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Texas Instruments LM311D
- Part No.:
- LM311D
- Manufacturer:
- Texas Instruments
- Category:
- Comparators
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM311D.pdf
- Description:
- IC COMPARATOR 1 GEN PUR 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,982
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Product details
Overview
LM311D from Texas Instruments is a single high-speed voltage comparator with open-collector output, designed for precision level detection and signal conditioning in industrial and embedded systems. It delivers 165 ns response time, supports ±15 V or single 5-V supply operation, and drives loads up to 40 V at 50 mA - used in zero-crossing detectors, peak detectors, and oscillator circuits.
For engineers reviewing the LM311D datasheet, LM311D pinout, LM311D application, or LM311D equivalent, this page provides verified electrical specifications, SOIC-8 package details, strobe and balance functionality, thermal metrics, and real-world implementation guidance for comparator-based timing, sensing, and interface design.
Technical Context
The LM311D uses a PNP input stage enabling rail-to-rail common-mode input down to VCC−, followed by high-gain amplification and an isolated-emitter NPN open-collector output stage. Its differential input architecture supports precise voltage comparison with low input bias current (≤300 nA) and low offset voltage (≤7.5 mV).
Strobe (BAL/STRB) and balance (BALANCE) pins enable external offset trimming and synchronous output gating. The output can sink up to 50 mA and be wire-ORed with other comparators; it operates with load references to ground, VCC+, or VCC− without requiring level-shifting circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Response time | 165 ns high-to-low; enables fast edge detection in clock recovery and pulse-width modulation circuits |
| Input offset voltage | Max 7.5 mV at 25°C; defines minimum detectable voltage difference before output switching |
| Input bias current | Max 300 nA at full temperature range; ensures minimal loading on high-impedance sensor sources |
| Supply voltage range | 3.5 V to 30 V total (VCC+ − VCC−); supports single 5-V logic or dual ±15-V op-amp rails |
| Output capability | Open-collector, 40 V max collector-to-emitter voltage; drives relays, LEDs, or TTL/MOS logic directly |
| Operating temperature | 0°C to +70°C; validated for commercial-grade industrial control and consumer electronics |
| ESD rating | ±500 V HBM; meets standard handling requirements for board assembly and rework |
Pinout & Package
LM311D is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package measuring 4.90 mm × 3.91 mm, with gull-wing leads and standard JEDEC MS-012 footprint. Thermal resistance RθJA is 114.3°C/W, suitable for moderate-power comparator applications without forced airflow.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: EMIT OUT | Emitter output terminal | Provides emitter-follower output referenced to VCC−; used for level-shifted or low-impedance sourcing |
| 2: IN+ | Noninverting input | Accepts reference or signal voltage; common-mode range extends to VCC− − 14.7 V |
| 3: IN− | Inverting input | Accepts threshold or feedback voltage; differential comparison determines output state |
| 4: VCC− | Negative supply | Ground or negative rail connection; required even in single-supply configurations |
| 5: BALANCE | Offset null adjustment | Connects external potentiometer to trim input offset voltage for precision DC comparisons |
| 6: BAL/STRB | Strobe input | Active-low gate: pulls output high-impedance when current-driven to −3 mA; enables synchronized sampling |
| 7: COL OUT | Collector output | Open-collector NPN output; requires external pullup to define logic-high level and drive capability |
| 8: VCC+ | Positive supply | Primary power input; sets upper rail for internal circuitry and output pullup reference |
Key Features
| Feature | Design Value |
|---|---|
| Strobe-enabled output gating | Allows time-synchronized comparison windows - critical for sampled-data systems and noise rejection |
| Isolated emitter output | Enables independent output referencing to VCC−, ground, or VCC+, eliminating need for level translators |
| Wire-OR compatible output | Supports multiple LM311D outputs tied to shared pullup for logical OR functions without external logic gates |
| Rail-to-rail input stage | PNP input allows valid operation with inputs as low as VCC− − 14.7 V, supporting wide dynamic range sensing |
| High-voltage output switching | Drives 40 V loads at 50 mA - sufficient for solenoids, lamps, and optocouplers without external drivers |
Applications
| Zero-Crossing Detection | Oscillator & Timing Circuits |
|---|---|
|
Use Scenario: Detecting AC line voltage polarity transitions in motor controllers and power supplies. IC Role / Device Role / Timing Role: Voltage comparator comparing sinusoidal input against ground reference to generate clean digital zero-cross pulses. Use Value: 165 ns response ensures sub-microsecond timing accuracy; open-collector output interfaces directly with MCU GPIO or optocoupler inputs. |
Use Scenario: Building free-running multivibrators and crystal oscillators for clock generation in legacy systems. IC Role / Device Role / Timing Role: Core timing element in relaxation oscillator topologies using RC feedback and hysteresis. Use Value: Strobe and balance pins allow frequency tuning and startup synchronization; 40 V output swing accommodates diverse tank circuit voltages. |
| Peak Detector | TTL/MOS Interface Level Shifting |
|
Use Scenario: Capturing maximum amplitude of analog waveforms in test equipment and audio signal processors. IC Role / Device Role / Timing Role: Comparator driving sample-and-hold latch on positive/negative peaks via diode-capacitor network. Use Value: Low input bias current (≤300 nA) prevents capacitor discharge error; wide supply range supports 5 V–15 V hold voltage rails. |
Use Scenario: Converting 3.3 V or 5 V logic signals to higher-voltage control lines for industrial I/O modules. IC Role / Device Role / Timing Role: Level translator with programmable output high level set by external pullup resistor and supply. Use Value: Open-collector output supports 40 V logic-high levels; strobe pin enables gated level translation for burst-mode communication. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage comparator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM393DR | Dual comparator in same SOIC-8 package; lower speed (1.3 µs), no strobe or balance pins, 36 V max supply | Suitable for cost-sensitive dual-threshold detection but lacks LM311D's high-speed and precision trimming features | Select LM393DR only when dual-channel function is needed and 165 ns response is not required |
| TL331IDBVR | Single comparator, SOT-23-5; 200 ns response, no strobe/balance, rail-to-rail input, 36 V max supply | Better for space-constrained PCBs but lacks isolated emitter output and external offset adjustment | Choose TL331IDBVR for compact designs where strobe control and precision nulling are unnecessary |
Compared with LM311D, LM393DR offers dual functionality at lower speed and cost, while TL331IDBVR provides ultra-small packaging but omits key analog calibration features - LM311D remains optimal for applications demanding strobe-synchronized, trimmable, high-voltage comparator performance.
