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Texas Instruments LM311MX/NOPB
- Part No.:
- LM311MX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Comparators
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM311MX/NOPB.pdf
- Description:
- IC COMPARATOR 1 GEN PUR 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:11,336
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Product details
Overview
LM311MX/NOPB from Texas Instruments is a precision voltage comparator with open-collector output, designed for single-supply (5V) or dual-supply (±15V) operation. It delivers 200 ns response time, ±30 V differential input range, and supports strobe control and offset balancing. It drives TTL/DTL/RTL loads and relays up to 50 V / 50 mA in industrial sensing and power control circuits.
For engineers reviewing the LM311MX/NOPB datasheet, LM311MX/NOPB pinout, LM311MX/NOPB application, or LM311MX/NOPB equivalent, this page provides verified electrical specs, SOIC-8 package details, real-world use cases including zero-crossing detection and relay driving, and validated alternative options for design continuity.
Technical Context
The LM311MX/NOPB uses a bipolar input stage with 100–250 nA typical input bias current and 6–70 nA offset current, enabling high-impedance signal comparison without loading source networks. Its strobe pin (Pin 6) allows current-driven output disable (2–5 mA), supporting time-gated comparisons and power sequencing.
It features internal offset null capability via Pins 5 and 6, supports wire-OR'ed outputs, and tolerates input common-mode voltages up to ±15 V - independent of supply rails. Output saturation voltage is 0.23 V (min) at 8 mA under single 5V supply, ensuring clean logic-level interfacing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | Single 5V or dual ±15V - enables direct interface with logic ICs and legacy op-amp systems. |
| Response Time | 200 ns - sufficient for 500 kHz zero-crossing detection and PWM timing in motor control. |
| Differential Input Voltage | ±30 V - permits direct comparison of signals across isolated domains or high-side sensing. |
| Output Drive Capability | 50 V / 50 mA sink - drives electromechanical relays, lamps, or MOSFET gates without external buffers. |
| Input Bias Current | 100–250 nA (max at 25°C) - preserves accuracy in high-Z sensor interfaces like photodiode or thermocouple amplifiers. |
| Strobe Control Current | 2–5 mA required at Pin 6 - enables precise gating of comparator action in synchronized sampling systems. |
| Operating Temperature | 0°C to +70°C - qualified for commercial-grade embedded controllers and instrumentation front-ends. |
Pinout & Package
LM311MX/NOPB is housed in an 8-pin SOIC (D package), 1.75 mm max height, RoHS-compliant with Sn lead finish and MSL Level-1 rating. Pin 1 is the output collector; Pin 2 is the inverting input; Pin 3 is the non-inverting input; Pin 4 is V−; Pin 5 is offset null (adjust); Pin 6 is strobe; Pin 7 is V+; Pin 8 is offset null (adjust).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Output Collector | Open-collector NPN output - requires external pull-up to define logic high level and drive load. |
| 2 | Inverting Input (−) | High-impedance node for reference voltage or feedback path in hysteresis configurations. |
| 3 | Non-Inverting Input (+) | Accepts signal to be compared against reference; supports rail-to-rail common-mode range. |
| 4 | V− (Negative Supply) | Reference for negative rail; can be grounded in single-supply operation (0 V to 5 V). |
| 5 | Offset Null (−) | Connects to one end of 5 kΩ potentiometer for trimming input offset voltage down to <2 mV. |
| 6 | Strobe | Sink current (2–5 mA) disables output - used for time-sliced comparisons or power gating. |
| 7 | V+ (Positive Supply) | Accepts 5 V (single) or +15 V (dual); supplies internal circuitry and defines output high limit. |
| 8 | Offset Null (+) | Connects to other end of 5 kΩ potentiometer; forms adjustable voltage divider for nulling. |
Key Features
| Feature | Design Value |
|---|---|
| Strobe-Controlled Output Disable | Enables synchronous sampling and eliminates false triggers during system initialization or calibration phases. |
| Offset Null Terminals | Allows trimming of input offset voltage to ≤2 mV, critical for precision threshold detection in analog-to-digital interfaces. |
| Wide Supply Range Compatibility | Operates from 5 V single supply up to ±15 V - simplifies integration into mixed-voltage systems without level-shifting. |
| Wire-OR'able Open-Collector Output | Supports multiple comparators sharing a common pull-up and bus line - reduces component count in alarm or priority encoder designs. |
| High Differential Input Voltage Rating | ±30 V tolerance prevents damage when comparing signals referenced to different grounds or floating sources. |
Applications
| Zero-Crossing Detection | Relay & Solenoid Driving |
|---|---|
Use Scenario: Detecting AC line voltage polarity transitions in power inverters and solid-state relays. IC Role / Device Role / Timing Role: Comparator compares sine wave against 0 V reference; output toggles on each crossing with 200 ns latency. Use Value: Enables phase-synchronized switching, reducing EMI and inrush current in grid-tied converters. |
Use Scenario: Controlling 24 V DC solenoids in HVAC actuators and industrial valves. IC Role / Device Role / Timing Role: LM311MX/NOPB output sinks 50 mA to energize coil; strobe pin disables output during fault conditions. Use Value: Eliminates need for discrete transistor driver stage while providing overvoltage protection via 50 V output rating. |
| Voltage-Controlled Oscillator (VCO) | Photodiode Signal Thresholding |
Use Scenario: Generating variable-frequency square waves in function generators and tone dialers. IC Role / Device Role / Timing Role: Configured as astable multivibrator with RC timing network; frequency adjusted by control voltage at Pin 3. Use Value: Achieves 10 Hz–10 kHz range with <5% linearity error using only passive components and LM311MX/NOPB. |
Use Scenario: Converting weak photodiode current into digital presence/absence signal in optical encoders. IC Role / Device Role / Timing Role: High-impedance input accepts transimpedance amplifier output; strobe synchronizes detection to illumination pulse. Use Value: 100–250 nA input bias avoids signal corruption; 200 ns response captures fast light pulses in motion sensing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage comparator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM393DR | Lower input bias current (25 nA typ), no strobe pin, dual-channel, 1.3 V min supply. | Better for ultra-low-power battery sensors; unsuitable where strobe gating or 50 V output swing is required. | Select LM393DR only if dual comparator functionality and sub-2 V operation are needed; verify strobe omission does not impact timing architecture. |
| TLV3011DBVR | Rail-to-rail input, 1.8–5.5 V supply, 350 ns response, integrated reference, no offset null pins. | Optimized for low-voltage portable systems; lacks external offset trim and high-voltage output drive. | Choose TLV3011DBVR for compact 3.3 V designs requiring internal reference; avoid when >5 V output swing or precision nulling is mandatory. |
Compared with LM311MX/NOPB, LM393DR offers dual channels and lower bias current but forfeits strobe control and 50 V output capability; TLV3011DBVR supports modern low-voltage rails and integrated reference but cannot replace LM311MX/NOPB in high-side sensing or relay-driving roles due to limited voltage range and missing null/strobe features.
