Texas Instruments UC3903DW

Overview

UC3903DW from Texas Instruments is a quad supply and line monitor IC designed for power system supervision in industrial and telecom power supplies. It monitors up to four voltage rails-including one negative rail via internal inverter-with programmable under- and over-voltage thresholds centered on a 2.5-V precision reference, 30-mA open-collector fault outputs, and 8-V to 40-V supply operation. It delivers early line/switcher failure warning via dedicated sense input.

For engineers reviewing the UC3903DW datasheet, UC3903DW pinout, UC3903DW application, or UC3903DW equivalent, this device supports precise multi-rail voltage monitoring with proportional hysteresis, independent fault window scaling per channel, and integrated op-amp/inverter for auxiliary sensing-critical for redundant power systems, telecom rectifiers, and industrial PLCs requiring robust power-good signaling.

Technical Context

The UC3903DW 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). Threshold hysteresis is fixed at 8% of the window magnitude, ensuring glitch-free transitions during fault recovery.

It integrates three high-current open-collector outputs: UV FAULT, OV FAULT, and POWER OK (active-low), each with ≥30 mA sink capability and user-programmable delay via external capacitors. A dedicated Sense 4 inverter enables direct negative supply monitoring without external components, while the uncommitted op-amp supports feedback buffering or error amplification in isolated DC/DC designs.

Key Specifications

Pinout & Package

UC3903DW is housed in an 18-pin SOIC (DW) package with 0.300-inch body width and standard JEDEC MS-013 footprint. Pin numbering follows top-view orientation with Pin 1 marked by notch or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM3914N-1 and TPS3808G33, UC3903DW uniquely combines quad independent monitoring, negative rail capability, proportional hysteresis, and a 2.5-V reference in one SOIC-18 package-enabling full power-system health assessment without external support circuitry.

Availability

UC3903DW is available at Aetrix Electronics and suitable for telecom rectifiers, industrial PLCs, redundant server PSUs, and isolated DC/DC converters requiring stable component supply and long-term design continuity.

Supply support for UC3903DW 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 over 50 years of innovation in industrial and automotive electronics.

The UC3903DW belongs to TI's UC1903/UC2903/UC3903 family of quad supply monitors, engineered specifically for high-reliability power supervision in telecom infrastructure, industrial automation, and server power systems where multi-rail integrity is mission-critical.

FAQ

What is the operating temperature range for UC3903DW?

The UC3903DW is specified for 0°C to +70°C ambient operation, matching its commercial-grade qualification. This range supports deployment in controlled-environment applications such as telecom equipment cabinets, industrial control panels, and data center power shelves where ambient temperatures remain within these limits. The UC3903DW datasheet confirms this range in the Electrical Characteristics table under "UC3903" column.

Can UC3903DW monitor negative supply voltages?

Yes, UC3903DW can monitor negative supplies using its dedicated Sense 4 inverter. By grounding the INVERT INPUT pin (Pin 5), the internal emitter-follower inverter converts a negative rail (e.g., –12 V) into a positive-swing signal referenced to GND, allowing direct comparison against the 2.5-V reference. This eliminates external level-shifting components and is explicitly documented in Figure 6 of the UC3903DW datasheet.

How does the WINDOW ADJUST pin affect fault thresholds?

The WINDOW ADJUST pin (Pin 4) sets the magnitude of the OV and UV fault windows as a percentage deviation from the 2.5-V reference. A 1.0-V input yields ±250 mV offset (±10%), while 2.5 V yields ±625 mV (±25%). Hysteresis scales automatically at 8% of the window width. This relationship is defined in Equation 1 and illustrated in Figure 2 of the UC3903DW datasheet.

What is the maximum sink current for UC3903DW's open-collector outputs?

Each of UC3903DW's three open-collector outputs (UV FAULT, OV FAULT, POWER OK) sinks ≥30 mA when active, verified at V_OUT = 2 V per the Electrical Characteristics table. This allows direct driving of LEDs, optocouplers, or microcontroller GPIO pins without external transistors. Saturation voltage remains ≤0.4 V at 12 mA, ensuring low power loss in typical loads.

Does UC3903DW include a built-in voltage reference?

Yes, UC3903DW integrates a precision 2.5-V bandgap reference (V_REF, Pin 2) with initial accuracy of ±15 mV and ±0.2% drift over temperature. This reference serves as the central voltage anchor for all fault threshold generation and enables accurate scaling of external resistor dividers for Sense 1–4 inputs. Its load regulation is ≤15 mV at 10 mA, supporting multiple divider networks.