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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Supervisors

Texas Instruments UC2903QTR

Name: UC2903QTR
Brand: Texas Instruments
SKU: UC2903QTR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: UC2903QTR

Manufacturer:: Texas Instruments

Category:: Supervisors

Package:: 20-LCC (J-Lead)

Datasheet:: UC2903QTR.pdf

Description:: IC SUPERVISOR 4 CHANNEL 20PLCC

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Product details

Overview

UC2903QTR 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 for UV/UV/POWER OK signaling in telecom power supplies.

For engineers reviewing the UC2903QTR datasheet, UC2903QTR pinout, UC2903QTR application, or UC2903QTR equivalent, this page delivers verified technical context, exact pin functions for PLCC-20 package, real-world timing behavior of fault delays, confirmed hysteresis scaling (10 mV/V per volt on Window Adjust), and validated alternatives for multi-rail monitoring in harsh-temperature industrial systems.

Technical Context

The UC2903QTR implements a fault window architecture where OV and UV thresholds are generated as symmetric offsets around the 2.5-V reference, with magnitude set by the voltage applied to Pin 4 (Window Adjust). Threshold hysteresis scales proportionally at 10–30 mV/V across the adjust range, ensuring glitch-free transitions during voltage transients.

It integrates a dedicated inverting amplifier for Sense 4 input (enabling negative supply monitoring), a general-purpose op-amp (20-mA source capability, 0.4 V/µs slew rate), and separate line/switcher sense comparator (2.0-V threshold, 175-mV hysteresis) that drives the POWER OK output independently of rail faults.

Key Specifications

Parameter	Value and Actual Design Meaning
Supply Range	8 V to 40 V - supports wide-input industrial DC-DC converters and telecom rectifiers without external regulators.
Reference Voltage	2.485–2.515 V at 25°C - enables precise, temperature-stable fault window centering for ±0.5% threshold accuracy.
Fault Threshold Hysteresis	10–30 mV/V of Window Adjust voltage - provides scalable, proportional hysteresis to prevent chatter near trip points.
Open-Collector Output Sink	>30 mA per output - directly drives LEDs, optocouplers, or logic-level inputs without external buffers.
Operating Temperature	–40°C to +85°C - qualified for industrial-grade embedded power management in base stations and PLCs.
Line Sense Threshold	2.0 V ±60 mV - detects early AC line or switcher failure before downstream rails collapse.
UV Fault Delay Ratio	20–50 ms/µF - allows user-selectable delay via external capacitor to reject short transients while catching sustained faults.

Pinout & Package

UC2903QTR is packaged in a 20-pin PLCC (FN package drawing), surface-mount, lead-free (Pb-free, RoHS-compliant) ceramic body with gull-wing leads. The package is moisture-sensitive Level-2 (260°C peak reflow), rated for industrial temperature operation.

