Microchip Technology AT28BV64B-20JU-T

Overview

The AT28BV64B-20JU-T from Microchip Technology (formerly Atmel) is a 64 Kbit (8K × 8) parallel EEPROM with battery-voltage operation, JEDEC-standard byte-wide pinout, and software/hardware data protection. It delivers 200 ns read access time, 10 ms maximum page write cycle time, and operates across -40°C to +85°C industrial temperature range using a single 2.7V–3.6V supply. It is used in embedded systems requiring nonvolatile parameter storage with robust write-cycle control.

For engineers reviewing the AT28BV64B-20JU-T datasheet, AT28BV64B-20JU-T pinout, AT28BV64B-20JU-T application, or AT28BV64B-20JU-T equivalent, key selection criteria include its 64-byte page write capability, DATA polling and toggle-bit write completion detection, CMOS standby current of ≤20 µA, and green (Pb/Halide-free) 28-lead SOIC packaging.

Technical Context

The AT28BV64B-20JU-T functions as a static RAM-compatible parallel EEPROM: reads require CE and OE low with WE high; writes initiate on WE or CE low pulse while OE is high. Its internal 64-byte page register latches addresses and data for simultaneous multi-byte programming without bus hold.

Write operations require a three-byte Software Data Protection (SDP) command sequence (0x555 → 0x2AA → 0x555) before each byte or page write. End-of-write detection is supported via I/O7 DATA polling (complement-to-data) or I/O6 toggle-bit behavior-both usable at any point during t_WC.

Key Specifications

Pinout & Package

AT28BV64B-20JU-T is supplied in a 28-lead SOIC (28S) package per JEDEC MS-013, 0.300" body width, green (Pb/Halide-free) construction.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar parallel EEPROM applications.

Compared with ST M48T02-20MH1 and CAT28C64B-20L, the AT28BV64B-20JU-T uniquely combines software data protection, 64-byte page write, and 20 µA standby in a JEDEC-standard footprint - making it optimal for secure, low-power, field-upgradable embedded systems without RTC needs.

Availability

AT28BV64B-20JU-T is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostics equipment, telecom line cards, and automotive body control modules requiring stable component supply and long-term lifecycle support.

Supply support for AT28BV64B-20JU-T 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

Microchip Technology acquired Atmel in 2016 and maintains full product support, documentation, and manufacturing continuity for the AT28BV64B family.

The AT28BV64B series was designed as a drop-in upgrade path for legacy parallel EEPROMs in industrial and telecom systems, emphasizing low-voltage operation, write-cycle reliability, and JEDEC-compliant interoperability.

FAQ

What is the correct power-up sequence for reliable operation of the AT28BV64B-20JU-T?

The AT28BV64B-20JU-T requires VCC to stabilize above 1.8 V before enabling CE, OE, or WE. The device incorporates an internal 10 ms power-on delay after VCC reaches threshold, during which all write operations are inhibited. To ensure robust initialization, hold CE high and OE/WE high until ≥15 ms after VCC reaches 2.7 V. This prevents spurious writes during rail ramp-up and aligns with the hardware write-inhibit specification in the AT28BV64B-20JU-T datasheet.

Does the AT28BV64B-20JU-T support true random-access byte writes without page constraints?

Yes, the AT28BV64B-20JU-T supports individual byte writes: a single WE pulse with valid address and data initiates a self-timed byte programming cycle (≤10 ms). However, each byte write still requires the full three-byte Software Data Protection (SDP) unlock sequence. Unlike page writes, byte writes do not restrict address alignment or require consecutive timing - making AT28BV64B-20JU-T suitable for infrequent, scattered configuration updates.

How is end-of-write detection implemented in the AT28BV64B-20JU-T, and can both methods be used simultaneously?

The AT28BV64B-20JU-T provides two independent end-of-write detection mechanisms: DATA polling on I/O7 (returns complement of written data until completion) and toggle-bit monitoring on I/O6 (toggles between 0/1 until completion). Both methods are fully functional during the same write cycle and may be polled concurrently. No hardware configuration is needed - detection begins immediately after write initiation and remains valid throughout t_WC, allowing flexible host firmware implementation for the AT28BV64B-20JU-T.

What is the purpose and access method for the additional 64 bytes of device identification memory in the AT28BV64B-20JU-T?

AT28BV64B-20JU-T includes 64 bytes of dedicated identification EEPROM (addresses 0000H–003FH) accessible only when A9 is raised to 12.0 V ± 0.5 V. This high-voltage enable prevents accidental overwrite during normal 2.7–3.6 V operation. Once enabled, the ID region is read/written identically to main array memory - used for storing lot traceability, calibration certificates, or unique device serial numbers. Standard 3.3 V operation leaves this region fully protected.

Is the AT28BV64B-20JU-T pin-compatible with older Atmel AT28C64B devices?

Yes, the AT28BV64B-20JU-T maintains JEDEC-approved byte-wide pinout compatibility with AT28C64B-15/20 variants in the same 28-lead SOIC package. Signal names (A0–A12, I/O0–I/O7, CE, OE, WE, GND, VCC) and physical pin positions match exactly. However, AT28BV64B-20JU-T requires the SDP unlock sequence for writes - unlike AT28C64B - so firmware must be updated to issue 0x555/0x2AA/0x555 before each write to avoid silent failure.