Renesas X4165PI-2.7

Overview

X4165PI-2.7 from Xicor (now Renesas) 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 selectable watchdog timeout (200 ms/600 ms/1.4 s), low-V_CC reset assertion down to 1 V, four factory-standard reset thresholds (2.63 V, 2.93 V, 3.08 V, 4.65 V), and 400 kHz I²C-compatible 2-wire interface - used in embedded microcontroller systems requiring reliable boot sequencing and nonvolatile configuration storage.

For engineers reviewing the X4165PI-2.7 datasheet, X4165PI-2.7 pinout, X4165PI-2.7 application, or X4165PI-2.7 equivalent, key selection criteria include its dual-role RESET/RESET output (active-low/open-drain), programmable V_TRIP threshold, 64-byte page write capability, <1 µA watchdog-OFF standby current, and hardware write protection via WP pin and BP bits.

Technical Context

The X4165PI-2.7 implements a dedicated low-voltage detection comparator with hysteresis, independent watchdog timer circuitry monitoring SDA transitions during SCL HIGH, and on-chip power-on reset generator with 250 ms reset pulse width. Its EEPROM array uses CMOS floating-gate technology with self-timed 5 ms typical write cycles and built-in charge-pump programming.

Reset assertion is triggered by V_CC falling below the programmed V_TRIP, watchdog timeout, or power-up - all holding RESET/RESET active until V_CC exceeds V_TRIP for 200 ms. The device operates as an I²C slave with fixed 7-bit address (1010xxx) and supports byte/page writes, random reads, and sequential reads without external timing components.

Key Specifications

Pinout & Package

Package: 8-lead JEDEC SOIC (3.9 mm × 4.9 mm, 1.27 mm pitch). Pinout validated per Xicor REV 1.32 datasheet (May 2004).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6361KA27+T and STM8S105K4T6C, the X4165PI-2.7 uniquely combines field-programmable reset threshold, 16 Kbit EEPROM, and sub-1 V reset validity - delivering plug-and-play reliability without firmware or external components.

Availability

X4165PI-2.7 is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, automotive body electronics, and smart metering applications requiring stable component supply, long-term lifecycle support, and verified legacy part sourcing.

Supply support for X4165PI-2.7 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 by Renesas Electronics in 2017.

The X4163/5 family was designed to replace discrete reset ICs, watchdog timers, and serial EEPROMs in space-constrained microcontroller systems - targeting high-reliability embedded applications where power integrity and data persistence are critical.

FAQ

What is the factory-default reset threshold voltage for X4165PI-2.7?

The X4165PI-2.7 ships with a factory-programmed V_TRIP of 2.7 V ±1.5%, optimized for 2.7 V nominal supply rails. This threshold is stored nonvolatily and remains stable over temperature and time unless reprogrammed using the VP-assisted sequence described in the datasheet. The X4165PI-2.7 guarantees valid reset assertion down to V_CC = 1 V, ensuring robust operation during deep brownouts.

Does X4165PI-2.7 support true I²C communication or only 2-wire protocol?

The X4165PI-2.7 implements a 2-wire interface fully compatible with standard I²C protocol - supporting START/STOP conditions, 7-bit addressing (1010xxx), ACK/NACK handshaking, and 400 kHz maximum clock rate. It operates exclusively as a slave device and requires no external pull-up resistors beyond standard I²C bus requirements. The X4165PI-2.7 does not support I²C multi-master arbitration or clock stretching.

How is the watchdog timer reset on X4165PI-2.7?

The watchdog timer on X4165PI-2.7 is reset by a HIGH-to-LOW transition on the SDA pin while SCL is held HIGH - matching the I²C START condition timing. This allows the host microcontroller to service the watchdog using standard I²C bus activity without dedicated GPIO control. If no such transition occurs within the selected timeout period (200 ms/600 ms/1.4 s), the X4165PI-2.7 asserts RESET/RESET to force system recovery.

Can X4165PI-2.7's EEPROM be written to while RESET/RESET is active?

No. While RESET/RESET is asserted - whether due to power-up, brownout, or watchdog timeout - the X4165PI-2.7 disables all serial interface inputs and blocks new EEPROM write operations. In-progress writes are allowed to complete, but no new commands are accepted. This ensures data integrity during unstable power conditions and prevents corruption of critical configuration stored in the X4165PI-2.7's 16 Kbit EEPROM array.

What package options are available for X4165PI-2.7?

The X4165PI-2.7 is offered in 8-lead SOIC (X4165PI-2.7) and 8-lead TSSOP (X4165PT-2.7) packages. Both share identical pinout and electrical specifications; the SOIC variant (3.9 mm × 4.9 mm) is recommended for through-hole prototyping and legacy PCB compatibility, while the TSSOP (3.0 mm × 4.4 mm) suits high-density surface-mount layouts. No QFN, DFN, or wafer-level variants exist for this part number.