Renesas X4043PIZ-4.5A

Overview

X4043PIZ-4.5A from Intersil is a CPU supervisor IC integrating power-on reset control, watchdog timer, supply voltage supervision, and 4kbit EEPROM with Block Lock™ protection. It features active-low 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 X4043PIZ-4.5A datasheet, X4043PIZ-4.5A pinout, X4043PIZ-4.5A application, or X4043PIZ-4.5A equivalent, key selection considerations include its programmable VTRIP, 200ms reset timeout, open-drain RESET/RESET output, EEPROM endurance (1M cycles), and compatibility with legacy PDIP-based embedded designs.

Technical Context

The X4043PIZ-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 200ms, 600ms, or 1.4s - selectable via nonvolatile WD1/WD0 bits.

Internally, it integrates a 512 × 8-bit EEPROM array organized in 16-byte pages, accessed via standard 2-wire I²C protocol (slave address 0xA0 for write, 0xA1 for read). Block Lock™ protection enables selective write-locking of memory segments (e.g., 128 bytes, full array, or first 16 bytes) using BP2–BP0 bits stored in a nonvolatile control register at address 0x1FF.

Key Specifications

Pinout & Package

Package: 8-pin PDIP (Plastic Dual In-line Package), RoHS-compliant Pb-free plus anneal finish. Not recommended for new designs; superseded by MSOP/SOIC variants but retained for legacy board replacement.

Key Features

Applications

Equivalent & Alternatives

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

Compared with X4043PIZ-4.5A, the X4043S8IZ-4.5A offers identical functionality in a more manufacturable SOIC package, while the X4043M8IZ-4.5A provides further miniaturization at the cost of tighter assembly tolerances - both eliminate obsolescence risk without altering system-level timing or software drivers.

Availability

X4043PIZ-4.5A is available at Aetrix Electronics and suitable for industrial control systems, medical diagnostics equipment, and legacy HMI panels requiring stable component supply and long-term obsolescence mitigation.

Supply support for X4043PIZ-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 (now part of Renesas Electronics) is a semiconductor company specializing in precision analog, power management, and interface ICs for industrial, computing, and communications markets.

The X4043/X4045 family was designed to consolidate power supervision, watchdog safety, and nonvolatile memory into a single chip - reducing BOM count and improving reliability in microcontroller-based embedded systems.

FAQ

What is the reset behavior of the X4043PIZ-4.5A during power-up?

The X4043PIZ-4.5A asserts its active-low RESET output for a minimum of 250ms after VCC stabilizes above 4.5V. This ensures the host microcontroller's oscillator and power rails are fully settled before code execution begins. The reset pulse width is fixed and not user-adjustable - it is guaranteed across temperature and voltage variations per the FN8118 datasheet.

Can the reset threshold voltage of the X4043PIZ-4.5A be changed in-circuit?

Yes, the X4043PIZ-4.5A supports in-system VTRIP reprogramming using a 15–18V pulse applied to the WP pin while issuing specific I²C commands. This allows fine-tuning of the 4.5–4.75V factory-set threshold to match actual board-level supply tolerances - a capability confirmed in the FN8118 Rev 3.00 datasheet Section "VTRIP Programming".

Does the X4043PIZ-4.5A support standard I²C communication?

Yes, the X4043PIZ-4.5A implements a standard 2-wire I²C interface compliant with 400kHz Fast Mode. It uses slave address 0xA0 (write) / 0xA1 (read), supports byte and page writes (16-byte pages), and responds with ACK/NACK per I²C protocol - verified in the "Serial Interface Conventions" section of FN8118.

How does the watchdog timer in the X4043PIZ-4.5A get reset?

The X4043PIZ-4.5A watchdog timer resets on any valid I²C transaction - specifically, a Start condition followed by Clock Low, Clock High, and Stop. This four-step sequence must occur within the selected timeout (200ms/600ms/1.4s); failure triggers RESET assertion. The mechanism is detailed in Figure 1 and Section "Watchdog Timer" of FN8118.

Is the EEPROM in the X4043PIZ-4.5A protected against accidental writes?

Yes, the X4043PIZ-4.5A includes three layers of EEPROM write protection: hardware WP pin (HIGH disables all writes), Power-up/Power-down circuitry (blocks writes during VCC ramp), and Block Lock™ software protection (configurable via BP2–BP0 bits to lock 16-byte to full-array segments) - all documented in the "EEPROM Inadvertent Write Protection" section of FN8118.