Renesas X5045S8T1

Overview

X5045S8T1 from Intersil (now Renesas) is a 4K-bit SPI CPU supervisor IC integrating power-on reset, watchdog timer, supply voltage supervision, and block-lock protected EEPROM in an 8-lead SOIC package. It provides 2.93V reset threshold, 200ms reset timeout, and 1.4s watchdog timeout - used in industrial process controllers to ensure deterministic microcontroller startup and fault recovery during brownout events.

For engineers reviewing the X5045S8T1 datasheet, X5045S8T1 pinout, X5045S8T1 application, or X5045S8T1 equivalent, key selection criteria include VTRIP reprogrammability, SPI EEPROM endurance (1M cycles), active-low RESET output timing, and compatibility with 3.3MHz SPI buses in space-constrained embedded systems.

Technical Context

The X5045S8T1 implements a dual-function CS/WDI pin that serves as both chip select for SPI communication and watchdog input-toggling CS within the selected timeout interval resets the watchdog. Its internal voltage monitor uses a precision comparator with hysteresis to assert RESET until VCC exceeds the 2.93V trip point by ≥200ms.

EEPROM operations use a 16-byte page write mode with 5ms typical write cycle time; block lock protection is controlled via nonvolatile BL0/BL1 bits in the status register, enabling selective write-protection of 0%, 25%, 50%, or 100% of the 512×8 memory array.

Key Specifications

Pinout & Package

8-lead SOIC (Small Outline Integrated Circuit) package with standard 1.27mm pitch, RoHS-compliant matte tin termination, and Pb-free plus anneal construction per IPC/JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6361KA29+T and MCP809T-290I/SN, the X5045S8T1 uniquely integrates reset, watchdog, and 4K-bit EEPROM in one SOIC-8 device - reducing component count, PCB area, and qualification effort for systems requiring coordinated power management and persistent data storage.

Availability

X5045S8T1 is available at Aetrix Electronics and suitable for industrial process control, network infrastructure, medical instrumentation, and battery-powered data acquisition requiring stable component supply and long-term lifecycle support.

Supply support for X5045S8T1 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

Renesas Electronics (formerly Intersil) is a global semiconductor leader specializing in microcontrollers, analog, power management, and timing solutions for industrial, automotive, and communications markets.

The X5045S8T1 belongs to the X504x CPU Supervisor family designed to consolidate power monitoring, fault recovery, and nonvolatile configuration storage into a single IC - targeting space-constrained embedded systems needing high reliability and simplified design validation.

FAQ

What is the default reset threshold voltage for the X5045S8T1?

The X5045S8T1 ships with a factory-programmed VTRIP of 2.93V ±2.5%. This value is confirmed in the Ordering Information table on page 3 of FN8126 Rev 3.00, where "-2.7A" suffix denotes the 2.85–3.0V trip range corresponding to 2.93V nominal. The threshold remains stable over temperature and time unless reprogrammed using the VP-based procedure described on page 6.

Does the X5045S8T1 support SPI communication at 5MHz?

No, the X5045S8T1 supports a maximum SPI clock frequency of 3.3MHz as specified in the AC Electrical Specifications table on page 14. Attempting 5MHz operation violates the fSCK limit and may result in read/write errors or inconsistent status register reporting. The 3.3MHz rating applies across the full 2.7–5.5V VCC range and is validated under JEDEC-standard test conditions.

How does the watchdog timer in the X5045S8T1 get reset?

The X5045S8T1 watchdog timer is reset by a falling edge on the CS/WDI pin - not by toggling CS high/low. As stated on page 5, "A falling edge of CS will reset the watchdog timer." This means the host MCU must drive CS from high to low within the selected timeout period (e.g., 1.4s default) to prevent RESET assertion. Holding CS low continuously does not reset it; only the transition matters.

Can the EEPROM memory in the X5045S8T1 be partially write-protected?

Yes, the X5045S8T1 supports four levels of block lock protection via BL0/BL1 bits in the status register: none (00), upper quarter ($180–$1FF), upper half ($100–$1FF), or full array ($000–$1FF). This is defined in Table 2 on page 9 and implemented using nonvolatile bits programmed via the WRSR instruction. Protection is hardware-enforced - even with WREN issued and WP high, block-locked regions remain unwritable.

What is the minimum VCC required for the X5045S8T1 RESET output to remain valid?

The X5045S8T1 RESET output remains asserted and electrically valid down to VCC = 1V, as explicitly stated in the Features section on page 1. This ensures reliable reset signaling during deep brownout conditions where supply voltage collapses gradually. The specification is verified per the VRVALID parameter in the DC Electrical Specifications table on page 13, with no functional degradation below 1V until the absolute minimum rating of –0.5V is approached.