Renesas X4283S8-2.7

Overview

X4283S8-2.7 from Xicor (now part of Renesas) is a 16K × 8-bit CPU supervisor IC integrating power-on reset, watchdog timer, supply voltage supervision, and 128 Kbit serial EEPROM with Block Lock™ protection. It operates from 2.7V to 5.5V, asserts reset down to V_CC = 1V, supports 400 kHz I²C interface, and delivers <20 µA standby current with watchdog enabled - used in embedded microcontroller systems requiring reliable power sequencing and nonvolatile configuration storage.

For engineers reviewing the X4283S8-2.7 datasheet, X4283S8-2.7 pinout, X4283S8-2.7 application, or X4283S8-2.7 equivalent, key selection criteria include its programmable V_TRIP threshold (adjustable via VP programming), 64-byte page write capability, three selectable watchdog timeout periods (200 ms / 600 ms / 1.4 s), hardware write protection via WP pin + WPEN bit, and SOIC-8 packaging with verified pin mapping.

Technical Context

The X4283S8-2.7 implements a dual-function supervisory architecture: its analog reset generator monitors V_CC against a factory-set or user-programmed trip point (V_TRIP), asserting active-low RESET for ≥250 ms after stabilization; simultaneously, its watchdog circuit detects SDA activity (HIGH→LOW transitions while SCL is HIGH) to trigger reset if no valid start condition occurs within the selected timeout window.

Its EEPROM subsystem uses CMOS serial I²C protocol (400 kHz max), organized as 16K × 8 bits (128 Kbit), with 64-byte page write mode, self-timed 5 ms typical write cycle, and nonvolatile Block Protect bits (BP2–BP0) enabling selective lock of 64–512 bytes or 1/4/1/2/full array segments - all managed through address FFFFh control register with WEL/RWEL latching sequence.

Key Specifications

Pinout & Package

Package: 8-lead SOIC (JEDEC MS-012), body width 3.9 mm, lead pitch 1.27 mm - RoHS-compliant, surface-mount compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6361KA29+T and STM802LSD-27, the X4283S8-2.7 uniquely combines field-programmable V_TRIP, Fast-mode I²C, and 128 Kbit Block Lock EEPROM in one SOIC-8 package - reducing BOM count and PCB area while enabling robust, self-contained system supervision.

Availability

X4283S8-2.7 is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic devices, automotive body control modules, smart energy meters, and battery-backed embedded systems requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for X4283S8-2.7 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 2008. Its legacy products emphasize reliability, low-power operation, and integration density.

The X4283/85 product line was designed to consolidate power-on reset, voltage monitoring, watchdog safety, and serial EEPROM into a single chip - targeting space-constrained, safety-aware embedded systems where firmware integrity and supply resilience are critical.

FAQ

What is the default reset threshold voltage for the X4283S8-2.7?

The X4283S8-2.7 ships with a factory-default V_TRIP of 2.63V ±2%. This value is stored in nonvolatile circuitry and remains stable over temperature and time unless reprogrammed using the VP programming sequence described in the datasheet. The X4283S8-2.7 supports adjustment to custom thresholds between approximately 1.7V and 4.9V via dedicated programming voltage applied to the WP pin.

Does the X4283S8-2.7 require an external pull-up resistor on the SDA line?

Yes, the X4283S8-2.7 requires an external pull-up resistor on the SDA line because it features an open-drain output structure. A typical value is 4.7 kΩ to V_CC, ensuring proper I²C bus signaling at 400 kHz. The SCL line also requires a pull-up, and both resistors must be present for reliable communication - the X4283S8-2.7 does not include internal pull-ups.

How does the watchdog timer in the X4283S8-2.7 get reset?

The watchdog timer in the X4283S8-2.7 resets on a HIGH-to-LOW transition of the SDA line while SCL is held HIGH - matching the I²C start condition. This design ensures the timer is only refreshed during valid bus activity, not spurious noise. The X4283S8-2.7 does not respond to SCL toggling alone or SDA edges during SCL LOW. If no qualifying edge occurs within the selected timeout (200 ms / 600 ms / 1.4 s), RESET/RESET is asserted.

Can the EEPROM in the X4283S8-2.7 be written to while the RESET/RESET pin is active?

No, the X4283S8-2.7 blocks all EEPROM write operations while RESET/RESET is active - whether due to power-up, brownout, or watchdog timeout. This hardware-enforced lock prevents data corruption during unstable supply conditions. Additionally, in-progress writes are allowed to complete, but new writes are rejected until RESET/RESET deasserts and the device returns to normal operation.

What is the function of the S0 and S1 pins on the X4283S8-2.7?

The S0 and S1 pins on the X4283S8-2.7 configure the two least-significant bits of the I²C slave address, allowing up to four X4283S8-2.7 devices to share the same bus. With device identifier '1010', the full 7-bit address becomes 0x50 (S1=0,S0=0), 0x51 (S1=0,S0=1), 0x52 (S1=1,S0=0), or 0x53 (S1=1,S0=1). These pins are sampled at power-up and remain static during operation - no dynamic reconfiguration is supported.