Microchip Technology 25C040T-I/SN

Overview

25C040T-I/SN from Microchip Technology Inc. is a 4 Kbit (512 × 8) SPI-compatible serial EEPROM designed for nonvolatile data storage in automotive and industrial control systems. It operates at 4.5–5.5 V, supports up to 3 MHz clock frequency, features 16-byte page write capability, and delivers >200 years data retention with 1 million erase/write cycles. It is used in engine control units (ECUs) for calibration parameter storage.

For engineers reviewing the 25C040T-I/SN datasheet, 25C040T-I/SN pinout, 25C040T-I/SN application, or 25C040T-I/SN equivalent, key selection criteria include its automotive-grade temperature range (–40°C to +125°C), hardware write protection via WP pin, HOLD functionality for interrupt-safe SPI communication, and TSSOP-8 packaging suitable for space-constrained PCB layouts.

Technical Context

The 25C040T-I/SN implements a standard SPI Mode 0,0 interface with separate SI (data in) and SO (data out) lines, CS-controlled device selection, and SCK-synchronized transfers. Its internal architecture includes an 8-bit instruction register, STATUS register with WIP/WEL/BP bits, and page-based write logic enforcing 16-byte alignment within 512-byte memory space.

It integrates power-on reset circuitry that clears the write enable latch, built-in write-protection logic responsive to WP pin state and BP0/BP1 configuration, and self-timed internal write cycles completing in ≤5 ms. The HOLD pin suspends ongoing SPI transactions without resetting address pointers, enabling deterministic host interrupt handling.

Key Specifications

Pinout & Package

25C040T-I/SN is packaged in an 8-pin TSSOP (Thin Shrink Small Outline Package) with 0.65 mm pitch, 4.4 mm body width, and Pb-free matte tin terminations. This surface-mount package supports automated placement and reflow, with thermal and mechanical characteristics qualified for automotive under-hood use.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25C040T-I/SN, the 25C040-I/SN offers identical functionality in bulk packaging for manual assembly, while the 25LC040T-I/SN trades automotive qualification and 3 MHz speed for broader voltage tolerance - making it unsuitable as a drop-in replacement in safety-critical automotive systems.

Availability

25C040T-I/SN is available at Aetrix Electronics and suitable for engine control units, advanced driver assistance systems, and industrial motor drives requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 25C040T-I/SN 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 25C040T-I/SN belongs to Microchip's legacy SPI Serial EEPROM product line, engineered specifically for automotive and industrial applications demanding high reliability, extended temperature operation, and hardware-enforced data integrity.

FAQ

What is the operating temperature range of the 25C040T-I/SN?

The 25C040T-I/SN is rated for –40°C to +125°C, meeting AEC-Q100 Grade 1 automotive qualification. This range is explicitly defined for the 25C040 variant in the Device Selection Table and confirmed in Section 1.0 Electrical Characteristics. It supports deployment in engine compartments and other high-ambient-temperature locations where standard industrial EEPROMs would fail.

Does the 25C040T-I/SN support SPI Mode 0,0 only?

Yes, the 25C040T-I/SN implements SPI Mode 0,0 exclusively - meaning CPOL = 0 (clock idle low) and CPHA = 0 (data sampled on first clock edge). This is confirmed by the timing diagrams in Figures 1-2 and 1-3, and functional description in Section 3.1. It does not support Mode 1,1 or other SPI variants.

How does the HOLD pin function during an active write cycle?

The HOLD pin cannot suspend an internal write cycle once initiated; it only pauses serial command sequences. As stated in Section 2.6, "If an internal write cycle has already begun, WP going low will have no effect on the write," and the same applies to HOLD. The device completes the write autonomously, and HOLD resumes only after the write finishes and the device returns to standby.

What is the maximum write endurance of the 25C040T-I/SN?

The 25C040T-I/SN guarantees 1 million erase/write cycles per memory location, as specified in Table 1-2 AC CHARACTERISTICS (Param No. 21). This endurance is ensured by characterization per Note 2 and applies across the full –40°C to +125°C temperature range, enabling reliable logging in automotive telematics applications.

Can the 25C040T-I/SN be used with a 3.3 V microcontroller SPI interface?

No - the 25C040T-I/SN requires 4.5–5.5 V supply and specifies VIH1 ≥ 2.0 V only when VCC ≥ 2.7 V (Table 1-1 D001), but its absolute minimum VCC is 4.5 V. Driving SI/SO with 3.3 V logic violates the VIH/VIL thresholds and risks unreliable communication; use 25LC040T-I/SN instead for 3.3 V systems.