Texas Instruments TM124BBK32-80

Overview

TM124BBK32-80 from Texas Instruments is a 72-pin single in-line memory module (SIMM) implementing 1,048,576 × 32-bit dynamic RAM using eight TMS44400 4-Mbit DRAMs in plastic SOJ packages. It operates on a single 5-V ±10% supply, supports TTL-compatible I/O, and delivers 80 ns RAS access time for use in legacy PC memory subsystems requiring standardized 32-bit data width.

For engineers reviewing the TM124BBK32-80 datasheet, TM124BBK32-80 pinout, TM124BBK32-80 application, or TM124BBK32-80 equivalent, key selection criteria include its 16 ms distributed refresh period, presence detect pins (PD1–PD4), common CAS control across four blocks, and compatibility with socketed 72-pin SIMM slots in industrial computing and embedded systems of the early 1990s.

Technical Context

The TM124BBK32-80 implements a 4×(1048576 × 8)-bit organization via eight parallel TMS44400 DRAMs, each configured as 1048576 × 4-bit with shared A0–A9 addressing and independent RAS0–RAS3/CAS0–CAS3 strobes. Its common I/O architecture requires early write cycles to avoid D/Q bus contention.

It uses distributed refresh over 16 ms (1024 rows), with CAS held high during refresh to reduce power. All inputs and outputs are fully TTL-compatible, and the module features 3-state output drivers with VCC = 4.5–5.5 V and operating temperature range of 0°C to 70°C.

Key Specifications

Pinout & Package

TM124BBK32-80 is housed in a 72-pin single in-line memory module (SIMM) with gold-plated nickel-underplate contacts on a 1.27 mm thick PCB substrate. The module is single-sided (BK type) and uses plastic SOJ-packaged TMS44400 DRAMs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DRAM module applications.

Compared with TM124BBK32-70 and TM124BBK32-60, the TM124BBK32-80 offers the lowest power consumption (640 mA active current) and widest timing margin (80 ns tRAC), making it optimal for thermally constrained or cost-sensitive legacy systems where absolute peak bandwidth is not required.

Availability

TM124BBK32-80 is available at Aetrix Electronics and suitable for industrial control panel memory, legacy PC expansion slot upgrades, medical imaging data buffering, and telecom baseband processing requiring stable component supply across long-lifecycle programs.

Supply support for TM124BBK32-80 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

Texas Instruments is a U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and memory solutions for industrial, automotive, and communications markets.

The TM124BBK32-80 belongs to TI's legacy DRAM module product line designed specifically for socketed 72-pin SIMM systems in the early 1990s, targeting cost-effective, reliable memory expansion in commercial and industrial computing platforms.

FAQ

What is the memory organization of the TM124BBK32-80?

The TM124BBK32-80 is organized as four times 1,048,576 × 8-bit banks, totaling 1,048,576 × 32-bit (4 MiB). It achieves this using eight TMS44400 4-Mbit DRAMs, each configured as 1048576 × 4-bit, mounted on a single-sided substrate with integrated decoupling capacitors. This structure enables efficient 32-bit data transfers aligned with ISA and early PCI bus widths.

Does the TM124BBK32-80 support automatic presence detection?

Yes, the TM124BBK32-80 includes four dedicated presence detect pins - PD1 (pin 67), PD2 (pin 68), PD3 (pin 69), and PD4 (pin 70) - which provide hardwired identification signals to the host system. These pins enable BIOS or firmware to automatically detect module insertion, verify capacity, and configure memory mapping without manual jumper settings or software calibration.

What is the significance of the "-80" suffix in TM124BBK32-80?

The "-80" suffix in TM124BBK32-80 denotes the device's RAS access time rating: 80 ns maximum tRAC. This distinguishes it from the -60 (60 ns) and -70 (70 ns) speed grades within the same family. All three variants share identical pinout, package, and functional architecture - only timing parameters and corresponding current consumption differ, allowing direct substitution where system timing margins permit.

Can the TM124BBK32-80 operate with a 3.3-V supply?

No, the TM124BBK32-80 is specified exclusively for single 5-V ±10% operation (4.5 V to 5.5 V). Its input thresholds, output drive strength, and internal DRAM core voltage are designed for TTL-compatible 5-V logic levels. Applying 3.3 V will result in non-compliant VIH/VIL margins, unreliable read/write cycles, and potential data corruption - no 3.3-V operation mode or dual-voltage support is documented.

How does the TM124BBK32-80 handle memory refresh?

The TM124BBK32-80 implements distributed refresh over a 16 ms interval, requiring exactly 1024 RAS strobes - one per row - within that window. Address lines A0–A9 must be cycled through all 1024 combinations during refresh, while CAS may remain high to minimize power. This scheme avoids full memory stall and is managed externally by the memory controller, consistent with TMS44400 DRAM specifications.