Renesas X4043S8-2.7A

Overview

X4043S8-2.7A 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-low open-drain RESET output, 2.7V–5.5V operation, 2.85V–3.0V reset threshold, 400kHz I²C interface, and <20µA standby current with watchdog enabled - used in embedded microcontroller systems requiring reliable brownout detection and nonvolatile configuration storage.

For engineers reviewing the X4043S8-2.7A datasheet, X4043S8-2.7A pinout, X4043S8-2.7A application, or X4043S8-2.7A equivalent, key selection criteria include VTRIP accuracy at low-voltage rails, EEPROM block-lock granularity, watchdog timeout configurability, and compatibility with I²C bus timing constraints in space-constrained industrial controllers.

Technical Context

The X4043S8-2.7A 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 2.85V and remains stable for 200ms. Its watchdog timer monitors SDA/SCL activity using a state-machine-based transition detector - not clocked by internal oscillator - and supports three timeout intervals (200ms/600ms/1.4s) via nonvolatile WD1/WD0 bits.

EEPROM operation uses Intersil's Direct Write™ cell technology (1M write cycles, 100-year retention), organized as 512 × 8-bit array with 16-byte page writes. Block Lock™ protection is controlled by BP2/BP1/BP0 bits, enabling selective write lock of 16–128 byte segments or full-array protection, independent of WP pin state when configured.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (JEDEC MS-012, 150 mil width), RoHS-compliant Pb-free + anneal finish.

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 X4043S8-2.7A uniquely balances field-programmable VTRIP, 4kbit EEPROM with granular lock, and ultra-low standby current - making it optimal for applications requiring post-deployment calibration and extended data logging without MCU intervention.

Availability

X4043S8-2.7A is available at Aetrix Electronics and suitable for industrial PLC modules, medical sensor nodes, automotive body control units, and smart energy meters requiring stable component supply and long-term lifecycle support.

Supply support for X4043S8-2.7A 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, now part of Renesas Electronics, designs high-performance analog and mixed-signal ICs for power management, precision sensing, and embedded control applications.

The X4043/X4045 family was developed to consolidate reset, watchdog, voltage monitoring, and nonvolatile storage into a single 8-pin package - targeting space-constrained microcontroller systems where reliability and field serviceability are critical.

FAQ

What is the factory-default watchdog timeout setting for the X4043S8-2.7A?

The X4043S8-2.7A ships with the watchdog timer disabled (WD1=1, WD0=1). This is the factory default state, ensuring no unintended reset activation during initial power-up or system bring-up. To enable watchdog supervision, the control register must be written via the I²C interface using the three-step WEL/RWEL sequence specified in the FN8118 datasheet. The X4043S8-2.7A does not assert RESET due to watchdog timeout unless explicitly configured and enabled by the host system.

Can the X4043S8-2.7A VTRIP threshold be adjusted in-circuit without removing the device?

Yes, the X4043S8-2.7A supports in-system VTRIP adjustment using a 15–18V programming pulse applied to the WP pin while issuing specific I²C commands (slave address A0h, byte address 01h, data 00h). This procedure requires no device removal or reflow - only temporary high-voltage access to the WP pin and I²C bus control. The X4043S8-2.7A retains the new threshold value nonvolatily, and the operation does not affect EEPROM contents or control register settings.

Does the X4043S8-2.7A support standard I²C addressing without custom configuration?

Yes, the X4043S8-2.7A responds to standard 7-bit I²C slave addresses: 0xA0 (write) and 0xA1 (read) for EEPROM access, and 0xB0 (write) and 0xB1 (read) for control register access. No hardware strapping or initialization sequence is needed to establish basic I²C communication. The X4043S8-2.7A powers up ready to accept commands on these fixed addresses, with WEL bit cleared to prevent accidental writes until explicitly enabled.

How does the X4043S8-2.7A handle EEPROM write operations during power loss?

The X4043S8-2.7A incorporates hardware power-fail detection that aborts ongoing EEPROM writes when VCC drops below ~2.5V and holds RESET active. Any incomplete write is discarded, and the memory array retains its pre-write state. Completed writes survive down to VCC = 1V. The X4043S8-2.7A also features built-in write-enable latches (WEL/RWEL) and Block Lock™ protection, ensuring that partial or corrupted writes cannot overwrite protected sectors even during abrupt power interruption.

Is the X4043S8-2.7A pin-compatible with other members of the X4043/X4045 family?

Yes, all X4043 and X4045 variants - including X4043S8-2.7A, X4043S8Z-4.5A, and X4045S8IZ-2.7A - share identical 8-pin SOIC pinout and electrical interface. Differences are limited to VTRIP threshold, temperature grade, and reset polarity (X4043 = active-low RESET, X4045 = active-high RESET). The X4043S8-2.7A can be substituted for other X4043 variants in the same package without PCB changes, provided the 2.85V–3.0V reset threshold meets system requirements.