Renesas X4043S8-2.7

Overview

X4043S8-2.7 from Intersil is a CPU supervisor IC integrating power-on reset control, watchdog timer, supply voltage supervision, and 4kbit EEPROM in an 8-pin SOIC package. It features active-low RESET output, 2.7V–5.5V operation, 2.55V–2.7V reset threshold, <1µA standby current (watchdog off), and 400kHz I²C interface - used in microcontroller-based embedded systems for reliable boot sequencing and brownout protection.

For engineers reviewing the X4043S8-2.7 datasheet, X4043S8-2.7 pinout, X4043S8-2.7 application, or X4043S8-2.7 equivalent, key selection criteria include reset threshold accuracy, EEPROM block-lock protection granularity, watchdog timeout configurability, and compatibility with 2-wire bus timing constraints in space-constrained industrial controllers.

Technical Context

The X4043S8-2.7 implements a dual-function reset architecture: power-on reset asserts RESET for ≥250ms after VCC stabilization, while low-VCC detection holds RESET active until VCC rises above 2.55V–2.7V and remains stable for 200ms. Its watchdog timer monitors SDA/SCL activity and triggers reset if no valid I²C start/stop sequence occurs within 200ms, 600ms, or 1.4s - selectable via nonvolatile WD1/WD0 bits.

Internally, it combines a CMOS serial EEPROM array organized as 512 × 8 bits with Intersil's Block Lock™ protection, supporting 16-byte page writes and 5ms typical write cycle time. The device uses Direct Write™ memory cells rated for 1M write cycles and 100-year data retention, with WP pin and software-controlled BP2–BP0 bits enabling flexible write protection of 16–512 byte blocks or full array.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (JEDEC MS-012AA), RoHS-compliant Pb-free + anneal finish, moisture sensitivity level (MSL) compliant with IPC/JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6375US27+T and STM8AF6266TCY, the X4043S8-2.7 uniquely delivers tightly coupled watchdog supervision, reprogrammable VTRIP, and granular Block Lock™ EEPROM protection in a single 8-pin SOIC - reducing BOM count and eliminating timing-critical software reset handlers.

Availability

X4043S8-2.7 is available at Aetrix Electronics and suitable for industrial PLC controllers, medical handheld diagnostics, smart energy meters, and automotive body control modules requiring stable component supply and long-term lifecycle support.

Supply support for X4043S8-2.7 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

Intersil (now part of Renesas Electronics) is a semiconductor company specializing in precision analog, power management, and interface ICs for industrial, aerospace, and communications markets.

The X4043S8-2.7 belongs to Intersil's CPU Supervisor family, designed specifically to consolidate reset, watchdog, voltage monitoring, and EEPROM functions into one die - targeting cost-sensitive, space-constrained embedded systems needing high reliability without software overhead.

FAQ

What is the factory-default reset threshold voltage for the X4043S8-2.7?

The X4043S8-2.7 ships with a factory-programmed reset threshold range of 2.55V to 2.7V, optimized for 3.3V system rails. This VTRIP value is nonvolatile and remains stable over temperature and time unless explicitly reprogrammed using the high-voltage WP pulse sequence described in the FN8118 datasheet. The X4043S8-2.7 maintains this threshold across its full operating temperature range of 0°C to 70°C.

Does the X4043S8-2.7 support I²C Fast Mode Plus (1MHz)?

No, the X4043S8-2.7 supports only standard-mode and Fast-mode I²C up to 400kHz. Its SDA and SCL input buffers are designed for 400kHz maximum clock frequency, and the internal timing logic does not meet the setup/hold requirements for 1MHz operation. For systems requiring 1MHz I²C, an external level-shifting buffer or alternative supervisor with Fast Mode Plus support would be needed - the X4043S8-2.7 is not rated for operation beyond 400kHz.

Can the watchdog timer on the X4043S8-2.7 be disabled permanently?

Yes, the watchdog timer on the X4043S8-2.7 can be disabled permanently by setting WD1=1 and WD0=1 in the nonvolatile control register (address 1FFh). Once programmed, this state persists across power cycles. Disabling the watchdog removes the requirement for periodic SDA/SCL activity but eliminates fail-safe recovery from MCU lockups - the X4043S8-2.7 retains all other functions including reset generation and EEPROM access.

How many bytes of EEPROM can be protected simultaneously using Block Lock™ on the X4043S8-2.7?

The X4043S8-2.7 supports eight distinct Block Lock™ protection configurations via BP2–BP0 bits, enabling simultaneous write protection of 16, 32, 64, 128, 256, or 512 bytes, the upper quarter (128 bytes), upper half (256 bytes), or the full 512-byte EEPROM array. Protection is enforced at the hardware level - any write attempt to a locked block is ignored and generates no acknowledge, ensuring robust data integrity for the X4043S8-2.7 in mission-critical applications.

Is the X4043S8-2.7 pin-compatible with other members of the X4043/X4045 family?

Yes, the X4043S8-2.7 is pin-compatible with all 8-pin SOIC variants in the X4043/X4045 family, including X4043S8Z-4.5A, X4043S8IZ-2.7, and X4045S8Z-2.7. All share identical pinout, electrical characteristics, and functional block diagram - differing only in factory-set VTRIP voltage, temperature grade, and reset polarity (X4045 has active-high RESET). PCB layouts designed for any 8-pin SOIC X4043/X4045 variant can accommodate the X4043S8-2.7 without modification.