is the nonvolatile memory retention period for DS2250T-64-16 under normal operating conditions?

The DS2250T-64-16 guarantees nonvolatile memory retention of greater than 10 years at room temperature (25°C) without applied VCC. This applies to all 64kB of internal SRAM, configuration registers, and RTC data. Retention time decreases at elevated temperatures per Arrhenius modeling, but the device is rated for 0°C to +70°C operational range with full specification compliance.

Does DS2250T-64-16 require an external crystal for real-time clock operation?

Yes, DS2250T-64-16 requires an external crystal connected between XTAL1 and XTAL2 pins to operate the integrated real-time clock. The datasheet specifies use of an on-board crystal for hundredth-second resolution timing, and the crystal start-up time is documented as tCSU (see AC Characteristics section). No internal RC oscillator is provided for RTC.

Can DS2250T-64-16 execute encrypted firmware, and how is security enforced?

Yes, DS2250T-64-16 supports encrypted software execution via five dedicated encryption registers and a hardware security lock bit (MCON.0). When enabled, the device decrypts instructions on-the-fly during fetch cycles and prevents unauthorized readback of NV RAM contents. Security is enforced at silicon level-no software-only bypass exists once the lock is set.

What programming interfaces does DS2250T-64-16 support for firmware loading?

DS2250T-64-16 supports two firmware loading methods: serial bootstrap loader (via UART at 300–9600 bps) and parallel programming (timing-compatible with 87C51H). Serial loading uses ASCII commands (e.g., 'L' for load, 'V' for verify) and requires only RX/TX/GND; parallel loading requires PROG, VPP, and address/data bus signals during reset initiation.

Is DS2250T-64-16 pin-compatible with other devices in the DS2250(T) family?

Yes, DS2250T-64-16 shares identical 40-pin SIMM pinout and electrical characteristics with all DS2250(T) variants-including DS2250T-32-16 and DS2250-64-16-differing only in RAM size and RTC inclusion. This allows direct substitution in existing designs where memory or RTC requirements change, without PCB modification.