Renesas X4165PIZ-4.5A

Overview

X4165PIZ-4.5A from Xicor (now part of 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, and 400 kHz I²C-compatible 2-wire interface - deployed in embedded microcontroller systems requiring reliable boot sequencing and nonvolatile configuration storage.

For engineers reviewing the X4165PIZ-4.5A datasheet, X4165PIZ-4.5A pinout, X4165PIZ-4.5A application, or X4165PIZ-4.5A equivalent, key selection criteria include its factory-programmed 4.5 V reset threshold, active-HIGH RESET output, 2.7–5.5 V supply range, EEPROM page-write capability, and hardware write protection via WP pin and WPEN bit.

Technical Context

The X4165PIZ-4.5A implements a dual-function reset architecture: power-on reset with 250 ms timeout and brownout detection at 4.5 V nominal (factory-set, reprogrammable), asserting an active-HIGH open-drain RESET signal. Its watchdog timer monitors SDA transitions during SCL HIGH and supports three fixed timeout intervals via nonvolatile WD1/WD0 bits.

It embeds a 2K × 8-bit EEPROM array with 64-byte page write mode, self-timed 5 ms typical write cycle, and multi-level write protection - including volatile WEL/RWEL latches, nonvolatile block lock (BP2–BP0), and hardware write protect enabled by WP pin + WPEN bit. Communication uses standard I²C protocol at up to 400 kHz.

Key Specifications

Pinout & Package

Package: 8-lead JEDEC SOIC (3.9 mm × 4.9 mm, 1.27 mm pitch).

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 STM8T142M2U6, the X4165PIZ-4.5A uniquely combines factory-4.5 V reset, reprogrammable threshold, and 16 Kbit EEPROM in one die - reducing component count and enabling field-tunable brownout response without redesign.

Availability

X4165PIZ-4.5A is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic devices, automotive body control modules, smart energy meters, and embedded instrumentation requiring stable component supply and long-term obsolescence management.

Supply support for X4165PIZ-4.5A 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 integration, reliability, and programmability.

The X416x family was designed to replace discrete reset ICs, watchdog timers, and serial EEPROMs in space-constrained embedded systems - targeting cost-sensitive, high-reliability applications across industrial and medical markets.

FAQ

What is the factory-set reset threshold voltage for the X4165PIZ-4.5A?

The X4165PIZ-4.5A ships with a factory-programmed reset threshold of 4.5 V nominal. This value is stored in nonvolatile circuitry and remains stable over temperature and time unless explicitly reprogrammed using the V_TRIP adjustment sequence defined in the datasheet. The 4.5 V setting makes X4165PIZ-4.5A suitable for 5 V systems where brownout must be detected before regulator dropout.

Does the X4165PIZ-4.5A provide active-HIGH or active-LOW reset output?

The X4165PIZ-4.5A features an active-HIGH RESET output (labeled RESET/RESET), implemented as an open-drain driver requiring an external pull-up resistor. This differs from the X4163 variant, which provides active-LOW reset. The active-HIGH polarity simplifies interface with MCUs that require high-true reset inputs and avoids level-shifting in 3.3 V/5 V mixed-signal designs.

Can the watchdog timeout period of the X4165PIZ-4.5A be changed after soldering?

Yes - the watchdog timeout period of the X4165PIZ-4.5A is controlled by nonvolatile WD1/WD0 bits in the control register and can be reconfigured in-system via the I²C interface. Valid settings are 200 ms, 600 ms, 1.4 s, or disabled. Changes persist across power cycles and require the three-step write sequence (WEL → RWEL → data) with WP pin LOW during programming.

How does hardware write protection work on the X4165PIZ-4.5A?

Hardware write protection on the X4165PIZ-4.5A activates when both the WP pin is driven HIGH and the WPEN bit in the control register is set to 1. When enabled, it blocks all writes to EEPROM blocks covered by BP2–BP0 and prevents modification of the control register itself. This provides tamper-resistant storage for critical firmware parameters or calibration data without relying solely on software locks.

Is the X4165PIZ-4.5A pin-compatible with other members of the X4163/5 family?

Yes - the X4165PIZ-4.5A shares identical pinout, package (8-pin SOIC), and electrical interface with all X4163/5 variants, including X4163PIZ-2.6A and X4165PIZ-3.08A. Differences are limited to factory-set V_TRIP voltage and RESET output polarity (X4165 = active-HIGH, X4163 = active-LOW). No PCB changes are required when substituting within the same package option.