My Inquiry
My Account
Texas Instruments LM311N
- Part No.:
- LM311N
- Manufacturer:
- Texas Instruments
- Category:
- Comparators
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM311N.pdf
- Description:
- IC COMPARATOR 1 GEN PUR 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,233
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM311N from Texas Instruments is an 8-pin DIP-packaged voltage comparator with open-collector output, operating from single 5V or dual ±15V supplies, featuring 200 ns response time, ±30V differential input range, and 0°C to +70°C temperature rating for industrial and embedded signal conditioning applications.
For engineers reviewing the LM311N datasheet, LM311N pinout, LM311N application, or LM311N equivalent, this page delivers verified electrical specs, strobe and offset trim functionality, TTL/DTL/MOS-compatible output drive, relay/lamp switching capability up to 40V, and real-world zero-crossing, peak detection, and oscillator circuit implementation guidance.
Technical Context
The LM311N implements a high-gain, wide-bandwidth bipolar comparator architecture with separate strobe and offset null terminals (Pins 6 and 5), enabling precise threshold control and synchronous output disable. Its open-collector output supports wire-OR logic and direct interface to loads referenced to ground, V+, or V−.
Input stage isolation allows common-mode operation beyond supply rails, while internal compensation avoids external frequency compensation. Strobe current drive (2–5 mA) disables output without grounding Pin 6, preventing latch-up or transients during sequencing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Range | Single 5V or dual ±15V; enables compatibility with logic and analog subsystems without level-shifting. |
| Response Time | 200 ns (100 mV step, 5 mV overdrive); suitable for medium-speed digital edge detection and PWM timing. |
| Differential Input Voltage | ±30V; permits direct comparison of signals across isolated domains or high-voltage sensing nodes. |
| Output Drive Capability | 50 mA sink at ≤1.5 V saturation; drives relays, LEDs, or logic inputs without external buffers. |
| Input Bias Current | 100–300 nA max (0°C to +70°C); preserves accuracy in high-impedance sensor interfaces like photodiodes. |
| Strobe Control Current | 2–5 mA required to disable output; eliminates need for pull-down resistors or active low-side switches. |
| Operating Temperature | 0°C to +70°C; qualified for commercial-grade embedded systems, power supplies, and instrumentation. |
Pinout & Package
LM311N is supplied in an 8-pin plastic dual-in-line package (PDIP, Package Code P), 0.300" wide, with standard through-hole mounting and JEDEC MS-001 compliant footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Emitter) | Output emitter / collector reference | Connect to load return path; enables output sinking to ground, V+, or V− depending on load configuration. |
| 2 (−IN) | Inverting input | Differential comparison node; accepts signals up to ±15V relative to supply rails. |
| 3 (+IN) | Non-inverting input | Primary signal input; used with hysteresis or reference voltage for threshold detection. |
| 4 (V−) | Negative supply | Supports dual-supply operation; may be tied to ground for single-supply use with appropriate input biasing. |
| 5 (Offset Null) | Offset adjustment terminal | Connects to potentiometer wiper for trimming input offset voltage; critical for precision DC comparisons. |
| 6 (Strobe) | Output enable/disable control | Current-sink input: drawing 2–5 mA disables output; never ground directly to avoid damage. |
| 7 (V+) | Positive supply | Accepts 5V to 15V; powers internal circuitry and defines output high-level reference when pull-up used. |
| 8 (Collector) | Open-collector output | Sinks current only; requires external pull-up resistor to define logic high level and drive capability. |
Key Features
| Feature | Design Value |
|---|---|
| Isolated Inputs & Outputs | Input and output stages electrically decoupled from system ground, enabling floating measurements and mixed-rail interfacing. |
| Wire-OR Output Capability | Multiple LM311N outputs can share a single pull-up resistor for priority encoding or alarm bus architectures. |
| Strobe-Controlled Output Disable | Enables synchronized blanking in time-critical systems (e.g., ADC sampling windows or multiplexed sensor arrays). |
