onsemi NCP112D

Overview

NCP112D from onsemi is a supervisory IC designed for desktop and ATX multi-output switch-mode power supply monitoring. It provides simultaneous over/undervoltage protection for 3.3 V, 5.0 V, and 12 V rails, features a 2.5 V precision voltage reference with 20 mA sourcing capability, supports programmable delays via external 100 nF capacitors, and delivers fault and power-good outputs compliant with ATX specifications.

For engineers reviewing the NCP112D datasheet, pinout, applications, or equivalent options, this device is selected for precise rail supervision in PC power supplies where timing-controlled fault latching, remote reset sequencing, and hysteresis-stabilized threshold detection are required.

Technical Context

The NCP112D integrates three independent UV/OV comparators with built-in hysteresis (e.g., 40 mV for 3.3 V OV, 100 mV for 3.3 V UV), a dedicated adjustable OVP input (ADJ, 1.28 V threshold), and logic-controlled fault latching with 100 µs delay to reject transient spikes. Its internal 2.5 V reference feeds external circuitry and enables accurate threshold setting without external components.

It implements three user-programmable RC timing functions-undervoltage blanking (CTUV), remote on/off delay (CTREMOTE), and power-good assertion (CTPG)-all linearly scaled by capacitor value and driven by internal current sources. The FAULT output sinks ≥20 mA, while PGO is open-collector with 30 mA capability and 0.4 V saturation at 20 mA.

Key Specifications

Pinout & Package

Package: SOIC-14 (Case 751A), Pb-free, surface-mount. Dimensions: 8.75 mm × 4.00 mm × 1.75 mm (L × W × H).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL331IDR and TSM112DR, the NCP112D delivers integrated triple-rail supervision with programmable delays, PGI override, and ADJ expansion-enabling single-chip ATX compliance without external logic or timing components.

Availability

NCP112D is available at Aetrix Electronics and suitable for ATX desktop power supplies, server PSUs, and industrial embedded power systems requiring stable component supply, long-term lifecycle support, and Pb-free compliance.

Supply support for NCP112D 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 delivering energy-efficient silicon solutions for automotive, industrial, cloud, and intelligent edge applications.

The NCP112D belongs to onsemi's power management supervisory IC product line, engineered specifically for reliable, standards-compliant monitoring of multi-output switch-mode power supplies in computing and industrial infrastructure.

FAQ

What is the primary function of the NCP112D in a power supply design?

The NCP112D serves as a dedicated supervisory IC that continuously monitors the 3.3 V, 5 V, and 12 V output rails of a switch-mode power supply. It detects overvoltage and undervoltage conditions, asserts a FAULT signal to disable the PWM controller, and generates a timed PGO signal to indicate stable operation. Its integrated timing capacitors, hysteresis, and logic functions make it ideal for ATX-compliant systems without requiring external supervision circuitry.

Does the NCP112D support Pb-free manufacturing and RoHS compliance?

Yes, the NCP112D is explicitly marked as a Pb-free device in its ordering code (NCP112DR2G) and meets RoHS requirements. The datasheet confirms "This is a Pb−Free Device" and specifies Pb-free plating for the SOIC-14 package. All thermal and electrical ratings-including maximum junction temperature of +150°C and storage range up to +150°C-are validated for the Pb-free construction.

How does the ADJ pin on the NCP112D extend its supervision capability?

The ADJ pin on the NCP112D provides a fourth overvoltage monitoring channel with a fixed 1.28 V threshold and hysteresis. It is logically ORed with the main OV detectors, so any fault on ADJ triggers the same FAULT output and latching behavior as the primary rails. This allows designers to monitor auxiliary rails (e.g., 24 V, −12 V, or 5 VSB) or external signals like thermal shutdown flags without modifying the core supervision architecture.

Can the NCP112D replace the TSM112 in existing designs?

Yes, the NCP112D is explicitly positioned as an enhanced replacement for the TSM112, with identical SOIC-14 pinout and backward-compatible timing behavior. Key improvements include the ADJ input, PGI override, tighter voltage thresholds (±1.6% vs ±2%), and improved hysteresis. No PCB changes are required, but designers should verify timing capacitor values and update firmware logic if leveraging new features like PGI control.

What is the role of the CTUV, CTPG, and CTREMOTE capacitors in the NCP112D circuit?

These three external capacitors configure critical timing functions: CTUV sets the undervoltage blanking delay during power-up (100–500 ms with 100 nF), CTPG sets the power-good assertion delay (same range), and CTREMOTE sets the remote on/off pulse width (35–60 ms). All use internal current sources for linear, predictable timing-eliminating resistor tolerances and enabling low-cost 100 nF ceramic capacitors instead of precision timing networks.