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Texas Instruments LM2931CT/LF03
- Part No.:
- LM2931CT/LF03
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-3
- Datasheet:
-
LM2931CT/LF03.pdf
- Description:
- IC REG LIN POS ADJ 100MA TO220-3
- Quantity:
- Payment:
- Shipping:
Inventory:3,718
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Product details
Overview
LM2931CT/LF03 from Texas Instruments is a 5V fixed-output low-dropout linear regulator in TO-220-5 package, delivering ≥100 mA output current with dropout voltage as low as 0.2 V at 10 mA and 0.6 V at 100 mA. It features reverse battery protection (−50 V transient), 60 V load dump immunity, and 1 mA quiescent current-designed for automotive memory standby and low-power processor supplies.
For engineers reviewing the LM2931CT/LF03 datasheet, LM2931CT/LF03 pinout, LM2931CT/LF03 application, or LM2931CT/LF03 equivalent, key selection criteria include input-output differential tolerance (<0.6 V), reverse polarity survivability (−50 V), thermal shutdown behavior, and ON/OFF control capability in the 5-lead TO-220 configuration.
Technical Context
The LM2931CT/LF03 implements an internal PNP pass transistor architecture enabling ultra-low dropout operation and inherent reverse-battery fault tolerance without external components. Its ON/OFF pin (Pin 5) provides TTL-compatible enable control with 1.2–3.25 V threshold range, allowing system-level power sequencing.
Protection circuitry includes integrated thermal overload shutdown, short-circuit current limiting, and mirror-image insertion immunity. The regulator maintains stability with ≥100 μF output capacitance and operates across −40°C to +85°C ambient temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.0 V ±3.8% (A-grade tolerance), stable under 5–100 mA load and −40°C to +85°C. |
| Dropout Voltage | 0.2 V max at 10 mA; 0.6 V max at 100 mA-enables regulation down to VIN = 5.6 V. |
| Quiescent Current | 1.0 mA max at 10 mA load-critical for battery-backed memory retention circuits. |
| Reverse Polarity Protection | Withstands −50 V transient (1 ms) and −15 V DC-eliminates need for external series diode. |
| Load Dump Immunity | Survives 60 V line transients (1 ms)-meets automotive ISO 7637-2 Pulse 5a requirements. |
| ON/OFF Control | TTL-compatible enable pin (Pin 5); logic-high >2.0 V enables regulation, <1.2 V disables output. |
| Operating Temperature | −40°C to +85°C ambient-qualified for under-hood automotive and industrial environments. |
Pinout & Package
LM2931CT/LF03 uses the TO-220-5 (KC) package: thermally enhanced 5-lead through-hole outline with isolated tab (non-connected). Pin 1 is Input, Pin 2 is Ground, Pin 3 is Output, Pin 4 is Bypass, Pin 5 is ON/OFF-pin numbering follows standard TO-220 front-view orientation (flat side facing viewer, leads down).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (IN) | Unregulated input supply | Accepts 6–26 V DC; withstands 60 V transients and −50 V reverse spikes. |
| Pin 2 (GND) | Ground reference | Common return for input, output, bypass, and ON/OFF logic; must be low-impedance. |
| Pin 3 (OUT) | Regulated 5 V output | Delivers up to 100 mA; requires ≥100 μF output capacitor for stability across temperature. |
| Pin 4 (BYPASS) | Internal reference bypass | Connects to OUT via 0.33 μF ceramic capacitor to reduce noise and improve ripple rejection. |
| Pin 5 (ON/OFF) | Enable/disable control | TTL-compatible; drives regulator into low-IQ shutdown state when pulled ≤1.2 V. |
Key Features
| Feature | Design Value |
|---|---|
| Low dropout operation | 0.2 V dropout at 10 mA enables use in 5.5 V systems where conventional 7805 regulators fail. |
| Integrated reverse battery protection | −50 V transient rating eliminates external blocking diode, reducing BOM count and forward drop loss. |
| TTL-compatible ON/OFF control | Pin 5 accepts standard logic levels-supports microcontroller-driven power sequencing without level shifters. |
| Automotive-grade transient immunity | 60 V load dump survival and −50 V reverse spike tolerance meet ISO 7637-2 compliance requirements. |
| Thermal and short-circuit protection | Automatic shutdown at TJ > 125°C and current limiting prevent damage during fault conditions. |
Applications
| Automotive Memory Backup | Industrial Sensor Node Power |
|---|---|
|
Use Scenario: Maintaining SRAM or real-time clock data during vehicle ignition-off periods using a 12 V battery with wide voltage swing and transients. IC Role / Device Role / Timing Role: Low-quiescent-current 5 V regulator supplying standby power to volatile memory and RTC ICs. Use Value: 1 mA IQ extends backup battery life; −50 V reverse protection prevents damage during jump-starts. |
Use Scenario: Powering low-power wireless sensor nodes (e.g., LoRaWAN, NB-IoT) deployed in remote industrial sites with unregulated 12–24 V DC rails. IC Role / Device Role / Timing Role: Primary 5 V LDO providing clean, stable supply to MCU, RF transceiver, and analog front-end. Use Value: 60 V load dump immunity ensures reliability during generator switching; ON/OFF pin enables deep-sleep wake-up control. |
| POS Terminal Logic Supply | Medical Diagnostic Module Standby |
|
Use Scenario: Providing regulated 5 V to microcontroller and display logic in point-of-sale terminals subject to AC adapter disconnect/reconnect events. IC Role / Device Role / Timing Role: Main system regulator handling dynamic load steps while maintaining tight output regulation. Use Value: 0.6 V dropout at 100 mA allows operation down to 5.6 V input-prevents brownout during brief AC dips. |
Use Scenario: Delivering always-on 5 V to watchdog timers and communication interfaces in portable diagnostic equipment with battery + wall adapter dual input. IC Role / Device Role / Timing Role: Fault-tolerant standby regulator ensuring system responsiveness during main power transitions. Use Value: Mirror-image insertion protection prevents damage during field service; thermal shutdown avoids overheating in sealed enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar low-dropout regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2931T-5.0/NOPB | 3-pin TO-220 variant without ON/OFF pin; no enable functionality. | Suitable only for always-on 5 V regulation; lacks power sequencing capability. | Select when system does not require controlled startup/shutdown and board space is constrained. |
| TPS7A1633DRBR | 3.3 V fixed output, 1.5 μA quiescent current, 650 mA output, 6-pin WSON package. | Higher current, lower IQ, but no reverse-battery or load-dump protection. | Choose for ultra-low-power 3.3 V systems where external protection is already implemented. |
Compared with LM2931T-5.0/NOPB, LM2931CT/LF03 adds critical ON/OFF control for power management; versus TPS7A1633DRBR, it trades higher IQ for integrated automotive-grade fault resilience-making it uniquely suited for ruggedized 5 V standby domains.
