NXP Semiconductors PCF1252-1T/F4,118

Overview

PCF1252-1T/F4,118 from NXP Semiconductors (formerly Philips) is a low-power CMOS voltage threshold detector and reset generator designed for microcontroller system supervision. It features a factory-programmed 4.55 V trip voltage (±50 mV accuracy), 10 µA typical supply current, and dual comparator architecture with RESET pulse delay controlled by external capacitor CT. It delivers precise power-on reset and advance power-fail warning in industrial embedded systems.

For engineers reviewing the PCF1252-1T/F4,118 datasheet, PCF1252-1T/F4,118 pinout, PCF1252-1T/F4,118 application, or PCF1252-1T/F4,118 equivalent, key selection considerations include its fixed 4.55 V detection threshold, ±50 mV temperature-stable accuracy, externally adjustable reset timing, POWF output for data retention, and dual-comparator capability for secondary voltage monitoring.

Technical Context

The PCF1252-1T/F4,118 integrates two independent comparators: Comparator 1 monitors VDD against an internal precision reference to generate RESET and POWF signals, while Comparator 2 accepts an external input at COMIN with a fixed 1.30 V switch point for secondary monitoring. Its internal hysteresis (15–50 mV) prevents oscillation near the trip point.

RESET pulse duration (tR = 400–2000 µs) and POWF-to-RESET save time (tS = 40–200 µs) are both determined by the external capacitor CCT connected to pin CT. SELECT pin polarity determines active-high or active-low RESET output, and POWF asserts LOW when VDD falls below 4.55 V.

Key Specifications

Pinout & Package

PCF1252-1T/F4,118 is housed in an SO8 plastic small outline package (SOT96-1), 8-lead, 3.9 mm body width, surface-mount compatible.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage supervisor and reset generator applications.

Compared with MAX691CPA+ and TPS3808G12DBVR, the PCF1252-1T/F4,118 offers a unique combination of factory-trimmed 4.55 V detection, integrated POWF output with defined save time, and dual-comparator capability-making it optimal for cost-sensitive, fixed-threshold industrial systems requiring deterministic power-fail response without added components.

Availability

PCF1252-1T/F4,118 is available at Aetrix Electronics and suitable for industrial control panels, medical data loggers, automotive body electronics, and telecom infrastructure equipment requiring stable component supply across extended product lifecycles.

Supply support for PCF1252-1T/F4,118 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

NXP Semiconductors is a global semiconductor leader delivering high-performance analog, logic, interface, and power management solutions for automotive, industrial, and IoT applications.

The PCF1252-X family was developed by Philips (now NXP) specifically for robust, low-power microcontroller system supervision-emphasizing precision threshold detection, fail-safe reset generation, and advance power-fail signaling in harsh industrial environments.

FAQ

What is the factory-programmed voltage trip point for PCF1252-1T/F4,118?

The PCF1252-1T/F4,118 has a factory-programmed voltage trip point of 4.55 V, with guaranteed accuracy of ±50 mV across the full operating temperature range (−40 to +85 °C). This value is laser-trimmed during manufacturing and cannot be adjusted externally. The '1' in the part number denotes the specific variant within the PCF1252-X family corresponding to this 4.55 V threshold.

How does the CT pin affect reset timing in PCF1252-1T/F4,118?

The CT pin on the PCF1252-1T/F4,118 connects to an external capacitor that directly controls both the RESET pulse duration (tR) and the POWF-to-RESET save time (tS). With a 1 nF capacitor, tR is typically 1000 µs and tS is 100 µs. The relationship is approximately tR (ms) = 0.1 + CCT (nF) and tS (ms) = 0.01 + 0.1 × CCT (nF). Internal capacitance is 100 pF, so no capacitor yields minimum timing.

Can PCF1252-1T/F4,118 monitor a second voltage rail, and how is it implemented?

Yes, the PCF1252-1T/F4,118 includes a second comparator (Comparator 2) accessible via the COMIN pin, which triggers at a fixed 1.30 V switch point. To monitor a second rail (e.g., 3.3 V), an external resistive divider scales the rail down to ≤1.30 V at COMIN. COMOUT then provides a digital flag: HIGH if the scaled voltage exceeds 1.30 V, LOW otherwise. No hysteresis is applied to this comparator, so noise filtering may be needed.

What is the function of the POWF output in PCF1252-1T/F4,118, and how is it used?

The POWF (Power Fail) output on the PCF1252-1T/F4,118 goes LOW when VDD falls below the 4.55 V trip point, providing early warning of imminent power loss. It activates before RESET, allowing a defined save time (tS) - determined by the CT capacitor - for the microcontroller to store critical data. This hardware-based warning eliminates software polling delays and ensures deterministic response during brownout conditions.

Does PCF1252-1T/F4,118 support both active-high and active-low reset outputs?

Yes, the PCF1252-1T/F4,118 supports configurable RESET polarity via the SELECT pin. When SELECT is tied to VSS (LOW), RESET is active-HIGH during power-on; when SELECT is tied to VDD (HIGH), RESET is inverted to active-LOW. This flexibility allows direct compatibility with microcontrollers requiring either reset polarity without external inverters or level-shifting circuitry.