Renesas X5323S8IT1

Overview

X5323S8IT1 from Intersil is a CPU supervisor IC with integrated 32kbit SPI EEPROM, combining power-on reset control, watchdog timer, supply voltage supervision, and block-lock protected memory in a single 8-lead SOIC package. It operates from 2.7V to 5.5V, provides five factory-standard VTRIP thresholds (e.g., 4.25–4.5V), supports 2MHz SPI interface (modes 0,0 and 1,1), and delivers <1µA standby current with watchdog disabled - used in microcontroller-based industrial controllers for reliable boot sequencing and firmware parameter storage.

For engineers reviewing the X5323S8IT1 datasheet, X5323S8IT1 pinout, X5323S8IT1 application, or X5323S8IT1 equivalent, this device serves as a system-level supervisory solution where deterministic reset timing, field-programmable VTRIP, volatile flag-based reset source identification, and hardware-block-locked EEPROM are required for embedded safety-critical firmware storage and brown-out recovery.

Technical Context

The X5323S8IT1 implements a dual-function CS/WDI pin that enables both chip select and watchdog input functionality, with watchdog timeout periods selectable via nonvolatile WD0/WD1 bits (200ms, 600ms, or 1.4s). Its low-VCC detection circuit asserts RESET/RESET down to 1V and holds it active for 200ms after VCC exceeds VTRIP, supporting stable microprocessor initialization.

VTRIP is reprogrammable using a dedicated VP-based sequence on SCK/SI pins, allowing field adjustment of reset threshold voltage within 1.7–5.0V range; the device also includes a volatile flag bit to distinguish watchdog-initiated resets from power-fail resets, and Block Lock™ protection enabling selective write-protection of 0%, 25%, 50%, or 100% of the EEPROM array.

Key Specifications

Pinout & Package

Package: 8-lead SOIC (Pb-free, RoHS compliant), body width 3.9mm, standard JEDEC MS-012AC footprint.

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 STM8AF5288TDY, the X5323S8IT1 uniquely combines field-programmable VTRIP, 32kbit SPI EEPROM, and watchdog timeout persistence - making it optimal for retrofitting legacy systems needing enhanced reset precision and scalable nonvolatile storage without MCU redesign.

Availability

X5323S8IT1 is available at Aetrix Electronics and suitable for industrial automation, medical device firmware storage, and automotive body electronics requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for X5323S8IT1 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) is a semiconductor manufacturer specializing in precision analog, power management, and interface ICs for industrial, aerospace, and communications markets.

The X5323 product line delivers integrated CPU supervision with serial EEPROM for embedded systems requiring deterministic reset behavior, field-configurable voltage thresholds, and secure nonvolatile data storage - designed specifically for reliability-critical firmware and calibration retention.

FAQ

What is the function of the CS/WDI pin on the X5323S8IT1?

The CS/WDI pin on the X5323S8IT1 serves a dual role: as Chip Select (CS), it enables SPI communication when driven LOW; as Watchdog Input (WDI), a HIGH-to-LOW transition resets the internal watchdog timer. This shared pin reduces pin count while maintaining independent control of both functions - the watchdog remains active even when CS is HIGH, ensuring continuous supervision regardless of SPI bus activity. The X5323S8IT1 uses this pin to provide fail-safe microcontroller monitoring without requiring additional GPIO resources.

Does the X5323S8IT1 support reprogramming of its VTRIP voltage in-system?

Yes, the X5323S8IT1 supports in-system VTRIP reprogramming using a dedicated VP-based sequence applied to SCK and SI pins while holding CS/WDI and WP HIGH. This allows field adjustment of the reset threshold between 1.7V and 5.0V - for example, tuning from the default 4.25–4.5V range to 4.6V for tighter 5V rail tolerance. The procedure requires no special programming hardware beyond controlled VP pulses (15–18V), and the new VTRIP value persists across power cycles. This capability is unique to the X5323S8IT1 among comparable supervisors.

How does the X5323S8IT1 distinguish between a watchdog timeout reset and a low-voltage reset?

The X5323S8IT1 uses a volatile flag bit in its status register to differentiate reset causes: the flag is set automatically on watchdog timeout and cleared on power-up or low-voltage reset. Software reads this flag via the RDSR instruction immediately after reset to determine root cause - enabling distinct recovery routines (e.g., task watchdog restart vs. power rail diagnostics). Unlike many supervisors, the X5323S8IT1 provides this diagnostic capability without requiring external logic or additional pins, and the flag state is preserved until explicitly cleared by firmware.

What EEPROM protection mechanisms does the X5323S8IT1 implement?

The X5323S8IT1 implements three-tiered EEPROM protection: (1) Power-up/power-down write inhibit circuitry prevents spurious writes during supply transitions; (2) Block Lock™ protection controlled by nonvolatile BL0/BL1 bits locks 0%, 25%, 50%, or 100% of the 32kbit array; (3) In-circuit programmable ROM mode enabled by WPEN bit + WP pin grounding disables all status register writes post-configuration. These features ensure that critical calibration data stored in the X5323S8IT1's EEPROM remains immune to accidental or malicious overwrite during field operation.

What are the key timing parameters for SPI communication with the X5323S8IT1?

The X5323S8IT1 supports SPI clock frequencies up to 2MHz with defined timing margins: tSU (data setup) ≥50ns, tH (data hold) ≥50ns, tWH/tWL (clock high/low) ≥200ns/250ns, and tCYC (cycle time) ≤500ns. It operates in SPI modes 0,0 and 1,1, with data latched on SCK rising edge (SI) and output on falling edge (SO). The device also guarantees tDIS (output disable) ≤250ns and tV (output valid from clock low) ≤250ns - ensuring clean, glitch-free data transfers compatible with standard microcontroller SPI peripherals without added delay loops. These specs apply across the full 2.7–5.5V supply range.