Renesas X5643S14

Overview

X5643S14 from Intersil is a CPU supervisor IC with integrated 64Kbit SPI EEPROM, combining power-on reset control, watchdog timer, supply voltage supervision, and block-lock protected memory in a single 14-lead SOIC package. It features selectable watchdog timeout (200 ms to 1.4 s), reprogrammable V_TRIP threshold (2.55–4.75 V), <1 µA standby current with watchdog disabled, and 2 MHz SPI interface supporting modes 0,0 and 1,1 - deployed in industrial microcontroller systems requiring reliable brownout protection and nonvolatile configuration storage.

For engineers reviewing the X5643S14 datasheet, X5643S14 pinout, X5643S14 application, or X5643S14 equivalent, key selection criteria include its dual-role RESET/RESET output (active LOW), programmable V_TRIP calibration capability, 32-byte page write EEPROM timing, Block Lock™ protection granularity (0/¼/½/all array), and compatibility with 2.7–5.5 V supply rails in space-constrained embedded designs.

Technical Context

The X5643S14 implements a hardware-based power-on reset circuit that asserts RESET/RESET down to V_CC = 1 V and holds it active for 100–280 ms after stabilization. Its watchdog timer uses two nonvolatile status register bits (WD0, WD1) to select fixed timeout intervals - 200 ms, 600 ms, or 1.4 s - and resets on CS/WDI pin transition absence, independent of software execution.

Voltage supervision relies on an adjustable comparator with five factory-standard V_TRIP options (2.55 V, 2.85 V, 4.25 V, 4.5 V, 4.63 V), all reprogrammable via VP-pulse sequence on SCK/SI pins. The EEPROM subsystem uses Intersil's Direct Write™ cell architecture, guaranteeing ≥100,000 write cycles and ≥100 years data retention, organized as 8K × 8 with 32-byte page write capability.

Key Specifications

Pinout & Package

Package: 14-lead SOIC (Small Outline Integrated Circuit), 3.9 mm × 8.7 mm body, gull-wing leads, RoHS-compliant.

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 STM8AF6266TAY, the X5643S14 uniquely combines field-programmable V_TRIP, sub-1 V reset validity, and autonomous watchdog - enabling plug-and-play reliability without MCU intervention or external components.

Availability

X5643S14 is available at Aetrix Electronics and suitable for industrial PLC I/O modules, medical infusion pump controllers, automotive body control units, smart energy meters, and battery-backed telemetry systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for X5643S14 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 ICs for industrial, aerospace, and communications markets.

The X5643S14 belongs to Intersil's CPU Supervisor family designed to replace discrete reset + EEPROM solutions in microcontroller-based systems where board space, BOM count, and system-level reliability are critical constraints.

FAQ

What is the function of the CS/WDI pin on the X5643S14?

The CS/WDI pin on the X5643S14 serves a dual role: as Chip Select (CS) to enable SPI communication when pulled LOW, and as Watchdog Input (WDI) to reset the internal watchdog timer on each HIGH-to-LOW transition. This pin must be toggled within the selected timeout interval - 200 ms, 600 ms, or 1.4 s - to prevent assertion of the RESET/RESET signal. Its multiplexed function reduces pin count while maintaining independent hardware supervision.

Can the reset threshold voltage (V_TRIP) of the X5643S14 be changed after soldering?

Yes, the V_TRIP of the X5643S14 can be reprogrammed post-soldering using a VP-pulse programming sequence applied to SCK and SI pins while holding CS/WDI and WP HIGH. This allows field calibration to match actual system rail tolerances - for example, adjusting from factory-default 4.5 V to 4.63 V - without requiring PCB redesign or component replacement. The procedure is documented in FN8135 Rev 1.00, pages 3–4.

How does the X5643S14 protect against unintended EEPROM writes?

The X5643S14 employs three layers of write protection: (1) a volatile Write Enable Latch (WEL) that must be set via WREN instruction before any write; (2) nonvolatile Block Lock™ bits (BL0/BL1) to protect 0%, 25%, 50%, or 100% of the EEPROM array; and (3) in-circuit programmable ROM mode activated when WP pin is LOW and WPEN bit = 1, which disables all status register writes. These mechanisms prevent corruption during power transitions or firmware bugs.

What is the maximum SPI clock frequency supported by the X5643S14?

The X5643S14 supports a maximum SPI clock frequency of 2 MHz across its full operating voltage range (2.7–5.5 V). This is validated under DC operating conditions with SCK rise/fall times ≤10 ns and input levels at V_CC × 0.1 / V_CC × 0.9. The device operates in SPI modes 0,0 and 1,1, with data latched on the rising edge of SCK (SI) and output on the falling edge (SO), ensuring interoperability with common microcontroller SPI peripherals.

Does the X5643S14 provide both active-low and active-high reset outputs?

No - the X5643S14 provides a single open-drain RESET/RESET output that is active LOW by default. The datasheet clarifies that "X5643 = RESET" (active LOW) and "X5645 = RESET" (active HIGH) denote separate part numbers; the X5643S14 variant corresponds to the X5643 family and therefore delivers an active LOW reset signal. Pull-up resistors are required externally to establish HIGH-state voltage level and drive strength.