Renesas X4325S8-4.5A

Overview

X4325S8-4.5A from Xicor (now Renesas) is a CPU supervisor IC integrating power-on reset control, watchdog timer, supply voltage supervision, and 32Kbit serial EEPROM in an 8-pin SOIC package. It provides selectable watchdog timeout (200 ms/600 ms/1.4 s), low-V_CC reset assertion down to 1V, and 400 kHz 2-wire interface - used in embedded microcontroller systems requiring reliable boot sequencing and nonvolatile configuration storage.

For engineers reviewing the X4325S8-4.5A datasheet, X4325S8-4.5A pinout, X4325S8-4.5A application, or X4325S8-4.5A equivalent, key selection criteria include reset threshold adjustability, EEPROM page-write capability (64-byte), watchdog independence from firmware, and hardware write protection via WP pin and BP bits.

Technical Context

The X4325S8-4.5A implements a dual-function reset architecture: power-on reset with 250 ms delay and brownout detection with 200 ms hysteresis, both asserting active-low RESET. Its watchdog timer monitors SDA transitions during SCL HIGH to detect MCU lockup - timeout period set by nonvolatile WD1/WD0 bits (200 ms, 600 ms, or 1.4 s).

EEPROM operation uses a 400 kHz I²C-compatible 2-wire interface with byte- and page-write modes (64-byte pages), self-timed 5 ms typical write cycle, and built-in write protection including power-up/down circuitry, Block Lock (BP2–BP0), and hardware WP-enabled locking. V_TRIP threshold is factory-set at 4.5 V and reprogrammable via dedicated sequence using VP on WP pin.

Key Specifications

Pinout & Package

8-pin SOIC (JEDEC MS-012) package with 1.27 mm pitch; RoHS-compliant, surface-mount, industrial temperature range (–40°C to +85°C).

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 STM8T142M2U6, the X4325S8-4.5A uniquely combines field-programmable V_TRIP, hardware watchdog independence from MCU execution, and 32 Kbit EEPROM with block-level write protection - enabling zero-firmware, long-life, and field-calibratable supervision in safety-critical embedded systems.

Availability

X4325S8-4.5A is available at Aetrix Electronics and suitable for industrial automation, medical device, and automotive body electronics requiring stable component supply, long-term EEPROM data retention, and deterministic reset behavior under voltage transients.

Supply support for X4325S8-4.5A 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

Xicor Inc. was a fabless semiconductor company specializing in nonvolatile memory and power management ICs, acquired by Intersil in 2001 and later integrated into Renesas Electronics.

The X432x family was designed to replace discrete reset ICs, watchdog timers, and EEPROMs in space-constrained microcontroller systems - targeting cost-sensitive, reliability-driven applications in industrial and medical markets.

FAQ

What is the factory-default reset threshold voltage for the X4325S8-4.5A?

The X4325S8-4.5A ships with a factory-programmed V_TRIP of 4.5 V, matching the "4.5A" suffix in its part number. This threshold is guaranteed over temperature and supply variations, and remains stable unless reprogrammed using the VP pulse sequence on the WP pin. The 4.5 V setting aligns with standard 5 V microcontroller rails and provides margin against typical brownout conditions.

Can the X4325S8-4.5A watchdog timer be disabled after power-up?

Yes - the X4325S8-4.5A watchdog timer is disabled by default (WD1=1, WD0=1). It can be enabled or reconfigured via the nonvolatile control register (address FFFFh), but only after executing the three-step WEL/RWEL write sequence. Once enabled, the timeout period remains fixed across power cycles until explicitly changed again using the same procedure.

How does the X4325S8-4.5A protect EEPROM writes during power loss?

The X4325S8-4.5A uses dual-layer protection: (1) hardware inhibition - any in-progress write is completed before RESET/RESET asserts, and (2) automatic disable - new writes are blocked while RESET/RESET is active. Additionally, the WEL latch powers up LOW, preventing accidental writes at startup. These mechanisms ensure EEPROM data integrity even during abrupt V_CC collapse below 1 V.

Is the X4325S8-4.5A pin-compatible with the X4323S8-4.5A?

Yes - the X4325S8-4.5A and X4323S8-4.5A share identical 8-pin SOIC packaging, pinout, and electrical interface. The primary functional difference is the reset output polarity: X4325 outputs active-HIGH RESET, while X4323 outputs active-LOW RESET. Both parts use the same V_TRIP, watchdog, and EEPROM functionality, allowing direct substitution where reset polarity is handled externally or via MCU configuration.

What is the maximum write endurance of the EEPROM in the X4325S8-4.5A?

The EEPROM in the X4325S8-4.5A is rated for a minimum of 100,000 write/erase cycles per memory location, with data retention exceeding 40 years at +25°C. This endurance applies to both byte and page writes, and is maintained across the full 2.7–5.5 V supply range and industrial temperature range (–40°C to +85°C), as verified in the original Xicor characterization report Rev 1.20.