Renesas X4043S8IZ

Overview

X4043S8IZ from Intersil (now Renesas) is a CPU supervisor IC integrating power-on reset control, watchdog timer, supply voltage supervision, and 4kbit EEPROM in a single 8-pin SOIC package. It features active-low RESET output, 4.5V–5.5V supply range, −40°C to +85°C industrial temperature grade, and 400kHz I²C interface - used for microcontroller system reliability in embedded instrumentation and industrial controllers.

For engineers reviewing the X4043S8IZ datasheet, X4043S8IZ pinout, X4043S8IZ application, or X4043S8IZ equivalent, this page delivers verified functional identity, validated pin roles, confirmed VTRIP programming capability, exact EEPROM block-lock protection granularity, and real-world watchdog timeout options - all specific to the X4043S8IZ-4.5A variant with Pb-free SOIC packaging and extended temperature rating.

Technical Context

The X4043S8IZ 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 the programmable 4.5V–4.75V trip point and remains above it for ≥200ms. Its watchdog timer monitors SDA/SCL activity using a state-machine-based transition detector, not clocked timing - restart requires full I²C start/stop sequence.

EEPROM operation uses Intersil's Direct Write™ cell technology (1M write cycles, 100-year retention), organized as 512 × 8 bits with 16-byte page writes. Block Lock™ protection is controlled via nonvolatile BP2–BP0 bits, enabling selective lock of 16–512 bytes or full array - independent of WP pin status when configured.

Key Specifications

Pinout & Package

8-pin JEDEC SOIC package (RoHS-compliant, matte tin finish), 5.0mm × 4.0mm body, 1.27mm pitch. Pin 1 index marked; NC pins are unconnected die pads - no internal bonding.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6361KA29+T and STM8T142M2U6, the X4043S8IZ uniquely combines factory-programmable VTRIP, 4kbit EEPROM with granular Block Lock™, and zero-software watchdog enforcement - making it optimal for industrial designs requiring field-tunable brownout margins and robust nonvolatile parameter storage without MCU overhead.

Availability

X4043S8IZ is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and smart metering applications requiring stable component supply, extended temperature operation, and long-term lifecycle support.

Supply support for X4043S8IZ 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, designs high-performance analog and mixed-signal ICs for power management, precision sensing, and system supervision.

The X4043S8IZ belongs to Intersil's CPU Supervisor family, engineered to consolidate reset, watchdog, voltage monitoring, and EEPROM into one die - targeting cost-sensitive, space-constrained embedded systems needing guaranteed boot integrity and field-serviceable configuration storage.

FAQ

What is the exact reset threshold voltage for X4043S8IZ, and can it be changed?

The X4043S8IZ is factory-configured with a VTRIP range of 4.5V to 4.75V, optimized for 5V systems. Yes, this threshold is fully reprogrammable using a 15–18V pulse applied to the WP pin during an I²C command sequence - enabling precise field calibration to match system-specific brownout requirements without external components. The X4043S8IZ retains the new value nonvolatily across power cycles.

Does X4043S8IZ support both active-high and active-low reset outputs?

No - the X4043S8IZ provides only an active-low open-drain RESET output (pin 3). The X4045S8IZ variant offers active-high RESET, but X4043S8IZ is strictly active-low. This is fixed by silicon design and cannot be altered via configuration bits or external circuitry; proper pull-up sizing (e.g., 4.7kΩ to VCC) is required for correct logic level translation.

How does the watchdog timer in X4043S8IZ detect microcontroller failure?

The X4043S8IZ watchdog monitors SDA and SCL pin transitions - not instruction execution. It triggers RESET if no valid I²C START/STOP sequence occurs within the selected timeout (200ms/600ms/1.4s). This detects firmware lockups that halt bus communication, not just CPU stalls, making it more robust than clock-based watchdogs. The X4043S8IZ requires explicit firmware intervention to refresh the timer via I²C traffic.

What EEPROM protection mechanisms does X4043S8IZ provide beyond the WP pin?

In addition to the WP pin, the X4043S8IZ implements Block Lock™ protection via nonvolatile BP2–BP0 bits - allowing hardware-enforced write lock of 16, 32, 64, 128, 256, 512 bytes, or full array. This operates independently of WP status and persists through power loss. The X4043S8IZ also includes power-up/power-down write inhibition and volatile WEL/RWEL latches to prevent accidental writes during bus arbitration.

Is X4043S8IZ pin-compatible with earlier versions like X4043S8Z?

Yes - X4043S8IZ shares identical 8-pin SOIC pinout, electrical characteristics, and functional behavior with X4043S8Z, differing only in temperature grade (−40°C to +85°C vs. 0°C to +70°C) and Pb-free anneal process. No PCB layout changes are needed when upgrading; the X4043S8IZ maintains full electrical and mechanical compatibility while extending operational range for harsher environments.