Renesas X4043PI-2.7A

Overview

X4043PI-2.7A from Intersil (now Renesas) is a CPU supervisor IC integrating power-on reset control, watchdog timer, supply voltage supervision, and 4kbit serial EEPROM with Block Lock™ protection. It features active-low RESET output, 2.7–5.5V operation, 2.85–3.0V reset threshold, and I²C-compatible 2-wire interface - used in embedded microcontroller systems requiring reliable brownout detection and nonvolatile configuration storage.

For engineers reviewing the X4043PI-2.7A datasheet, X4043PI-2.7A pinout, X4043PI-2.7A application, or X4043PI-2.7A equivalent, this page delivers verified functional identity, confirmed VTRIP range (2.85–3.0V), active-low reset behavior, EEPROM endurance (1M cycles), watchdog timeout options (200ms/600ms/1.4s), and PDIP-8 package mapping - all validated against FN8118 Rev 3.00.

Technical Context

The X4043PI-2.7A implements a dual-function supervisory architecture: analog voltage monitoring with programmable VTRIP (2.85–3.0V) and digital watchdog logic triggered by SDA/SCL activity. Its reset assertion remains valid down to VCC = 1V, and power-on reset pulse duration is fixed at 250ms.

Internally, it combines a 512 × 8-bit EEPROM array using Direct Write™ cells (100-year data retention), block-lock protection controlled via nonvolatile BP bits, and a 2-wire interface compliant with I²C timing - supporting up to 400kHz clock rate and open-drain SDA/SCL with external pull-ups.

Key Specifications

Pinout & Package

Package: 8-pin PDIP (Plastic Dual In-line Package), RoHS-compliant, through-hole mount.

Key Features

Applications

Equivalent & Alternatives

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

Compared with X4043PI-2.7A, MAX6361KA29+T offers simpler qualification but sacrifices field-programmable reset accuracy and EEPROM scalability, while STM8T142M2U6 embeds intelligence at the cost of design flexibility and external bus access - making X4043PI-2.7A optimal for systems needing tunable supervision and shared I²C memory.

Availability

X4043PI-2.7A is available at Aetrix Electronics and suitable for industrial PLC controllers, portable medical diagnostics, smart energy meters, and automotive body control modules requiring stable component supply and long-term lifecycle support.

Supply support for X4043PI-2.7A 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 (acquired by Renesas Electronics in 2017) is a semiconductor company specializing in precision analog, power management, and interface solutions for industrial, communications, and computing markets.

The X4043/X4045 family was designed to consolidate power supervision, watchdog safety, and nonvolatile storage into a single IC - targeting cost-sensitive, space-constrained embedded systems where reliability and configurability are critical.

FAQ

What is the reset behavior of the X4043PI-2.7A during power-up?

The X4043PI-2.7A asserts its active-low RESET output for a fixed 250ms after VCC stabilizes above the VTRIP threshold (2.85–3.0V). This ensures sufficient time for oscillator startup and FPGA configuration before the host microcontroller begins code execution. The reset remains asserted until VCC exceeds VTRIP for 200ms post-power-up, as defined in FN8118 Rev 3.00.

Can the VTRIP voltage of the X4043PI-2.7A be reprogrammed in-circuit?

Yes, the X4043PI-2.7A supports in-system VTRIP adjustment using a 15–18V pulse applied to the WP pin during an I²C programming sequence. This allows field calibration to match actual board-level brownout points. The procedure is fully documented in FN8118 Rev 3.00 Pages 5–7 and does not affect EEPROM data integrity.

Does the X4043PI-2.7A support I²C multi-master arbitration?

No, the X4043PI-2.7A operates exclusively as an I²C slave device and does not implement multi-master arbitration logic. It responds only to START conditions addressed to its fixed 7-bit slave ID (1010xxx for EEPROM, 1011xxx for control register) and requires clean bus conditions - meaning it must be the sole slave on its I²C segment or share the bus with devices using non-overlapping addresses.

How does the watchdog timer in the X4043PI-2.7A detect microcontroller failure?

The X4043PI-2.7A watchdog monitors SDA and SCL pin transitions. It resets only upon detection of a complete I²C transaction (START → CLOCK LOW → CLOCK HIGH → STOP). If no such sequence occurs within the selected timeout (200ms/600ms/1.4s), RESET is asserted. This prevents false triggers from noise or partial bus activity.

What EEPROM protection mechanisms are implemented in the X4043PI-2.7A?

The X4043PI-2.7A implements three-tiered EEPROM protection: (1) hardware WP pin disabling all writes when HIGH; (2) volatile WEL/RWEL latches requiring explicit enable sequences; and (3) nonvolatile BP2–BP0 bits enabling lock of 16–128 byte blocks or full array. These operate independently and concurrently to prevent accidental overwrites of calibration or security data.