27C512QC-55 - 512Kbit 64Kx8 CMOS UV EPROM 55ns | Macronix
N.º de pieza: 27C512QC-55 ✗ Fin de vida| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $6.5 | $6,50 |
| 10 | $5.85 | $58,50 |
| 100 | $5.2 | $520,00 |
| 500 | $4.68 | $2.340,00 |
| 1.000 | $4.22 | $4.220,00 |
27C512QC-55 Descripción general
An EPROM (Erasable Programmable Read-Only Memory) is a non-volatile semiconductor memory that retains programmed data without power. Data is written electrically and erased in bulk by exposure to ultraviolet light through the quartz window for approximately 15-20 minutes, making EPROMs ideal for firmware development where occasional pattern updates are needed. In the memory hierarchy, EPROM sits between one-time-programmable OTP ROM and electrically erasable EEPROM/flash memory.
Key features include the 64K x 8 organization, single +5V read supply, fast 55 ns access time for zero-wait-state operation with 8- and 16-bit microprocessors, totally static operation requiring no clocks, and completely TTL-compatible inputs and outputs. The family is offered in 45/55/70/90/100/120/150 ns speed grades, so designers can trade speed against cost.
The device uses a standard 28-pin JEDEC EPROM pinout with 15 address lines (A0-A14), eight data lines (D0-D7), chip enable, and output enable/programming voltage pins. CMOS technology gives low standby power compared with earlier NMOS 27-series parts. Programming follows the standard 27C512 algorithm with VPP at +12.5V.
Typical applications include legacy embedded system firmware, retro-computing and arcade board restoration, industrial controller boot code, and telecommunication equipment character storage.
When designing with the 27C512QC-55, ensure address setup and output enable access margins meet the host microprocessor timing; for -55 grade devices at 5V, worst-case access of 55 ns must be guaranteed across the full temperature range.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Alternativas directas para 27C512QC-55 — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Variantes de esta serie
Modelos de la misma serie compatibles directamente con 27C512QC-55 (mismo factor de forma y huella) — difiere en Memory Type, Package, Organization, Access Time, Control Signals.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
27C512QC-45
✅ Sustitución directa ⚠️ Especificaciones sin verificar📋 Alternativa de referencia (no en el catálogo)
27C512QC-70
✅ Sustitución directa ⚠️ Especificaciones sin verificar📋 Alternativa de referencia (no en el catálogo)
27C512QC-90
✅ Sustitución directa ⚠️ Especificaciones sin verificar📋 Alternativa de referencia (no en el catálogo)
27C512-20
✅ Sustitución directa✓ En stock
$4.1 / unidad
Ver hoja de datos →27C512-25-X
✅ Sustitución directa✓ En stock
$2.95 / unidad
Ver hoja de datos →27C512-15FA
✅ Sustitución directa✓ En stock
$1.65 / unidad
Ver hoja de datos →M27C512
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
27C512QC-55 Valores máximos y características eléctricas
| Memory Organization | 512K-bit (64K x 8) |
| Tipo de memoria | CMOS UV EPROM |
| Access Time | 55 ns |
| Supply Voltage (Read) | Single +5 V |
| Programming Voltage (VPP) | +12.5 V |
| Family Speed Grades | 45/55/70/90/100/120/150 ns |
| Operation | Totally static |
| Interface Compatibility | Completely TTL compatible |
| Address Bus | A0 to A14 (15 lines) |
| Data Bus | D0 to D7 (8 lines, bidirectional 3-state) |
| Encapsulado | 28-pin ceramic DIP with quartz window (QC) |
| Erase Method | Ultraviolet light through quartz window |
| Tipo de montaje | Through Hole |
Configuración de pines de 27C512QC-55
| Pin 1 | A15 — Address input bit 15 |
| Pin 2 | A12 — Address input bit 12 |
| Pin 3 | A7 — Address input bit 7 |
| Pin 4 | A6 — Address input bit 6 |
| Pin 5 | A5 — Address input bit 5 |
| Pin 6 | A4 — Address input bit 4 |
| Pin 7 | A3 — Address input bit 3 |
| Pin 8 | A2 — Address input bit 2 |
| Pin 9 | A1 — Address input bit 1 |
| Pin 10 | A0 — Address input bit 0 |
| Pin 11 | D0 — Data input/output bit 0 (3-state) |
| Pin 12 | D1 — Data input/output bit 1 (3-state) |
