Renesas HM1-6551B/883

Overview

HM1-6551B/883 from Intersil is a 256 × 4-bit (1,024-bit) fully static CMOS RAM in a 22-lead CERDIP package, operating over –55°C to +125°C with 220 ns max access time, TTL-compatible I/O, and three-state outputs for bus sharing. It serves as on-board data memory in radiation-tolerant avionics and military control systems requiring indefinite data retention at 2.0 V.

For engineers reviewing the HM1-6551B/883 datasheet, HM1-6551B/883 pinout, HM1-6551B/883 application, or HM1-6551B/883 equivalent, key selection criteria include guaranteed 220 ns access at full military temperature range, internal address latching, chip-select-controlled high-impedance outputs, and MIL-STD-883 Class B compliance for space-grade reliability.

Technical Context

The HM1-6551B/883 implements synchronous static RAM architecture with on-chip address register and data output latches triggered by falling-edge E (Chip Enable). Its dual chip select inputs (S1, S2) enable hierarchical decoding, while W (Write Enable) controls bidirectional I/O bus direction without external logic.

All timing is referenced to E's falling edge for address latching and read/write initiation; output data is valid after TELQV (220 ns max), and write pulse hold times (e.g., TELWH = 120–180 ns) ensure reliable data capture under worst-case skew. The device uses self-aligned silicon gate CMOS process with 1930-gate die complexity and supports common I/O bus operation via W-controlled three-state buffers.

Key Specifications

Pinout & Package

HM1-6551B/883 is housed in a 22-lead Ceramic Dual-In-Line Package (CERDIP), MIL-STD-1835 GDIP1-T22 (F22.4), with frit-sealed ceramic body and gold-plated leads. Package dimensions: 1.111″ × 0.410″ × 0.225″ (28.22 mm × 10.41 mm × 5.72 mm), thermal resistance θJA = 60°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar static RAM applications.

Compared with HM1-6551/883 and IS61LV25616AL-10TLI, the HM1-6551B/883 uniquely delivers 220 ns access within full military temperature range and MIL-STD-883 Class B screening - making it irreplaceable in certified avionics and space hardware where timing predictability and radiation hardness are non-negotiable.

Availability

HM1-6551B/883 is available at Aetrix Electronics and suitable for avionics flight control, tactical radio buffering, spacecraft telemetry storage, and nuclear plant safety controller applications requiring stable component supply across extended lifecycle demands.

Supply support for HM1-6551B/883 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

Intersil Corporation (now part of Renesas Electronics) is a U.S.-based semiconductor designer specializing in high-reliability analog and mixed-signal ICs for aerospace, defense, and industrial markets.

The HM1-6551B/883 belongs to Intersil's legacy military-grade static RAM product line, engineered specifically for mission-critical systems demanding guaranteed performance under extreme thermal, radiation, and vibration stress.

FAQ

What is the maximum guaranteed access time for HM1-6551B/883 across its full operating temperature range?

The HM1-6551B/883 has a maximum guaranteed Chip Enable Access Time (TELQV) of 220 ns at VCC = 4.5 V and –55°C to +125°C, as verified per MIL-STD-883 Group A Subgroups 9–11 testing. This value applies exclusively to the HM1-6551B/883 variant; the HM1-6551/883 variant is rated at 300 ns. HM1-6551B/883 maintains this timing without derating across the full temperature range.

Does HM1-6551B/883 require an external clock signal to operate?

No, HM1-6551B/883 is a fully static RAM and requires no clock input. All operations are controlled asynchronously by edge-triggered control signals: falling edge of E latches address and S2, while rising edge of E latches output data. HM1-6551B/883 retains data indefinitely at VCC ≥ 2.0 V with zero external timing references.

Can HM1-6551B/883 share a common data bus with other devices?

Yes, HM1-6551B/883 supports common bus operation via three-state outputs controlled independently by E, S1, or S2. When any of these signals is high, Q0–Q3 enter high-impedance state, allowing bidirectional data transfer on a shared 4-bit bus. HM1-6551B/883 also features internal latched outputs to prevent bus contention during transitions.

What is the minimum supply voltage at which HM1-6551B/883 guarantees data retention?

HM1-6551B/883 guarantees data retention at VCC ≥ 2.0 V across –55°C to +125°C, with maximum data retention current (ICCDR) of 10 µA. This specification is validated per MIL-STD-883 Method 5004 and enables battery-backed operation in systems where primary power may be interrupted for extended periods.

Is HM1-6551B/883 pin-compatible with HM1-6551/883?

Yes, HM1-6551B/883 and HM1-6551/883 share identical pinout, package (CERDIP F22.4), DC/AC specifications, and functional behavior - differing only in guaranteed access time (220 ns vs. 300 ns) and associated test conditions. No PCB or schematic changes are required when substituting HM1-6551B/883 for HM1-6551/883 in new designs.