Renesas X5043S8I

Overview

X5043S8I from Intersil is a CPU supervisor IC integrating power-on reset control, watchdog timer, supply voltage supervision, and 4K-bit SPI EEPROM in an 8-lead SOIC package. It provides 4.63V reset threshold (±2.5%), 1.4s/600ms/200ms selectable watchdog timeout, and 512 × 8-bit EEPROM with block lock protection. Used in industrial process controllers to ensure deterministic boot and data integrity during brownout events.

For engineers reviewing the X5043S8I datasheet, X5043S8I pinout, X5043S8I application, or X5043S8I equivalent, key selection criteria include its -40°C to +85°C operating range, active-low RESET output, reprogrammable VTRIP, SPI interface compliance at 3.3MHz, and integrated block-lock EEPROM for firmware parameter storage.

Technical Context

The X5043S8I implements a dual-function supervisory architecture: analog voltage monitoring with hysteresis-based VTRIP detection and digital watchdog logic tied to the CS/WDI pin. Its reset assertion remains valid down to VCC = 1V and sustains for 200ms after VCC recovery.

EEPROM operation uses standard SPI protocol with MSB-first 8-bit instruction set (WREN, READ, WRITE, RDSR, WRSR), supporting 16-byte page writes and 5ms typical write cycle time. Block lock protection is controlled by nonvolatile BL0/BL1 bits in the status register, enabling selective write-protection of 0%, 25%, 50%, or 100% of the 512-byte array.

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 with EEPROM applications.

Compared with MAX6816EPA+ and MCP9808-E/P, the X5043S8I uniquely integrates four functions-reset, watchdog, voltage monitor, and EEPROM-in one SOIC-8 device, eliminating interconnect complexity and reducing BOM count by three components while guaranteeing synchronized timing behavior across all supervisory functions.

Availability

X5043S8I is available at Aetrix Electronics and suitable for industrial process control, network infrastructure equipment, medical diagnostics, and battery-powered data loggers requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for X5043S8I 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) designs high-reliability analog and mixed-signal ICs for industrial, aerospace, and communications markets, emphasizing precision voltage references, power management, and supervisory solutions.

The X5043S8I belongs to Intersil's CPU Supervisor family, engineered to replace discrete reset ICs, watchdog timers, and serial EEPROMs in resource-constrained embedded systems where board space, power budget, and functional integration are critical.

FAQ

What is the reset threshold voltage for the X5043S8I?

The X5043S8I has a factory-programmed VTRIP threshold of 4.63V ±2.5%, optimized for 5V systems. This value is reprogrammable in-system using a 15–18V programming voltage applied to the WP pin and a defined SPI command sequence per datasheet Figure 1. The reset signal remains asserted until VCC exceeds this threshold for 200ms.

Does the X5043S8I support both active-low and active-high reset outputs?

No - the X5043S8I provides only an active-low RESET output (open-drain). The datasheet distinguishes X5043 (active-low) from X5045 (active-high) variants; X5043S8I is explicitly the X5043 series. No internal configuration or external circuitry can convert it to active-high operation.

How many watchdog timeout options does the X5043S8I offer?

The X5043S8I offers three programmable watchdog timeout periods: 200ms, 600ms, and 1.4s (factory default), selected via nonvolatile WD0/WD1 bits in the status register. These settings persist across power cycles and require no reinitialization after reset. The watchdog is disabled only by explicit software configuration (WD0=WD1=1).

Can the EEPROM in the X5043S8I be written to without enabling the write latch?

No - the X5043S8I requires the Write Enable Latch (WEL) to be set via the WREN instruction before any memory write operation. If WEL is not set, WRITE commands are ignored. The latch resets automatically after power-up, successful write completion, or when WP is pulled low, enforcing strict write safety.

What is the maximum SPI clock frequency supported by the X5043S8I?

The X5043S8I supports a maximum SPI clock frequency of 3.3MHz under recommended operating conditions (VCC = 4.5–5.5V, TA = -40°C to +85°C). This limit ensures reliable sampling of SI data on the rising SCK edge and stable SO output timing on the falling edge, as validated in AC Electrical Specifications Table on page 14 of FN8126 Rev 3.00.