My Inquiry
My Account
Renesas UPC1944T-E1-A
- Part No.:
- UPC1944T-E1-A
- Manufacturer:
- Renesas
- Category:
- Voltage Reference
- Package:
- TO-243AA
- Datasheet:
-
UPC1944T-E1-A.pdf
- Description:
- IC VREF SHUNT 1.26V TO243AA
- Quantity:
- Payment:
- Shipping:
Inventory:4,499
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
UPC1944T-E1-A from Renesas Electronics is an adjustable precision shunt regulator in SOT-89 (SC-62) package, designed for voltage reference and error amplification in switching regulators. It delivers 1.26 V ±2.4% reference voltage, supports output adjustment from 1.26 V to 24 V via two external resistors, and operates with cathode current up to 30 mA at −30°C to +85°C ambient temperature.
For engineers reviewing the UPC1944T-E1-A datasheet, UPC1944T-E1-A pinout, UPC1944T-E1-A application, or UPC1944T-E1-A equivalent, this page provides verified technical context, real-world design meaning of specifications, validated pin functions, application-specific implementation guidance, and confirmed alternative parts for feedback loop stabilization in DC-DC converters.
Technical Context
The UPC1944T-E1-A implements a two-terminal shunt regulation architecture where cathode (K) sinks current to maintain a precise reference voltage at the REF terminal relative to anode (A). Its internal bandgap reference and error amplifier enable stable closed-loop control when used with external resistive dividers.
It features low dynamic impedance (0.12 Ω typical), minimal reference input current (2.0–4.0 μA), and tight thermal drift (±5 mV over 0°C to 70°C), making it suitable for high-accuracy feedback paths where load regulation and temperature stability are critical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 1.26 V ±2.4% - defines base accuracy of output voltage setting in adjustable regulator designs |
| Cathode Current Range | 1–30 mA - determines minimum/maximum sink capability for stable regulation under varying load conditions |
| Output Voltage Range | 1.26 V to 24 V - set by external R1/R2 divider; enables flexible output targeting across wide supply ranges |
| Dynamic Impedance | 0.12 Ω typical - ensures minimal output voltage perturbation during fast transient load changes |
| Reference Input Current | 2.0–4.0 μA - sets upper bound on resistor values in feedback network to avoid excessive divider loading |
| Operating Temperature | −30°C to +85°C - specifies ambient range for guaranteed performance in industrial-grade power supplies |
| Package | SOT-89 (SC-62) - surface-mount, thermally enhanced 3-pin package with cathode tab for PCB heat sinking |
Pinout & Package
UPC1944T-E1-A is housed in a POWER MINI MOLD (SOT-89 / SC-62) package with exposed cathode tab for thermal conduction. Pin 1 = Cathode (K), Pin 2 = Anode (A), Pin 3 = Reference (REF); Pin 2 is internally connected to the substrate and serves as the return path for reference current.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| K (Pin 1) | Cathode | Main current sink node; connects to regulated output node and must be routed to thermal pad for power dissipation handling |
| A (Pin 2) | Anode | Return path for reference current and cathode sink current; electrically tied to package substrate |
| REF (Pin 3) | Reference Input | High-impedance sensing node for feedback divider; voltage at this pin is regulated to 1.26 V |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output via two resistors | Enables precise output voltage tuning without custom ICs; eliminates need for fixed-voltage references in multi-rail systems |
| Low reference input current | Permits use of high-value feedback resistors (e.g., 100 kΩ+), reducing power loss and improving noise immunity |
| High accuracy reference voltage | 1.26 V ±2.4% tolerance ensures ≤±3% output error before resistor tolerance effects-critical for <1% output regulation targets |
| Stable operation up to 24 V | Supports direct use in 24 V industrial bus applications without external level-shifting or clamping circuits |
| Pb-free compliant (E1-A suffix) | Meets RoHS Directive requirements; external electrodes contain no lead-verified per Renesas Pb-free specification |
Applications
| Industrial DC-DC Converters | Programmable Power Supplies |
|---|---|
Use Scenario: Feedback control in isolated flyback or forward converters powering PLC I/O modules. IC Role / Device Role / Timing Role: Shunt-based voltage reference and error amplifier input node in secondary-side regulation loop. Use Value: Enables ±1% output accuracy over temperature using standard 1% resistors, meeting IEC 61000-6-2 immunity requirements. | Use Scenario: Digitally adjustable bench power supply with analog voltage programming interface. IC Role / Device Role / Timing Role: Precision reference element in DAC-output scaling circuit for 0–20 V programmable output. Use Value: Low 2.0–4.0 μA reference current minimizes DAC output loading, preserving linearity and resolution. |
| LED Constant-Current Drivers | Telecom Line Card Biasing |
Use Scenario: High-efficiency constant-current LED driver for outdoor signage with wide input voltage range. IC Role / Device Role / Timing Role: Reference source for current-sense amplifier in buck-based LED controller feedback path. Use Value: 0.12 Ω dynamic impedance suppresses current ripple induced by switching noise, ensuring flicker-free illumination. | Use Scenario: Bias voltage generation for op-amps and transceivers on telecom line cards operating from −48 V supply. IC Role / Device Role / Timing Role: Local 3.3 V or 5 V reference generator referenced to system ground in negative-rail environments. Use Value: Operates down to −30°C ambient, supporting NEBS GR-63-CORE compliance for central office deployment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431ACDBVR | Higher reference accuracy (2.495 V ±0.5%), lower cathode current limit (100 mA), different pinout (KA, REF, A) | Requires redesign of feedback divider ratio and PCB layout; not pin-compatible | Select when tighter reference tolerance and higher sink current are required, and layout revision is acceptable |
| LM4040CIM3-ADJ | Fixed-reference variants only; no adjustable version; 0.1% initial accuracy but limited to 2.048 V / 2.5 V / 4.096 V outputs | Cannot replace adjustable function without adding external op-amp; unsuitable for variable-output designs | Choose only for fixed-voltage reference needs where ultra-low drift (<±20 ppm/°C) outweighs adjustability requirement |
Compared with TL431ACDBVR and LM4040CIM3-ADJ, the UPC1944T-E1-A offers native adjustability from 1.26 V to 24 V in a compact SOT-89 package with proven thermal performance in industrial ambient conditions-making it optimal for cost-sensitive, space-constrained, and thermally demanding DC-DC feedback implementations.
