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Texas Instruments UC1903L
- Part No.:
- UC1903L
- Manufacturer:
- Texas Instruments
- Category:
- Supervisors
- Package:
- 20-CLCC
- Datasheet:
-
UC1903L.pdf
- Description:
- QUAD SUPPLY AND LINE MONITOR 20-
- Quantity:
- Payment:
- Shipping:
Inventory:2,080
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Product details
Overview
UC1903L from Texas Instruments is a military-grade quad supply and line monitor IC designed for high-reliability power system supervision in aerospace, defense, and industrial control. 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 precision 2.5-V reference, 30-mA open-collector fault outputs, and 8-V to 40-V supply operation. It is used in avionics power sequencers and ruggedized DC/DC converter supervision.
For engineers reviewing the UC1903L datasheet, UC1903L pinout, UC1903L application, or UC1903L equivalent, key selection considerations include its –55°C to +125°C operating range, J- or FK-package compatibility, programmable hysteresis scaling, line/switcher sense input for early failure warning, and integrated general-purpose op-amp for auxiliary feedback conditioning.
Technical Context
The UC1903L implements a fault window architecture where OV and UV thresholds are generated as ±offsets from the 2.5-V reference, with magnitude and hysteresis both proportional to the voltage applied at Pin 4 (Window Adjust). Its dedicated Sense 4 inverter enables direct monitoring of negative supplies without external components, while the line/switcher sense comparator triggers POWER OK deassertion when input falls below 2.0 V with 175 mV hysteresis.
Three open-collector outputs-OV FAULT, UV FAULT, and POWER OK-respond with user-programmable delays (20–50 ms/µF) to respective fault conditions. The uncommitted op-amp provides 20-mA source capability and is fully specified for use in isolated feedback paths, error amplification, or logic-level translation within the same supply domain.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 8 V to 40 V - supports wide-input industrial and military DC bus voltages without external regulation. |
| Reference Output | 2.5 V ±15 mV (TJ = 25°C) - stable, low-drift reference for precise threshold generation and external divider scaling. |
| Fault Threshold Hysteresis | 10–30 mV/V of window adjust voltage - ensures glitch-free response during slow-ramping or noisy supply transitions. |
| Open-Collector Output Sink | >30 mA per output - directly drives LEDs, optocouplers, or logic inputs without external buffers. |
| Operating Temperature | –55°C to +125°C - qualified for extended-range military applications per MIL-PRF-38535 Class B. |
| Sense Input Range | –0.3 V to +20 V - accommodates negative rails (via inverter) and high-side positive sensing with clamped protection. |
| Line Sense Threshold | 2.0 V ±60 mV - enables early detection of AC line sag or switcher collapse before downstream rail collapse. |
Pinout & Package
LCCC-20 (FK package), hermetically sealed ceramic leadless chip carrier with 20 terminals; suitable for high-reliability, high-vibration, and extended-temperature environments.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| +VIN | Main supply input | Power source for internal circuitry; enables operation across 8–40 V with 7-mA standby current. |
| VREF | Precision 2.5-V reference output | Stable voltage reference for external resistor dividers; capable of sourcing/sinking up to 40 mA. |
| GND | Analog/digital ground reference | Common return for all internal comparators, op-amps, and reference; two pins (Pins 3 & 4) ensure low-impedance grounding. |
| WINDOW ADJUST | Fault window scaling input | Voltage (0–10 V) sets proportional magnitude and hysteresis of OV/UV thresholds around VREF. |
| SENSE 1–4 | Monitor inputs for supply rails | Four independent inputs; SENSE 4 supports inverted configuration for negative voltage sensing. |
| LINE/SWITCHER SENSE | Early power failure detector | Comparator referenced to 2.0 V; asserts fault before main outputs collapse, enabling graceful shutdown. |
| POWER OK | Active-low status output | Low when all monitored rails are within window and line sense is valid; indicates system power health. |
| OV FAULT / UV FAULT | Dedicated fault indication outputs | Open-collector outputs with independent delay timing; active low on respective threshold violation. |
| OV DELAY / UV DELAY | External RC timing nodes | Connect capacitor to set fault response delay (20–50 ms/µF); discharge path internal for fast recovery. |
| G.P. OP-AMP OUT/N.I./INV | Uncommitted operational amplifier | Full rail-to-rail input; 20-mA source/40-mA sink; usable for error amplification, level shifting, or isolation feedback. |
