Renesas X40626S14I

Overview

X40626S14I from Xicor (now part of Renesas) is a dual-voltage CPU supervisor IC integrating power-on reset control, watchdog timer, low-V_CC monitoring, and 64 Kbit serial EEPROM. It features user-programmable V_TRIP threshold (standard options: 2.63V/2.93V/3.08V/4.65V), 200ms reset timeout, 400 kHz I²C interface, and Block Lock™ EEPROM protection. Used in embedded microcontroller systems requiring reliable brownout recovery and nonvolatile configuration storage.

For engineers reviewing the X40626S14I datasheet, X40626S14I pinout, X40626S14I application, or X40626S14I equivalent, key selection criteria include dual-supply voltage supervision (V_CC + V_2MON), programmable reset threshold, watchdog timeout selection (200 ms / 600 ms / 1.4 s), open-drain RESET and V_2FAIL outputs, and 64-byte page EEPROM with hardware write protection via WP pin and BP bits.

Technical Context

The X40626S14I implements independent analog comparators for V_CC and V_2MON, each driving dedicated reset logic: RESET asserts on V_CC < V_TRIP (with 200 ms hysteresis delay), while V_2FAIL asserts immediately when V_2MON < V_TRIP2. Its watchdog timer monitors SDA transitions during SCL HIGH to detect MCU lockup.

EEPROM operation uses standard I²C protocol with slave address 0xA0–0xA6 (S1/S0 selectable), supports byte/page writes (64-byte pages), and enforces write protection via volatile WEL/RWEL latches and nonvolatile BP2–BP0 bits controlling eight memory segments. The device retains data for ≥100 years and withstands ≥100,000 write cycles per page.

Key Specifications

Pinout & Package

Package: 14-lead SOIC (Small Outline Integrated Circuit), 150 mil width, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6362ESA+ and STM8T142M2U6, the X40626S14I uniquely delivers dual independent voltage supervision with programmable thresholds, 64K I²C EEPROM, and hardware-configurable block protection - making it optimal for space-constrained, multi-rail embedded systems needing field-updatable configuration storage and deterministic fault response.

Availability

X40626S14I is available at Aetrix Electronics and suitable for industrial automation, medical diagnostics, automotive body electronics, and smart metering applications requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for X40626S14I 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

Xicor was a fabless semiconductor company specializing in nonvolatile memory and power management ICs, acquired by Renesas Electronics in 2002. Known for innovations in EEPROM architecture and supervisor reliability.

The X40626 product line was designed to consolidate power-on reset, watchdog, voltage monitoring, and EEPROM into a single chip for microcontroller-based systems - reducing board area, BOM count, and system-level validation effort in cost-sensitive embedded designs.

FAQ

What is the default V_TRIP threshold voltage for the X40626S14I?

The X40626S14I ships with a standard factory-set V_TRIP threshold - commonly 4.65V, though 2.63V, 2.93V, and 3.08V are also offered as standard options depending on date code and wafer lot. This value is nonvolatile and remains fixed unless reprogrammed using the VP=12–15V method on the WP pin. The exact shipped V_TRIP is specified in the device's top-marking or accompanying test report. For the X40626S14I, verification against the actual unit's marking or Renesas' official datasheet revision is recommended prior to design-in.

Can the X40626S14I monitor two independent power supplies simultaneously?

Yes, the X40626S14I provides true dual-supply monitoring: V_CC is monitored for reset generation with 200 ms hysteresis, while V_2MON is monitored separately to drive the open-drain V_2FAIL output with no delay. V_2MON accepts an external resistor divider for scaling unregulated rails, and its comparator has no hysteresis - enabling precise, real-time detection of secondary supply faults. This capability is intrinsic to the X40626S14I's architecture and does not require external components beyond the divider. Both channels operate independently and concurrently.

How does the watchdog timer in the X40626S14I get reset?

The X40626S14I watchdog timer is reset by a HIGH-to-LOW transition on the SDA pin while SCL is held HIGH - this matches the I²C start condition. The microcontroller must generate this edge within the selected timeout period (200 ms / 600 ms / 1.4 s) to prevent RESET assertion. Unlike software-triggered watchdogs, this method requires no dedicated control register access - it leverages existing I²C bus activity. If the MCU hangs and stops toggling SDA, the X40626S14I asserts RESET automatically. The timeout value is stored nonvolatily in WD1/WD0 bits and persists across power cycles.

What EEPROM protection mechanisms does the X40626S14I support?

The X40626S14I implements three layered EEPROM protections: (1) Power-cycle write inhibition - writes are blocked while RESET is active; (2) Software Block Lock™ - BP2–BP0 bits permanently configure write protection for segments from 64 bytes to full 64K array; (3) Hardware write protect - tying WP HIGH *and* setting WPEN bit in the control register disables all writes, including to the control register itself. These mechanisms operate simultaneously and are validated in the X40626S14I's production test flow. No external components are needed to enable any level of protection.

Is the X40626S14I pin-compatible with other Xicor supervisor+EEPROM devices?

The X40626S14I uses a 14-pin SOIC/TSSOP package with a defined pinout documented in the official datasheet (Rev 1.2, p.3). While earlier Xicor parts like X40426 share functional similarity, they differ in pin assignment - notably, X40426 lacks V_2FAIL and V_2MON pins and repurposes those positions for NC or alternate functions. Therefore, the X40626S14I is not pin-compatible with X40426 or X40625. Direct replacement requires PCB layout revision. Always verify pin mapping against the latest Renesas datasheet for X40626S14I before migration.