Microchip Technology 25LC320AT-I/ST

Overview

25LC320AT-I/ST from Microchip Technology 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 up to 10 MHz at 4.5–5.5V, supports hardware write protection via WP pin, and features self-timed 5 ms write cycles - used in microcontroller-based data logging, configuration storage, and firmware parameter retention.

For engineers reviewing the 25LC320AT-I/ST datasheet, 25LC320AT-I/ST pinout, 25LC320AT-I/ST application, or 25LC320AT-I/ST equivalent, key selection criteria include SPI timing compliance at 10 MHz, VCC range (2.5–5.5V), HOLD/CS-controlled pause capability, and AEC-Q100-qualified reliability for embedded control systems.

Technical Context

The 25LC320AT-I/ST implements a standard SPI Mode 0,0 interface with separate SI/SO lines, CS-selectable operation, and HOLD-initiated communication suspension without sequence reset. Its internal architecture includes an 8-bit instruction register, status register with WIP/WEL/BP bits, and page latches enabling up to 32-byte writes within aligned 32-byte boundaries.

Write protection is implemented through dual-layer control: nonvolatile BP0/BP1 bits in the STATUS register define 0%, 25%, 50%, or 100% array protection, while the WP pin-when enabled by WPEN bit-adds hardware-level lockout of STATUS register writes. Power-on defaults disable writes and place SO in high-impedance state.

Key Specifications

Pinout & Package

25LC320AT-I/ST is packaged in an 8-lead TSSOP (Thin Shrink Small Outline Package) with 0.65 mm pitch, 4.4 mm × 3.0 mm body, and exposed pad optional grounding per Microchip Drawing C04-057-TS Rev G. Pin 1 is marked with dot or bevel; orientation follows standard TSSOP pin 1 indicator.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA320AT-I/ST and AT25DF321A-SSH-T, the 25LC320AT-I/ST uniquely balances AEC-Q100 qualification, 2.5–5.5V operation, and proven 32-Kbit SPI EEPROM compatibility - making it optimal for cost-sensitive automotive and industrial control where reliability trumps raw speed or density.

Availability

25LC320AT-I/ST is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, automotive body control modules, and smart energy meter firmware requiring stable component supply across multi-year production cycles.

Supply support for 25LC320AT-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 family delivers SPI EEPROMs optimized for robustness in automotive and industrial environments, emphasizing AEC-Q100 qualification, wide VCC tolerance, and deterministic write-cycle timing for safety-critical firmware and calibration storage.

FAQ

What is the maximum SPI clock frequency supported by the 25LC320AT-I/ST?

The 25LC320AT-I/ST supports up to 10 MHz SPI clock frequency when VCC is between 4.5V and 5.5V. At 2.5V ≤ VCC < 4.5V, the maximum clock drops to 5 MHz, and at 1.8V ≤ VCC < 2.5V, it is limited to 3 MHz. These limits ensure reliable setup/hold timing for SI and SO signals across voltage ranges, as specified in Table 1-2 of DS20001828H.

Does the 25LC320AT-I/ST require external pull-up resistors on its SPI lines?

No, the 25LC320AT-I/ST does not require external pull-ups on SI, SO, SCK, or CS - all inputs have internal weak pull-downs, and SO is actively driven or tri-stated. However, WP and HOLD should be externally pulled high (typically 10 kΩ to VCC) unless actively driven low for protection or pause functions, per Microchip's recommended application circuit.

How does the HOLD function behave during an active write cycle in the 25LC320AT-I/ST?

The HOLD function has no effect on an ongoing internal write cycle in the 25LC320AT-I/ST. Once initiated by CS rising edge after a valid write sequence, the 5 ms self-timed write proceeds to completion regardless of HOLD state. HOLD only suspends serial communication (read/write instructions), not active erase/write operations already committed to silicon.

Can the 25LC320AT-I/ST be used in systems powered by 3.3V logic without level shifters?

Yes, the 25LC320AT-I/ST operates natively from 2.5V to 5.5V and is fully compatible with 3.3V SPI buses. Its VIH1 threshold is 0.7×VCC (≥2.31V at 3.3V), and VOL is ≤0.4V at IOL = 2.1 mA - ensuring noise margins exceed 0.5V for robust communication with standard 3.3V MCUs without level translation.

What happens if a page write crosses a 32-byte boundary in the 25LC320AT-I/ST?

If a page write command attempts to cross a 32-byte boundary in the 25LC320AT-I/ST, data wrap around to the start of the current page instead of advancing to the next page. For example, writing 32 bytes starting at address 0x001F fills addresses 0x001F–0x003F, but the last byte overwrites 0x0020. Software must enforce page alignment to prevent unintended data corruption.