| Offset Null Terminal | Allows calibration of input offset error down to <10 mV, improving DC accuracy in precision threshold detection. |
| Relay & Lamp Drive | Direct 40V/50 mA switching capability eliminates driver transistors in industrial control I/O modules. |
Applications
| Zero-Crossing Detection | Peak Voltage Detection |
|---|---|
Use Scenario: Monitoring AC mains waveform to trigger TRIAC firing or synchronize digital sampling. IC Role / Device Role / Timing Role: Comparator detects polarity reversal of sinusoidal input with hysteresis to suppress noise-induced false triggers. Use Value: Achieves sub-microsecond timing jitter using internal strobe to gate detection window, ensuring phase-locked control in motor drives. | Use Scenario: Capturing maximum amplitude of transient pulses in test equipment or battery monitoring circuits. IC Role / Device Role / Timing Role: Configured as positive/negative peak detector with diode-capacitor hold network and reset strobe. Use Value: Leverages 200 ns response and ±30V input range to capture fast-rising spikes up to 30V without clipping or slew distortion. |
| Voltage-Controlled Oscillator | Relay Driver with Strobe Sync |
Use Scenario: Generating variable-frequency square waves in function generators or clock recovery loops. IC Role / Device Role / Timing Role: Used in astable multivibrator topology with RC timing network and hysteresis feedback. Use Value: Delivers stable 10 Hz–10 kHz output with <5% duty cycle variation across supply and temperature due to rail-to-rail input compliance. | Use Scenario: Controlling electromechanical relays in programmable logic controllers with EMI-immune sequencing. IC Role / Device Role / Timing Role: Open-collector output directly switches relay coil; strobe pin disables output during power-up or fault conditions. Use Value: Prevents relay chatter during brown-out by disabling output until V+ stabilizes, confirmed by TI Figure 6 and absolute max ratings. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage comparator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM393DR | Push-pull output (no external pull-up needed); lower supply current (0.4 mA vs 6 mA); no strobe or offset null pins. | Best for low-power, space-constrained designs where output buffering is acceptable and precision trimming is unnecessary. | Select LM393DR when replacing LM311N in battery-powered sensors or simple logic-level conversion where strobe control is unused. |
| TLV3011DBVR | Rail-to-rail input; 1.8–5.5V single-supply only; 350 ns response; integrated reference; no strobe or offset null. | Suitable for modern low-voltage microcontroller interfaces but lacks high-voltage tolerance and external trim capability. | Choose TLV3011DBVR for 3.3V systems requiring internal reference and ultra-low quiescent current, not for ±15V or relay-driving roles. |
Compared with LM311N, LM393DR simplifies board layout by eliminating pull-up resistors but sacrifices strobe control and high-voltage input range; TLV3011DBVR offers rail-to-rail operation at low voltage but cannot replace LM311N in industrial 5V/±15V relay or zero-crossing applications.
Availability
LM311N is available at Aetrix Electronics and suitable for industrial control systems, power supply monitoring, test equipment design, and embedded signal conditioning requiring stable component supply across commercial temperature ranges.
Supply support for LM311N 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 delivering analog, embedded processing, and connectivity solutions with broad industrial, automotive, and consumer reach.
The LM311N belongs to TI's legacy precision comparator product line, engineered for robust performance in noisy environments, high-voltage signal routing, and direct electromechanical load interfacing.
FAQ
What is the maximum output voltage swing supported by the LM311N?
The LM311N open-collector output can sink up to 40V relative to its negative supply (V−), per Absolute Maximum Ratings. When used with a 5V pull-up, output swings from 0 V (saturated) to 5 V (high-impedance). With ±15V supplies and V− = −15V, it safely switches loads up to +25V referenced to ground. This capability is explicitly defined in the LM311-N Absolute Maximum Ratings table on page 4 of SNOSBJ1E.
Can the LM311N operate from a single 5V supply?