Pin/Terminal	Circuit Role	Design Meaning
+VIN	Main supply input	Accepts 8–40 V DC; powers all internal circuitry including reference, comparators, and outputs.
VREF (Pin 2)	Precision 2.5-V reference output	Stable, low-drift reference used to bias sense dividers and calibrate fault windows; ±15 mV load regulation (0–10 mA).
GND (Pin 3)	Analog/digital ground reference	Common return for all internal circuits; referenced for all voltage specifications and threshold calculations.
WINDOW ADJUST (Pin 4)	Fault window magnitude control	Voltage (0–2.5 V) sets proportional offset: OV = VREF + 0.25×V_ADJ, UV = VREF – 0.25×V_ADJ.
SENSE 4 INVERT INPUT (Pin 5)	Inverting amplifier non-inverting input	Connects to emitter of internal NPN inverter; enables direct sensing of negative supplies when tied high to disable inversion.
SENSE 4 (Pin 6)	Inverted sense input	Receives inverted signal from Pin 5; used to monitor negative rails (e.g., –5 V, –12 V) with same fault window logic as positive rails.
SENSE 3 (Pin 7)	Third positive rail monitor input	High-impedance input (±3 µA bias) for voltage divider-connected rail; clamped to –0.3 V to +20 V.
SENSE 2 (Pin 8)	Second positive rail monitor input	Identical electrical specs to SENSE 3; supports independent fault window scaling via external resistor networks.
SENSE 1 (Pin 9)	First positive rail monitor input	Primary sense input; internally clamped with 2-kΩ resistor + 5.7-V zener for overvoltage protection.
OV DELAY (Pin 10)	Overvoltage fault timer capacitor node	Connects to external capacitor; 60-µA charging current yields 20–50 ms/µF delay to OV FAULT assertion.
OV FAULT (Pin 11)	Open-collector overvoltage indicator	Sinks ≥30 mA when any monitored rail exceeds programmed OV threshold after delay; active-low.
UV FAULT (Pin 12)	Open-collector undervoltage indicator	Sinks ≥30 mA when any monitored rail falls below programmed UV threshold after delay; active-low.
UV DELAY (Pin 13)	Undervoltage fault timer capacitor node	Same timing architecture as OV DELAY; capacitor discharge path enabled when fault clears for fast recovery.
LINE/SWITCHER SENSE (Pin 14)	Early power source failure detector	2.0-V comparator input with 175-mV hysteresis; asserts POWER OK low upon drop below 2.0 V, independent of rail faults.
POWER OK (Pin 15)	System health status output	Active-low open-collector output; low during any fault (UV/OV/line/under-supply); high only when all conditions nominal.
G.P. OP-AMP N.I. (Pin 16)	General-purpose op-amp non-inverting input	Uncommitted input; usable for error amplification, feedback buffering, or logic-level translation in isolated supplies.
G.P. OP-AMP INV. (Pin 17)	General-purpose op-amp inverting input	Paired with Pin 16; supports unity-gain follower, differential sensing, or active filter configurations.
G.P. OP-AMP OUT (Pin 18)	General-purpose op-amp output	Capable of sourcing 20 mA; includes substrate-based sink enhancement for transient response in feedback loops.
NC (Pin 19)	No-connect terminal	Internally unused; must be left floating or tied to GND per layout guidelines to avoid noise coupling.

Key Features

Feature	Design Value
Four independent voltage monitoring channels	Supports simultaneous supervision of +3.3 V, +5 V, +12 V, and –5 V rails in single-chip solution-reducing BOM count and PCB area vs discrete comparators.
Programmable fault window with proportional hysteresis	Window width and hysteresis scale together from Pin 4 voltage (0.5–2.5 V), eliminating need for separate hysteresis resistors and guaranteeing consistent noise immunity across all thresholds.
Dedicated Sense 4 inverter	Enables true bipolar monitoring without external op-amps or level shifters-critical for legacy industrial systems with split-rail analog circuitry.
Integrated 2.5-V precision reference	Drives all internal comparators and external sense dividers; ±0.1% initial accuracy and <±0.01%/V line regulation ensure stable thresholds across input voltage variation.
Three high-current open-collector outputs	Each sinks ≥30 mA at 0.4 V saturation-directly interfaces with optocouplers (e.g., PC817), relay drivers, or microcontroller GPIOs without pull-up resistors or buffer stages.
Line/switcher sense comparator	Provides early warning of upstream failures (e.g., transformer open, rectifier diode short) before downstream rails decay-enabling graceful shutdown in telecom rectifiers.

