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Texas Instruments LM2931CT
- Part No.:
- LM2931CT
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-5
- Datasheet:
-
LM2931CT.pdf
- Description:
- IC REG LIN POS ADJ 100MA TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,060
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Product details
Overview
LM2931CT from Texas Instruments is a 5V fixed-output, adjustable-enable low-dropout linear regulator in TO-220-5 package, delivering ≥100 mA output current with ≤0.6 V input-output differential at 100 mA and reverse battery protection up to −50 V. It operates across −40°C to +85°C and is designed for automotive memory standby and low-power processor supply rails.
For engineers reviewing the LM2931CT datasheet, LM2931CT pinout, LM2931CT application, or LM2931CT equivalent, key selection criteria include dropout voltage at full load, quiescent current under light-load conditions, reverse transient immunity, ON/OFF control threshold accuracy, and thermal performance in TO-220-5 without heatsink.
Technical Context
The LM2931CT integrates an internal PNP pass transistor, enabling ultra-low dropout operation (0.2 V typical at 10 mA) and sub-1 mA quiescent current during standby. Its ON/OFF pin provides TTL-compatible enable control with 1.2–3.25 V threshold range, supporting system-level power sequencing.
Protection circuitry includes reverse polarity handling (−50 V transient), 60 V load dump shutdown, short-circuit current limiting, and thermal overload shutdown. The regulator requires a minimum 100 μF output capacitor with specified ESR for stability across temperature and load extremes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.0 V ±3.8% (A grade), stable over −40°C to +85°C ambient |
| Max Output Current | ≥100 mA continuous, with foldback current limiting during short circuit |
| Dropout Voltage | 0.6 V max at 100 mA load - enables regulation from 5.6 V input in worst case |
| Quiescent Current | 1.0 mA max at 10 mA load - supports ultra-low-power standby modes |
| Reverse Protection | Withstands −50 V transient (1 ms) - eliminates need for external series diode in automotive battery-reverse scenarios |
| Enable Threshold | ON at ≤2.0 V, OFF at ≥2.2 V (TTL-compatible) - allows direct interface with microcontroller GPIO |
| Thermal Shutdown | Activates at 125°C junction temperature - prevents damage during sustained overload or poor heatsinking |
Pinout & Package
LM2931CT is housed in a TO-220-5 thermally enhanced package with exposed tab (pin 5), rated for 50°C/W junction-to-ambient thermal resistance when mounted on PCB copper area ≥1 in².
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Input) | Unregulated DC input | Accepts 6–26 V DC; withstands 60 V load dump transients via internal clamp |
| 2 (Ground) | Power ground reference | Common return for input, output, and enable; must be low-impedance path to minimize noise coupling |
| 3 (Output) | Regulated 5 V output | Delivers up to 100 mA; requires ≥100 μF low-ESR capacitor for stability |
| 4 (ON/OFF) | Enable control input | TTL-compatible logic input; pulls high internally; <2.0 V disables regulator, >2.2 V enables |
| 5 (Tab) | Thermal pad / case | Internally connected to ground; must be soldered to PCB copper pour for thermal management |
Key Features
| Feature | Design Value |
|---|---|
| Low-quiescent-current LDO | 0.4–1.0 mA typical operating current enables >1-year battery life in always-on memory backup circuits |
| Integrated reverse-battery protection | Eliminates need for external series diode - reduces BOM count and forward voltage drop in 12 V automotive systems |
| Load-dump transient immunity | Shuts down automatically during 60 V/1 ms transients - protects downstream logic and preserves system reliability |
| TTL-compatible ON/OFF control | Direct interface with MCU I/O pins without level-shifting - simplifies power sequencing in embedded controllers |
| Stable with standard electrolytic capacitors | Validated with 100 μF aluminum or 47 μF tantalum output caps - avoids costly polymer or ceramic alternatives |
Applications
| Automotive Memory Backup | Industrial Sensor Node Power |
|---|---|
|
Use Scenario: Maintaining SRAM and real-time clock data during vehicle ignition-off periods using 12 V battery. IC Role / Device Role / Timing Role: Low-quiescent LDO supplying clean 5 V to non-volatile memory subsystems. Use Value: 1.0 mA max quiescent current extends battery hold-up time beyond 30 days without recharge. |
Use Scenario: Powering ultra-low-power wireless sensor nodes (e.g., LoRaWAN edge devices) from primary lithium cells. IC Role / Device Role / Timing Role: Primary voltage regulator enabling sleep-mode operation with fast wake-up response. Use Value: Sub-1 mA quiescent draw minimizes self-discharge, extending 2000 mAh cell life to >5 years in duty-cycled deployments. |
| POS Terminal Peripheral Supply | Medical Diagnostic Module Bias |
|
Use Scenario: Providing isolated 5 V rail for barcode scanners and magnetic stripe readers in retail point-of-sale terminals. IC Role / Device Role / Timing Role: Secondary regulated supply decoupled from main 12 V system bus. Use Value: Reverse polarity protection prevents field failure due to accidental battery misconnection during service. |
