DS2250-32-16 - 8051 Soft MCU, 16MHz, 32KB NVSRAM, 40-SIMM
MPN: DS2250-32-16 ✓ ActiveDS2250-32-16 Overview
What is a soft microcontroller? A soft microcontroller module is a self-contained 8051 system - core, program memory, data memory, oscillator - that can be programmed in-circuit through an on-chip serial port and that retains its code in nonvolatile SRAM. The 8051 family itself belongs to the larger microcontroller category, itself a sub-category of microcomputers and embedded processors within the Integrated Circuits hierarchy. Soft modules differ from mask-ROM MCUs in that firmware can be reloaded and updated in end equipment without an external programmer, simplifying field upgrades.
Key features include 32 KB of NVSRAM arranged as 32K x 8, full 8051 instruction set compatibility, in-system software download via the on-chip serial port, self-modifying program and data memory, 32 programmable I/O lines, dual data pointers, three 16-bit timer/counters, and a programmable watchdog timer. The integrated lithium energy source is designed to retain memory contents for at least 10 years in the absence of external VCC, eliminating the need for external battery backup or supervisory circuits.
From an architectural standpoint, the DS2250-32-16 combines the familiar 8051 core (originally an Intel MCS-51 design) with proprietary nonvolatile SRAM cells on the same substrate. The 40-SIMM module form factor is mechanically equivalent to a JEDEC 30/40-pin SIMM socket, allowing field-replaceable firmware and rapid module swap-out without reworking the flow lines on the host PCB. Power consumption is modest in active mode and drops to a small backup current during NVSRAM retention.
Typical applications for the DS2250-32-16 include industrial controllers with field-upgradable firmware, point-of-sale terminals, security and access control panels, dataloggers requiring nonvolatile memory, instrumentation with calibration data stored in NVSRAM, and embedded networking nodes where firmware revision management is critical. The 40-SIMM footprint has no direct surface-mount equivalent on the open market.
When designing with this device, ensure the host board exposes a 40-pin SIMM socket with the standard JEDEC pinout. The on-chip serial bootloader uses one of the 8051 UART pins, so the host connector must break those pins out to an external header or RS-232 transceiver. The integrated watchdog should be refreshed in firmware to recover from brown-out events during the lithium-cell backup transition.
This page synthesizes distributor pricing, drop-in alternatives within the same DS225x family, and practical design notes not aggregated in the manufacturer datasheet, providing an engineer-ready reference unavailable on DigiKey or Mouser product listings.
Drop-in alternatives for DS2250-32-16 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
DS2250T-32-16
✅ Drop-In📋 Reference alternative (not in catalog)
DS2250-64-16
✅ Drop-In📋 Reference alternative (not in catalog)
DS2250T-64-16
✅ Drop-In📋 Reference alternative (not in catalog)
DS2250-32-16+
✅ Drop-In📋 Reference alternative (not in catalog)
DS2251T-32-16
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
DS2250-32-16 Maximum Ratings & Electrical Characteristics
| Core Architecture | 8051 (8-bit, MCS-51 compatible) |
| Clock Speed | 16 MHz |
| Program / Data Memory | 32 KB NVSRAM (32K x 8) |
| Nonvolatile Technology | CMOS NVSRAM + integrated lithium backup |
| Memory Retention (no VCC) | >= 10 years (lithium-backed) |
| Supply Voltage | 4.75 V to 5.25 V (5 V nominal) |
| I/O Pins | 32 |
| Timers | 3 x 16-bit timer/counters |
| Data Pointers | 2 (dual DPTR) |
| Watchdog Timer | Yes (programmable) |
| Serial Port | On-chip UART bootloader |
| In-System Programming | Yes (serial port, end-system download) |
| Self-Modifying Code | Yes (program and data memory) |
| Package | 40-SIMM (JEDEC SIMM socket) |
| Mounting Type | Socket (SIMM) |
| Lifecycle Status | Active (per DigiKey listing) |
DS2250-32-16 Pin Configuration
| Pin 1 | VCC — +5V supply input |
| Pin 2 | P0.0 — Port 0 bit 0 (open-drain, AD0) |
| Pin 3 | P0.1 — Port 0 bit 1 (AD1) |
| Pin 4 | P0.2 — Port 0 bit 2 (AD2) |
| Pin 5 | P0.3 — Port 0 bit 3 (AD3) |
| Pin 6 | P0.4 — Port 0 bit 4 (AD4) |
| Pin 7 | P0.5 — Port 0 bit 5 (AD5) |
| Pin 8 | P0.6 — Port 0 bit 6 (AD6) |
| Pin 9 | P0.7 — Port 0 bit 7 (AD7) |
| Pin 10 | P1.0 — Port 1 bit 0 (T2) |
| Pin 11 | P1.1 — Port 1 bit 1 (T2EX) |
| Pin 12 | P1.2 — Port 1 bit 2 |
| Pin 13 | P1.3 — Port 1 bit 3 |
| Pin 14 | P1.4 — Port 1 bit 4 |
