onsemi CAT1641LI-45-G

Overview

CAT1641LI-45-G from onsemi is an integrated supervisory circuit with 64 kbit I²C EEPROM, providing active-high reset output and precision V_CC monitoring for 5 V systems (4.50–4.75 V threshold). It operates from 3.0 V to 5.5 V, supports 400 kHz I²C communication, and delivers guaranteed reset validity down to V_CC = 1.0 V - used in microcontroller-based power-up sequencing and brown-out protection for industrial control modules.

For engineers reviewing the CAT1641LI-45-G datasheet, pinout, applications, or equivalent options, key selection criteria include active-high reset polarity, 4.50–4.75 V threshold tolerance, 64-byte page write capability, 1 M endurance cycles, and PDIP-8 package compatibility with legacy board layouts.

Technical Context

The CAT1641LI-45-G integrates a precision voltage monitor with hysteresis (15 mV) and an open-drain active-high RESET output, ensuring reliable assertion during V_CC drop below 4.50 V and release after ≥200 ms timeout once V_CC exceeds 4.75 V. Its embedded 64 kbit EEPROM uses I²C protocol with 64-byte page buffering and hardware write protection triggered by V_CC < reset threshold.

Reset timing includes 5 µs V_TH-to-RESET delay, 30 ns glitch rejection, and manual reset input support with 100 ns immunity. Memory operation features ACK polling, sequential/random read modes, and 5 ms typical write cycle time - all synchronized to the 400 kHz I²C clock with t_LOW = 1.3 µs and t_HIGH = 0.6 µs minimum timing compliance.

Key Specifications

Pinout & Package

Package: 8-pin PDIP (Case 646AA), 0.300-inch width, through-hole mounting compatible with legacy PCB tooling and manual assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar supervisory + EEPROM applications.

Compared with MAX6361LKA29+T and STM8S105K4T6C, the CAT1641LI-45-G uniquely combines fixed-precision 4.50–4.75 V reset with 64 kbit I²C EEPROM in a single PDIP-8 package - eliminating interconnect routing, timing skew, and qualification overhead of discrete solutions.

Availability

CAT1641LI-45-G is available at Aetrix Electronics and suitable for industrial PLCs, smart metering systems, medical diagnostic equipment, and factory automation HMIs requiring stable component supply with long-term lifecycle assurance.

Supply support for CAT1641LI-45-G 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The CAT164x series was designed to consolidate power supervision and non-volatile storage into one IC for microcontroller-based systems - targeting cost-sensitive, reliability-critical applications in industrial control and instrumentation.

FAQ

What is the reset output behavior of the CAT1641LI-45-G during power-up?

During power-up, the CAT1641LI-45-G holds its RESET pin low until V_CC rises above 4.50 V, then maintains active-low reset for a guaranteed 130–270 ms timeout (typical 200 ms) before releasing it high. This ensures the host microcontroller remains held in reset long enough for all supply rails and clocks to stabilize - a critical requirement for deterministic boot in industrial systems. The CAT1641LI-45-G implements this using an internal timer synchronized to V_CC crossing the threshold.

Can the CAT1641LI-45-G be used with a 3.3 V microcontroller I²C bus?

Yes, the CAT1641LI-45-G supports I²C operation from 3.0 V to 5.5 V, so it interfaces directly with 3.3 V microcontrollers. Its SDA and SCL pins tolerate 0.3×V_CC low and 0.7×V_CC high logic thresholds, and VOL is specified at 0.4 V with 3 mA sink - compatible with standard 3.3 V I²C level definitions. However, the reset threshold remains fixed at 4.50–4.75 V, so it must be powered from a 5 V rail when supervising 5 V systems.

How does hardware write protection work in the CAT1641LI-45-G?

The CAT1641LI-45-G disables all EEPROM write operations whenever V_CC falls below the 4.50 V reset threshold or has not yet reached that level during power-up. This is implemented via internal voltage sensing that gates the write enable path - preventing partial writes, byte corruption, or inadvertent overwrites during brown-out or power ramp. Unlike software locks, this protection is always active and requires no firmware intervention.

What is the maximum number of CAT1641LI-45-G devices that can share one I²C bus?

Up to eight CAT1641LI-45-G devices can share a single I²C bus using the A0, A1, and A2 address pins. These three pins form the least-significant bits of the 7-bit slave address (default prefix 1010), allowing binary encoding of addresses 1010000 (0x50) through 1010111 (0x57). Each device must have a unique A0–A2 combination; unconnected pins default to logic low, so explicit pull-up/down resistors are required for deterministic addressing.

Does the CAT1641LI-45-G support manual reset functionality?

Yes, the RESET pin on the CAT1641LI-45-G serves dual purpose: it is an active-high open-drain output and a manual reset input. Driving the pin low (high-to-low edge) initiates a new 200 ms reset timeout, independent of V_CC status. This enables push-button recovery in deployed systems. Glitches shorter than 100 ns are ignored, and the pin requires an external pull-up resistor to function correctly in both modes.