Renesas X4043S8-4.5A

Overview

X4043S8-4.5A 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 SOIC package. It features active-low reset output, 4.5V–4.75V V_TRIP threshold, 400kHz I²C interface, <20µA standby current with watchdog enabled, and Block Lock™ EEPROM protection. It is used in microcontroller-based embedded systems requiring reliable power sequencing and nonvolatile configuration storage.

For engineers reviewing the X4043S8-4.5A datasheet, X4043S8-4.5A pinout, X4043S8-4.5A application, or X4043S8-4.5A equivalent, key selection considerations include its fixed 4.5V reset threshold, open-drain RESET output requiring external pull-up, 2-wire interface timing compliance, EEPROM page-write capability, and V_TRIP reprogrammability via high-voltage WP pin sequence.

Technical Context

The X4043S8-4.5A implements a dedicated low-voltage detection circuit that asserts RESET when V_CC falls below 4.5V and holds it active until V_CC rises above 4.75V for ≥200ms. Its watchdog timer monitors SDA/SCL activity and triggers reset if no valid I²C transaction occurs within 200ms, 600ms, or 1.4s - selectable via nonvolatile control register bits WD1/WD0.

Internally, the device combines a 512 × 8-bit EEPROM array using Direct Write™ cells (1M write cycles, 100-year retention) with hardware write protection logic tied to WP pin state and BP2–BP0 block lock bits. The 2-wire interface complies with standard I²C protocol, supporting byte and 16-byte page writes with self-timed 5ms typical write cycle time.

Key Specifications

Pinout & Package

Package: 8-lead JEDEC SOIC (Pb-free, RoHS compliant), 150 mil width, 1.27mm pitch.

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 X4043S8-4.5A uniquely delivers factory-trimmed 4.5V reset accuracy *plus* field-adjustable V_TRIP, 4kbit EEPROM capacity, and 400kHz I²C - making it optimal for cost-sensitive, high-volume industrial controllers where precision brownout response and firmware parameter storage are co-required.

Availability

X4043S8-4.5A is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic devices, automotive body control modules, smart energy meters, and battery-backed embedded systems requiring stable component supply across extended product lifecycles.

Supply support for X4043S8-4.5A 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, designs high-performance analog and mixed-signal ICs for power management, precision analog, and interface applications.

The X4043S8-4.5A belongs to Intersil's CPU Supervisor family, engineered specifically to consolidate reset, watchdog, voltage monitoring, and EEPROM functions into one die - reducing board space and improving system reliability in resource-constrained embedded designs.

FAQ

What is the exact V_TRIP range for X4043S8-4.5A?

The X4043S8-4.5A has a factory-set V_TRIP range of 4.5V to 4.75V. This means RESET asserts when V_CC drops to ≤4.5V and remains asserted until V_CC rises above 4.75V and stabilizes for ≥200ms. The value is guaranteed across 0°C to 70°C ambient temperature and can be reprogrammed to custom voltages using the WP pin high-voltage sequence - a feature unique to the X4043/X4045 family.

Does X4043S8-4.5A support I²C Fast Mode (400kHz)?

Yes, X4043S8-4.5A fully supports I²C Fast Mode with a maximum SCL clock frequency of 400kHz. Its SDA and SCL pins meet standard I²C electrical specifications, including open-drain outputs with defined rise/fall times and noise immunity. The device responds to slave address 0xA0 (write) or 0xA1 (read) and supports byte reads, sequential reads, and 16-byte page writes - all compliant with Philips I²C-bus specification Rev. 6.

How is the watchdog timeout configured on X4043S8-4.5A?

The watchdog timeout on X4043S8-4.5A is configured via two nonvolatile bits (WD1 and WD0) in the control register at address 0x1FF. These bits select one of four intervals: 200ms (10), 600ms (01), 1.4s (00), or disabled (11). Configuration requires a three-step write sequence involving WEL and RWEL latches, and the setting persists across power cycles. Once locked via WP pin, the timeout cannot be changed without re-enabling write access.

Can X4043S8-4.5A operate from a 3.3V supply?

No, X4043S8-4.5A is specified only for 4.5V–5.5V operation. Its V_TRIP range (4.5V–4.75V) and internal circuitry are optimized for +5V systems. Attempting to power it from 3.3V will result in improper reset assertion, failed I²C communication, and potential EEPROM corruption. For 3.3V applications, consider the X4043S8Z-2.7A variant, which supports 2.7V–5.5V supply and offers 2.85V–3.0V V_TRIP.

What EEPROM protection mechanisms does X4043S8-4.5A provide?

X4043S8-4.5A provides three-tier EEPROM protection: (1) Hardware WP pin - HIGH disables all writes; (2) Power-up/down protection - automatic write inhibition during supply transients; (3) Block Lock™ - eight software-selectable protection modes (e.g., lock first 128 bytes or full 4kbit array) controlled by nonvolatile BP2–BP0 bits. All mechanisms prevent inadvertent overwrite during firmware updates or system faults.