Renesas X5043S8ZT1

Overview

X5043S8ZT1 from Intersil (now Renesas) is a 4K-bit SPI CPU supervisor IC integrating power-on reset, watchdog timer, supply voltage supervision, and block-lock protected EEPROM in an 8-lead SOIC package. It operates from 2.7V to 5.5V, features four factory-programmable V_TRIP thresholds (e.g., 2.63V, 2.93V), and delivers 1.4s/600ms/200ms selectable watchdog timeout - used in industrial process controllers to prevent firmware lockup during brownout conditions.

For engineers reviewing the X5043S8ZT1 datasheet, X5043S8ZT1 pinout, X5043S8ZT1 application, or X5043S8ZT1 equivalent, key selection criteria include active-low RESET output timing (200ms release delay), SPI interface compatibility at up to 3.3MHz, 16-byte page write capability with 5ms typical cycle time, and reprogrammable V_TRIP threshold via dedicated VP programming sequence.

Technical Context

The X5043S8ZT1 implements a dual-function CS/WDI pin for both chip select and watchdog input, where falling edges reset the internal timer. Its nonvolatile status register stores WD0/WD1 bits that persist across power cycles, enabling fixed watchdog timeout selection independent of host initialization.

Voltage supervision uses a precision comparator with hysteresis to assert RESET when V_CC drops below the programmed V_TRIP; the output remains active until V_CC exceeds V_TRIP for 200ms and stabilizes above 1V. The integrated 512 × 8 EEPROM uses Direct Write™ cells rated for 1M write cycles and 100-year data retention.

Key Specifications

Pinout & Package

Package: 8-lead SOIC (Pb-free, RoHS compliant), 3.9mm × 4.9mm body, 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 MAX6816EPA+ and MCP9808-E/P, the X5043S8ZT1 uniquely integrates three critical supervisory functions plus EEPROM in one SOIC-8 device - reducing BOM count, PCB footprint, and qualification effort for embedded systems requiring coordinated reset, monitoring, and persistent storage.

Availability

X5043S8ZT1 is available at Aetrix Electronics and suitable for industrial process control, network infrastructure, medical diagnostics, and battery-powered IoT sensors requiring stable component supply and long-term lifecycle support.

Supply support for X5043S8ZT1 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 (formerly Intersil) is a global semiconductor leader specializing in microcontrollers, analog, and power management solutions for industrial, automotive, and communications markets.

The X5043S8ZT1 belongs to Renesas' legacy CPU supervisor product line, designed specifically to consolidate reset, watchdog, voltage monitoring, and EEPROM into a single SPI-compatible device for space-constrained embedded systems.

FAQ

What is the default watchdog timeout setting for the X5043S8ZT1?

The X5043S8ZT1 ships with watchdog timer disabled (WD1=1, WD0=1) as factory default. To enable it, the host MCU must issue a WRSR command to program WD0/WD1 bits in the status register. Valid timeout options are 200ms, 600ms, or 1.4s - all persist across power cycles. The X5043S8ZT1 does not auto-enable watchdog on power-up.

Can the V_TRIP threshold of the X5043S8ZT1 be adjusted after soldering?

Yes, the X5043S8ZT1 supports in-system V_TRIP reprogramming using a 15–18V pulse applied to the WP pin while holding V_CC at the desired trip voltage. This procedure modifies internal fuse settings and requires no special test equipment - only controlled voltage application per Figure 1 in the FN8126 datasheet. The X5043S8ZT1 retains the new threshold indefinitely.

Does the X5043S8ZT1 support standard SPI read/write commands?

Yes, the X5043S8ZT1 implements industry-standard SPI protocol with READ (0x03), WRITE (0x02), WREN (0x06), WRDI (0x04), RDSR (0x05), and WRSR (0x01) opcodes. It operates at up to 3.3MHz clock rate, supports MSB-first transmission, and uses standard timing (tSU=30ns, tH=30ns). The X5043S8ZT1 is compatible with most microcontroller SPI peripherals without custom drivers.

How does the block lock protection work on the X5043S8ZT1 EEPROM?

The X5043S8ZT1 uses two nonvolatile BL0/BL1 bits in its status register to configure write protection for 0%, 25%, 50%, or 100% of the 512-byte EEPROM array. When enabled, protected blocks remain readable but reject all write attempts - even if WREN is issued and WP is HIGH. This feature is independent of the WP pin and persists across power cycles. The X5043S8ZT1 enforces this at the silicon level, not via software emulation.

What is the minimum V_CC required for the X5043S8ZT1 RESET output to remain valid?

The X5043S8ZT1 RESET output remains asserted and electrically valid down to V_CC = 1V, ensuring reliable reset signaling during deep brownout conditions. Once V_CC rises above the programmed V_TRIP threshold (e.g., 2.63V), the RESET signal deasserts only after 200ms of stable voltage - preventing premature release during recovery transients. This behavior is guaranteed across the full -40°C to +85°C temperature range for the X5043S8ZT1.