Renesas X4045S8I-4.5A

Overview

X4045S8I-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 with Block Lock™ protection. It features active-high open-drain RESET output, 4.5–4.75V reset threshold, -40°C to +85°C operating range, and 400kHz I²C interface - used in industrial microcontroller systems requiring reliable brownout detection and nonvolatile configuration storage.

For engineers reviewing the X4045S8I-4.5A datasheet, X4045S8I-4.5A pinout, X4045S8I-4.5A application, or X4045S8I-4.5A equivalent, key selection considerations include its programmable VTRIP, 16-byte page write EEPROM, <1µA watchdog-OFF standby current, and compatibility with I²C-bus timing requirements for embedded reset management.

Technical Context

The X4045S8I-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 rises above 4.5V and remains stable for 200ms. Its watchdog timer monitors SDA/SCL activity and triggers reset if no valid I²C start/stop sequence occurs within 200ms, 600ms, or 1.4s - selectable via nonvolatile WD1/WD0 bits.

EEPROM operation uses Intersil's Direct Write™ cell technology (1M write cycles, 100-year data retention) and supports 400kHz I²C communication with slave address 0xA0 (array) or 0xB0 (control register). Block Lock™ protection is controlled by BP2–BP0 bits, enabling write lock of 16–128 bytes or full array, and is enforced alongside WP pin logic and power-fail write inhibition.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (JEDEC MS-012AA), RoHS-compliant Pb-free plus anneal finish, moisture sensitivity level (MSL) compliant with IPC/JEDEC J-STD-020 at Pb-free peak reflow.

Key Features

Applications

Equivalent & Alternatives

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

Compared with X4045S8I-4.5A, MAX6361KA29+T offers lower cost but sacrifices VTRIP flexibility and EEPROM size, while STM8T142M2U6 embeds intelligence at the expense of external configurability - making X4045S8I-4.5A optimal for field-programmable, externally managed reset and storage systems.

Availability

X4045S8I-4.5A is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and smart metering applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for X4045S8I-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, specializes in high-performance analog and power management ICs for industrial, computing, and communications markets.

The X4045S8I-4.5A belongs to Intersil's CPU Supervisor family designed to consolidate reset, watchdog, voltage monitoring, and EEPROM functions into a single 8-pin package - targeting space-constrained embedded systems needing robust power management and nonvolatile parameter storage.

FAQ

What is the reset output polarity and drive type of the X4045S8I-4.5A?

The X4045S8I-4.5A features an active-high open-drain RESET output (Pin 3). It requires an external pull-up resistor to VCC and drives low during power-up, brownout (VCC < 4.5V), or watchdog timeout. This design allows direct interfacing with microcontrollers having active-low reset inputs via simple inversion or logic gating - a key feature confirmed in the FN8118 datasheet Figure 4 and Pin Configuration table.

Can the reset threshold voltage (VTRIP) of the X4045S8I-4.5A be modified after soldering?

Yes, the X4045S8I-4.5A supports post-manufacturing VTRIP adjustment using a 15–18V pulse applied to the WP pin and a defined I²C command sequence (slave address 0xA0, byte address 01h). The procedure is detailed in FN8118 Pages 5–7 and enables field calibration to ±0.05V precision - critical for applications where factory-set 4.5–4.75V tolerance is insufficient.

How does the X4045S8I-4.5A prevent EEPROM corruption during power failure?

The X4045S8I-4.5A employs three-tiered write protection: (1) automatic write abort when VCC falls below VTRIP, (2) Block Lock™ bits (BP2–BP0) enabling hardware lock of 16–128 byte segments, and (3) WP pin logic that disables all writes when held HIGH. These mechanisms - documented in FN8118 Sections 5 and 9 - ensure EEPROM integrity even during abrupt brownout events.

What is the maximum I²C clock frequency supported by the X4045S8I-4.5A?

The X4045S8I-4.5A supports up to 400kHz I²C clock frequency (standard-mode), as specified in the "Features" section of FN8118 Rev 3.00. This enables efficient 16-byte page writes in ~5ms and permits integration into systems with tight timing budgets - such as real-time industrial controllers where EEPROM updates must complete within defined interrupt latency windows.

Does the X4045S8I-4.5A watchdog timer require external components to operate?

No, the X4045S8I-4.5A watchdog timer is fully self-contained and requires no external RC network or components. It monitors SDA/SCL pin transitions and resets the system if no valid I²C start/stop sequence occurs within the selected timeout interval (200ms/600ms/1.4s). This autonomous operation - described in FN8118 Page 5 - reduces BOM count and improves reliability versus discrete timer solutions.