Renesas X4043P-2.7

Overview

X4043P-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 in a single 8-pin PDIP package. It features active-low reset output, 2.7–5.5V operation, 2.55–2.7V V_TRIP threshold, <1µA standby current (watchdog off), and 400kHz I²C interface - deployed in embedded microcontroller systems requiring reliable brownout protection and nonvolatile configuration storage.

For engineers reviewing the X4043P-2.7 datasheet, X4043P-2.7 pinout, X4043P-2.7 application, or X4043P-2.7 equivalent, key selection considerations include its fixed 2.55–2.7V reset threshold, PDIP package compatibility with legacy through-hole designs, EEPROM block-lock protection granularity, watchdog timeout configurability, and absence of internal pull-up on RESET.

Technical Context

The X4043P-2.7 implements a dual-function supervisory architecture: analog voltage monitoring circuitry asserts RESET when V_CC drops below 2.7V (typical), with reset hold time t_PURST ≥200ms after recovery; simultaneously, a digital watchdog monitors SDA/SCL activity and triggers reset if no valid I²C transaction occurs within user-selectable intervals (200ms/600ms/1.4s or disabled). Its EEPROM uses Direct Write™ cells for 1M write cycles and 100-year data retention.

Reset assertion is open-drain and requires external pull-up; the WP pin enables hardware write protection; V_TRIP is factory-programmed and reprogrammable via high-voltage sequence on WP (15–18V); all nonvolatile control bits (WD1/WD0, BP2/BP1/BP0) reside in a dedicated control register at address 1FFh accessed via slave address 1011b.

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 MAX6361LKA27+T and STM8T142M2U6, the X4043P-2.7 uniquely balances field-programmable V_TRIP, 4kbit block-locked EEPROM, and 400kHz I²C in a through-hole PDIP package - making it optimal for legacy-replacement and calibration-critical industrial controllers.

Availability

X4043P-2.7 is available at Aetrix Electronics and suitable for industrial automation, medical device manufacturing, and energy metering applications requiring stable component supply, long-term obsolescence management, and RoHS-compliant through-hole assembly.

Supply support for X4043P-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 Corporation, now part of Renesas Electronics, is a semiconductor company specializing in power management, precision analog, and interface ICs for industrial, communications, and computing markets.

The X4043P-2.7 belongs to Intersil's CPU Supervisor family designed to consolidate reset generation, voltage monitoring, watchdog safety, and nonvolatile storage into one die - targeting space-constrained, reliability-critical embedded systems where board area and failure modes must be minimized.

FAQ

What is the exact V_TRIP range for X4043P-2.7?

The X4043P-2.7 has a factory-set V_TRIP range of 2.55V to 2.7V, specified at T_A = 0°C to 70°C. This threshold is reprogrammable using a 15–18V pulse on the WP pin and a defined I²C sequence. The device guarantees reset assertion down to V_CC = 1V and holds RESET active until V_CC exceeds V_TRIP for ≥200ms after recovery. This range makes X4043P-2.7 suitable for 3.3V and 2.8V logic systems with tight brownout margins.

Does X4043P-2.7 support I²C clock stretching?

No, X4043P-2.7 does not support I²C clock stretching. It operates strictly as an I²C slave with fixed 400kHz maximum clock rate and relies on acknowledge polling to indicate EEPROM write completion. During internal write cycles (typical 5ms), the device ignores all I²C traffic and returns no ACK - requiring the host to poll using repeated START + slave address until ACK is received. This design eliminates timing dependency on slave clock control and simplifies host firmware.

Can X4043P-2.7 be used as a direct replacement for X4043S8Z-2.7?

No, X4043P-2.7 is not a pin-compatible replacement for X4043S8Z-2.7 due to differing packages: X4043P-2.7 uses 8-pin PDIP, while X4043S8Z-2.7 uses 8-pin SOIC. Although electrical functionality and pin functions are identical (including NC pins 1/2, RESET on pin 3, VSS on pin 4, etc.), PCB layout and soldering processes differ significantly. Migration requires mechanical redesign. X4043P-2.7 remains viable for through-hole legacy systems where SOIC footprint adaptation is impractical.

How is EEPROM write protection configured on X4043P-2.7?

EEPROM write protection on X4043P-2.7 is controlled via three nonvolatile block protect bits (BP2, BP1, BP0) in the control register at address 1FFh. These bits define eight protection modes - from no protection (000) to full array lock (011) or page-level locks (100–111 for 16/32/64/128 bytes). Configuration requires a three-step I²C sequence: set WEL bit (02h), set RWEL bit (06h), then write desired BP/WD bits. WP pin HIGH provides hardware override, disabling all writes regardless of BP settings.

What is the maximum watchdog timeout setting supported by X4043P-2.7?

The maximum watchdog timeout setting supported by X4043P-2.7 is 1.4 seconds, selected by setting WD1=0 and WD0=0 in the control register. Other options are 600ms (WD1=0, WD0=1), 200ms (WD1=1, WD0=0), or disabled (WD1=1, WD0=1 - factory default). Timeout is triggered when SDA remains static (HIGH or LOW) longer than the selected interval, indicating MCU firmware hang. The watchdog state persists across power cycles unless explicitly reconfigured.