Key Features
| Feature | Design Value |
|---|---|
| Quad independent voltage monitoring | Four sense inputs with shared reference and scalable windows-enables consolidated supervision of multi-rail systems (e.g., ±15 V, +5 V, +3.3 V). |
| Internal inverter for negative rail sensing | Eliminates need for external inverting amplifier when monitoring –5 V, –12 V, or other negative supplies via SENSE 4. |
| Proportional hysteresis architecture | Hysteresis scales automatically with window width-ensures consistent noise immunity across all programmed thresholds. |
| Programmable fault delay timing | RC-based delay (20–50 ms/µF) prevents false triggering on transient dips; fast internal discharge enables rapid recovery after fault clears. |
| Integrated general-purpose op-amp | 20-mA source capability and substrate-assisted sinking-supports closed-loop feedback in isolated DC/DC controllers without adding discrete op-amps. |
Applications
| Avionics Power Sequencing | Industrial Motor Drive Control |
|---|---|
Use Scenario: Supervising multiple DC bus voltages (+28 V primary, ±15 V analog, +5 V logic) in flight control computers with strict startup/shutdown sequencing requirements. IC Role / Device Role / Timing Role: UC1903L acts as centralized power-good arbiter, asserting POWER OK only after all rails stabilize within tolerance and remain stable for programmable delay. Use Value: Prevents premature processor boot or actuator enablement by enforcing interlocked power-up order and rejecting short-duration transients. | Use Scenario: Monitoring gate driver supplies, IGBT collector-emitter voltage feedback, and auxiliary bias rails in variable-frequency motor drives operating in harsh EMI environments. IC Role / Device Role / Timing Role: UC1903L serves as real-time fault detector-triggering immediate shutdown via UV/OV FAULT outputs upon undervoltage or overvoltage events on critical rails. Use Value: Enables sub-100-ms fault response without software intervention, protecting IGBTs from shoot-through or thermal runaway. |
| Ruggedized Telecom Power Systems | Military Radar Signal Processing |
Use Scenario: Supervising redundant -48 V telecom rectifier outputs and intermediate +12 V distribution rails in outdoor base station cabinets exposed to wide ambient temperature swings. IC Role / Device Role / Timing Role: UC1903L functions as dual-role monitor-using LINE/SWITCHER SENSE for early rectifier failure detection and SENSE 1–4 for rail-level validation. Use Value: Delivers predictive maintenance capability by distinguishing between upstream AC loss and downstream load faults, reducing false alarms. | Use Scenario: Ensuring clean power delivery to high-speed ADCs, DACs, and FPGA clock domains in airborne radar front-ends subject to vibration, shock, and radiation. IC Role / Device Role / Timing Role: UC1903L provides radiation-tolerant, hermetic-package power integrity verification-monitoring +3.3 V, +1.8 V, and –5.2 V rails with hysteresis scaled to match FPGA voltage tolerance specs. Use Value: Guarantees deterministic power-on reset behavior and eliminates latent failures caused by marginal rail operation during cold start. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad supply monitoring applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UC2903J | Commercial temperature grade (–40°C to +85°C); identical pinout and electrical architecture but lower reliability screening. | Not qualified for military/aerospace use; lacks MIL-PRF-38535 Class B testing and hermetic packaging. | Select UC2903J only for cost-sensitive industrial prototypes or non-critical commercial systems. |
| LM3914N-1 | Single-rail LED driver with bar-graph display; no fault outputs, no programmable delay, no negative rail support. | Designed for visual indication-not for automated fault response or system-level power arbitration. | Use LM3914N-1 only for basic analog voltage visualization; not a functional substitute for UC1903L's supervisory logic. |
Compared with UC2903J and LM3914N-1, the UC1903L uniquely combines military-grade temperature range, hermetic LCCC packaging, negative rail sensing, and three independent open-collector fault outputs-making it irreplaceable in safety-critical, high-reliability power supervision roles.
Availability
UC1903L is available at Aetrix Electronics and suitable for avionics power sequencers, ruggedized telecom rectifiers, industrial motor drive controllers, and military radar signal processing systems requiring stable component supply across extended temperature and long product lifecycles.
