Renesas X4043M8I-2.7A

Overview

X4043M8I-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, 2.7V–5.5V operation, 2.85V–3.0V reset threshold, -40°C to +85°C temperature range, and 400kHz I²C interface - used in embedded microcontroller systems requiring reliable brownout detection and nonvolatile configuration storage.

For engineers reviewing the X4043M8I-2.7A datasheet, X4043M8I-2.7A pinout, X4043M8I-2.7A application, or X4043M8I-2.7A equivalent, key selection criteria include its programmable VTRIP threshold, open-drain RESET timing (250ms power-up delay, tPURST), 16-byte page write EEPROM, <1µA watchdog-OFF standby current, and MSOP-8 package compatibility with space-constrained industrial controllers.

Technical Context

The X4043M8I-2.7A implements a dual-function supervisory architecture: analog voltage monitoring circuitry asserts RESET when VCC drops below 2.85V (min), holding it active until VCC exceeds VTRIP for 200ms; simultaneously, a watchdog timer monitors SDA/SCL activity and triggers RESET if no valid I²C transaction occurs within 200ms, 600ms, or 1.4s - selectable via nonvolatile WD1/WD0 bits.

Its EEPROM subsystem uses Intersil's Direct Write™ cell technology (1M write cycles, 100-year data retention), organized as 512 × 8-bit, accessed via standard 2-wire protocol with slave address 0xA0 (array) or 0xB0 (control register). Block Lock™ protection is controlled by BP2–BP0 bits, enabling selective write lock of 16–128 byte segments or full array.

Key Specifications

Pinout & Package

8-pin MSOP (JEDEC MO-187AA), RoHS-compliant, Pb-free plus anneal termination. Pin 1 and Pin 2 are NC (no internal connection); Pin 3 is active-low open-drain RESET requiring external pull-up; Pin 7 (WP) enables hardware write protection; all I/O pins (SDA, SCL) are 5V-tolerant with internal pull-downs disabled.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6375US29D3+ and STM8T142M2U6, the X4043M8I-2.7A uniquely balances field-programmable VTRIP, 4kbit EEPROM capacity, and minimal 8-pin MSOP footprint - making it optimal for cost-sensitive, space-constrained designs requiring both robust supervision and persistent parameter storage without MCU overhead.

Availability

X4043M8I-2.7A is available at Aetrix Electronics and suitable for industrial PLC controllers, medical infusion pumps, automotive body control modules, smart energy meters, and battery-backed IoT gateways requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for X4043M8I-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 Corporation, now part of Renesas Electronics, is a semiconductor manufacturer 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 chip - targeting cost- and space-constrained microcontroller-based systems needing certified reliability in harsh environments.

FAQ

What is the factory-default watchdog timeout setting for the X4043M8I-2.7A?

The X4043M8I-2.7A ships with watchdog timer disabled (WD1=1, WD0=1) as the factory default. This state prevents unintended resets during initial system bring-up. To enable watchdog functionality, the nonvolatile WD1/WD0 bits must be programmed via the control register using the three-step WEL/RWEL sequence documented in the FN8118 datasheet. The X4043M8I-2.7A retains this setting across power cycles.

Can the X4043M8I-2.7A's reset threshold voltage be adjusted after soldering to the PCB?

Yes, the X4043M8I-2.7A's VTRIP threshold can be reprogrammed in-system using a 15–18V pulse applied to the WP pin while executing a specific I²C command sequence (Slave Address A0h → Byte Address 01h → Data 00h). This procedure requires no rework or component replacement. The X4043M8I-2.7A supports both upward and downward VTRIP adjustments, with post-programming verification performed by ramping VCC and measuring RESET assertion voltage.

Does the X4043M8I-2.7A support standard I²C addressing without custom configuration?

Yes, the X4043M8I-2.7A uses standard I²C addressing: 0xA0 (write) / 0xA1 (read) for EEPROM array access, and 0xB0 (write) / 0xB1 (read) for control register access. No external address pins or configuration resistors are needed. The X4043M8I-2.7A responds to these addresses immediately after power-up, with no initialization sequence required beyond standard I²C start/stop conditions.

How does the X4043M8I-2.7A prevent accidental EEPROM writes during power transitions?

The X4043M8I-2.7A employs three-tiered write protection: (1) hardware WP pin - HIGH disables all writes; (2) power-up/power-down detection - blocks writes when VCC < VTRIP; (3) volatile WEL latch - must be explicitly set before any nonvolatile write. These mechanisms ensure that the X4043M8I-2.7A cannot corrupt stored data during brownout, reset, or noise-induced glitches on the I²C bus.

Is the MSOP-8 package of the X4043M8I-2.7A compatible with automated optical inspection (AOI) and reflow processes?

Yes, the X4043M8I-2.7A's MSOP-8 package (JEDEC MO-187AA) is fully compatible with standard SMT assembly processes, including lead-free reflow (J-STD-020-compliant peak temperature ≥260°C) and AOI. Its gull-wing leads and 0.65mm pitch allow reliable solder joint inspection. The X4043M8I-2.7A's Pb-free plus anneal finish ensures compatibility with both SnPb and Pb-free solder pastes without dewetting or voiding issues.