Applications

Telecom Rectifier Supervision	Industrial PLC Power Monitoring
Use Scenario: Monitors +48 V DC input, +3.3 V control rail, +5 V I/O rail, and –5 V analog rail in a 48 V telecom rectifier module. IC Role / Device Role / Timing Role: UC2903QTR acts as centralized power-good arbiter, asserting POWER OK only when all rails are within ±3% tolerance and line input remains above 42 V. Use Value: Prevents system boot under marginal input conditions and avoids brownout-induced firmware corruption in base station controllers.	Use Scenario: Supervises redundant 24 V DC power feeds, CPU core voltage (+1.2 V), I/O bus voltage (+5 V), and isolated analog sensor supply (–15 V) in an industrial PLC backplane. IC Role / Device Role / Timing Role: UC2903QTR generates independent UV/OV delays (100 ms) per rail and latches faults until manual reset, enabling deterministic fail-safe shutdown. Use Value: Eliminates need for four separate supervisor ICs and associated RC timing networks-reducing design complexity and qualification effort.
Medical Imaging Power Sequencing	Avionics DC Distribution Panel
Use Scenario: Controls startup sequencing of X-ray generator HV supply (+200 V), detector bias (–12 V), FPGA core (+1.0 V), and cooling fan rail (+12 V) in portable imaging equipment. IC Role / Device Role / Timing Role: UC2903QTR uses its general-purpose op-amp to buffer and scale the 2.5-V reference for custom threshold generation, while Sense 4 inverter monitors negative bias rail. Use Value: Ensures safe ramp-up order and prevents arcing or thermal runaway by enforcing strict voltage sequencing before enabling HV modules.	Use Scenario: Monitors primary 28 V aircraft bus, avionics 5 V logic rail, inertial navigation sensor supply (+15 V/–15 V), and backup battery feed in a Line Replaceable Unit (LRU). IC Role / Device Role / Timing Role: UC2903QTR's line sense input detects main bus sag before secondary supplies droop, triggering automatic switchover to backup battery within 5 ms. Use Value: Meets DO-160 Section 20 surge/ripple immunity requirements by providing faster fault detection than downstream rail monitors alone.

Telecom Rectifier Supervision

Industrial PLC Power Monitoring

Use Scenario: Monitors +48 V DC input, +3.3 V control rail, +5 V I/O rail, and –5 V analog rail in a 48 V telecom rectifier module.

IC Role / Device Role / Timing Role: UC2903QTR acts as centralized power-good arbiter, asserting POWER OK only when all rails are within ±3% tolerance and line input remains above 42 V.

Use Value: Prevents system boot under marginal input conditions and avoids brownout-induced firmware corruption in base station controllers.

Use Scenario: Supervises redundant 24 V DC power feeds, CPU core voltage (+1.2 V), I/O bus voltage (+5 V), and isolated analog sensor supply (–15 V) in an industrial PLC backplane.

IC Role / Device Role / Timing Role: UC2903QTR generates independent UV/OV delays (100 ms) per rail and latches faults until manual reset, enabling deterministic fail-safe shutdown.

Use Value: Eliminates need for four separate supervisor ICs and associated RC timing networks-reducing design complexity and qualification effort.

Medical Imaging Power Sequencing

Avionics DC Distribution Panel

Use Scenario: Controls startup sequencing of X-ray generator HV supply (+200 V), detector bias (–12 V), FPGA core (+1.0 V), and cooling fan rail (+12 V) in portable imaging equipment.

IC Role / Device Role / Timing Role: UC2903QTR uses its general-purpose op-amp to buffer and scale the 2.5-V reference for custom threshold generation, while Sense 4 inverter monitors negative bias rail.

Use Value: Ensures safe ramp-up order and prevents arcing or thermal runaway by enforcing strict voltage sequencing before enabling HV modules.

Use Scenario: Monitors primary 28 V aircraft bus, avionics 5 V logic rail, inertial navigation sensor supply (+15 V/–15 V), and backup battery feed in a Line Replaceable Unit (LRU).

IC Role / Device Role / Timing Role: UC2903QTR's line sense input detects main bus sag before secondary supplies droop, triggering automatic switchover to backup battery within 5 ms.

Use Value: Meets DO-160 Section 20 surge/ripple immunity requirements by providing faster fault detection than downstream rail monitors alone.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
UC3903Q	Same pinout and function but rated for 0°C to +70°C commercial temperature range; lacks extended industrial qualification.	Not suitable for deployments requiring –40°C cold-start or sustained +85°C operation (e.g., outdoor telecom cabinets).	Select UC3903Q only for cost-sensitive, non-industrial applications where ambient temperature stays within 0–70°C.
TPS3808G33	Single-channel 3.3-V supervisor with fixed thresholds and no window adjust, inverter, or line sense; 6-pin SOT-23 package.	Cannot replace UC2903QTR in multi-rail systems-requires four TPS3808G33s plus external circuitry to replicate functionality.	Use TPS3808G33 only for simple single-rail monitoring where size and cost outweigh feature requirements.

Compared with UC3903Q and TPS3808G33, UC2903QTR uniquely delivers industrial-temperature quad monitoring with integrated negative rail support and scalable fault windows in a single PLCC-20 package-reducing component count, layout area, and qualification burden for complex power systems.

