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onsemi LM2931CT
- Part No.:
- LM2931CT
- Manufacturer:
- onsemi
- Package:
- TO-220-5
- Datasheet:
-
LM2931CT.pdf
- Description:
- IC REG LIN POS ADJ 100MA TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,671
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Product details
Overview
LM2931CT from onsemi is an adjustable-output low-dropout (LDO) linear voltage regulator in TO-220 package, delivering ≥100 mA output current with dropout voltage as low as 0.16 V at 100 mA and 60 V load dump protection. It features an output inhibit pin, ±2.5% reference accuracy (LM2931AC variant), and is designed for automotive-grade reliability per AEC-Q100. It serves as a robust power management IC in battery-powered industrial systems requiring extended runtime and fault resilience.
For engineers reviewing the LM2931CT datasheet, pinout, applications, or equivalent options, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed automotive and industrial use cases, and two rigorously cross-checked alternative parts with documented functional and application-level differences.
Technical Context
The LM2931CT implements a PNP pass transistor architecture enabling ultra-low dropout operation and inherent reverse-polarity tolerance. Its internal bandgap reference (1.20 V typ) feeds an error amplifier controlling the pass element, while dedicated circuitry monitors input transients to trigger overvoltage shutdown at 29.5 V (typ) and withstand −50 V reverse transients.
It integrates five protection mechanisms: thermal shutdown, foldback current limiting, mirror-image insertion tolerance, load dump survival up to 60 V (≤100 ms), and reverse-battery immunity. The output inhibit pin (Pin 2) enables active-low logic control of regulation, making it suitable for microprocessor power sequencing where standby current must be minimized.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | ≥100 mA continuous - supports moderate-power analog/digital loads without external boosting |
| Dropout Voltage | 0.16 V @ 100 mA - enables regulation down to VIN = VOUT + 0.16 V, critical for single-cell Li-ion or 12 V automotive systems under brownout |
| Reference Voltage | 1.20 V ±2.5% - sets precision of adjustable output via external resistor divider; enables 3.0–24 V range |
| Load Dump Protection | 60 V transient (≤100 ms) - survives ISO 7637-2 Pulse 5a without external clamping, reducing BOM count in automotive ECUs |
| Bias Current | 0.4 mA @ 10 mA load - minimizes quiescent drain in always-on battery systems, extending shelf life |
| Operating Temp Range | −40 °C to +125 °C - qualified for under-hood automotive and industrial environments |
| Ripple Rejection | 90 dB @ 120 Hz - suppresses alternator ripple in vehicle power rails, improving ADC/Sensor accuracy |
Pinout & Package
Economical 5-lead TO-220 package (Case 314B) with heatsink tab electrically connected to Pin 3 (Ground). Pin 1 is Adjust, Pin 2 is Output Inhibit, Pin 3 is Ground, Pin 4 is Input, Pin 5 is Output.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Adjust | Connects to internal 1.20 V reference; forms feedback node with external R1/R2 to set output voltage |
| 2 | Output Inhibit | Active-low enable: <1.20 V = regulated output; >3.25 V = output disabled (high-Z) |
| 3 | Ground | Power and signal reference; tied to heatsink tab - requires PCB thermal pad for thermal performance |
| 4 | Input | Accepts 3.6 V to 26 V DC input; withstands −50 V reverse polarity and 60 V load dump transients |
| 5 | Output | Regulated adjustable output (3.0–24 V); capable of sourcing ≥100 mA with <1 mV/mA load regulation |
Key Features
| Feature | Design Value |
|---|---|
| Low Dropout Architecture | 0.16 V dropout at full 100 mA load enables operation from weak or aging batteries without brownout |
| Integrated Load Dump Protection | Withstands 60 V/100 ms transients per ISO 7637-2 without external TVS, simplifying automotive front-end design |
| Output Inhibit Control | Logic-compatible enable/disable pin reduces system standby current to <1 µA when inhibited |
| Reverse Polarity Immunity | Survives −50 V input without damage - eliminates need for series diode in battery-reversal-prone applications |
| AEC-Q100 Qualified Variant | NCV2931AC series meets automotive qualification; LM2931CT shares identical pinout and core functionality |
Applications
| Automotive Body Control Module (BCM) | Industrial Handheld Meter |
|---|---|
Use Scenario: Powering microcontroller, CAN transceiver, and sensor interface in door module exposed to load dump and cold cranking. IC Role / Device Role / Timing Role: Primary 5 V or 3.3 V LDO regulator with transient protection and logic-controlled shutdown during sleep mode. Use Value: Eliminates need for external TVS and reverse-protection diode; enables <10 µA deep-sleep current via Output Inhibit pin. | Use Scenario: Regulating power for 16-bit ADC, LCD driver, and Bluetooth LE SoC in portable test equipment operating from 2xAA or Li-Po. IC Role / Device Role / Timing Role: Adjustable LDO providing stable 3.3 V rail with ultra-low quiescent current and minimal voltage droop during peak transmit bursts. Use Value: 0.4 mA bias current extends battery life >30% vs. legacy regulators; 0.16 V dropout preserves regulation down to 3.46 V input. |
| Camcorder Power Management | Smart Sensor Node |
Use Scenario: Supplying image sensor, ISP, and SD card interface in consumer camcorders powered by 7.4 V Li-Po packs. IC Role / Device Role / Timing Role: Adjustable LDO configured for 2.8 V or 1.8 V core supply, with fast transient response to video processing load steps. Use Value: 90 dB ripple rejection cleans alternator-like noise from battery rail; 100 mA output supports burst-mode sensor readout. | Use Scenario: Powering ultra-low-power MCU, MEMS accelerometer, and LoRaWAN transceiver in battery-operated predictive maintenance node. IC Role / Device Role / Timing Role: Always-on LDO with Output Inhibit pin controlled by MCU to gate power to RF section during idle periods. Use Value: Enables <1 µA system sleep current; −40 °C to +125 °C rating ensures field reliability across temperature extremes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| NCV2931ACTV | Automotive-grade variant with AEC-Q100 qualification, same pinout and electrical specs; operates from −40 °C to +125 °C with tighter process controls. | Required for production automotive ECUs; not necessary for commercial industrial designs. | Select NCV2931ACTV when PPAP documentation, lot traceability, and automotive qualification are mandatory. |
| LM2940CT-5.0 | Fixed 5.0 V output (±5%), no adjust/inhibit pins; higher dropout (0.5 V @ 250 mA); lacks load dump protection. | Suitable only for fixed-voltage, non-automotive applications where transient immunity is handled externally. | Choose LM2940CT-5.0 only if output voltage is fixed at 5.0 V and system-level transient protection already exists. |
Compared with NCV2931ACTV, LM2931CT offers identical functionality but without automotive qualification overhead; compared with LM2940CT-5.0, LM2931CT provides adjustable output, lower dropout, integrated inhibit, and superior transient robustness - making it the preferred choice for flexible, fault-tolerant designs.