Use Scenario: Generating stable 5 V bias for analog front-end amplifiers and ADC references in portable diagnostic equipment. IC Role / Device Role / Timing Role: Precision low-noise power source for signal chain components requiring <500 μVrms ripple. Use Value: 500 μVrms output noise and 80 dB ripple rejection ensure accurate 12-bit ADC conversion without post-processing correction. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar low-dropout regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2931ACZ-5.0/NOPB | TO-92-3 package, no ON/OFF pin, fixed 5 V only, 3.8% tolerance | Lacks enable control and thermal performance of TO-220-5; limited to <100 mA with heatsink | Select when board space is constrained and enable functionality is unnecessary |
| TPS76350DBVR | SOT-23-5 package, 5 V fixed, 85 μA quiescent current, no reverse-battery protection | Lower IQ but no −50 V transient immunity; requires external diode for reverse-polarity hardening | Select for battery-powered IoT nodes where ultra-low standby current outweighs automotive robustness needs |
Compared with LM2931ACZ-5.0/NOPB and TPS76350DBVR, the LM2931CT uniquely combines TO-220-5 thermal capability, integrated reverse-battery protection, and TTL-compatible enable - making it the only choice for automotive-grade, field-serviceable 5 V LDO designs requiring both robustness and controllability.
Availability
LM2931CT is available at Aetrix Electronics and suitable for automotive memory backup, industrial sensor node power, POS terminal peripheral supply, and medical diagnostic module bias requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LM2931CT 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 company headquartered in Dallas, Texas, specializing in analog and embedded processing technologies with over 90 years of innovation in power management ICs.
The LM2931-N series was engineered specifically for automotive and industrial environments demanding high transient immunity, reverse-polarity resilience, and ultra-low standby power - targeting memory retention, ECU auxiliary rails, and safety-critical subsystems.
FAQ
What is the maximum input voltage rating for LM2931CT?
The LM2931CT has an absolute maximum input voltage rating of 26 V DC under normal operating conditions. During line transients such as automotive load dump events, it can withstand up to 60 V for 1 ms before entering protective shutdown - a critical feature confirmed in TI's SNOSBE5G datasheet Section 6.1.
Does LM2931CT require an external output capacitor, and what value is recommended?
Yes, LM2931CT requires a minimum 100 μF output capacitor with appropriate ESR for stability, as specified in Figure 12 and Application Hints section of the datasheet. Aluminum electrolytic or tantalum types are validated; ceramic capacitors alone are insufficient due to ESR dependency.
How does the ON/OFF pin function on LM2931CT?
The ON/OFF pin (Pin 4) provides TTL-compatible enable control: applying ≤2.0 V disables regulation, while ≥2.2 V enables it. The internal pull-up ensures default-on behavior if left unconnected, and the pin draws <50 μA - allowing direct drive from microcontroller GPIO without buffering.
Is LM2931CT compatible with reverse battery connection?
Yes, LM2931CT is explicitly rated for −50 V reverse transient protection (1 ms duration) and −15 V DC reverse polarity per datasheet Section 6.1. This eliminates the need for an external series diode in automotive applications where battery jump-start errors may occur.
What thermal performance can be expected from LM2931CT in TO-220-5 package without heatsink?
In free-air conditions with no heatsink, LM2931CT in TO-220-5 exhibits θJA = 50°C/W. At 100 mA output and 10 V input differential, power dissipation is ~1 W, resulting in ~50°C junction rise above ambient - well within the 125°C shutdown threshold, provided ambient stays below 75°C.
LM2931CT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- TO-220-5
- Packaging:
- Bulk
- 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-220-5
LM2931CT FAQ
1.How can I place an order for LM2931CT through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2931CT 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 reliable?
The price and inventory of LM2931CT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2931CT is usually 5 days.
3.What payment methods are accepted for LM2931CT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2931CT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2931CT?
LM2931CT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2931CT 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?
For technical support, including LM2931CT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2931CT requirements.
6.How does Aetrix verify that LM2931CT is sourced from the original manufacturer or authorized distributors?
All LM2931CT 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 meets industry standards.
7.What is the process for return or replacement of LM2931CT?
All LM2931CT units undergo pre-shipment inspection (PSI). If there is an issue with LM2931CT, 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 part is unused and in its original packaging.
Return procedure for LM2931CT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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