My Inquiry
My Account
Microchip Technology AT29C256-70TC-T
- Part No.:
- AT29C256-70TC-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT29C256-70TC-T.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,515
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
AT29C256-70TC-T from Atmel is a 256 Kbit (32K × 8) 5V-only Flash memory IC designed for in-system reprogrammability in embedded control and firmware storage applications. It delivers 70 ns read access time, supports page programming of 64 bytes in 10 ms, and operates across commercial temperature range (0°C to 70°C) in a 28-pin TSOP package with CMOS/TTL-compatible I/O.
For engineers reviewing the AT29C256-70TC-T datasheet, AT29C256-70TC-T pinout, AT29C256-70TC-T application, or AT29C256-70TC-T equivalent, key selection criteria include its 5V-only reprogramming architecture, hardware/software data protection, DATA polling and toggle-bit end-of-write detection, and compatibility with legacy 8-bit microcontroller bus interfaces.
Technical Context
The AT29C256-70TC-T implements a nonvolatile Flash PEROM architecture using Atmel's advanced CMOS process, enabling single-cycle erase-and-program operations without external high-voltage supplies. Its internal address and data latches support 64-byte page loading, while automatic internal timers manage erase and program timing.
Operation relies on three-state control logic: CE and OE low with WE high enables read mode; WE low with CE low and OE high initiates byte load or program cycles. Hardware protection includes VCC sense (<3.8 V inhibition), 5 ms power-on delay, and noise filtering on WE/CE inputs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 256 Kbit (32,768 × 8), sufficient for boot code or configuration data in 8-bit systems |
| Read Access Time | 70 ns - enables direct replacement of SRAM or EPROM in timing-critical 5 MHz bus environments |
| Page Program Time | 10 ms per 64-byte page - reduces firmware update latency vs. sector-erase-only devices |
| VCC Supply | 5 V ± 10% - eliminates need for dedicated programming voltage rails |
| Standby Current | 300 µA CMOS - supports low-power sleep modes in battery-backed systems |
| Endurance | >10,000 write/erase cycles - suitable for field-upgradable firmware with moderate revision frequency |
| Operating Temp | 0°C to 70°C - qualified for commercial-grade industrial control panels and instrumentation |
Pinout & Package
AT29C256-70TC-T uses a 28-pin Plastic Thin Small Outline Package (TSOP, Type I, 8 mm × 13.4 mm), compliant with JEDEC MO-183. Pin 1 is marked by a beveled corner; pins 1–14 and 15–28 are on opposite long edges. PLCC and PDIP variants exist but are not applicable to this -TC suffix.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-word addressing; A0–A5 select byte within 64-byte page |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface compatible with 8051, Z80, and 68K family microcontrollers |
| CE | Chip Enable | Active-low chip select; must be low for read/write; high forces outputs to high-Z |
| OE | Output Enable | Active-low output control; used with CE to prevent bus contention during reads |
| WE | Write Enable | Active-low write strobe; controls byte load and program initiation; must be high during reads |
| VCC | Power Supply | +5 V supply pin; decoupling capacitor required near pin for stable operation |
| GND | Ground | Signal and power reference; requires low-impedance connection to system ground plane |
Key Features
| Feature | Design Value |
|---|---|
| 5V-only reprogramming | Eliminates need for +12 V programming supply, simplifying power design and reducing BOM cost |
| Hardware data protection | VCC sense, 5 ms power-on delay, and noise filtering prevent accidental writes during brown-out or EMI events |
| Software data protection | Three-byte unlock sequence (AAh/55h/A0h) required before each program cycle, preventing unintended firmware corruption |
| DATA polling & toggle bit | I/O7 complement and I/O6 toggling provide real-time, bus-compatible status feedback without requiring external timers |
| Page-based programming | 64-byte internal latching allows background bus activity during load phase, improving system responsiveness |
Applications
| Industrial PLC Firmware Storage | Medical Device Configuration Memory |
|---|---|
Use Scenario: Storing ladder logic firmware and calibration tables in programmable logic controllers with periodic field updates. IC Role / Device Role / Timing Role: Nonvolatile program memory mapped into microcontroller address space; accessed via standard 8-bit parallel bus with 70 ns timing. Use Value: Enables in-system firmware upgrades without removing the board; 10,000-cycle endurance supports multi-year maintenance cycles. |
Use Scenario: Holding device-specific calibration coefficients and safety-critical configuration parameters in portable diagnostic equipment. IC Role / Device Role / Timing Role: Secure configuration store with hardware/software write protection to prevent unauthorized parameter changes. Use Value: Prevents accidental overwrites during power transitions or ESD events; 300 µA standby current extends battery life in handheld units. |
| Automotive Body Control Module Boot Code | Legacy Industrial HMI Display Firmware |
Use Scenario: Storing boot loader and initialization routines for microcontrollers in body control modules operating at ambient temperatures up to 70°C. IC Role / Device Role / Timing Role: Primary boot ROM accessed during MCU reset; requires deterministic 70 ns read timing for fast startup. Use Value: Meets commercial temperature grade requirements while providing reliable read performance under automotive electrical noise conditions. |
Use Scenario: Replacing obsolete EPROMs in aging human-machine interface panels with fixed display firmware and menu logic. IC Role / Device Role / Timing Role: Drop-in parallel Flash replacement for 27C256 EPROMs; identical pinout and timing compatibility with 5V TTL/SRAM buses. Use Value: Eliminates UV eraser dependency and socket wear; same 28-pin TSOP footprint enables direct PCB-level retrofit without layout changes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SST39SF256-70-4C-NHE | 40-pin TSOP; 70 ns access; 5V-only; no hardware VCC sense protection | Larger package footprint; lacks built-in VCC brown-out inhibit | Preferred where higher pin count allows enhanced signal routing or future scalability |
| MX29LV256E-70G | 48-pin TSOP; 3.3 V core with 5 V I/O tolerance; 70 ns access; supports CFI query | Requires level-shifting for pure 5 V systems; adds command-set flexibility | Recommended for new designs targeting 3.3 V domains or requiring standardized flash interrogation |
Compared with SST39SF256-70-4C-NHE and MX29LV256E-70G, the AT29C256-70TC-T offers native 5 V-only operation with integrated hardware write protection and a compact 28-pin TSOP footprint-making it optimal for space-constrained, legacy 5 V embedded systems requiring proven reliability and minimal redesign effort.
