Renesas X4323S8I-4.5A

Overview

X4323S8I-4.5A from Xicor (now part of Renesas) is a CPU supervisor IC integrating power-on reset control, watchdog timer, supply voltage supervision, and 32Kbit serial EEPROM in a single 8-pin SOIC package. It features a factory-set 4.5V reset threshold, 400kHz I²C interface, <1µA standby current with watchdog disabled, and supports block-lock write protection across 64-byte pages.

For engineers reviewing the X4323S8I-4.5A datasheet, X4323S8I-4.5A pinout, X4323S8I-4.5A application, or X4323S8I-4.5A equivalent, key selection considerations include its programmable V_TRIP capability, open-drain active-low RESET output timing (250ms release delay), EEPROM page-write performance (5ms typical cycle), and hardware write protection via WP pin and WPEN bit.

Technical Context

The X4323S8I-4.5A implements a dual-function reset architecture: power-on reset asserts RESET for 250ms after V_CC stabilizes above 4.5V, while low-V_CC detection reasserts RESET if V_CC drops below 4.5V and holds it until V_CC exceeds 4.5V for 200ms. Its watchdog timer monitors SDA transitions during SCL HIGH and offers three timeout options (200ms/600ms/1.4s) set via nonvolatile WD1/WD0 bits.

The integrated 32Kbit (4K × 8) EEPROM operates on the same 2-wire bus, supports 64-byte page writes, and enforces write protection through volatile WEL/RWEL latches, nonvolatile BP2–BP0 block lock bits, and hardware-level WP/WPEN control - all coordinated by command decode logic tied to SDA/SCL state machines.

Key Specifications

Pinout & Package

Package: 8-lead SOIC (JEDEC MS-012, 150 mil width), RoHS-compliant, moisture sensitivity level 3.

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 STM8AF6266TCY, the X4323S8I-4.5A uniquely balances fixed 4.5V precision supervision with field-reprogrammable threshold capability, full 32Kbit EEPROM capacity, and hardware-enforced write protection - making it optimal for industrial and medical systems where deterministic reset behavior and data integrity are non-negotiable.

Availability

X4323S8I-4.5A is available at Aetrix Electronics and suitable for industrial PLC controllers, medical infusion pumps, smart energy meters, and automotive body control modules requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for X4323S8I-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 was a fabless semiconductor company specializing in nonvolatile memory and power management ICs, acquired by Renesas Electronics in 2002. Known for innovation in EEPROM-integrated supervisors and programmable voltage references.

The X4323 family was designed to consolidate reset, watchdog, voltage monitoring, and data storage functions into a single chip for space-constrained embedded systems - targeting reliability-critical applications in industrial automation and medical equipment.

FAQ

What is the factory-programmed reset threshold voltage for X4323S8I-4.5A?

The X4323S8I-4.5A ships with a factory-set reset threshold of 4.5V ±100mV. This value is laser-trimmed during production and remains stable over temperature, voltage, and time. It is confirmed in the device marking "4.5A" and validated in the datasheet's Electrical Characteristics table under V_TRIP specification. The X4323S8I-4.5A supports reprogramming to other thresholds using the VP pulse method, but the default remains 4.5V unless modified.

Can the watchdog timer on X4323S8I-4.5A be disabled, and how is it configured?

Yes, the watchdog timer on X4323S8I-4.5A can be permanently disabled by setting WD1=1 and WD0=1 in the Control Register (address FFFFh). This configuration is nonvolatile and persists across power cycles. Disabling requires a three-step write sequence: first set WEL=1 (02h), then RWEL=1 (06h), then write 0x03 to the control register. Once disabled, the X4323S8I-4.5A will not assert RESET due to watchdog timeout, though power-on and low-V_CC reset remain fully functional.

How does the X4323S8I-4.5A protect EEPROM contents during power loss?

The X4323S8I-4.5A employs multi-layer EEPROM protection: (1) Power-up/power-down circuitry inhibits all I²C communication while RESET is active; (2) Volatile WEL latch must be set before any write; (3) Nonvolatile BP2–BP0 bits lock specific 64-byte pages; (4) Hardware WP pin + WPEN bit blocks writes entirely when both are HIGH. During brownout, RESET assertion halts ongoing writes and prevents new commands - ensuring the X4323S8I-4.5A never leaves EEPROM in a partially written or corrupted state.

Is the X4323S8I-4.5A pin-compatible with other members of the X4323/X4325 family?

Yes, the X4323S8I-4.5A shares identical 8-pin SOIC pinout and I²C interface compatibility with all X4323/X4325 variants (e.g., X4323S8I-2.9A, X4325S8I-4.5A). Differences are limited to factory-set V_TRIP voltage and RESET polarity (X4323 = active-low RESET, X4325 = active-high RESET). The X4323S8I-4.5A uses the same S0/S1 addressing, SDA/SCL timing, and control register map - enabling drop-in replacement where 4.5V threshold and active-low reset are required.

What is the maximum write endurance and data retention for the EEPROM in X4323S8I-4.5A?

The EEPROM in X4323S8I-4.5A is rated for 100,000 write/erase cycles per byte and guarantees 40 years of data retention at +25°C. These specifications are measured per JEDEC standards and apply to all 32Kbit cells. Page-write mode (64 bytes per cycle) does not degrade endurance beyond the per-byte rating. The X4323S8I-4.5A includes built-in write-cycle timing control and automatic write completion detection to ensure each operation meets these endurance and retention targets.