Microchip Technology AT17C256-10SC

Overview

AT17C256-10SC from Atmel is a 256 Kbit (262,144 × 1-bit) serial EEPROM FPGA configuration memory with 5V ±5% supply, 12.5 MHz max clock frequency, programmable reset polarity, and cascading CEO support for multi-FPGA daisy-chain loading in Master Serial Mode.

For engineers reviewing the AT17C256-10SC datasheet, AT17C256-10SC pinout, AT17C256-10SC application, or AT17C256-10SC equivalent, key selection factors include its 20-lead SOIC package, in-system programmability via 2-wire bus, compatibility with Xilinx XC3000/XC4000/SPARTAN®, Altera FLEX®, and Atmel AT40K/AT6000 FPGAs, and cascading capability for extended configuration storage.

Technical Context

The AT17C256-10SC operates in FPGA Master Serial Mode, where the FPGA's CCLK drives the device's CLK input and DATA output feeds the FPGA's DIN. Its CEO output enables daisy-chained configuration of multiple FPGAs or higher-density arrays.

It supports two reset configurations: active-High or active-Low, programmable via internal EEPROM byte; SER_EN must be held High during configuration but pulled Low to enter 2-wire ISP mode. CE assertion places the device in low-power standby (<75 µA at 5V), disabling address counters and tri-stating DATA.

Key Specifications

Pinout & Package

AT17C256-10SC is packaged in a 20-lead, 0.300" wide plastic gull-wing small outline (SOIC), JEDEC standard 20S footprint, pin-compatible across the AT17C/LV65/128/256 family.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT17C256-10SI, the AT17C256-10SC offers lower cost and identical functionality within commercial temperature limits; compared with XCR3256XL-10VQG100I, it preserves existing FPGA-centric design while delivering dedicated, field-upgradable nonvolatile configuration storage.

Availability

AT17C256-10SC is available at Aetrix Electronics and suitable for industrial PLCs, Xilinx SPARTAN®-based test equipment, and Altera FLEX®-enabled telecom infrastructure requiring stable component supply and long-lifecycle support.

Supply support for AT17C256-10SC 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 AT17 Series was designed specifically to provide cost-effective, serial, in-system programmable configuration memory for SRAM-based FPGAs including Xilinx, Altera, and Atmel families.

FAQ

What is the primary function of the AT17C256-10SC in an FPGA-based system?

The AT17C256-10SC serves as a dedicated serial configuration EEPROM that stores and delivers the bitstream to SRAM-based FPGAs (e.g., Xilinx SPARTAN®, Altera FLEX®) during power-up or reset. It operates in Master Serial Mode, where the FPGA generates CCLK to clock data from the AT17C256-10SC's DATA pin into its DIN pin. Its 256 Kbit capacity supports medium-complexity FPGA designs, and its CEO output enables cascading for larger configurations.

Can the AT17C256-10SC be used with 3.3V FPGAs?

No - the AT17C256-10SC is a 5V-only device (VCC = 5V ±5%). For 3.3V systems, use the pin-compatible AT17LV256-10SC, which operates at 3.3V ±10% and shares identical pinout, timing structure, and feature set. Mixing AT17C256-10SC with 3.3V FPGA I/O may violate absolute maximum ratings and cause reliability issues.

How does the programmable reset polarity of the AT17C256-10SC simplify system design?

The AT17C256-10SC allows users to configure the RESET/OE pin as either active-High or active-Low via internal EEPROM programming. This eliminates the need for external inverters in reset signal routing - for example, when interfacing with an FPGA that asserts an active-Low reset, the AT17C256-10SC can be programmed for active-Low RESET/OE, ensuring synchronous address counter reset without added components or board space.

Is the AT17C256-10SC pin-compatible with other devices in the AT17C/LV65/128/256 family?

Yes - all AT17C and AT17LV variants (65K/128K/256K) share identical pinouts across package types (20J PLCC, 20S SOIC, 8P3 PDIP, 8S1 SOIC). The AT17C256-10SC in 20S SOIC is mechanically and electrically compatible with AT17C128-10SC and AT17C65-10SC in the same package, enabling layout reuse and simplified BOM management across density tiers.

What is the role of the SER_EN pin on the AT17C256-10SC, and how should it be connected?

SER_EN is a mode-select input: when held High, the AT17C256-10SC operates in normal FPGA configuration mode; when pulled Low, it enters 2-wire serial programming mode for in-system bitstream updates. During FPGA operation, SER_EN must be tied to VCC. Leaving it floating or incorrectly biased risks unintended entry into programming mode, halting configuration and potentially corrupting memory contents.