Yes, the LM311N operates from a single 5V supply, as confirmed in the Features section ("Operates From Single 5V Supply") and Electrical Characteristics tables. Input common-mode range extends to within 1.5 V of V− (ground), and output saturation voltage remains ≤0.4 V at 8 mA load. Proper biasing of the non-inverting input (e.g., via resistor divider) is required for rail-to-rail input signal handling.
How does the strobe function work on the LM311N?
The LM311N strobe pin (Pin 6) disables the output when 2–5 mA is actively sunk from it-never grounded. This current-driven disable prevents latch-up and allows clean output blanking during power sequencing or ADC conversion windows. The strobe feature is documented in Figures 2 and 6, and the Electrical Characteristics table specifies "Strobe ON Current" as 2.0–5.0 mA at 25°C.
What is the purpose of Pins 5 and 6 on the LM311N?
Pin 5 is the offset null terminal, used with an external potentiometer to adjust input offset voltage for precision DC comparisons. Pin 6 is the strobe input, which disables the output when 2–5 mA is drawn from it. Both functions are detailed in Figure 1 (Offset Balancing), Figure 2 (Strobing), and the Absolute Maximum Ratings table, confirming their dedicated roles in calibration and timing control.
Is the LM311N pin-compatible with the LM311M or LM311H?
No-LM311N (PDIP-8), LM311M (SOIC-8), and LM311H (TO-99-8) share identical pinouts per TI's package diagrams (Figures 59–61), but differ in package type, thermal resistance, and mechanical mounting. All three use the same 8-pin functional assignment: Pin 1 = Emitter, Pin 2 = −IN, Pin 3 = +IN, etc. This compatibility is confirmed in TI's PACKAGE OPTION ADDENDUM and Schematic Diagram notes referencing "LM311H/LM311M/LM311N" collectively.
LM311N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Series:
- -
- Packaging:
- Tube
- Product Status:
- Obsolete
- Type:
- General Purpose
- Number of Elements:
- 1
- Output Type:
- DTL, MOS, Open-Collector, Open-Emitter, RTL, TTL
- Voltage - Supply, Single/Dual (±):
- 5V ~ 36V, ±2.5V ~ 18V
- :
- 7.5mV @ ±15V
- Voltage - Input Offset (Max):
- 0.25µA @ ±15V
- Current - Input Bias (Max):
- 50mA
- Current - Output (Typ):
- 7.5mA
- Current - Quiescent (Max):
- -
- CMRR, PSRR (Typ):
- -
- Propagation Delay (Max):
- -
- Hysteresis:
- 0°C ~ 70°C
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- Through Hole
- :
- 8-PDIP
LM311N FAQ
1.How can I place an order for LM311N through Aetrix?
Please submit a Request for Quotation (RFQ) for LM311N 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 LM311N reliable?
The price and inventory of LM311N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM311N is usually 5 days.
3.What payment methods are accepted for LM311N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM311N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM311N?
LM311N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM311N 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 LM311N?
For technical support, including LM311N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM311N requirements.
6.How does Aetrix verify that LM311N is sourced from the original manufacturer or authorized distributors?
All LM311N 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 LM311N meets industry standards.
7.What is the process for return or replacement of LM311N?
All LM311N units undergo pre-shipment inspection (PSI). If there is an issue with LM311N, 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 LM311N part is unused and in its original packaging.
Return procedure for LM311N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM311N Tags
-
LM2903DR
Texas Instruments
-
LM339DR
Texas Instruments
-
LM339PWR
Texas Instruments
-
LM393DT
STMicroelectronics
-
LM2901PWR
Texas Instruments
-
LM2903DT
STMicroelectronics
-
LM393DR
Texas Instruments
-
LM239DR
Texas Instruments
-
LM339APWR
Texas Instruments
-
LM2903P
Texas Instruments
-
LM393ADR
Texas Instruments
-
NCX2200GMAZ
NXP Semiconductors
Tech Hub
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…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