Availability

UC2903QTR is available at Aetrix Electronics and suitable for telecom rectifier supervision, industrial PLC power monitoring, medical imaging power sequencing, and avionics DC distribution panels requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for UC2903QTR 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 components.

The UC2903QTR belongs to TI's UCx903 family of precision power supervisors, engineered specifically for robust, multi-rail voltage monitoring in mission-critical industrial and telecom infrastructure where fault detection speed, temperature stability, and design simplicity are paramount.

FAQ

What is the operating temperature range of the UC2903QTR?

The UC2903QTR is specified for operation from –40°C to +85°C, making it suitable for industrial environments such as factory automation controllers, outdoor telecom cabinets, and transportation electronics where ambient temperatures exceed commercial-grade limits. This range is explicitly defined in the Electrical Characteristics table for UC2903 devices and confirmed in TI's Package Option Addendum for the Q (PLCC-20) variant.

How does the Window Adjust pin (Pin 4) set fault thresholds in UC2903QTR?

In UC2903QTR, the Window Adjust pin (Pin 4) sets both overvoltage and undervoltage thresholds as proportional offsets from the 2.5-V reference: OV = 2.5 V + (0.25 × V_ADJ) and UV = 2.5 V – (0.25 × V_ADJ). For example, applying 1.0 V to Pin 4 yields a ±250-mV window (2.25 V to 2.75 V). Hysteresis scales linearly at 10–30 mV/V, ensuring consistent noise margin across all settings.

Can UC2903QTR monitor a negative supply voltage?

Yes, UC2903QTR can monitor a negative supply using its dedicated Sense 4 inverter. By connecting the negative rail to Pin 5 (SENSE 4 INVERT INPUT) and grounding Pin 6 (SENSE 4), the internal NPN emitter-follower inverts the signal so that a –5 V input appears as +5 V at the comparator input. This eliminates the need for external level-shifting circuitry and is explicitly detailed in Figure 6 of the UC2903 datasheet.

What is the purpose of the LINE/SWITCHER SENSE input on UC2903QTR?

The LINE/SWITCHER SENSE input (Pin 14) on UC2903QTR provides early warning of upstream power source failure-such as AC line sag, rectifier diode open, or switcher controller lockup-before downstream rails collapse. With a fixed 2.0-V threshold and 175-mV hysteresis, it asserts POWER OK low independently of rail faults, enabling predictive shutdown in telecom rectifiers and UPS systems.

Does UC2903QTR include an internal voltage reference, and what are its key specs?

Yes, UC2903QTR integrates a precision 2.5-V bandgap reference (Pin 2) with initial accuracy of ±0.1% (2.485–2.515 V at 25°C), ±0.01%/V line regulation, and ±15 mV load regulation (0–10 mA). This reference serves as the absolute centerpoint for all fault thresholds and is electrically isolated from supply ripple-ensuring stable window positioning even under noisy input conditions.

UC2903QTR Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: -

Package/Case:: 20-LCC (J-Lead)

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Programmable:: Not Verified

Type:: Multi-Voltage Supervisor

Number of Voltages Monitored:: 4

Voltage - Threshold:: Adjustable/Selectable

Output:: Open Drain or Open Collector

Reset:: Active Low

Reset Timeout:: Adjustable/Selectable

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-PLCC (9x9)

UC2903QTR FAQ

1.How can I place an order for UC2903QTR through Aetrix?

Please submit a Request for Quotation (RFQ) for UC2903QTR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for UC2903QTR reliable?

The price and inventory of UC2903QTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC2903QTR is usually 5 days.

3.What payment methods are accepted for UC2903QTR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC2903QTR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for UC2903QTR?

UC2903QTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your UC2903QTR order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for UC2903QTR?

For technical support, including UC2903QTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC2903QTR requirements.

6.How does Aetrix verify that UC2903QTR is sourced from the original manufacturer or authorized distributors?

All UC2903QTR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that UC2903QTR meets industry standards.

7.What is the process for return or replacement of UC2903QTR?

All UC2903QTR units undergo pre-shipment inspection (PSI). If there is an issue with UC2903QTR, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The UC2903QTR part is unused and in its original packaging.

Return procedure for UC2903QTR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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