Microchip Technology 25LC320A-E/ST

Overview

25LC320A-E/ST from Microchip Technology Inc. is a 32-Kbit SPI Serial EEPROM with 4096 × 8-bit organization, 32-byte page size, and automotive-grade AEC-Q100 qualification for extended temperature operation (−40°C to +125°C). It operates at up to 10 MHz clock frequency with 5 mA read/write current at 5.5 V and supports hardware write protection via WP pin and STATUS register control - used in engine control units, battery management systems, and industrial sensor calibration storage.

For engineers reviewing the 25LC320A-E/ST datasheet, 25LC320A-E/ST pinout, 25LC320A-E/ST application, or 25LC320A-E/ST equivalent, key selection criteria include its AEC-Q100 Extended-temp rating, 5 ms max self-timed write cycle, block-level write protection (0%, 25%, 50%, or 100% array), and compatibility with standard SPI Mode 0,0 and Mode 1,1 interfaces on microcontroller host systems.

Technical Context

The 25LC320A-E/ST implements a serial peripheral interface with separate SI (data in) and SO (data out) lines, controlled by CS, SCK, HOLD, and WP signals. Its internal architecture includes a status register with WIP, WEL, BP0/BP1, and WPEN bits, enabling programmable block protection and hardware write-enable gating.

It supports sequential read, byte/page write, and hold-pause functionality - allowing interruption of ongoing SPI transfers without sequence restart. All operations are synchronized to SCK edges: data latched on rising edge (SI), output updated after falling edge (SO), and HOLD asserted only when SCK is low to ensure deterministic suspension.

Key Specifications

Pinout & Package

25LC320A-E/ST is packaged in an 8-lead TSSOP (Thin Shrink Small Outline Package) with 0.65 mm pitch, 3.0 mm × 4.4 mm body, and exposed pad option (not electrically connected per datasheet Note 1).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA320A-I/ST, the 25LC320A-E/ST trades 1.8 V operation for AEC-Q100 validation and extended temperature support - essential for powertrain systems. Versus AT25DF321A-SH-B, it offers simpler SPI protocol, deterministic 5 ms writes, and hardware safety features at lower density - better suited for parameter storage than executable code.

Availability

25LC320A-E/ST is available at Aetrix Electronics and suitable for automotive powertrain control, industrial sensor calibration, and medical device data logging requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 25LC320A-E/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 U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and memory products, with global design and manufacturing infrastructure.

The 25LC320A belongs to Microchip's serial EEPROM product line, engineered for reliable nonvolatile data storage in harsh environments - particularly targeting automotive, industrial, and medical applications demanding AEC-Q100 compliance and long-term data integrity.

FAQ

What is the maximum clock frequency supported by the 25LC320A-E/ST?

The 25LC320A-E/ST supports up to 10 MHz clock frequency when VCC is 4.5 V to 5.5 V. At 2.5 V ≤ VCC < 4.5 V, maximum clock drops to 5 MHz; below 2.5 V, it is rated for 3 MHz. These limits are defined in Table 1-2 AC Characteristics and ensure timing margin compliance across voltage and temperature ranges.

Does the 25LC320A-E/ST require external pull-up resistors on its SPI lines?

The 25LC320A-E/ST does not require external pull-ups on SI or SCK, as these are CMOS inputs. However, SO is an open-drain output and must be pulled up externally (typically 4.7 kΩ to VCC) to ensure valid logic-high levels. CS, WP, and HOLD also benefit from weak pull-ups (10–100 kΩ) in noisy environments to prevent floating states.

How does hardware write protection work on the 25LC320A-E/ST?

Hardware write protection on the 25LC320A-E/ST activates only when both the WP pin is low AND the WPEN bit in the STATUS register is set to 1. When enabled, it blocks writes to nonvolatile STATUS register bits (BP0, BP1, WPEN) but allows normal memory reads, writes, and volatile WEL control - preserving system flexibility while securing configuration.

Can the 25LC320A-E/ST be used with a 1.8 V microcontroller?

No - the 25LC320A-E/ST has a minimum VCC of 2.5 V and is not rated for 1.8 V operation. For 1.8 V systems, consider the pin-compatible 25AA320A-I/ST variant, which supports 1.8–5.5 V but lacks AEC-Q100 qualification and extended temperature range. Direct interface without level shifting is not supported for 25LC320A-E/ST at 1.8 V.

What happens to the 25LC320A-E/ST during a power-on reset sequence?

At power-on, the 25LC320A-E/ST initializes in low-power Standby mode (CS = high), with SO in high-impedance state and the write enable latch reset. A high-to-low transition on CS is required before any instruction can be accepted. This ensures no spurious writes occur during power ramp-up, satisfying automotive ASIL-B functional safety expectations.