Texas Instruments UC2903N

Overview

UC2903N from Texas Instruments is a quad supply and line monitor IC designed for industrial power system supervision. It monitors up to four independent voltage rails-including one negative rail via internal inverter-with programmable under- and over-voltage thresholds centered on a 2.5-V precision reference, 7-mA standby current, and three >30-mA open-collector fault outputs (UV/OK/OV) for power sequencing in telecom and embedded power supplies.

For engineers reviewing the UC2903N datasheet, UC2903N pinout, UC2903N application, or UC2903N equivalent, this device supports precise multi-rail voltage monitoring with proportional hysteresis, early line/switcher failure warning, and auxiliary op-amp use in feedback loops-critical for high-reliability 8–40-V DC power systems requiring stable fault detection timing and thermal robustness across –40°C to +85°C.

Technical Context

The UC2903N implements a fault window architecture where OV and UV thresholds are generated as symmetric offsets around the 2.5-V reference, scaled linearly by the voltage applied to Pin 4 (Window Adjust), with hysteresis fixed at 8% of window magnitude. Its dedicated Sense 4 inverter enables direct negative supply sensing without external components.

Three open-collector outputs-UV FAULT, OV FAULT, and POWER OK-respond with user-programmable delays (via external capacitors on Pins 16 and 17) and remain active during any fault condition including supply under-voltage, line/switcher failure, or sense input excursion. The integrated general-purpose op-amp delivers 20-mA source capability and supports isolated feedback buffering or error amplification.

Key Specifications

Pinout & Package

UC2903N is housed in an 18-pin plastic dual in-line package (PDIP-N), RoHS-compliant with CU NIPDAU finish, rated for –40°C to +85°C operation. Pin numbering follows standard DIP top-view convention (Pin 1 = top-left corner, Pin 18 = bottom-right).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad voltage monitoring applications.

Compared with UC3903N, UC2903N offers broader temperature range and higher reliability for industrial deployment; compared with TPS3808G33, it integrates four-channel supervision, negative rail sensing, and auxiliary op-amp functionality-reducing component count and board space by >70% in complex power systems.

Availability

UC2903N is available at Aetrix Electronics and suitable for telecom power shelves, industrial PLCs, medical equipment power sequencing, and test instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for UC2903N 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of heritage in high-reliability industrial and aerospace-grade ICs.

The UC2903N belongs to TI's UC1903/UC2903/UC3903 family of quad voltage supervisors, engineered specifically for robust, multi-rail power system monitoring in harsh industrial environments where precision, thermal stability, and fault resilience are critical.

FAQ

What is the operating temperature range for UC2903N?

The UC2903N is specified for operation from –40°C to +85°C, making it suitable for industrial environments where ambient temperatures exceed commercial-grade limits. This range is confirmed in the Electrical Characteristics table and Package Option Addendum, distinguishing it from the UC3903N (0°C to +70°C) and UC1903 (–55°C to +125°C). All parameters in the UC2903N datasheet apply within this temperature window.

Can UC2903N monitor a negative supply voltage?

Yes, UC2903N can monitor a negative supply using its dedicated Sense 4 inverter. When Pin 5 (INVERT INPUT) is held high, the internal emitter-follower inverter converts the negative rail into a positive-swing signal referenced to GND, allowing direct connection to SENSE 4 (Pin 6). This eliminates the need for external level-shifting circuitry and is explicitly supported in the Block Diagram and Figure 6 of the datasheet.

How is the fault window programmed on UC2903N?

The fault window on UC2903N is programmed via Pin 4 (WINDOW ADJUST), which accepts a voltage from 0.5 V to 2.5 V. This voltage sets both the OV and UV threshold offsets proportionally around the 2.5-V reference-e.g., 1.0 V on Pin 4 yields ±0.25 V offsets (±10% for a 2.5-V nominal). Hysteresis scales automatically at 8% of the window width, ensuring stable operation without manual tuning.

What are the key differences between UC2903N and UC3903N?

UC2903N and UC3903N share identical pinout, functionality, and electrical behavior-but differ in temperature rating: UC2903N operates from –40°C to +85°C, while UC3903N is limited to 0°C to +70°C. Additionally, UC2903N is marked as LIFEBUY in TI's packaging addendum, indicating planned discontinuation with last-time-buy availability, whereas UC3903N remains ACTIVE in SOIC packaging.

Does UC2903N include an internal voltage reference?

Yes, UC2903N integrates a precision 2.5-V bandgap reference (Pin 2, V_REF) with ±15 mV typical accuracy at 25°C and ±0.2% max drift over –40°C to +85°C. This reference serves as the centerpoint for all fault thresholds and is also available as a buffered output to drive external resistor dividers for custom window scaling-confirmed in the Reference Output section of the Electrical Characteristics table.