Supply support for UC1903L 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 high-reliability components for industrial, automotive, aerospace, and defense markets.
The UC1903L belongs to TI's military-grade power supervision product line, engineered specifically for fault-tolerant, multi-rail power integrity monitoring in mission-critical systems where failure is not an option.
FAQ
What is the operating temperature range of the UC1903L?
The UC1903L is rated for operation from –55°C to +125°C, meeting MIL-PRF-38535 Class B requirements for high-reliability military and aerospace applications. This extended range is enabled by its LCCC-20 hermetic ceramic package and internal circuit design optimized for thermal stability across extreme environmental conditions. The UC1903L maintains full specification compliance-including reference accuracy, fault threshold tolerance, and output drive strength-throughout this entire range.
How does the UC1903L support negative voltage monitoring?
The UC1903L supports negative voltage monitoring through a dedicated inverter circuit tied to the SENSE 4 input. By connecting the negative rail to the inverter's input (Pin 5) and configuring the emitter-follower output to drive SENSE 4 (Pin 6), the device converts the negative voltage into a positive-swing signal referenced to GND. This eliminates the need for external op-amps or level shifters. The UC1903L datasheet confirms this functionality is fully characterized and production-tested for –5 V, –12 V, and –15 V rails.
Can the UC1903L be used with non-hermetic packages?
No-the UC1903L part number specifically denotes the LCCC-20 (FK) hermetic ceramic package, as confirmed by TI's official packaging addendum. While functionally identical variants exist in CDIP (J) and SOIC (DW) packages (e.g., UC1903J), those carry distinct part numbers and are not interchangeable with UC1903L without redesign verification. The UC1903L's qualification for military applications depends entirely on its hermetic seal, thermal performance, and mechanical robustness-attributes not present in plastic or non-hermetic alternatives.
What is the purpose of the WINDOW ADJUST pin on the UC1903L?
On the UC1903L, the WINDOW ADJUST pin (Pin 4) sets both the magnitude of the OV/UV fault window and its proportional hysteresis. Applying a voltage between 0.5 V and 2.5 V generates symmetric ±offsets around the 2.5-V reference-e.g., 1.0 V at Pin 4 yields ~±0.25 V window with ~20 mV hysteresis. This allows precise, resistor-divider-based tuning of trip points for each monitored rail without recalibrating the reference. The UC1903L's internal bias cancellation ensures low input current (<10 µA), preserving divider accuracy.
Does the UC1903L include a built-in op-amp, and how is it used?
Yes, the UC1903L integrates a general-purpose op-amp (pins G.P. OP-AMP N.I., INV, and OUT) with 20-mA source and 40-mA sink capability. It is fully specified for use in isolated feedback loops-e.g., buffering optocoupler outputs in flyback converters-or as an error amplifier in regulated DC/DC stages. Unlike generic op-amps, its output stage uses an NPN emitter follower (Q6) plus substrate transistor (Q3) for enhanced transient sinking, making it suitable for driving capacitive loads or low-impedance references. This op-amp is electrically identical across all UC1903 family members, including UC1903L.
UC1903L Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 20-CLCC
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- -
- Type:
- Monitor
- Number of Voltages Monitored:
- 4
- Voltage - Threshold:
- 2.5V, Adj
- Output:
- Open Drain or Open Collector
- Reset:
- Active Low
- Reset Timeout:
- -
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-LCCC (8.89x8.89)
UC1903L FAQ
1.How can I place an order for UC1903L through Aetrix?
Please submit a Request for Quotation (RFQ) for UC1903L 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 UC1903L reliable?
The price and inventory of UC1903L are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC1903L is usually 5 days.
3.What payment methods are accepted for UC1903L?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC1903L transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC1903L?
UC1903L orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UC1903L 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 UC1903L?
For technical support, including UC1903L datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC1903L requirements.
6.How does Aetrix verify that UC1903L is sourced from the original manufacturer or authorized distributors?
All UC1903L 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 UC1903L meets industry standards.
7.What is the process for return or replacement of UC1903L?
All UC1903L units undergo pre-shipment inspection (PSI). If there is an issue with UC1903L, 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 UC1903L part is unused and in its original packaging.
Return procedure for UC1903L:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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