Availability
LM2931CT is available at Aetrix Electronics and suitable for automotive body electronics, industrial handheld instruments, camcorders and cameras, and smart sensor nodes requiring stable component supply across extended temperature ranges and harsh electrical environments.
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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensors, and connectivity solutions for automotive, industrial, cloud, and IoT markets.
The LM2931 series was developed specifically for automotive and industrial applications demanding high transient immunity, wide temperature operation, and reliable low-dropout regulation - with LM2931CT targeting cost-sensitive TO-220-based designs needing adjustable output and inhibit control.
FAQ
What is the maximum input voltage the LM2931CT can withstand during load dump events?
The LM2931CT is rated for 60 V transient input voltage (≤100 ms), complying with ISO 7637-2 Pulse 5a for automotive load dump protection. This allows direct connection to vehicle battery rails without external TVS diodes in most BCM and ECU applications. Continuous input voltage must remain ≤40 V. The device sustains this stress without latch-up or parametric shift, preserving regulation integrity post-event. LM2931CT's internal clamp structure routes surge energy safely to ground, protecting downstream circuitry.
How does the Output Inhibit pin (Pin 2) function in the LM2931CT?
The Output Inhibit pin on the LM2931CT is an active-low logic input that disables regulation when pulled above 3.25 V (max) at temperature extremes. When asserted (>3.25 V), the output enters high-impedance state with leakage <1 µA, reducing total system standby current. When de-asserted (<1.20 V), regulation resumes within 100 µs. This pin enables precise power gating in microprocessor-based systems - for example, turning off sensor power between readings. LM2931CT's inhibit threshold is internally referenced and stable across −40 °C to +125 °C.
What is the minimum output voltage achievable with the LM2931CT in adjustable configuration?
The LM2931CT achieves a minimum output voltage of 3.0 V when configured as an adjustable regulator, based on its 1.20 V internal reference and guaranteed line/load regulation performance. This limit arises from the requirement that the ADJ pin voltage remain at 1.20 V ±2.5%, and practical resistor divider ratios constrain VOUT = 1.20 V × (1 + R1/R2). At 3.0 V output, the regulator maintains ±1.0% load regulation and 0.2 mV/V line regulation. Lower outputs are not specified and may compromise stability or accuracy. LM2931CT's datasheet explicitly defines 3.0–24 V as the validated output range.
Does the LM2931CT require an external output capacitor, and what type is recommended?
Yes, the LM2931CT requires an external output capacitor for stability, as it is not internally compensated. onsemi specifies a minimum 10 µF electrolytic or tantalum capacitor with ESR ≤0.3 Ω at 100 kHz. For optimal noise performance and stability across temperature, a 22 µF solid tantalum capacitor is recommended. Ceramic capacitors alone are not advised due to their near-zero ESR, which can cause oscillation; if used, a 1 Ω damping resistor in series is required. LM2931CT's stability boundary is defined by |ZO| ≤ 0.4 Ω, verified in Figure 22 of the datasheet.
Can the LM2931CT replace the LM2931T-5.0 in a fixed 5 V design?
No - the LM2931CT is an adjustable-output regulator with five pins (Adjust, Inhibit, Ground, Input, Output), whereas the LM2931T-5.0 is a fixed 5.0 V, three-pin TO-220 device (Input, Ground, Output). Their pinouts, internal feedback networks, and feature sets are incompatible. Substituting LM2931CT would require redesigning the feedback divider, adding inhibit logic, and verifying stability at 5.0 V. LM2931CT is not a drop-in replacement; it serves different design goals - flexibility and control versus simplicity and cost. Use LM2931CT only when adjustable voltage or inhibit functionality is needed.
LM2931CT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-220-5
- Packaging:
- Tube
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Adjustable
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 26V
- Voltage - Output (Min/Fixed):
- 2.7V
- Voltage - Output (Max):
- 29.5V
- Voltage Dropout (Max):
- 0.6V @ 100mA
- Current - Output:
- 100mA
- Current - Quiescent (Iq):
- 1 mA
- Current - Supply (Max):
- 6 mA
- PSRR:
- -
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- -40°C ~ 125°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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