Renesas X4045M8-4.5A

Overview

X4045M8-4.5A from Intersil (now Renesas) is a CPU supervisor IC integrating power-on reset control, watchdog timer, supply voltage supervision, and 4kbit serial EEPROM in a single 8-pin MSOP package. It features active-high RESET output, 4.5–4.75V reset threshold, 400kHz I²C interface, <1µA standby current (watchdog off), and Block Lock™ EEPROM protection. It is used in microcontroller-based embedded systems requiring reliable power sequencing and nonvolatile configuration storage.

For engineers reviewing the X4045M8-4.5A datasheet, X4045M8-4.5A pinout, X4045M8-4.5A application, or X4045M8-4.5A equivalent, key selection considerations include its active-high reset polarity, factory-programmed 4.5V VTRIP, MSOP-8 thermal profile, 200ms reset timeout, and compatibility with standard I²C bus timing and block-lock memory protection schemes.

Technical Context

The X4045M8-4.5A implements a dual-function reset architecture: power-on reset asserts RESET for 250ms after VCC stabilization, while low-VCC detection holds RESET active until VCC exceeds 4.5V for 200ms. Its watchdog timer monitors SDA/SCL activity and triggers reset if no valid I²C transaction occurs within the selected timeout (200ms/600ms/1.4s or disabled).

EEPROM operation uses a 400kHz 2-wire interface with software-addressable Block Lock™ protection covering 16–128 byte blocks or full array, plus hardware write protection via WP pin. The device employs Direct Write™ memory cells rated for 1,000,000 write cycles and 100-year data retention.

Key Specifications

Pinout & Package

Package: 8-pin MSOP (JEDEC MO-187AA), 3.0mm × 3.0mm body, 0.65mm pitch, Pb-free RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar CPU supervisor with EEPROM applications.

Compared with X4045M8-4.5A, X4045S8Z-4.5A delivers identical supervision and EEPROM functionality in a larger SOIC package, while MAX6361KA29+T trades memory integration for ultra-low power and fixed-threshold simplicity - making X4045M8-4.5A optimal for compact, self-contained supervisory systems.

Availability

X4045M8-4.5A is available at Aetrix Electronics and suitable for industrial PLC controllers, medical infusion pumps, automotive body control modules, and smart energy meters requiring stable component supply and long-term lifecycle support.

Supply support for X4045M8-4.5A 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

Intersil Corporation, now part of Renesas Electronics, is a semiconductor manufacturer specializing in power management, precision analog, and mixed-signal ICs for industrial, computing, and communications markets.

The X4045 family was designed to consolidate power monitoring, reset generation, watchdog safety, and nonvolatile storage into one die - reducing bill-of-materials count and improving reliability in microcontroller-based embedded systems.

FAQ

What is the reset behavior of the X4045M8-4.5A during power-up?

The X4045M8-4.5A asserts its active-high RESET output for 250ms after VCC stabilizes above the 4.5V threshold. This guarantees sufficient time for the microcontroller's power supply and crystal oscillator to settle before code execution begins. The reset pulse is generated internally and does not require external timing components.

Can the VTRIP threshold of the X4045M8-4.5A be adjusted, and how?

Yes, the X4045M8-4.5A's VTRIP threshold is factory-set to 4.5V but can be reprogrammed to any value between 1.7V and 5.5V using a 15–18V programming pulse applied to the WP pin during an I²C write sequence. The procedure requires issuing specific slave address and data bytes (A0h/01h/00h) and is detailed in the FN8118 datasheet Section "VTRIP Programming".

Does the X4045M8-4.5A support page writes to its EEPROM, and what is the page size?

Yes, the X4045M8-4.5A supports 16-byte page writes to its 4kbit EEPROM. A single I²C transaction can load up to 16 bytes starting from any address within a page, with automatic address increment and wraparound. Each page write completes in 5ms typical, enabling efficient bulk configuration storage without host-side timing overhead.

How does the watchdog timer in the X4045M8-4.5A detect microcontroller failure?

The X4045M8-4.5A's watchdog timer monitors SDA and SCL lines for valid I²C activity. It resets only upon detection of a complete Start–Clock Low–Clock High–Stop sequence. If no such sequence occurs within the selected timeout (200ms/600ms/1.4s), the device asserts RESET. This prevents false triggers from noise or partial transactions.

Is the X4045M8-4.5A pin-compatible with the X4043M8-4.5A?

No - the X4045M8-4.5A has an active-high RESET output, while the X4043M8-4.5A provides active-low RESET. Though both share identical pinout, package, and electrical interface, their reset polarity differs. Interchanging them requires corresponding logic inversion in the host circuit or firmware, making them functionally distinct rather than drop-in replacements.