Microchip Technology AT17C256A-10JI

Overview

AT17C256A-10JI from Atmel is a 256-kilobit serial EEPROM FPGA configuration memory designed for Altera FLEX® devices, operating at 5V ±10% over -40°C to +85°C industrial temperature range, featuring cascading support via nCASC pin and programmable reset polarity for system-level configuration control in embedded programmable logic systems.

For engineers reviewing the AT17C256A-10JI datasheet, AT17C256A-10JI pinout, AT17C256A-10JI application, or AT17C256A-10JI equivalent, key selection criteria include 20-pin PLCC package compatibility, 12.5 MHz max clock frequency in standalone mode, cascaded configuration capability for multi-FPGA systems, and 5V industrial-grade reliability with <75 µA standby current.

Technical Context

The AT17C256A-10JI implements a dedicated serial configuration interface for Altera FLEX FPGAs using three control signals-nCS, OE, and DCLK-to drive a synchronous bitstream from its internal EEPROM array to the FPGA's DATA0 input. Its address counter and tri-state DATA output are directly synchronized to the FPGA's external clock source.

It supports both standalone and cascaded operation: when configured in a daisy chain, the nCASC output of one device drives the nCS input of the next, enabling automatic handoff after full data transfer; SER_EN must remain high during FPGA loading and is only pulled low to enter 2-wire programming mode.

Key Specifications

Pinout & Package

AT17C256A-10JI is housed in a 20-lead Plastic J-leaded Chip Carrier (PLCC) package, surface-mount compatible across the AT17A Series and mechanically interchangeable with industry-standard 20J footprints.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT17LV256A-10JI, the AT17C256A-10JI delivers faster configuration speed and simpler 5V integration; versus Altera EPC1213, it adds programmable reset polarity and 2-wire reprogrammability-critical for production test and field maintenance workflows.

Availability

AT17C256A-10JI is available at Aetrix Electronics and suitable for industrial automation, FPGA-based motor control, and automated test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AT17C256A-10JI 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, non-volatile memory, and programmable logic solutions.

The AT17A Series was designed specifically as FPGA configuration EEPROMs for Altera FLEX devices, emphasizing ease of integration, cascading scalability, and industrial-grade reliability in embedded programmable logic systems.

FAQ

What is the primary function of the AT17C256A-10JI in an FPGA-based system?

The AT17C256A-10JI serves as a dedicated serial configuration memory that stores and delivers the bitstream required to configure Altera FLEX® FPGAs at power-up. It interfaces directly with FPGA control pins (nCS, OE, DCLK, DATA0) and operates without external intelligence-enabling autonomous, repeatable initialization. Its 256-kilobit capacity supports mid-range FLEX devices like EPF8K, and the AT17C256A-10JI is optimized for 5V industrial environments with guaranteed operation from -40°C to +85°C.

Can the AT17C256A-10JI be used in a cascaded configuration with other AT17C256A-10JI devices?

Yes, the AT17C256A-10JI supports cascading via its nCASC output pin, which goes active-Low when its internal address counter reaches maximum value. In a daisy-chain setup, this signal drives the nCS input of the next AT17C256A-10JI device, enabling automatic handoff of configuration data. The AT17C256A-10JI's cascaded AC characteristics specify 10 MHz max clock frequency and 35–40 ns nCASC propagation delay-ensuring timing-compliant multi-device operation without external logic.

What does the SER_EN pin do on the AT17C256A-10JI, and when must it be asserted?

The SER_EN pin on the AT17C256A-10JI enables 2-wire serial programming mode: it must be driven Low to allow in-system reprogramming of the EEPROM array using standard programmers or Atmel's ATDH2200E kit. During normal FPGA configuration, SER_EN must remain High to ensure proper operation of the nCS/OE/DCLK control interface. Asserting SER_EN Low during configuration disrupts timing and may cause FPGA configuration failure-so the AT17C256A-10JI requires strict separation between programming and runtime modes.

How does the programmable reset polarity feature work on the AT17C256A-10JI?

The AT17C256A-10JI allows users to program the OE pin's functional polarity-either as active-High output enable or active-Low reset-by writing a specific byte during 2-wire programming. For Altera FLEX applications, it must be set to active-Low reset to synchronize with the FPGA's nCONFIG signal. This eliminates external inverters and simplifies timing alignment. The setting persists through power cycles and is verified during programming using industry-standard algorithms supported by the AT17C256A-10JI's EEPROM architecture.

Is the AT17C256A-10JI pin-compatible with the AT17LV256A-10JI?

No, the AT17C256A-10JI is not pin-compatible with the AT17LV256A-10JI despite identical 20-pin PLCC packaging and shared pin numbering. They differ electrically: AT17C256A-10JI operates at 5V ±10% with 12.5 MHz standalone clock speed, while AT17LV256A-10JI requires 3.3V ±10% and runs at 10 MHz max in cascade mode. Interchanging them risks overvoltage damage or timing failure. The AT17C256A-10JI and AT17LV256A-10JI share footprint but require separate PCB designs and power delivery networks.