Availability
LM311D is available at Aetrix Electronics and suitable for industrial control panels, power supply monitoring, and embedded sensor interface designs requiring stable component supply across multi-year production cycles.
Supply support for LM311D 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 expertise in precision analog ICs and industrial-grade components.
The LM311D belongs to TI's legacy high-speed comparator product line, engineered for robust voltage comparison in noisy environments, wide supply ranges, and direct interfacing with electromechanical loads - targeting industrial automation, power conversion, and instrumentation.
FAQ
What is the maximum output voltage swing supported by the LM311D?
The LM311D collector output supports up to 40 V between COL OUT and VCC−, as specified in its absolute maximum ratings. This allows direct driving of 24 V industrial relays or 36 V logic interfaces when paired with appropriate pullup resistors and supply rails. The LM311D's 40 V rating is lower than the LM111/LM211 (50 V), reflecting its commercial temperature grade.
Can the LM311D operate from a single 5-V supply?
Yes, the LM311D is fully functional with a single 5-V supply (VCC+ = 5 V, VCC− = GND). Its input common-mode range extends from VCC− + 0.5 V to VCC+ − 1.5 V, and its output can sink current into ground or pull up to 5 V via external resistor. This configuration is widely used in microcontroller-based threshold detection and logic-level translation.
How does the BAL/STRB pin function in the LM311D?
The BAL/STRB pin serves dual roles: as a strobe input (active-low, current-driven at −3 mA) to force high-impedance output state, and as a balance node for offset nulling when used with external resistors. When not used for strobing, it must be left unconnected or tied to VCC+ - never shorted to ground, as that disables output functionality.
What is the purpose of the EMIT OUT pin on the LM311D?
The EMIT OUT pin provides an emitter-follower output referenced to VCC−, offering low-impedance sourcing capability and flexible load referencing. Unlike COL OUT, EMIT OUT does not require a pullup resistor and can drive loads tied to VCC+, ground, or intermediate voltages - enabling level-shifted outputs without additional transistors.
Does the LM311D require external components for basic comparator operation?
Yes - the LM311D requires at minimum an external pullup resistor on COL OUT to define logic-high voltage and enable sinking operation. For precision applications, a 10-kΩ potentiometer between BALANCE and VCC± is recommended for offset nulling. Bypass capacitors (0.1 µF) on VCC+ and VCC− are also advised to suppress supply noise affecting comparison accuracy.
LM311D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Series:
- -
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- General Purpose
- Number of Elements:
- 1
- Output Type:
- MOS, Open-Collector, Open-Emitter, TTL
- Voltage - Supply, Single/Dual (±):
- 3.5V ~ 30V, ±1.75V ~ 15V
- :
- 7.5mV @ ±15V
- Voltage - Input Offset (Max):
- 0.25µA @ ±15V
- Current - Input Bias (Max):
- -
- Current - Output (Typ):
- 7.5mA
- Current - Quiescent (Max):
- -
- CMRR, PSRR (Typ):
- -
- Propagation Delay (Max):
- -
- Hysteresis:
- 0°C ~ 70°C
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- Surface Mount
- :
- 8-SOIC
LM311D FAQ
1.How can I place an order for LM311D through Aetrix?
Please submit a Request for Quotation (RFQ) for LM311D 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 LM311D reliable?
The price and inventory of LM311D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM311D is usually 5 days.
3.What payment methods are accepted for LM311D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM311D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM311D?
LM311D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM311D 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 LM311D?
For technical support, including LM311D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM311D requirements.
6.How does Aetrix verify that LM311D is sourced from the original manufacturer or authorized distributors?
All LM311D 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 LM311D meets industry standards.
7.What is the process for return or replacement of LM311D?
All LM311D units undergo pre-shipment inspection (PSI). If there is an issue with LM311D, 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 LM311D part is unused and in its original packaging.
Return procedure for LM311D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM311D Tags
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