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Texas Instruments LM311P
- Part No.:
- LM311P
- Manufacturer:
- Texas Instruments
- Category:
- Comparators
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM311P.pdf
- Description:
- IC COMPARATOR 1 GEN PUR 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:12,422
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Product details
Overview
LM311P 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 TTL/MOS interface circuits.
For engineers reviewing the LM311P datasheet, LM311P pinout, LM311P application, or LM311P equivalent, key selection criteria include input offset voltage (max 7.5 mV), strobe-enabled blanking, emitter/collector dual-output flexibility, wide common-mode range (–14.7 V to +13.8 V), and PDIP-8 packaging suitable for prototyping and legacy board designs.
Technical Context
The LM311P uses a PNP input stage enabling rail-to-rail sensing near VCC−, followed by high-gain amplification and an isolated-emitter NPN open-collector output stage. Its strobe (BAL/STRB) pin allows external current-driven blanking (–3 mA to –5 mA), while BALANCE enables offset trimming via external resistor network.
Unlike standard comparators, the LM311P supports load referencing to ground, VCC+, or VCC−, and permits wire-OR connection of multiple outputs. It operates across 0°C to +70°C, with input bias current ≤300 nA and input offset current ≤70 nA - critical for low-drift analog thresholding.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Response time | 165 ns high-to-low; enables fast edge detection in pulse-width modulation and clock recovery. |
| Input offset voltage | Max 7.5 mV at 25°C; defines minimum detectable differential voltage without trimming. |
| Supply voltage range | 3.5 V to 30 V total (±15 V or single 5 V); supports mixed-signal system interfacing. |
| Output drive capability | 40 V collector-to-emitter max, 50 mA sink current; directly switches relays, lamps, or logic gates. |
| Input bias current | Max 300 nA; minimizes loading on high-impedance sources like photodiodes or sensor bridges. |
| Common-mode range | –14.7 V to +13.8 V (at ±15 V supplies); allows direct comparison of signals referenced to negative rails. |
| Strobe input current | –3 mA to –5 mA required for blanking; prevents false triggering during system initialization or noise bursts. |
Pinout & Package
LM311P is housed in an 8-pin PDIP (Plastic Dual In-line Package) with 9.81 mm × 6.35 mm body size and 0.3-inch lead spacing - compatible with through-hole prototyping and legacy PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: EMIT OUT | Emitter output terminal | Provides low-side switching reference; connects load between VCC− and this pin for grounded-load configurations. |
| 2: IN+ | Noninverting input | Accepts reference or signal voltage; high-impedance PNP input enables accurate threshold setting. |
| 3: IN− | Inverting input | Accepts monitored signal; differential comparison against IN+ determines output state. |
| 4: VCC− | Negative supply rail | Reference for internal circuitry and emitter output; supports dual-supply or single-supply (ground-referenced) operation. |
| 5: BALANCE | Offset null adjustment | Connects external potentiometer (typically 10 kΩ) between VCC+ and VCC− to trim input offset voltage. |
| 6: BAL/STRB | Strobe control input | Current-sink input: pulling –3 mA disables output regardless of input differential - used for synchronization or noise immunity. |
| 7: COL OUT | Collector output terminal | Open-collector NPN output; requires external pullup to define logic-high level and drive TTL/MOS loads. |
| 8: VCC+ | Positive supply rail | Primary power input; sets upper limit for output swing and internal biasing; tolerant of 3.5–30 V total supply range. |
Key Features
| Feature | Design Value |
|---|---|
| Strobe-enabled blanking | Hardware-controlled output disable via BAL/STRB pin eliminates false triggers during power-up or transient events. |
| Dual-output configuration | Separate EMIT OUT and COL OUT terminals allow flexible load referencing - e.g., sinking to ground or sourcing from VCC+. |
| Wide supply compatibility | Operates from ±15 V op-amp rails or single 5-V logic supplies - simplifies integration into mixed-voltage systems. |
| Wire-OR output capability | Multiple LM311P units can share a common pullup resistor for priority encoding or OR logic without external diodes. |
| Rail-sensing PNP input stage | Enables reliable operation with inputs within 1.5 V of VCC− - critical for low-voltage signal monitoring and battery-powered designs. |
Applications
| Zero-Crossing Detection | Oscillator Circuits |
|---|---|
Use Scenario: Detecting AC waveform polarity transitions in motor control or power supply feedback loops. IC Role / Device Role / Timing Role: Voltage comparator comparing sinusoidal input to ground reference; generates clean digital edge on each crossing. Use Value: Enables precise phase-aligned switching with 165 ns propagation delay - reduces EMI and improves efficiency in TRIAC/digital dimmer designs. |
Use Scenario: Building free-running multivibrators or crystal-based timing oscillators for clock generation. IC Role / Device Role / Timing Role: Core comparator in hysteresis-based relaxation oscillator; defines frequency via RC time constant and output feedback. Use Value: Stable 100-kHz operation achievable with external 1 kΩ/100 pF network - avoids need for dedicated oscillator ICs in cost-sensitive applications. |
| Peak Detection | TTL/MOS Interface Level Shifting |
Use Scenario: Capturing maximum amplitude of analog sensor outputs (e.g., audio envelope, vibration peaks). IC Role / Device Role / Timing Role: Comparator driving sample-and-hold latch; strobe pin synchronizes capture window to system clock. Use Value: Input bias current ≤300 nA prevents discharge of hold capacitor - extends peak retention time beyond 100 ms without active refresh. |
Use Scenario: Converting industrial sensor outputs (±10 V) to 3.3 V or 5 V logic levels for MCU input. IC Role / Device Role / Timing Role: Level translator with programmable threshold; COL OUT pulls down to ground while EMIT OUT references VCC−. Use Value: Supports bidirectional level shift: drives 5 V TTL loads from 3.3 V microcontrollers or interfaces 12 V sensors to 3.3 V ADC references. |
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 pullup needed); lower supply current (0.4 mA vs 5.1 mA); no strobe or balance pins. | Lacks blanking and offset trim - unsuitable for noise-prone or precision threshold applications. | Select when simplicity and low power outweigh strobe control and fine offset adjustment needs. |
| TLV3011DBVR | Rail-to-rail input; 360 ns response; 1.8–5.5 V supply only; integrated reference; no strobe or dual output. | Optimized for low-voltage battery systems; cannot replace LM311P in ±15 V or 40 V load-switching roles. | Choose for portable devices requiring sub-2 V operation and built-in reference - not for industrial relay driving. |
Compared with LM393DR and TLV3011DBVR, the LM311P uniquely combines high-voltage open-collector drive, strobe blanking, and offset trimming in PDIP-8 - making it irreplaceable in legacy industrial controls where load isolation and noise immunity are mandatory.
