Microchip Technology AT17N256-10NC

Overview

AT17N256-10NC from Atmel is a 256-Kbit serial EEPROM FPGA configuration memory, operating at 3.3V ±10%, compatible with Xilinx Spartan-II/IIE/XL FPGAs in Master Serial mode, featuring pin compatibility with XC17SXXXA/L PROMs and low-power standby current of ≤50 µA.

For engineers reviewing the AT17N256-10NC datasheet, AT17N256-10NC pinout, AT17N256-10NC application, or AT17N256-10NC equivalent, this device serves as a drop-in replacement for legacy Xilinx-compatible configuration PROMs in industrial-grade FPGA boot systems requiring 20-year data retention and 10K write endurance.

Technical Context

The AT17N256-10NC implements a serial-access architecture synchronized to FPGA CCLK, using CE and RESET/OE to control address counter enablement and DATA output tri-state behavior. Its SER_EN pin selects between FPGA loading (SER_EN = High) and Two-Wire ISP programming (SER_EN = Low).

It supports Master Serial configuration mode only - no slave or JTAG interface - and relies on FPGA-driven timing with guaranteed TCAC ≤80 ns (Commercial), THCE = 0 ns hold requirement, and FMAX = 10 MHz clock rate. Internal voltage generation enables in-system programming without external high-voltage supplies.

Key Specifications

Pinout & Package

AT17N256-10NC is packaged in an 8-lead SOIC (JEDEC 8S1, 0.150" wide body), with gull-wing leads, 1.27 mm pitch, and thermal resistance θJA = 150°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FPGA configuration memory applications.

Compared with AT17N256-10NC, AT17LV256-10CU offers broader voltage flexibility and higher endurance but shares identical footprint and FPGA interface behavior, whereas XC17S256A provides pin-for-pin compatibility at the cost of permanent programming - making AT17N256-10NC the optimal balance of reusability, industrial rating, and drop-in legacy support.

Availability

AT17N256-10NC is available at Aetrix Electronics and suitable for industrial automation, FPGA-based motor control, and legacy test equipment requiring stable component supply with verified 20-year data retention and industrial temperature operation.

Supply support for AT17N256-10NC 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 semiconductor manufacturer specializing in microcontrollers, nonvolatile memory, and FPGA configuration solutions.

The AT17N series was designed specifically to replace Xilinx OTP PROMs in SRAM-based FPGA configuration systems, emphasizing pin compatibility, industrial reliability, and seamless integration into Master Serial boot architectures.

FAQ

What is the primary function of the AT17N256-10NC in an FPGA system?

The AT17N256-10NC serves as a serial configuration EEPROM that stores and delivers the bitstream to SRAM-based FPGAs (e.g., Xilinx Spartan-II/IIE/XL) during power-up in Master Serial mode. It interfaces directly with FPGA control signals (CCLK, DIN, CE, RESET/OE) and requires no external controller. The AT17N256-10NC ensures deterministic, self-contained FPGA initialization with guaranteed timing compliance and industrial-grade reliability.

Is the AT17N256-10NC pin-compatible with Xilinx XC17S256A PROMs?

Yes, the AT17N256-10NC is explicitly pin-compatible with Xilinx XC17SXXXA and XC17SXXXXL PROMs, including XC17S256A. Pin assignments, signal names (DATA, CLK, RESET/OE, CE), and timing parameters match exactly per Atmel's datasheet Table 1 and Pin Configuration diagrams. This allows direct substitution without PCB modification, preserving existing layout and FPGA interface logic.

How does the SER_EN pin affect the operation of the AT17N256-10NC?

The SER_EN pin determines operational mode: when held High (tied to VCC), the AT17N256-10NC operates in FPGA configuration mode; when pulled Low, it enters Two-Wire Serial Programming mode for in-system reprogramming. SER_EN is not used during normal FPGA boot - incorrect SER_EN state prevents configuration. The AT17N256-10NC datasheet mandates SER_EN = VCC for reliable Master Serial operation.

What is the maximum clock frequency supported by the AT17N256-10NC?

The AT17N256-10NC supports a maximum clock frequency of 10 MHz in Commercial temperature range (0°C to +70°C) and 10 MHz in Industrial range (-40°C to +85°C), as specified in the AC Characteristics table. This matches the CCLK timing requirements of Spartan-II FPGAs. Exceeding 10 MHz may violate TCAC (CLK-to-Data delay) and cause configuration failure. The AT17N256-10NC does not support higher frequencies even with reduced load.

Can the AT17N256-10NC be used in new designs, or is it obsolete?

The AT17N256-10NC remains available and functional but is designated "Not Recommended For New Design" per Atmel's migration notice, superseded by AT17LV256-10CU. However, it is fully supported for legacy design refresh, repair, and continuity programs. Aetrix Electronics maintains active inventory and supply chain visibility for AT17N256-10NC, ensuring long-term availability for industrial customers maintaining existing systems.