Availability
LM2931CT/LF03 is available at Aetrix Electronics and suitable for automotive memory backup, industrial sensor node power, and medical diagnostic module standby requiring stable component supply with long lifecycle assurance.
Supply support for LM2931CT/LF03 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 and embedded processing technologies, with decades of automotive qualification expertise and broad power management portfolio coverage.
The LM2931-N series was engineered specifically for automotive and industrial standby power applications demanding robust fault tolerance, low quiescent current, and extended temperature operation-prioritizing reliability over raw efficiency.
FAQ
What is the maximum input voltage rating for LM2931CT/LF03?
The LM2931CT/LF03 has a maximum operational input voltage of 26 V DC under continuous conditions. It also withstands transient overvoltages up to 60 V (load dump) and reverse transients down to −50 V for 1 ms, per its automotive-grade protection design. These ratings are absolute limits-not recommended operating points-and sustained operation above 26 V will cause permanent damage.
Does LM2931CT/LF03 require an external bypass capacitor?
Yes, LM2931CT/LF03 requires a 0.33 μF ceramic capacitor between Pin 4 (BYPASS) and Pin 3 (OUT) to stabilize the internal reference and achieve specified ripple rejection (80 dB at 120 Hz). Omitting this capacitor degrades noise performance and may cause instability under light loads or high-frequency transients.
Can LM2931CT/LF03 be used in adjustable-output configurations?
No-LM2931CT/LF03 is a fixed 5 V output variant. Adjustable versions (e.g., LM2931CS) use different pinouts and internal feedback networks. Attempting to configure LM2931CT/LF03 as adjustable by adding external resistors will not yield stable regulation and violates its internal topology.
What thermal derating applies to LM2931CT/LF03 in TO-220-5 package?
In free-air conditions, the TO-220-5 package has θJA = 50°C/W. At 25°C ambient, maximum continuous power dissipation is 2 W before junction temperature reaches 125°C. With a heatsink reducing θJA to 10°C/W, dissipation rises to 10 W. Thermal shutdown activates if TJ exceeds 125°C.
Is LM2931CT/LF03 RoHS compliant and lead-free?
Yes, LM2931CT/LF03 is RoHS compliant and features 100% matte tin (Sn) lead finish per TI's official packaging documentation. It meets JEDEC J-STD-020 moisture sensitivity Level 1 (unlimited floor life at ≤30°C/85% RH) and is rated for reflow peak temperatures up to 260°C.
LM2931CT/LF03 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- TO-220-3
- Packaging:
- Tube
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Adjustable
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 26V
- Voltage - Output (Min/Fixed):
- 3V
- Voltage - Output (Max):
- 24V
- Voltage Dropout (Max):
- 0.3V @ 100mA
- Current - Output:
- 100mA
- Current - Quiescent (Iq):
- 1 mA
- Current - Supply (Max):
- 15 mA
- PSRR:
- 55dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Temperature, Reverse Polarity, Short Circuit
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-3
LM2931CT/LF03 FAQ
1.How can I place an order for LM2931CT/LF03 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2931CT/LF03 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 LM2931CT/LF03 reliable?
The price and inventory of LM2931CT/LF03 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2931CT/LF03 is usually 5 days.
3.What payment methods are accepted for LM2931CT/LF03?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2931CT/LF03 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2931CT/LF03?
LM2931CT/LF03 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2931CT/LF03 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 LM2931CT/LF03?
For technical support, including LM2931CT/LF03 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2931CT/LF03 requirements.
6.How does Aetrix verify that LM2931CT/LF03 is sourced from the original manufacturer or authorized distributors?
All LM2931CT/LF03 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 LM2931CT/LF03 meets industry standards.
7.What is the process for return or replacement of LM2931CT/LF03?
All LM2931CT/LF03 units undergo pre-shipment inspection (PSI). If there is an issue with LM2931CT/LF03, 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 LM2931CT/LF03 part is unused and in its original packaging.
Return procedure for LM2931CT/LF03:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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