Renesas X5043S8Z

Overview

X5043S8Z from Intersil (now Renesas) is a 4K-bit CPU supervisor IC integrating power-on reset, watchdog timer, supply voltage supervision, and SPI EEPROM in an 8-lead SOIC package. It features a 4.63V ±2.5% V_TRIP, 1.4s watchdog timeout (default), and 3.3MHz SPI interface - used in industrial process controllers to ensure deterministic boot and fault recovery.

For engineers reviewing the X5043S8Z datasheet, X5043S8Z pinout, X5043S8Z application, or X5043S8Z equivalent, key selection criteria include its factory-programmed 4.63V reset threshold, block-lock EEPROM protection, active-low open-drain RESET output, and compatibility with 2.7–5.5V systems requiring brownout immunity and nonvolatile configuration storage.

Technical Context

The X5043S8Z implements a dual-function CS/WDI pin for chip select and watchdog input, with reset assertion triggered by either V_CC falling below 4.63V or CS remaining static beyond the watchdog timeout. Its internal status register contains nonvolatile WD0/WD1 bits that retain watchdog configuration across power cycles.

Reset timing includes a guaranteed 200ms t_PURST after V_CC exceeds V_TRIP, and the RESET output remains valid down to V_CC = 1V. The SPI EEPROM uses Direct Write™ technology with 1M write endurance, 100-year data retention, and 16-byte page writes completing in 5ms typical.

Key Specifications

Pinout & Package

Package: 8-lead SOIC (Pb-free, RoHS compliant), 3.9mm × 4.9mm body, 1.27mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6361KA29+T and MCP809T-460I/P, the X5043S8Z delivers integrated supervision, memory, and watchdog in one SOIC-8 device - reducing BOM count by up to 3 components and eliminating interconnect reliability risks in high-vibration environments.

Availability

X5043S8Z is available at Aetrix Electronics and suitable for industrial process controllers, network infrastructure equipment, and battery-powered data loggers requiring stable component supply and long-term lifecycle support.

Supply support for X5043S8Z 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 (acquired by Renesas Electronics in 2017) is a semiconductor company specializing in precision analog, power management, and interface solutions for industrial and communications markets.

The X5043S8Z belongs to Intersil's CPU Supervisor family, designed to consolidate reset, watchdog, voltage monitoring, and nonvolatile storage into a single IC for embedded systems demanding high reliability and minimal footprint.

FAQ

What is the factory-set reset threshold voltage for the X5043S8Z?

The X5043S8Z ships with a factory-programmed V_TRIP of 4.63V ±2.5%, optimized for 5V systems. This value is permanently stored and remains stable over temperature and time unless reprogrammed using the VP (15–18V) method described in the datasheet. The X5043S8Z does not require external resistors or calibration to achieve this threshold.

Does the X5043S8Z support SPI communication at 5MHz?

No, the X5043S8Z supports a maximum SPI clock frequency of 3.3MHz as specified in the AC Electrical Characteristics table. Operating above this rate may cause read/write errors or command misinterpretation. The X5043S8Z is designed for reliable operation in resource-constrained microcontrollers where 3.3MHz provides optimal balance between speed and noise immunity.

Can the watchdog timer on the X5043S8Z be disabled?

Yes, the watchdog timer on the X5043S8Z can be disabled by programming WD1=1 and WD0=1 in the status register via the WRSR instruction. This configuration is the factory default. Once set, the watchdog remains disabled across power cycles because these bits are nonvolatile. Disabling it removes CS/WDI monitoring but retains all other supervisor functions.

How many bytes can be written in a single page write operation on the X5043S8Z EEPROM?

The X5043S8Z supports 16-byte page writes to its 512×8 EEPROM array. Each page begins at addresses ending in 0000b (e.g., 0x00, 0x10, 0x20) and ends at addresses ending in 1111b. Writing beyond a page boundary causes automatic rollover to the start of the same page, potentially overwriting prior data. The X5043S8Z completes each page write in 5ms typical time.

Is the RESET pin on the X5043S8Z push-pull or open-drain?

The RESET pin on the X5043S8Z is an open-drain output, requiring an external pull-up resistor to V_CC or another logic rail. This architecture allows multiple devices (e.g., other supervisors or PMICs) to share a common reset bus using wired-OR logic. The X5043S8Z drives the line low during reset assertion and releases it high-impedance otherwise.