Availability
LM311P is available at Aetrix Electronics and suitable for industrial automation, power supply monitoring, and test equipment requiring stable component supply with long-term obsolescence management.
Supply support for LM311P 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 over 90 years of innovation in precision analog components.
The LM311P belongs to TI's legacy high-speed comparator family, engineered for robust performance in industrial control, instrumentation, and power conversion - emphasizing reliability, wide supply tolerance, and field-serviceable adjustability.
FAQ
What is the operating temperature range for the LM311P?
The LM311P is specified for operation from 0°C to +70°C ambient temperature. This commercial-grade range distinguishes it from the LM211 (–40°C to +85°C) and LM111 (–55°C to +125°C). The LM311P datasheet confirms this range under Recommended Operating Conditions, and thermal metrics such as RθJA = 57.5°C/W apply specifically to the PDIP-8 package at this temperature span. Always verify derating curves if operating near extremes.
Can the LM311P drive a 24 V relay directly?
Yes, the LM311P COL OUT pin supports up to 40 V collector-to-emitter voltage and 50 mA sink current - sufficient for most 24 V DC relays with coil resistance ≥480 Ω. Use a flyback diode across the relay coil and ensure the pullup resistor connects to 24 V. Note that EMIT OUT must remain unconnected or tied to VCC− in this configuration, and BAL/STRB should be left open or pulled high via current-limiting resistor to avoid unintended blanking of LM311P output.
How do I configure the BALANCE and BAL/STRB pins for offset nulling?
To null input offset voltage on the LM311P, connect a 10 kΩ potentiometer between VCC+ (pin 8) and VCC− (pin 4); the wiper goes to BALANCE (pin 5). Leave BAL/STRB (pin 6) unconnected or tie it to VCC+ via a 10 kΩ resistor. Do not short BALANCE and BAL/STRB together unless strobe functionality is intentionally disabled - doing so may degrade offset stability. Full procedure is documented in Figure 17 of the LM311P datasheet.
Is the LM311P pin-compatible with other LM311 variants like LM311D or LM311PW?
No - the LM311P (PDIP-8) shares identical pinout and function with LM311D (SOIC-8) and LM311PW (TSSOP-8), but mechanical dimensions, thermal resistance, and soldering requirements differ significantly. While electrical behavior is consistent across packages, PCB layout must match the specific footprint: LM311P requires through-hole pads, LM311D uses gull-wing leads, and LM311PW needs fine-pitch reflow. No PCB changes are required only if swapping within same package type.
Does the LM311P support single-supply operation with VCC− grounded?
Yes, the LM311P fully supports single-supply operation with VCC− connected to ground and VCC+ supplied with +5 V to +30 V. In this mode, IN+ and IN− accept inputs from 0.5 V above ground to VCC+ – 1.5 V, and COL OUT sinks current to ground. EMIT OUT becomes inactive (must be left open), and the common-mode range shifts accordingly. This configuration is explicitly validated in Section 6.3 of the LM311P datasheet and used in TTL interface examples.
LM311P Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Series:
- -
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- General Purpose
- Number of Elements:
- 1
- Output Type:
- DTL, MOS, Open-Collector, Open-Emitter, RTL, 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):
- 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
LM311P FAQ
1.How can I place an order for LM311P through Aetrix?
Please submit a Request for Quotation (RFQ) for LM311P 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 LM311P reliable?
The price and inventory of LM311P are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM311P is usually 5 days.
3.What payment methods are accepted for LM311P?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM311P transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM311P?
LM311P orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM311P 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 LM311P?
For technical support, including LM311P datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM311P requirements.
6.How does Aetrix verify that LM311P is sourced from the original manufacturer or authorized distributors?
All LM311P 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 LM311P meets industry standards.
7.What is the process for return or replacement of LM311P?
All LM311P units undergo pre-shipment inspection (PSI). If there is an issue with LM311P, 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 LM311P part is unused and in its original packaging.
Return procedure for LM311P:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM311P Tags
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