Renesas X5045S8I-2.7A

Overview

X5045S8I-2.7A from Intersil (now Renesas) is a 4K-bit SPI EEPROM with integrated CPU supervisor featuring power-on reset, watchdog timer, supply voltage supervision, and block-lock memory protection. It operates from 2.7V to 5.5V, provides 2.93V ±2.5% reset threshold, supports 3.3 MHz SPI interface, and delivers 1M write-cycle endurance - used in industrial controllers for reliable firmware parameter storage and brownout-safe microcontroller boot sequencing.

For engineers reviewing the X5045S8I-2.7A datasheet, X5045S8I-2.7A pinout, X5045S8I-2.7A application, or X5045S8I-2.7A equivalent, key selection criteria include its active-high RESET output, -40°C to +85°C industrial temperature range, reprogrammable VTRIP capability, 8-lead SOIC package, and dual-function CS/WDI pin enabling watchdog monitoring without dedicated hardware.

Technical Context

The X5045S8I-2.7A integrates four independent functional blocks: a POR circuit asserting RESET for ≥200 ms after VCC exceeds 2.93V; a nonvolatile-configurable watchdog timer with selectable timeouts (200 ms / 600 ms / 1.4 s / disabled); a low-voltage detector that holds RESET active until VCC rises above 2.93V and stabilizes for 200 ms; and a 512 × 8-bit SPI EEPROM with Direct Write™ cells.

Its SPI interface uses standard four-wire protocol (CS/WDI, SI, SO, SCK), supports 16-byte page writes with 5 ms typical write cycle time, and implements dual-layer write protection via both software-controlled block lock bits (BL0/BL1) and hardware WP pin - all operating within a single 2.7–5.5V supply rail.

Key Specifications

Pinout & Package

Package: 8-lead SOIC (Small Outline Integrated Circuit), RoHS-compliant, Pb-free plus anneal finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP9800T-E/MS and MAX6361KA29+T, the X5045S8I-2.7A uniquely consolidates reset supervision, watchdog timing, and secure 4K-bit EEPROM into one die - reducing BOM count, PCB footprint, and qualification effort for embedded systems requiring coordinated power management and persistent storage.

Availability

X5045S8I-2.7A is available at Aetrix Electronics and suitable for industrial process controllers, network infrastructure equipment, medical infusion pumps, and smart energy meters requiring stable component supply across extended product lifecycles.

Supply support for X5045S8I-2.7A 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 (acquired by Renesas Electronics in 2017) is a semiconductor company specializing in precision analog, power management, and interface solutions for industrial, communications, and computing markets.

The X5045 family was designed to replace discrete reset ICs, watchdog timers, and serial EEPROMs in space-constrained embedded systems - targeting applications where reliability, low power, and integration reduce system-level validation burden.

FAQ

What is the reset output polarity of the X5045S8I-2.7A?

The X5045S8I-2.7A features an active-high RESET output (pin 8), which asserts logic high during power-up, brownout, or watchdog timeout. This differs from the X5043 variant's active-low RESET and simplifies interfacing with MCUs requiring high-asserted reset inputs without external inverters. The X5045S8I-2.7A maintains this behavior across its full -40°C to +85°C operating range.

Can the VTRIP voltage of the X5045S8I-2.7A be modified after soldering?

Yes, the X5045S8I-2.7A supports field-programmable VTRIP adjustment using a 15–18V programming voltage applied to the WP pin while holding VCC at the desired trip level. This procedure allows precise calibration to match system-specific brownout thresholds without requiring component replacement. The new setting is stored nonvolatily and persists through power cycles - a capability confirmed in FN8126 Rev 3.00 Section 6.

How does the watchdog timer in the X5045S8I-2.7A interact with the CS/WDI pin?

The CS/WDI pin serves dual roles: chip select for SPI operations and watchdog input. A falling edge on CS/WDI resets the watchdog timer, while failure to toggle it within the selected timeout period (200 ms / 600 ms / 1.4 s) triggers RESET assertion. This eliminates need for dedicated WDI routing - the same signal used for SPI access also fulfills watchdog monitoring, reducing MCU GPIO usage in the X5045S8I-2.7A implementation.

What EEPROM protection mechanisms does the X5045S8I-2.7A provide?

The X5045S8I-2.7A implements three independent EEPROM protections: (1) hardware WP pin disabling all writes when low; (2) software-configurable block lock bits (BL0/BL1) protecting 0%, 25%, 50%, or 100% of the 512×8 array; and (3) write-enable latch requiring WREN instruction before any write. These layers ensure robust defense against accidental or malicious overwrites - critical for storing calibration data in the X5045S8I-2.7A.

Is the X5045S8I-2.7A compatible with 1.8V I/O systems?

No, the X5045S8I-2.7A requires VCC between 2.7V and 5.5V and specifies VIH = VCC × 0.7 and VIL = VCC × 0.3 for all digital inputs. While it can operate at 2.7V minimum supply, its logic thresholds scale with VCC - meaning it is not 1.8V-tolerant. For 1.8V systems, external level-shifting or alternative supervisors like the CAT1024 would be required instead of the X5045S8I-2.7A.