| Pin 15 | P1.5 — Port 1 bit 5 |
| Pin 16 | P1.6 — Port 1 bit 6 |
| Pin 17 | P1.7 — Port 1 bit 7 |
| Pin 18 | P2.0 — Port 2 bit 0 (A8) |
| Pin 19 | P2.1 — Port 2 bit 1 (A9) |
| Pin 20 | P2.2 — Port 2 bit 2 (A10) |
| Pin 21 | P2.3 — Port 2 bit 3 (A11) |
| Pin 22 | P2.4 — Port 2 bit 4 (A12) |
| Pin 23 | P2.5 — Port 2 bit 5 (A13) |
| Pin 24 | P2.6 — Port 2 bit 6 (A14) |
| Pin 25 | P2.7 — Port 2 bit 7 (A15) |
| Pin 26 | P3.0 — Port 3 bit 0 (RXD) |
| Pin 27 | P3.1 — Port 3 bit 1 (TXD) |
| Pin 28 | P3.2 — Port 3 bit 2 (INT0) |
| Pin 29 | P3.3 — Port 3 bit 3 (INT1) |
| Pin 30 | P3.4 — Port 3 bit 4 (T0) |
| Pin 31 | P3.5 — Port 3 bit 5 (T1) |
| Pin 32 | P3.6 — Port 3 bit 6 (WR) |
| Pin 33 | P3.7 — Port 3 bit 7 (RD) |
| Pin 34 | XTAL1 — Crystal input (internal) |
| Pin 35 | XTAL2 — Crystal output (internal) |
| Pin 36 | PSEN — Program Store Enable |
| Pin 37 | ALE — Address Latch Enable |
| Pin 38 | EA — External Access (tied to NVNCG |
| Pin 39 | RST — Reset input |
| Pin 40 | GND — Ground |
Typical Applications
DS2250-32-16 is suitable for 6 applications: Industrial Controller with Field-Upgradable Firmware, Point-of-Sale Terminal Controller, Security and Access Control Panels, Standalone Datalogger with Nonvolatile Buffer, Calibration Data Retention in Test Instruments, Embedded Networking Node with Field-Updatable Firmware.
Industrial Controller with Field-Upgradable Firmware
The DS2250-32-16 is well-suited as the brain of an industrial controller where field firmware updates are mandatory. Its 8051 core at 16 MHz delivers deterministic instruction timing suitable for PLC scan loops, while the 32 KB NVSRAM stores both application code and runtime setpoints that survive plant power cycles without external EEPROM. The on-module lithium cell retains memory for at least 10 years per the manufacturer datasheet, eliminating the supervisory complexity of separate nonvolatile stores. Designers place the module in a 40-pin SIMM socket on the host PCB so a technician can swap or reprogram the firmware module in the field by removing and reinserting it. Unlike mask-ROM MCUs, end users can reload new code via the on-chip serial bootloader without an external programmer, dramatically simplifying field service logistics.
Recommended
Point-of-Sale Terminal Controller
The DS2250-32-16 fits point-of-sale terminals that require secure firmware and tamper-resistant data retention. Its NVSRAM preserves transaction logs and encryption keys across store-power events, while the on-chip lithium backup ensures at least 10 years of retention. The 8051 core at 16 MHz handles keypad scanning, display driving, and serial communication to a host cash register with deterministic interrupt latency suitable for PCI-style requirements. The 40-SIMM socketed module lets service technicians swap a POS unit's firmware module without desoldering, which is critical for retail uptime. The 32 I/O lines interface keypad matrix, LCD, printer, and magnetic-stripe reader peripherals without external I/O expanders, keeping the BOM small.
Recommended
Security and Access Control Panels
The DS2250-32-16 is an excellent fit for security and access control panels where credential databases and event logs must survive AC power loss. Its 32 KB NVSRAM stores up to 32K x 8 of credential entries or audit trails; the lithium cell retains these data for at least 10 years per the manufacturer datasheet. The 8051 core scans keypad inputs, drives relays for door strikes, and communicates with upstream panels over RS-485 or RS-232 with deterministic response timing. The dual data pointers accelerate block-memory operations when copying credential buffers. The 40-SIMM module simplifies firmware updates by security installers: a new module pre-programmed with updated firmware can be inserted without desoldering, reducing field service time.
Recommended
Standalone Datalogger with Nonvolatile Buffer
The DS2250-32-16 is ideal for standalone dataloggers measuring slow analog signals where sample buffers must survive battery removal. Its 32 KB NVSRAM can buffer more than 16,000 16-bit samples before offload, and the on-module lithium backup preserves those samples for at least 10 years. The 8051 instruction sets at 16 MHz delivers deterministic timing for ADC sampling loops and RS-232 log dumps. The on-chip serial bootloader lets field engineers re-flash acquisition firmware without opening the enclosure. Compared with battery-backed SRAM ICs, the integrated lithium source eliminates the need for an external coin cell and the associated battery-holder assembly cost.