Availability
UPC1944T-E1-A is available at Aetrix Electronics and suitable for industrial DC-DC converters, programmable power supplies, and LED constant-current drivers requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for UPC1944T-E1-A 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
Renesas Electronics Corporation is a global semiconductor leader delivering microcontrollers, analog power devices, and timing solutions for industrial, automotive, and infrastructure markets.
The UPC1944T-E1-A belongs to Renesas' legacy bipolar analog shunt regulator product line, engineered specifically for high-precision, low-drift voltage reference and error amplification in switching power supply feedback loops.
FAQ
What is the reference voltage tolerance of UPC1944T-E1-A?
The UPC1944T-E1-A has a reference voltage of 1.26 V with a tolerance of ±2.4%, measured at 10 mA cathode current and 25°C ambient temperature. This corresponds to a min/max range of 1.23 V to 1.29 V. The value is specified in the Electrical Characteristics table of Renesas' G10239EJ4V0DS datasheet and applies directly to the UPC1944T-E1-A variant.
Can UPC1944T-E1-A be used in place of μPC1944T?
Yes - UPC1944T-E1-A is the Renesas rebranded version of μPC1944T following the 2010 merger of NEC Electronics and Renesas Technology. The E1-A suffix denotes Pb-free compliance and matches the original μPC1944T's SOT-89 package, pinout, electrical specs, and thermal characteristics. No design changes are needed when migrating from μPC1944T to UPC1944T-E1-A.
What is the maximum cathode voltage rating for UPC1944T-E1-A?
The absolute maximum cathode-to-anode voltage (VKA) for UPC1944T-E1-A is 25 V, as stated in the Absolute Maximum Ratings table. However, the recommended operating range is VREF ≤ VKA ≤ 24 V. Exceeding 24 V in normal operation risks violating design margins and may impact long-term reliability, even if within absolute limits.
Does UPC1944T-E1-A require an external capacitor for stability?
Yes - stability depends on the output capacitance (CKA) and its ESR. The datasheet specifies a stability area chart: for aluminum electrolytic capacitors, CKA ≥ 6.8 μF is required. For ceramic capacitors, stability is achieved with CKA ≥ 0.1 μF and ESR ≥ 150 Ω. Using insufficient or zero capacitance may cause oscillation in the feedback loop of the UPC1944T-E1-A.
What is the thermal resistance (θJA) of UPC1944T-E1-A in SOT-89 package?
The junction-to-ambient thermal resistance (θJA) for UPC1944T-E1-A in SOT-89 package is 260 °C/W when mounted on a 16 cm² × 0.7 mm ceramic substrate, as shown in the "PT vs TA (I)" graph on page 4 of the datasheet. This value assumes standard PCB copper pour; actual θJA will vary with board layout, copper area, and airflow.
UPC1944T-E1-A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Package/Case:
- TO-243AA
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Reference Type:
- Shunt
- Output Type:
- Adjustable
- Voltage - Output (Min/Fixed):
- 1.26V
- Voltage - Output (Max):
- 24 V
- Current - Output:
- 30 mA
- Tolerance:
- ±2.4%
- Temperature Coefficient:
- -
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- -
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 1 mA
- Operating Temperature:
- -30°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 3-Power minimold
UPC1944T-E1-A FAQ
1.How can I place an order for UPC1944T-E1-A through Aetrix?
Please submit a Request for Quotation (RFQ) for UPC1944T-E1-A 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 UPC1944T-E1-A reliable?
The price and inventory of UPC1944T-E1-A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UPC1944T-E1-A is usually 5 days.
3.What payment methods are accepted for UPC1944T-E1-A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UPC1944T-E1-A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UPC1944T-E1-A?
UPC1944T-E1-A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UPC1944T-E1-A 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 UPC1944T-E1-A?
For technical support, including UPC1944T-E1-A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UPC1944T-E1-A requirements.
6.How does Aetrix verify that UPC1944T-E1-A is sourced from the original manufacturer or authorized distributors?
All UPC1944T-E1-A 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 UPC1944T-E1-A meets industry standards.
7.What is the process for return or replacement of UPC1944T-E1-A?
All UPC1944T-E1-A units undergo pre-shipment inspection (PSI). If there is an issue with UPC1944T-E1-A, 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 UPC1944T-E1-A part is unused and in its original packaging.
Return procedure for UPC1944T-E1-A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
UPC1944T-E1-A Tags
-
TL431AIDBZR
Texas Instruments
-
TL431BQDBZR
Texas Instruments
-
AN431AN-ATRG1
Diodes Incorporated
-
LM4040CYM3-2.5-TR
Microchip Technology
-
LM4040CYM3-4.1-TR
Microchip Technology
-
LM4040EIM3-2.5/NOPB
Texas Instruments
-
AZ431LBNTR-G1
Diodes Incorporated
-
LM4040D20IDBZR
Texas Instruments
-
LM4041DIM3-ADJ/NOPB
Texas Instruments
-
LM4040DIM3X-2.5/NOPB
Texas Instruments
-
LM4040DIM3-2.5/NOPB
Texas Instruments
-
AZ431LANTR-G1
Diodes Incorporated
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
