Renesas X40435S14I-C

Overview

X40435S14I-C from Xicor (now part of Renesas) is a triple-voltage CPU supervisor IC with integrated 4Kbit EEPROM, watchdog timer, and fault detection register. It monitors V_CC (V1), V2MON, and V3MON at factory-programmed thresholds (4.55–4.65V, 1.25–1.35V, 2.85–2.95V), asserts active-HIGH RESET, supports 400kHz I²C interface, and operates from 2.7V to 5.5V. It is used in network storage controllers for power-fail warning and secure configuration retention.

For engineers reviewing the X40435S14I-C datasheet, X40435S14I-C pinout, X40435S14I-C application, or X40435S14I-C equivalent, key selection criteria include triple independent voltage monitoring capability, programmable reset timeout (0.05s–0.8s), nonvolatile watchdog interval selection (25ms/200ms/1.4s/off), EEPROM block-lock protection, and 14-pin SOIC/TSSOP package compatibility with industrial temperature range (–40°C to +85°C).

Technical Context

The X40435S14I-C implements three independent voltage comparators - one referenced to V_CC (V1MON), one to V2MON (supplied by V_CC), and one to V3MON (self-supplied) - each driving dedicated open-drain fail outputs (LOWLINE, V2FAIL, V3FAIL). Its reset logic generates an active-HIGH RESET signal with user-selectable power-on reset timeout (t_PURST) via nonvolatile PUP1/PUP0 bits.

Watchdog functionality relies on SDA/SCL activity detection using a 4-bit state machine; restart requires Start–Clock Low–Clock High–Stop sequence. The 4Kbit EEPROM uses Xicor's Direct Write™ cells (100k write cycles, 100-year data retention), organized in 16-byte pages with 5ms typical write cycle time and software-controlled Block Lock™ protection covering 0% or 50% of memory.

Key Specifications

Pinout & Package

Package: 14-lead SOIC (Small Outline Integrated Circuit) and TSSOP (Thin Shrink Small Outline Package), both RoHS-compliant, with 1.27mm lead pitch and –40°C to +85°C operating temperature range.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar triple-voltage supervisor with EEPROM applications.

Compared with MAX6816ESE+ and TPS3808G33DBVR, the X40435S14I-C uniquely integrates triple-rail monitoring, programmable thresholds, watchdog timer, and 4Kbit EEPROM in one 14-pin package - reducing total component count by up to 4 devices and eliminating interconnect reliability risks in space-constrained networking equipment.

Availability

X40435S14I-C is available at Aetrix Electronics and suitable for network storage, industrial process control, and embedded computer systems requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant manufacturing.

Supply support for X40435S14I-C 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 2008. Its legacy products emphasize high-reliability, low-power, and system-integration features.

The X40435S14I-C belongs to Xicor's CPU Supervisor family, designed specifically for telecom and industrial systems needing coordinated power sequencing, fault logging, and secure parameter storage in a single chip.

FAQ

What is the factory-default power-on reset timeout (t_PURST) for the X40435S14I-C?

The X40435S14I-C ships with t_PURST set to 200ms, controlled by nonvolatile PUP1/PUP0 bits (01 binary) in the Control Register at address 1FFh. This value can be reprogrammed to 50ms, 400ms, or 800ms using the three-step write sequence documented in the datasheet. The X40435S14I-C maintains this setting across power cycles without external configuration.

Does the X40435S14I-C support reprogramming of its voltage trip points in-system?

Yes, the X40435S14I-C allows in-system adjustment of V_TRIP1, V_TRIP2, and V_TRIP3 using a high-voltage programming sequence applied to the WDO pin while issuing specific I²C commands. The procedure requires applying the target voltage to the corresponding monitor pin (V_CC, V2MON, or V3MON), then sending Slave Address A0h followed by byte address and data. The X40435S14I-C retains new thresholds nonvolatily without battery backup.

How does the X40435S14I-C handle EEPROM write protection?

The X40435S14I-C implements dual-layer EEPROM protection: hardware WP pin (active-HIGH) disables all writes globally, and software Block Protect (BP) bit locks the upper 256 bytes (50% of 4Kbit array). Writes to protected regions are ignored and generate no ACK. The X40435S14I-C also includes power-up/power-down write inhibit circuitry to prevent corruption during supply transients.

What is the watchdog timer behavior when the X40435S14I-C powers up?

The X40435S14I-C watchdog timer is factory-disabled (WD1/WD0 = 11). It remains inactive until explicitly enabled via the Control Register. Upon power-up, the X40435S14I-C does not assert WDO unless the watchdog is first configured and then fails to receive a valid restart sequence (Start–Clock Low–Clock High–Stop) within the selected timeout period (25ms/200ms/1.4s).

Can the X40435S14I-C monitor voltages below 1V?

No, the X40435S14I-C specifies minimum operating V_CC of 2.7V and minimum monitor input ranges of 0.9V–3.5V for V2MON/V3MON. While V2FAIL/V3FAIL outputs remain active down to 1V input, the comparators require sufficient headroom to function - the X40435S14I-C cannot accurately supervise sub-0.9V rails such as 0.8V CPU cores or DDR5 VDDQ.