Renesas X4043M8I-2.7

Overview

X4043M8I-2.7 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, 2.7V–5.5V operation, 2.55V–2.7V reset threshold, -40°C to +85°C industrial temperature range, and 400kHz I²C interface - deployed in embedded microcontroller systems requiring reliable brownout recovery and nonvolatile configuration storage.

For engineers reviewing the X4043M8I-2.7 datasheet, X4043M8I-2.7 pinout, X4043M8I-2.7 application, or X4043M8I-2.7 equivalent, this page delivers verified technical context, exact pin functions, real-world use cases, and validated alternative options - all grounded in FN8118 Rev 3.00 and official Renesas product documentation.

Technical Context

The X4043M8I-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 integrates a 512 × 8-bit EEPROM array using Direct Write™ cells (1M write cycles, 100-year data retention), organized into 16-byte pages with software-controlled Block Lock™ protection (BP2–BP0). Communication uses standard I²C protocol at up to 400kHz, with open-drain SDA/SCL, active-low open-drain RESET, and hardware WP pin for full-array write disable.

Key Specifications

Pinout & Package

8-pin MSOP package (JEDEC MO-187AA), RoHS-compliant, Pb-free plus anneal finish. Pin 1 and Pin 2 are NC (no internal connection); Pin 3 is active-low open-drain RESET requiring external pull-up; Pin 7 is hardware write-protect input.

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 STM8T142M2U6, the X4043M8I-2.7 uniquely combines field-adjustable VTRIP, three-user-selectable watchdog intervals, and 4kbit Block Lock™ EEPROM - delivering superior configurability for systems demanding precise brownout response and robust nonvolatile storage without MCU intervention.

Availability

X4043M8I-2.7 is available at Aetrix Electronics and suitable for industrial automation, medical handhelds, smart meters, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for X4043M8I-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

Renesas Electronics Corporation (formerly Intersil) is a global semiconductor leader specializing in microcontrollers, analog, power management, and timing solutions for industrial, automotive, and IoT applications.

The X4043M8I-2.7 belongs to Renesas' legacy CPU Supervisor family, designed specifically to consolidate reset, watchdog, voltage monitoring, and EEPROM functions into a single IC - reducing board space and improving system-level reliability in resource-constrained embedded designs.

FAQ

What is the factory-default reset threshold voltage for X4043M8I-2.7?

The X4043M8I-2.7 ships with a factory-programmed VTRIP range of 2.55V to 2.7V, optimized for 3.3V supply monitoring. This threshold is nonvolatile and remains stable over temperature and time unless reprogrammed using the high-voltage WP pulse sequence defined in FN8118 Rev 3.00 Section 5. The actual trip point can be verified by ramping VCC and measuring RESET deassertion voltage.

Does X4043M8I-2.7 support I²C clock stretching or multi-master arbitration?

No - the X4043M8I-2.7 operates strictly as an I²C slave device with no clock stretching capability or multi-master arbitration support. Its SCL input is purely synchronous; it does not hold SCL low to delay transactions. The device acknowledges addresses and data per standard I²C timing but relies entirely on the master for bus control and clock generation.

Can the watchdog timer on X4043M8I-2.7 be disabled permanently?

Yes - the watchdog timer on X4043M8I-2.7 is disabled by default (WD1=1, WD0=1) and remains disabled until explicitly reconfigured via the nonvolatile control register. Once set to "disabled", it stays disabled across power cycles unless rewritten. Disabling eliminates periodic SDA/SCL activity requirements and reduces standby current to <1µA.

How is EEPROM write protection enforced on X4043M8I-2.7 during power transitions?

X4043M8I-2.7 enforces EEPROM write protection during power transitions through dual mechanisms: (1) automatic WEL latch reset on power-up (disabling all writes), and (2) hardware lockout when VCC falls below VTRIP - halting all I²C communication and aborting in-progress writes. These features ensure no partial or corrupted writes occur during brownout or power-down sequences.

Is the RESET pin on X4043M8I-2.7 compatible with 5V-tolerant microcontrollers?

Yes - the RESET pin on X4043M8I-2.7 is an open-drain output rated for 5.5V maximum, making it directly compatible with 5V-tolerant MCU reset inputs. An external pull-up resistor to the target MCU's VDD (3.3V or 5V) is required. The pin sinks current only when active (LOW), with typical VOL ≤ 0.4V at 3.2mA - meeting standard TTL and CMOS reset input thresholds.