Renesas X5045S8I

Overview

X5045S8I from Intersil (now Renesas) is a CPU supervisor IC integrating power-on reset control, watchdog timer, supply voltage supervision, and 4Kbit SPI EEPROM in a single 8-lead SOIC package. It features a 4.63V ±2.5% reset threshold, selectable watchdog timeout (200ms/600ms/1.4s), and 512 × 8-bit EEPROM with block lock protection - used in industrial process controllers to ensure deterministic microcontroller startup and critical parameter retention during brownout events.

For engineers reviewing the X5045S8I datasheet, X5045S8I pinout, X5045S8I application, or X5045S8I equivalent, key selection considerations include its -40°C to +85°C industrial temperature range, active-low RESET output, reprogrammable VTRIP capability, and compatibility with standard SPI microcontroller interfaces requiring ≤3.3MHz clock rate and 16-byte page write support.

Technical Context

The X5045S8I implements a dual-function CS/WDI pin for chip select and watchdog input, where a falling edge resets the watchdog timer. Its internal power-on reset circuit asserts RESET for ≥200ms after VCC exceeds 4.63V, and holds RESET active until VCC remains above threshold for that duration.

Voltage supervision uses an analog comparator with factory-trimmed 4.63V ±2.5% trip point, reprogrammable via VP=15–18V on WP and precise VCC biasing. The EEPROM employs Direct Write™ technology enabling 1M write cycles and 100-year data retention, with nonvolatile status register bits controlling both watchdog timeout and 1/4–full array block lock protection.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6361KA29+T and MCP9800T-E/MS, the X5045S8I uniquely combines field-adjustable reset threshold, industrial temperature rating, and 1M-cycle EEPROM in one package - making it irreplaceable for 5V systems requiring both robust supervision and long-term parameter storage.

Availability

X5045S8I is available at Aetrix Electronics and suitable for industrial process controllers, rugged network routers, medical infusion pumps, and smart energy meters requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for X5045S8I 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) designs high-reliability analog and mixed-signal ICs for industrial, aerospace, and communications markets.

The X5045S8I belongs to Intersil's CPU Supervisor family, engineered to consolidate reset, watchdog, voltage monitoring, and nonvolatile storage into a single die - targeting space-constrained embedded systems needing fail-safe operation and field-upgradable configuration.

FAQ

What is the factory-default watchdog timeout setting for the X5045S8I?

The X5045S8I ships with watchdog timer disabled (WD1=1, WD0=1). This default state prevents unintended system resets during initial deployment. To enable watchdog supervision, the host microcontroller must issue a WRSR command to set WD0 and WD1 to values corresponding to 200ms, 600ms, or 1.4s timeout. The setting persists through power cycles due to nonvolatile storage in the status register.

Can the X5045S8I's 4.63V reset threshold be adjusted, and what equipment is required?

Yes, the X5045S8I's VTRIP can be reprogrammed to custom voltages using the procedure in FN8126 Rev 3.00 Section 6. It requires applying the target voltage to VCC, connecting WP to a 15–18V programming supply (VP), issuing WREN followed by writing 00h to address 01h, then bringing WP low. No special programmer is needed - standard SPI interface and HV supply suffice. The operation also writes 00h to EEPROM address 01h.

Does the X5045S8I support SPI Mode 0 (CPOL=0, CPHA=0), and what are the timing constraints?

Yes, the X5045S8I operates in SPI Mode 0: data sampled on rising SCK edge (CPHA=0) with idle clock low (CPOL=0). Per FN8126 Section 8, setup time (tSU) is 30ns, hold time (tH) is 30ns, and maximum SCK frequency is 3.3MHz. CS must remain low throughout instruction, address, and data transfer; high-to-low CS transition initiates each operation.

How does the X5045S8I's block lock protection interact with the WP pin and WREN command?

Block lock protection (BL0/BL1 bits) and WP pin operate independently. When WP is LOW, all nonvolatile writes (EEPROM and status register) are blocked regardless of WREN state or BL settings. When WP is HIGH, WREN must be issued to enable writes, but BL bits determine which EEPROM addresses (0%, 25%, 50%, or 100%) remain write-protected. Both mechanisms must be satisfied for a write to succeed.

What is the minimum VCC required for the X5045S8I's RESET output to remain valid and functional?

The X5045S8I's RESET output remains asserted and electrically valid down to VCC = 1V, as specified in FN8126 Section 1. This ensures fail-safe behavior during deep brownout conditions where other supervisors may release reset prematurely. RESET stays active until VCC rises above 4.63V and remains stable for 200ms, providing clean power sequencing even under severe supply sag.