Renesas X4163S8I

Overview

X4163S8I from Xicor is a CPU supervisor IC integrating power-on reset control, watchdog timer, supply voltage supervision, and 16 Kbit serial EEPROM in a single 8-pin SOIC package. It provides V_CC reset threshold detection (factory-set at 4.63 V), selectable watchdog timeout (200 ms / 600 ms / 1.4 s), and 2-wire (I²C-compatible) interface operating from 2.7 V to 5.5 V - used in microcontroller-based embedded systems for reliable boot sequencing and data retention.

For engineers reviewing the X4163S8I datasheet, X4163S8I pinout, X4163S8I application, or X4163S8I equivalent, key selection criteria include reset assertion validity down to V_CC = 1 V, programmable V_TRIP threshold, 64-byte page write capability, <20 µA standby current with watchdog enabled, and hardware write protection via WP pin and BP bits.

Technical Context

The X4163S8I implements a dual-function reset architecture: power-on reset (t_PURST = 250 ms nominal) and low-V_CC detection with hysteresis, asserting active-low RESET/RESET until V_CC exceeds V_TRIP for 200 ms. Its watchdog timer monitors SDA transitions during SCL HIGH to detect MCU lockup.

Reset and watchdog logic are decoupled from EEPROM operations: nonvolatile writes are blocked while RESET/RESET is active, and Block Lock protection (BP2–BP0) enables selective write-disable of 64-byte to 2-Kbyte memory segments. The device uses volatile WEL/RWEL latches and nonvolatile control register (address FFFFh) to configure WD1/WD0 and BP bits.

Key Specifications

Pinout & Package

Package: 8-lead SOIC (JEDEC MS-012AC), 150 mil width, 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 MCP9804-E/MS, the X4163S8I uniquely integrates field-programmable reset voltage, multi-interval watchdog, and high-capacity EEPROM in a single 8-pin SOIC - enabling board-level consolidation unattainable with either alternative.

Availability

X4163S8I is available at Aetrix Electronics and suitable for industrial PLC controllers, medical infusion pumps, automotive body control modules, and smart energy meters requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for X4163S8I 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 Inc. was a fabless semiconductor company specializing in nonvolatile memory and power management ICs, acquired by Intersil in 2001 and later integrated into Renesas Electronics.

The X4163 series was designed as an integrated CPU supervisor targeting cost-sensitive embedded systems needing combined reset, watchdog, voltage monitoring, and EEPROM - reducing bill-of-materials count and PCB footprint versus discrete solutions.

FAQ

What is the factory-default reset threshold voltage for the X4163S8I?

The X4163S8I ships with a factory-default V_TRIP threshold of 4.63 V ±1.5%. This value is nonvolatile and remains stable over temperature and time unless reprogrammed using the documented V_TRIP adjustment sequence. The X4163S8I supports reprogramming to custom thresholds between approximately 1.7 V and 5.0 V, enabling precise alignment with target microcontroller reset specifications.

How does the watchdog timer in the X4163S8I get reset during normal operation?

The X4163S8I watchdog timer is reset by a HIGH-to-LOW transition on the SDA pin while SCL is held HIGH - which corresponds to the I²C START condition. This design eliminates the need for a dedicated watchdog feed pin, leveraging existing bus activity. If no such transition occurs within the selected timeout interval (200 ms, 600 ms, or 1.4 s), the X4163S8I asserts RESET/RESET to force system recovery.

Can the X4163S8I's EEPROM be written to while the RESET/RESET output is active?

No. The X4163S8I blocks all EEPROM write operations while RESET/RESET is active - whether due to power-up, brownout, or watchdog timeout. This hardware-enforced prohibition prevents data corruption during unstable power conditions. Additionally, in-progress writes are allowed to complete, but new writes are rejected until RESET/RESET deasserts and the device returns to normal operation.

What is the purpose of the S0 and S1 pins on the X4163S8I?

The S0 and S1 pins on the X4163S8I serve as device address inputs for the 2-wire (I²C-compatible) interface. They determine bits A1 and A0 of the 7-bit slave address (1010 S1 S0 R/W), allowing up to four X4163S8I devices to share the same SDA/SCL bus without address conflict. These pins are sampled at power-up and remain static during operation - enabling flexible system-level EEPROM expansion without additional GPIOs.

Does the X4163S8I support both byte-write and page-write EEPROM operations?

Yes. The X4163S8I supports both byte-write and 64-byte page-write modes for its 16 Kbit EEPROM. Page writes significantly improve throughput - a full 64-byte page completes in one 5 ms typical self-timed cycle, whereas 64 individual byte writes would require 64 × 5 ms plus inter-byte bus overhead. The device automatically increments the internal address counter during page writes, wrapping within the 64-byte boundary to enable robust partial-page updates.