Renesas X4043P

Overview

X4043P from Intersil is a CPU supervisor IC integrating power-on reset control, watchdog timer, supply voltage supervision, and 4kbit EEPROM with Block Lock™ protection. It features active-low RESET output, 4.5–4.75V reset threshold, 2.7–5.5V supply operation, and 400kHz I²C interface - used in embedded microcontroller systems requiring reliable brownout detection and nonvolatile configuration storage.

For engineers reviewing the X4043P datasheet, X4043P pinout, X4043P application, or X4043P equivalent, this page delivers verified technical context, exact pin functions for 8-pin PDIP layout, real-world use cases in industrial controllers and legacy instrumentation, and two validated alternative parts with documented functional trade-offs.

Technical Context

The X4043P 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 exceeds 4.5V 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 512 × 8-bit EEPROM array using Direct Write™ cells (1M write cycles, 100-year retention) with software-configurable block lock protection (BP2–BP0), write-enable latching (WEL/RWEL), and VTRIP reprogramming capability via 15–18V pulse on WP pin - all operating over a 0°C to 70°C temperature range in 8-pin PDIP package.

Key Specifications

Pinout & Package

Package: 8-pin PDIP (Plastic Dual In-line Package), 0.300" width, RoHS-compliant Pb-free plus anneal finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6375CSA+ and STM8T142M6, the X4043P uniquely balances field-adjustable VTRIP, sub-20µA watchdog-active standby, and full I²C-accessible 4kbit EEPROM - making it optimal for retrofitting legacy 5V systems requiring both reliability and configurability.

Availability

X4043P is available at Aetrix Electronics and suitable for industrial control, medical instrumentation, and point-of-sale terminals requiring stable component supply and long-lifecycle support.

Supply support for X4043P 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 power management, precision analog, and interface ICs for industrial, computing, and communications markets.

The X4043P belongs to Intersil's CPU Supervisor family, designed to consolidate reset, watchdog, voltage monitoring, and EEPROM into single-chip solutions for space-constrained microcontroller systems.

FAQ

What is the exact reset threshold voltage of the X4043P?

The X4043P has a factory-set VTRIP threshold of 4.5–4.75V, as specified in its ordering code "X4043PZ-4.5A". This value is guaranteed over temperature and can be reprogrammed using a 15–18V pulse on the WP pin - enabling fine-tuning for specific board-level supply tolerances. The X4043P maintains reset assertion down to VCC = 1V, ensuring robust recovery from deep brownout events.

Does the X4043P support I²C communication at standard mode speed?

Yes, the X4043P supports standard-mode I²C up to 400kHz, compliant with Philips I²C specification. Its SDA and SCL pins implement open-drain outputs with internal input buffers always active, allowing direct connection to standard I²C buses. Pull-up resistors are required on both lines, and the device acknowledges slave address 0xA0 (write) or 0xA1 (read) - matching the behavior expected by common microcontroller I²C peripherals.

Can the EEPROM in the X4043P be written to while the watchdog is enabled?

Yes, the EEPROM in the X4043P remains fully accessible for read and write operations regardless of watchdog timer state. The watchdog monitors only SDA/SCL transitions - not memory access - so valid I²C transactions (including page writes to protected or unprotected blocks) will reset the watchdog timer and prevent false resets. However, writing to a block-locked region will suppress the ACK response without affecting watchdog timing.

What is the purpose of the NC pins on the X4043P PDIP package?

Pins 1 and 2 of the X4043P in 8-pin PDIP are designated NC (No Connection) and have no internal bonding. They must remain unconnected in PCB layout; tying them to ground or VCC is not recommended and may cause unintended leakage paths. These pins exist for mechanical compatibility with other devices in the same package footprint and do not affect X4043P functionality or timing behavior.

Is the X4043P still in active production, and what is its recommended replacement?

The X4043P is marked "No longer available" in the official Intersil ordering table, with X4043M8Z-4.5A (8-pin MSOP) listed as the recommended replacement. While the X4043P remains supported through Aetrix Electronics' extended inventory and lifecycle management program, new designs should evaluate the MSOP variant for improved thermal performance and modern assembly compatibility - noting identical electrical specs, pinout mapping (with NC pins omitted), and full functional equivalence.