Renesas X4283S8I

Overview

X4283S8I from Xicor (now part of Renesas) is a CPU supervisor IC integrating power-on reset control, selectable watchdog timer, low-V_CC detection, and 128 Kbit serial EEPROM with Block Lock™ protection. It operates from 2.7V to 5.5V, features 400 kHz 2-wire interface, and delivers active reset assertion down to V_CC = 1V - used in microcontroller-based embedded systems requiring reliable boot sequencing and nonvolatile configuration storage.

For engineers reviewing the X4283S8I datasheet, X4283S8I pinout, X4283S8I application, or X4283S8I equivalent, key selection criteria include programmable V_TRIP threshold (adjustable via VP programming), three watchdog timeout options (200 ms / 600 ms / 1.4 s), 64-byte page write capability, hardware/software write protection granularity, and dual-package availability (SOIC-8/TSSOP-8).

Technical Context

The X4283S8I implements a dedicated analog voltage monitor for V_CC threshold detection with 250 ms reset timeout and guaranteed reset validity down to 1V. Its watchdog timer monitors SDA transitions during SCL HIGH to detect microcontroller lockup, with timeout period set by nonvolatile WD1/WD0 bits in the control register (FFFFh).

EEPROM functionality uses a 16K × 8-bit organization (128 Kbit total), internally segmented into 64-byte pages, supporting both byte and page writes with self-timed 5 ms typical write cycles. Block Lock™ protection is controlled by BP2–BP0 bits and optionally enabled via WP pin + WPEN bit for hardware-level write inhibit.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (JEDEC MS-012) and 8-pin TSSOP - both RoHS-compliant, surface-mount, and footprint-compatible for drop-in layout reuse.

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 STM8T142M2C, the X4283S8I uniquely combines field-adjustable V_TRIP, three-tier watchdog timeout, and hardware-block-lock EEPROM in a single 8-pin package - delivering superior flexibility for legacy MCU platforms needing drop-in supervision upgrades.

Availability

X4283S8I is available at Aetrix Electronics and suitable for industrial automation, medical diagnostics, automotive body electronics, and smart metering applications requiring stable component supply, long-term lifecycle support, and verified second-source alternatives.

Supply support for X4283S8I 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 pioneer in nonvolatile programmable supervisors and serial EEPROMs; acquired by Intersil in 2005 and later by Renesas Electronics in 2017 - maintaining legacy product support and qualification standards.

The X4283/85 family was designed specifically for embedded systems needing consolidated power management, fault detection, and secure nonvolatile storage - targeting cost-sensitive, high-reliability applications where board space and component count are constrained.

FAQ

What is the factory-default watchdog timeout setting for the X4283S8I?

The X4283S8I ships with the watchdog timer disabled (WD1=1, WD0=1). This is the default state after power-up or reset. To enable it, the nonvolatile control register at address FFFFh must be written with WD1/WD0 bits set to 00 (1.4 s), 01 (600 ms), or 10 (200 ms) using the three-step WEL/RWEL sequence. The X4283S8I will retain this setting across power cycles until explicitly reprogrammed.

Can the X4283S8I's V_TRIP threshold be adjusted in-circuit without removing the device?

Yes, the X4283S8I supports in-system V_TRIP adjustment using the VP programming method: apply 12–15V to the WP pin while holding V_CC at the desired threshold voltage, then issue the specific I²C write sequence (A0h → 00h → 01h → 00h). No device removal or socketing is required. The X4283S8I retains the new threshold permanently until reset or reprogrammed again.

How does the X4283S8I prevent unintended EEPROM writes during power transitions?

The X4283S8I incorporates dual-layer protection: (1) automatic hardware lock during RESET/RESET assertion (e.g., power-up, brownout, watchdog timeout), and (2) programmable Block Lock™ segments controlled by BP2–BP0 bits. Additionally, the WP pin + WPEN bit enable hardware-level write inhibition. These mechanisms ensure no EEPROM write can occur unless V_CC is stable, RESET/RESET is inactive, and both software and hardware write enables are asserted - a safeguard built into the X4283S8I's core architecture.

What is the maximum number of X4283S8I devices that can share the same I²C bus?

Up to four X4283S8I devices can operate on a single I²C bus, determined by the two hardware address pins S0 and S1. Each combination (00, 01, 10, 11) yields a unique 7-bit slave address (A0–A3), allowing independent communication without address conflict. The X4283S8I does not support software-configurable addresses, so physical pin strapping is required to differentiate units on the same bus.

Does the X4283S8I support standard I²C protocol or require proprietary command sequences?

The X4283S8I uses standard I²C protocol for all memory reads/writes (START → Slave Address → Word Address → Data → STOP), fully compatible with generic I²C masters. However, control register access (FFFFh), V_TRIP programming, and Block Lock™ configuration require precise multi-step sequences defined in the datasheet - these are extensions beyond base I²C but do not alter underlying bus timing or electrical signaling. The X4283S8I remains interoperable with standard I²C controllers.