Availability
LM311MX/NOPB is available at Aetrix Electronics and suitable for industrial automation, power supply monitoring, and test equipment requiring stable component supply across commercial temperature ranges.
Supply support for LM311MX/NOPB 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 and embedded processing solutions with emphasis on reliability, longevity, and broad application support.
The LM311 series belongs to TI's legacy precision analog comparator product line, engineered for robust performance in noisy industrial environments, high-voltage interfacing, and applications demanding strobe control and offset adjustment.
FAQ
What is the maximum output voltage swing supported by the LM311MX/NOPB?
The LM311MX/NOPB output is open-collector and can sink up to 50 V when used with an external pull-up. The absolute maximum output-to-negative-supply voltage is 40 V per datasheet Absolute Maximum Ratings for the LM311-N variant. This allows safe interfacing with 24 V PLC inputs or 48 V telecom systems when configured with appropriate pull-up resistors and clamping diodes. LM311MX/NOPB itself does not source voltage - its output voltage level is defined solely by the external pull-up network.
Can the LM311MX/NOPB operate from a single 3.3 V supply?
No - the LM311MX/NOPB is not specified for 3.3 V operation. Its minimum recommended single-supply voltage is 5 V, and electrical characteristics (e.g., saturation voltage, response time) are guaranteed only from 5 V up to ±15 V. At 3.3 V, output saturation rises above 0.5 V, input common-mode range shrinks significantly, and response time degrades beyond 200 ns. For 3.3 V systems, consider TI's TLV3011DBVR or LMV331IDBVR as alternatives. LM311MX/NOPB must be used at ≥5 V to meet published specifications.
How do I configure the strobe function on the LM311MX/NOPB?
To enable strobe control on LM311MX/NOPB, connect Pin 6 (strobe) to a current sink capable of drawing 2–5 mA - typically via an NPN transistor base or microcontroller GPIO with series resistor. When ≥2 mA is sunk, the output transistor turns off completely. Do not ground Pin 6 directly; instead, use active current control. In inactive state, leave Pin 6 open or pull it to V+ via ≥10 kΩ resistor. Strobing is commonly used to blank comparator output during ADC sampling windows or power-up sequences in LM311MX/NOPB-based systems.
Does the LM311MX/NOPB require external compensation for stability?
No external compensation is required for basic comparator operation. The LM311MX/NOPB is internally compensated for unity-gain stability in open-loop mode. However, oscillation may occur with high-impedance sources (>10 kΩ) or long input traces due to parasitic capacitance and high gain-bandwidth product. To prevent instability, TI recommends shorting Pins 5 and 6 if unused, adding 100–1000 pF across inputs for slow signals, and routing inputs away from output traces. These layout practices - not capacitor-based compensation - ensure reliable LM311MX/NOPB performance.
What is the purpose of the offset null pins (5 and 8) on the LM311MX/NOPB?
Pins 5 and 8 on the LM311MX/NOPB form a two-terminal interface for an external 5 kΩ potentiometer to null input offset voltage. Connecting the potentiometer wiper to V− (Pin 4) and its ends to Pins 5 and 8 creates a balanced current injection that cancels inherent input stage mismatches. This adjustment reduces effective offset to ≤2 mV, essential for precision threshold detection in applications like battery voltage monitors or analog-to-digital front-ends where 10 mV errors would cause unacceptable trip-point drift. LM311MX/NOPB offset nulling is performed once during calibration and remains stable over temperature.
LM311MX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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):
- -
- 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
LM311MX/NOPB FAQ
1.How can I place an order for LM311MX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM311MX/NOPB 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 LM311MX/NOPB reliable?
The price and inventory of LM311MX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM311MX/NOPB is usually 5 days.
3.What payment methods are accepted for LM311MX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM311MX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM311MX/NOPB?
LM311MX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM311MX/NOPB 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 LM311MX/NOPB?
For technical support, including LM311MX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM311MX/NOPB requirements.
6.How does Aetrix verify that LM311MX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM311MX/NOPB 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 LM311MX/NOPB meets industry standards.
7.What is the process for return or replacement of LM311MX/NOPB?
All LM311MX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM311MX/NOPB, 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 LM311MX/NOPB part is unused and in its original packaging.
Return procedure for LM311MX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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