AT27C512R-45JU

AT27C512R-45JU is Atmel/Microchip’s 512-kbit parallel EPROM. It stores 64K × 8 data, accessed via an 8-bit data bus with 16 address lines (A0–A15).
Key features:
- Density/organization: 512 Kbits, 64K bytes, 8-bit wide
- Speed: -45 means ~45 ns access time
- Interface: CE (Chip Enable), OE (Output Enable), WE (Write Enable); VCC and VPP (programming voltage)
- Voltage: VCC typically 4.5–5.5 V; programming voltage VPP ~12.5 V
- Erasable: UV-erasable PROM (windowed package) — requires UV light to erase before reprogramming
- Package: JU suffix denotes a 28-pin package (exact type varies by vendor)
Usage notes:
- Read: CE and OE active, WE inactive
- Program/Erase: apply VPP and follow the proper programming sequence; requires UV exposure to erase
- Commonly used for firmware storage or boot code in older systems; many designs have migrated to serial Flash
For exact pinout, timing, and programming procedure, consult the datasheet for the -45JU variant.

Equivalent parts (512 Kbit, 64K×8, 5V, 45 ns, DIP-28, same pinout):
- AM27C512 (AMD)
- M27C512 (ST/Microelectronics lineage)
- MX27C512 (Macronix)
- W27C512 (Winbond)
- F27C512 (Fujitsu)
Note: voltage, speed grade, and lot codes may vary slightly; check datasheets for exact package codes.

AT27C512R-45JU is a 512‑Kbit windowed UV‑EPROM. Key features:
- Memory: 64K x 8 (512 Kbit total)
- Type: UV‑erasable, windowed EPROM
- Speed: 45 ns access time
- Interface: 8‑bit data bus; A0–A15; CE and OE controls
- Power: Vcc = 5V; Vpp programming voltage ≈ 12.5V
- Package: 28‑pin ceramic DIP (JU)
- Data retention: long‑term retention; rewrite by UV erase and reprogram
- Applications: code/firmware storage (BIOS, embedded systems)

- Pin count: 28 pins (DIP package 28).
- Function: 512-kbit parallel-EPROM memory (64K × 8) with address (A0–A15), data (D0–D7), and control pins (CE, OE, WE), plus Vcc, Gnd, and programming voltage (VPP) for firmware storage.

Manufacturer: Atmel Corporation (now part of Microchip Technology). What kind of company: an American semiconductor company that designs and manufactures memory ICs (e.g., EPROM/ROM), microcontrollers, and other embedded processing products; acquired by Microchip in 2016.

Typical application areas for AT27C512R-45JU:
- Firmware storage for microcontroller and embedded systems (boot code, application code)
- BIOS-like firmware in consumer electronics (set-top boxes, printers, audio/video gear)
- Lookup tables and calibration data in automotive, industrial, and instrumentation equipment
- Prototyping, development, and replacement for legacy PROM-based designs
- Non-volatile storage for fixed software in test equipment, networking hardware, and appliances
Notes: it is a 512-kbit UV-erasable EPROM with 64K x 8 organization and 45 ns access time, used where permanent, reprogrammable firmware is required during development or deployment.

28-pin ceramic DIP (windowed) UV-erasable EPROM package.