Renesas X4165PZ-4.5A

Overview

X4165PZ-4.5A 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 features a programmable 4.5 V reset threshold, 400 kHz I²C interface, and supports block-lock write protection for EEPROM memory. It is used in embedded microcontroller systems requiring reliable power sequencing and data retention during brownout conditions.

For engineers reviewing the X4165PZ-4.5A datasheet, X4165PZ-4.5A pinout, X4165PZ-4.5A application, or X4165PZ-4.5A equivalent, key selection criteria include its factory-programmed 4.5 V V_TRIP, open-drain active-low RESET output with 250 ms timeout, 2.7–5.5 V operating range, and compatibility with standard 2-wire I²C protocols for system-level supervision and nonvolatile configuration storage.

Technical Context

The X4165PZ-4.5A implements a dual-function reset architecture: power-on reset with 250 ms release delay after V_CC stabilization, and low-V_CC detection asserting RESET when supply drops below 4.5 V. Its watchdog timer monitors SDA transitions during SCL HIGH to detect MCU lockup, with timeout options of 200 ms, 600 ms, or 1.4 s configured via nonvolatile control bits.

EEPROM functionality includes 64-byte page write mode, self-timed 5 ms typical write cycle, and hardware/software write protection using WP pin, WPEN bit, and BP2–BP0 block lock bits. The device operates as an I²C slave with fixed 7-bit address (1010xxx), supporting byte and random read/write operations without external clocking.

Key Specifications

Pinout & Package

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

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 STM8S105K4T6C, the X4165PZ-4.5A delivers unique value through its field-programmable 4.5 V reset point, larger 16 Kbit EEPROM, and autonomous watchdog - enabling robust, drop-in supervision without MCU intervention or design compromises.

Availability

X4165PZ-4.5A is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and automotive body electronics requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for X4165PZ-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 Intersil in 2001 and later integrated into Renesas Electronics.

The X4165PZ-4.5A belongs to Xicor's CPU Supervisor family, designed to consolidate reset, watchdog, voltage monitoring, and EEPROM functions into a single chip for space-constrained, high-reliability embedded systems.

FAQ

What is the factory-programmed reset threshold voltage for X4165PZ-4.5A?

The X4165PZ-4.5A is factory-programmed with a nominal 4.5 V reset threshold (V_TRIP) with ±100 mV tolerance. This value is laser-trimmed during production and remains stable over temperature and time unless reprogrammed using the VP pulse sequence on the WP pin. The 4.5 V setting targets 5 V systems where early reset is required before logic instability occurs.

Does X4165PZ-4.5A support I²C clock stretching or multi-master arbitration?

No, the X4165PZ-4.5A does not support clock stretching or multi-master arbitration. It operates strictly as an I²C slave with fixed 7-bit address (1010xxx), responding only to START/STOP sequences and ACK/NACK protocol. The device releases SDA after each byte transmission and does not hold SCL low - ensuring compatibility with standard I²C masters but excluding advanced bus-sharing scenarios.

Can the watchdog timer in X4165PZ-4.5A be disabled after power-up?

Yes, the watchdog timer in X4165PZ-4.5A can be disabled after power-up by writing WD1=1 and WD0=1 to the control register at address FFFFh. This requires a three-step volatile/nonvolatile write sequence (02h → 06h → 0xh) with WEL and RWEL bits set. Once disabled, the watchdog remains off until explicitly re-enabled or the device is power-cycled.

How is EEPROM write protection implemented in X4165PZ-4.5A?

X4165PZ-4.5A implements dual-layer EEPROM write protection: software-based via BP2–BP0 bits controlling 64–2048 byte lock segments, and hardware-based via the WP pin combined with the WPEN bit. When WP is HIGH and WPEN=1, writes to locked blocks and the control register are blocked regardless of software state - providing tamper-resistant security for critical firmware or calibration data.

What happens to the X4165PZ-4.5A RESET output during a brownout event?

During a brownout event where V_CC falls below the programmed 4.5 V threshold, the X4165PZ-4.5A asserts its open-drain RESET output low and holds it active until V_CC rises above 4.5 V and remains stable for ≥200 ms. The output remains valid down to V_CC = 1 V, ensuring clean system reset even during severe supply collapse - preventing partial execution or latch-up in downstream logic.