| Pin 13 | D2 — Data input/output bit 2 (3-state) |
| Pin 14 | GND — Ground reference |
| Pin 15 | D3 — Data input/output bit 3 (3-state) |
| Pin 16 | D4 — Data input/output bit 4 (3-state) |
| Pin 17 | D5 — Data input/output bit 5 (3-state) |
| Pin 18 | D6 — Data input/output bit 6 (3-state) |
| Pin 19 | D7 — Data input/output bit 7 (3-state) |
| Pin 20 | E — Chip enable (active low) |
| Pin 21 | A10 — Address input bit 10 |
| Pin 22 | OE/VPP — Output enable (active low) / programming voltage +12.5V |
| Pin 23 | A11 — Address input bit 11 |
| Pin 24 | A9 — Address input bit 9 |
| Pin 25 | A8 — Address input bit 8 |
| Pin 26 | A13 — Address input bit 13 |
| Pin 27 | A14 — Address input bit 14 |
| Pin 28 | VCC — +5V power supply |
Aplicaciones típicas
27C512QC-55 es adecuado para 6 aplicacións: Legacy Embedded Firmware Storage, Retro-Computing and Arcade Board Restoration, Industrial Controller Boot Code, Telecommunications Equipment Character Storage, Test and Measurement Instrument Firmware, Educational and Development Platforms.
Legacy Embedded Firmware Storage
The 27C512QC-55 stores boot code and application firmware in 8-bit and 16-bit microprocessor systems where a 64K x 8 non-volatile code space is required. Its 55 ns access time supports zero-wait-state fetch at common legacy CPU clock rates, while TTL-compatible 3-state outputs connect directly to the processor bus. The quartz window allows engineers to erase with UV light and reprogram during development, making it well suited to firmware iteration before committing to OTP parts. Because it is totally static and draws minimal standby current from the single +5V rail, it fits battery-backed industrial controllers. One consideration: at end of life, plan a last-time-buy or qualify a pin-compatible substitute for long-term production.
Recomendado
Retro-Computing and Arcade Board Restoration
Vintage computers, game consoles, and arcade PCBs from the 1980s and 1990s rely on 27C512-class EPROMs for game code and BIOS images. The 27C512QC-55 matches the JEDEC 28-pin DIP socket, +5V supply, and 55 ns timing expected by these boards, allowing direct replacement of corrupted or dead ROMs. Community repair guides note that used EPROMs frequently fail programming, so fresh windowed parts like this one are preferred. The quartz window enables repeated re-burning when testing ROM hacks or patched images. Use a verified ROM dump, confirm checksum after programming, and verify the board speed grade - faster grades always substitute safely into slower sockets.
Recomendado
Industrial Controller Boot Code
Programmable logic controllers, motor drives, and instrumentation often hold initialization and diagnostic code in a 64K x 8 EPROM. The 27C512QC-55 offers the wide temperature tolerance of a hermetic ceramic cerdip package, high immunity to data corruption in electrically noisy factory environments, and a simple parallel bus interface with TTL levels. The 55 ns access time covers address decoding through 74-series logic without penalty. Field-service technicians can erase the windowed device under UV and re-burn updated firmware without soldering changes. Designers should add a pull-up on chip enable to prevent bus contention during power-up sequencing and keep address lines short to preserve the 55 ns timing margin.
Recomendado
Telecommunications Equipment Character Storage
Legacy telecom line cards, modems, and PBX boards used 27C512 EPROMs for character tables, dialing code sets, and firmware. The 27C512QC-55's single +5V operation integrates directly into telecom backplane power schemes, and its totally static CMOS core avoids clock-related noise in sensitive analog front ends. With a 55 ns access time, table lookups complete within a single processor cycle. The UV-erasable ceramic package suits equipment that undergoes periodic field firmware updates by swapping pre-programmed devices. When maintaining such systems, keep spare programmed devices on hand, since erase-and-program cycles are limited and lamp aging affects erase consistency across production lots.