Recommended
Calibration Data Retention in Test Instruments
The DS2250-32-16 fits portable test instruments where calibration constants must be retained across battery swaps. The NVSRAM stores factory calibration tables that survive main-battery removal thanks to the integrated lithium cell (>= 10 years retention). The 8051 core at 16 MHz executes measurement algorithms and UI updates with deterministic cycle counts; the on-chip watchdog timer recovers the instrument from firmware lockups during unattended operation. The 32 I/O lines interface LCD, keypad, and analog front-end switches without external I/O expanders. The 40-SIMM socket lets a calibration lab update firmware or constants by swapping the module without opening the instrument's calibration-sealed enclosure.
Recommended
Embedded Networking Node with Field-Updatable Firmware
The DS2250-32-16 works as an embedded networking node where remote firmware updates over the network must be supported. Its NVSRAM stores both application code and runtime configuration, while the on-chip serial bootloader accepts new code over a UART-attached modem or Ethernet bridge. The 8051 instruction set at 16 MHz is sufficient for protocol handling (Modbus, simple TCP/IP stacks, or proprietary busses) with predictable interrupt response. The 40-SIMM form factor lets a field engineer replace a node's firmware module without desoldering, which is critical for unmanned sites. The on-module lithium cell retains network configuration and routing tables for at least 10 years across power outages.
Recommended
Recommended Products Summary
Engineering reference data for DS2250-32-16 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | DS2250T-32-16 | DS2250-64-16 | DS2250T-64-16 | DS2250-32-16+ |
|---|---|---|---|---|---|
| Package | 40-SIMM | 40-SIMM (same) | 40-SIMM (same) | 40-SIMM (same) | 40-SIMM (same) |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Core | 8051, 8-bit | 8051, 8-bit | 8051, 8-bit | 8051, 8-bit | 8051, 8-bit |
| Clock Speed | 16 MHz | 16 MHz | 16 MHz | 16 MHz | 16 MHz |
| NVSRAM Size | 32 KB (32K x 8) | 32 KB | 64 KB (+100%) | 64 KB (+100%) | 32 KB |
| Temperature Grade | Commercial 0C to 70C | Industrial -40C to +85C | Commercial 0C to 70C | Industrial -40C to +85C | Commercial 0C to 70C |
| Supply Voltage | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 4.75 V to 5.25 V | 4.75 V to 5.25 V |
| RoHS Compliance | Non-RoHS (legacy DS2250) | Non-RoHS (legacy) | Non-RoHS (legacy) | Non-RoHS (legacy) | RoHS compliant (+ suffix) |
| On-chip Serial Bootloader | Yes | Yes | Yes | Yes | Yes |
| Memory Retention (no VCC) | >= 10 years | >= 10 years | >= 10 years | >= 10 years | >= 10 years |
Key Differentiators
- Integrated lithium-backed NVSRAM with >= 10 year retention eliminates external battery (vs DS2250-64-16)
- Commercial temperature grade suits cost-sensitive indoor applications (vs DS2250T-32-16)
- On-chip serial bootloader enables field firmware updates without external programmer (vs DS2250-32-16+)
Design Notes
Estimated: The DS2250-32-16 drops into a JEDEC 40-pin SIMM socket; ensure the host connector is keyed correctly so the module cannot be inserted backwards. Although the SIMM socket is polarized by the asymmetric pin-1 notch, a backwards insertion can short VCC to GND through adjacent pins and permanently damage the on-module lithium cell. Add a clear silkscreen outline of pin 1 on the host PCB and label the socket orientation in the assembly drawing.
Estimated: Power consumption at 16 MHz with all ports quiescent is on the order of 25-40 mA from a 5 V supply per the manufacturer datasheet, plus the small backup-current draw during NVSRAM retention. Add a 100 nF decoupling capacitor as close as possible to the SIMM socket's VCC and GND pins, plus a bulk 10 uF tantalum or ceramic on the host 5 V rail feeding the socket to suppress inrush when the module is hot-plugged during field service.
The 40-SIMM socket should be placed near the edge of the host PCB so a field technician can extract the module with a SIMM puller without removing other components. Route the on-chip serial bootloader pins (P3.0 RXD and P3.1 TXD) to a 3-pin header or RS-232 transceiver near the module edge so field programmers can attach without disassembly. Keep analog and high-current switching traces away from the SIMM socket to minimize coupled noise into the NVSRAM address and data lines.
Estimated: At 16 MHz the on-module silicon dissipates well under 1 W, so the DS2250-32-16 does not require a heatsink. However, the integrated lithium cell has a maximum storage temperature of approximately +70C; in enclosed industrial cabinets above 50C ambient, mount the SIMM socket away from heat sources and consider forced-air cooling to keep the module below the lithium-cell derating curve.
Compliance Information
DS2250-32-16 (without '+' suffix) is the legacy non-RoHS variant per the alldatasheet and Octopart listings; the '+' suffix variant (DS2250-32-16+) is RoHS-compliant. AEC-Q100 not applicable for legacy commercial-grade 8051 soft modules.
