Microchip Technology 25LC320AX-I/ST

Overview

25LC320AX-I/ST from Microchip Technology Inc. is a 32-Kbit SPI Serial EEPROM with 4096 × 8-bit organization, 32-byte page size, and industrial temperature range (−40°C to +85°C). It operates at up to 10 MHz clock frequency with 5 mA read/write current at 5.5 V and features hardware write protection via WP pin and STATUS register control. It is used in microcontroller-based systems for nonvolatile parameter storage, calibration data retention, and firmware configuration.

For engineers reviewing the 25LC320AX-I/ST datasheet, 25LC320AX-I/ST pinout, 25LC320AX-I/ST application, or 25LC320AX-I/ST equivalent, key selection criteria include SPI interface timing compliance (T_CSS, T_SU, T_HOLD), V_CC range (2.5–5.5 V), block write protection granularity (0%, 25%, 50%, or 100% array), and AEC-Q100 qualification for automotive-grade reliability.

Technical Context

The 25LC320AX-I/ST implements a standard SPI Mode 0,0 or Mode 1,1 interface with separate SI (data-in) and SO (data-out) lines, CS-controlled device selection, and HOLD pin for transaction suspension without reset. Its internal architecture includes an 8-bit instruction register, page latches, and high-voltage generator for EEPROM programming.

It supports byte and page write operations (max 32 bytes/page), self-timed internal write cycles (≤5 ms), and sequential read with automatic address incrementing. Write enable requires explicit WREN instruction, and write protection is enforced via both volatile WEL bit and nonvolatile BP0/BP1 bits in the STATUS register, configurable via WRSR.

Key Specifications

Pinout & Package

25LC320AX-I/ST is supplied in an 8-lead TSSOP package (3.0 mm × 4.4 mm body, 0.65 mm pitch), RoHS-compliant and marked "25LC320A" with "I" temperature grade and "ST" package code.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar serial EEPROM applications.

Compared with 25AA320AT-I/ST, the 25LC320AX-I/ST offers automotive qualification and tighter V_CC minimum but excludes 1.8 V operation; versus AT25DF321A-SH-B, it provides deterministic SPI timing, hardware write protection, and direct drop-in replacement capability in legacy 32 Kbit designs.

Availability

25LC320AX-I/ST is available at Aetrix Electronics and suitable for automotive body control modules, industrial sensor nodes, medical infusion pumps, and smart energy meters requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant reliability.

Supply support for 25LC320AX-I/ST 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

Microchip Technology Inc. is a leading provider of microcontrollers, analog devices, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25LC320A product line delivers cost-effective, SPI-compatible serial EEPROMs optimized for industrial and automotive applications demanding robust data retention, flexible write protection, and seamless integration with PIC® and other SPI-capable MCUs.

FAQ

What is the maximum clock frequency supported by the 25LC320AX-I/ST?

The 25LC320AX-I/ST supports up to 10 MHz clock frequency when V_CC is between 4.5 V and 5.5 V. At lower supply voltages (2.5–4.5 V), the maximum clock drops to 5 MHz, and at 1.8–2.5 V, it is limited to 3 MHz. These derating values are specified in Table 1-2 of the DS20001828H datasheet and ensure reliable setup/hold timing margins across operating conditions. The 25LC320AX-I/ST must be operated within these limits to guarantee correct SPI communication and internal write-cycle completion.

Does the 25LC320AX-I/ST require external pull-up resistors on its SPI lines?

The 25LC320AX-I/ST does not require external pull-ups on SO, SI, or SCK - these pins are actively driven. However, CS and WP are active-low inputs with internal weak pull-ups disabled by default; external pull-ups (typically 4.7 kΩ to V_CC) are recommended for CS to prevent spurious selection during power-up and for WP to ensure predictable write-protection state when not actively driven. HOLD also benefits from a pull-up to avoid unintended hold activation. These recommendations are consistent with Microchip's layout guidelines in AN1179 and DS20001828H Section 4.0.

How does the HOLD function behave during an active write cycle in the 25LC320AX-I/ST?

The HOLD function is disabled during an internal write cycle in the 25LC320AX-I/ST: pulling HOLD low after CS has gone high to initiate writing has no effect on the ongoing self-timed 5 ms erase/write operation. The device ignores HOLD transitions until the write completes and returns to standby. This behavior is explicitly documented in Section 2.6 and Figure 1-1 of DS20001828H. Therefore, the 25LC320AX-I/ST must rely on software polling of the WIP bit (via RDSR) or timeout-based waiting - not HOLD - to manage write completion.

Can the 25LC320AX-I/ST be used in a 1.8 V system?

No, the 25LC320AX-I/ST is not rated for 1.8 V operation. Its specified V_CC range is 2.5 V to 5.5 V, as confirmed in the Device Selection Table and Table 1-1 of DS20001828H. Attempting to operate the 25LC320AX-I/ST below 2.5 V may result in unreliable read/write behavior, failed status register reads, or incomplete write cycles. For 1.8 V systems, the pin-compatible 25AA320A family (e.g., 25AA320AT-I/ST) is the appropriate alternative, offering identical functionality with 1.8 V minimum supply.

What package type does the 25LC320AX-I/ST use, and is it RoHS-compliant?

The 25LC320AX-I/ST uses an 8-lead TSSOP package (3.0 mm × 4.4 mm body, 0.65 mm pitch), identified by the "ST" suffix in the part number and confirmed in the Package Types section of DS20001828H. It is RoHS-compliant, as stated in the Features list on page 1 and verified by Microchip's packaging documentation. The package marking includes "25LC320A", temperature grade "I", and traceability codes - all consistent with Microchip's standard industrial-grade TSSOP labeling convention.