Recomendado
Test and Measurement Instrument Firmware
Bench instruments such as oscilloscope front panels, function generators, and data loggers stored operating firmware and lookup tables in 27C512 EPROMs. The 27C512QC-55 provides deterministic 55 ns access for microcoded state machines, TTL-compatible outputs that directly drive legacy bus transceivers, and stable data retention without refresh. Its ceramic windowed package lets calibration engineers revise firmware during instrument refurbishment. The single +5V supply simplifies retrofit into aging power rails. For instruments with 12-16 MHz CPUs, confirm the 55 ns timing meets the CPU cycle budget including decode delays; otherwise select the 27C512QC-45 grade, which substitutes pin-for-pin with an 18% faster access time.
Recomendado
Educational and Development Platforms
EPROM-based development boards remain a practical teaching tool for computer architecture courses because students can observe the full program-erase-verify cycle. The 27C512QC-55's quartz window demonstrates UV erasure physically, its 12.5V VPP programming illustrates early non-volatile memory physics, and its JEDEC 28-pin footprint fits standard breadboard adapters and universal programmers. The 64K x 8 map is large enough for meaningful programs yet simple to navigate in a hex editor. Because the device is static and TTL compatible, it connects to common 8-bit trainers without glue-logic complexity. Budget for a UV eraser and programmer, and note that erase cycles should be limited to preserve long-term reliability.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para 27C512QC-55 — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | 27C512QC-45 | 27C512-20 | 27C512-25-X | 27C512-15FA | M27C512 |
|---|---|---|---|---|---|---|
| Package | 28-pin ceramic DIP with quartz window (QC) | 28-pin ceramic DIP with quartz window - same | DIP-28 - same pinout | DIP-28 - same pinout | DIP-28 - same pinout | DIP-28 (UV/OTP variants) - same JEDEC pinout |
| Brand | Macronix International | Macronix International | Macronix International | Macronix International | Macronix International | STMicroelectronics |
| Organization | 64K x 8 (512 Kbit) | 64K x 8 | 64K x 8 | 64K x 8 | 64K x 8 | 64K x 8 (65536 x 8) |
| Read Supply Voltage | Single +5 V | Single +5 V | Single +5 V | Single +5 V | Single +5 V | Single +5 V |
| I/O Compatibility | TTL compatible, static | TTL compatible, static | TTL compatible, static | TTL compatible, static | TTL compatible, static | TTL compatible |
Diferenciadores clave
- Faster access in same ceramic windowed package (frente a 27C512QC-70)
- UV-erasable and reprogrammable for development (frente a M27C512 (OTP variants))
- Cross-brand pin compatibility widens sourcing (frente a M27C512)
Notas de diseño
Verify the 55 ns access time against your processor timing budget, including address decoder propagation (e.g., 74HC138 delay) and bus transceiver delays. Estimated: a 12 MHz 80C31 with ALE-based addressing leaves roughly 83 ns per cycle; subtracting decoder and latch delays of 20-30 ns leaves little margin over the 55 ns ROM access, so choose the 27C512QC-45 grade if measured margin is under 10 ns. Always validate at worst-case VCC (-5%) and maximum temperature.
Decouple VCC with a 0.1 uF ceramic capacitor placed within 10 mm of pin 28. Although CMOS EPROMs draw low standby current, output drivers switching 8 data lines can cause supply transients during zero-wait-state instruction fetch. Pull the chip enable pin high through a 10 kOhm resistor during power-up so the 3-state outputs stay off until the CPU bus is initialized, preventing bus contention with RAM or peripherals sharing the data bus.
Program only with VPP at +12.5V per the 27C512 algorithm - applying higher programming voltages permanently damages the cell array. Ensure the UV erasure window is covered with an opaque label in the field; ambient fluorescent light and direct sunlight will slowly erase data over months of exposure. Used or unmarked EPROMs frequently fail programming or have partially erased cells, so verify a blank read of FF hex in every location before programming production devices.
Información de cumplimiento
Legacy ceramic cerdip EPROM predating RoHS; provided web data does not state compliance status. Ceramic packaging historically used leaded glass seals - confirm with manufacturer for RoHS-restricted applications.