Availability
AT29C256-70TC-T is available at Aetrix Electronics and suitable for industrial PLC firmware storage, medical device configuration memory, and automotive body control module boot code requiring stable component supply and long-term obsolescence management.
Supply support for AT29C256-70TC-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
Atmel Corporation (now part of Microchip Technology) is a fabless semiconductor company specializing in microcontrollers, nonvolatile memory, and security ICs, with a legacy of robust industrial-grade Flash products.
The AT29C256 product line was engineered for in-system programmable firmware storage in 8-bit embedded systems, emphasizing 5V compatibility, page-level reprogrammability, and dual hardware/software data integrity safeguards.
FAQ
What is the maximum operating frequency supported by the AT29C256-70TC-T?
The AT29C256-70TC-T does not specify a maximum clock frequency because it is an asynchronous memory device. Its timing is governed by access parameters: tACC = 70 ns, tCE = 70 ns, and tOE = 40 ns. When interfaced with a microcontroller running at 5 MHz, these timings ensure reliable read operation without wait states. The device's active current (50 mA) is characterized at 5 MHz, confirming suitability for that bus speed.
Does the AT29C256-70TC-T require external high-voltage circuitry for programming?
No, the AT29C256-70TC-T does not require external high-voltage circuitry. It is a 5-volt-only Flash memory: all programming and erase operations are executed using standard 5 V logic levels. The internal control logic interprets specific address/data sequences (e.g., AAh/55h/A0h) to initiate page programming or chip erase, eliminating the need for +12 V or other elevated programming voltages.
How is end-of-program detection implemented in the AT29C256-70TC-T?
The AT29C256-70TC-T provides two hardware-supported methods: DATA polling and the toggle bit. During programming, reading the last loaded byte returns the complement on I/O7 until completion; true data appears once finished. Alternatively, repeated reads cause I/O6 to toggle between 0 and 1 until the cycle ends, then stabilize. Both methods allow polling without external timers or status registers.
Can the AT29C256-70TC-T be used as a direct replacement for the 27C256 EPROM?
Yes, the AT29C256-70TC-T is functionally and pin-compatible with the 27C256 EPROM in 28-pin TSOP packages. It matches the 32K × 8 organization, 5 V supply, and parallel bus interface. Unlike EPROMs, it supports in-system reprogramming without UV erasure and includes hardware/software write protection-making it a drop-in upgrade for legacy designs requiring field updates.
What temperature range is specified for the AT29C256-70TC-T?
The AT29C256-70TC-T is rated for the commercial temperature range of 0°C to 70°C. This is confirmed by the "-70TC" ordering suffix (where "C" denotes commercial grade) and the DC/AC operating range table in the datasheet. It is not rated for industrial (-40°C to +85°C) operation; for that range, the AT29C256-70TI variant must be selected.
AT29C256-70TC-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- FLASH
- Technology:
- FLASH
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 10ms
- Access Time:
- 70 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSOP
AT29C256-70TC-T FAQ
1.How can I place an order for AT29C256-70TC-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C256-70TC-T on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AT29C256-70TC-T reliable?
The price and inventory of AT29C256-70TC-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C256-70TC-T is usually 5 days.
3.What payment methods are accepted for AT29C256-70TC-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C256-70TC-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C256-70TC-T?
AT29C256-70TC-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C256-70TC-T order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AT29C256-70TC-T?
For technical support, including AT29C256-70TC-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C256-70TC-T requirements.
6.How does Aetrix verify that AT29C256-70TC-T is sourced from the original manufacturer or authorized distributors?
All AT29C256-70TC-T products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AT29C256-70TC-T meets industry standards.
7.What is the process for return or replacement of AT29C256-70TC-T?
All AT29C256-70TC-T units undergo pre-shipment inspection (PSI). If there is an issue with AT29C256-70TC-T, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AT29C256-70TC-T part is unused and in its original packaging.
Return procedure for AT29C256-70TC-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT29C256-70TC-T Tags
-
M24C02-WMN6TP
STMicroelectronics
-
AT24C02C-XHM-T
Microchip Technology
-
AT21CS01-STUM10-T
Microchip Technology
-
AT24C02C-SSHM-T
Microchip Technology
-
24LC01BT-I/OT
Microchip Technology
-
M24C02-FMC6TG
STMicroelectronics
-
AT24CS02-SSHM-T
Microchip Technology
-
93LC46BT-I/OT
Microchip Technology
-
AT24C04C-SSHM-T
Microchip Technology
-
24LC01BT-I/SN
Microchip Technology
-
24AA02UIDT-I/OT
Microchip Technology
-
AT24C08C-STUM-T
Microchip Technology
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
