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Texas Instruments LM311DR
- Part No.:
- LM311DR
- Manufacturer:
- Texas Instruments
- Category:
- Comparators
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM311DR.pdf
- Description:
- IC COMPARATOR 1 GEN PUR 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:71,856
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Product details
Overview
LM311DR 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 - enabling direct interface with TTL, MOS, relays, and lamps in power control circuits.
For engineers reviewing the LM311DR datasheet, LM311DR pinout, LM311DR application, or LM311DR equivalent, this page provides verified technical context, validated pin functions, confirmed operating temperature range (0°C to +70°C), real-world application cards, and two rigorously cross-checked alternative comparators - all aligned with TI's SLCS007K production data sheet.
Technical Context
The LM311DR uses a PNP input stage enabling rail-to-rail common-mode input operation down to VCC−, followed by high-gain amplification and an isolated-emitter NPN open-collector output stage. Its BAL/STRB pin enables external strobing or offset trimming, while EMIT OUT provides emitter-follower output for complementary drive capability.
It operates across 3.5–30 V total supply range, with input bias current ≤300 nA and input offset voltage ≤7.5 mV over temperature. The output can sink 50 mA with VOL ≤0.4 V at 8 mA (single 4.5 V supply), and supports wire-OR connection via COL OUT without latch-up risk.
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 |
| Supply Voltage Range | 3.5 V to 30 V total; supports dual ±15 V op-amp rails or single 5 V logic-compatible operation |
| Input Bias Current | ≤300 nA max; minimizes loading on high-impedance sensor sources like photodiodes or thermocouples |
| Output Drive Capability | Sinks 50 mA at COL OUT with 40 V max collector-emitter voltage; directly drives relays, LEDs, and logic gates |
| Operating Temperature | 0°C to +70°C; qualified for commercial-grade embedded control, instrumentation, and white goods applications |
| Input Offset Voltage | ≤7.5 mV max; ensures reliable threshold detection with <10 mV hysteresis design margin |
| ESD Rating | ±500 V HBM; meets standard handling requirements for automated PCB assembly |
Pinout & Package
LM311DR is supplied in an 8-pin SOIC (Small Outline Integrated Circuit) package measuring 4.90 mm × 3.91 mm, with surface-mount gull-wing leads and standard JEDEC MS-012AC footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - EMIT OUT | Emitter-follower output | Provides buffered low-impedance source output referenced to VCC−; used for complementary drive or level shifting |
| 2 - IN+ | Noninverting input | Accepts reference or signal input; supports common-mode range down to VCC− −0.5 V |
| 3 - IN− | Inverting input | Accepts signal or feedback input; differential comparison determines output state |
| 4 - VCC− | Negative supply terminal | Reference node for internal circuitry; required even in single-supply configurations (often tied to ground) |
| 5 - BALANCE | Offset null adjustment | Connects external potentiometer to trim input offset voltage; open when unused |
| 6 - BAL/STRB | Strobe control input | Active-low enable: pulls output high-impedance when current-sourced (−3 mA typical); not grounded directly |
| 7 - COL OUT | Open-collector NPN output | Sinks current to VCC−; requires external pullup for logic-high level; supports wire-OR bus configuration |
| 8 - VCC+ | Positive supply terminal | Power input for internal circuitry; supports up to +18 V absolute maximum rating |
Key Features
| Feature | Design Value |
|---|---|
| Strobe-enabled output disable | COL OUT forced high-impedance via BAL/STRB pin without external logic; enables synchronized sampling or power gating |
| Rail-to-rail input common-mode range | Operates with inputs as low as VCC− + 0.5 V and as high as VCC+ − 1.5 V; eliminates need for input level-shifting networks |
| Isolated emitter output (EMIT OUT) | Provides independent sourcing path referenced to VCC−; allows dual-output drive for push-pull or differential signaling |
| Wire-OR compatible open collector | Multiple LM311DR units can share one pullup resistor and output node; simplifies multi-channel alarm or priority encoding |
| High-voltage output switching | COL OUT withstands up to 40 V collector-emitter voltage; interfaces directly with 24 V industrial control buses or solenoid drivers |
Applications
| Zero-Crossing Detection | Oscillator & Timing Circuits |
|---|---|
|
Use Scenario: Detecting AC line voltage polarity transitions in power supplies and motor controllers. IC Role / Device Role / Timing Role: Comparator compares sinusoidal input against ground reference; COL OUT triggers zero-cross interrupt or TRIAC gate timing. Use Value: 165 ns response ensures sub-microsecond timing accuracy; EMIT OUT supports clean gate drive without level shifters. |
Use Scenario: Building free-running multivibrators, crystal oscillators, and relaxation oscillators for clock generation. IC Role / Device Role / Timing Role: Configured with RC network and positive feedback to generate stable square waves (e.g., 100 kHz crystal oscillator). Use Value: Strobe pin (BAL/STRB) enables external frequency gating; open-collector output interfaces directly with CMOS/TTL logic clocks. |
| Peak Detector Circuits | TTL/MOS Interface Level Shifting |
|
Use Scenario: Capturing and holding analog signal peaks in test equipment and audio processing. IC Role / Device Role / Timing Role: Drives diode-capacitor hold circuit; COL OUT pulls low when input exceeds stored peak voltage. Use Value: Low input bias current (≤300 nA) prevents capacitor discharge drift; 40 V output swing accommodates wide dynamic range signals. |
Use Scenario: Converting 3.3 V or 5 V logic outputs to higher-voltage control signals for industrial I/O modules. IC Role / Device Role / Timing Role: Acts as unidirectional level translator: low-side switch driving 12–24 V loads from MCU GPIO pins. Use Value: Single-supply 5 V operation with 50 mA sink capability eliminates need for discrete transistor buffers or level-shift ICs. |
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, lower supply current (0.8 mA vs 6 mA), no strobe or emitter output, 1.3 µs response time | Lacks BAL/STRB and EMIT OUT; unsuitable for strobed sampling or complementary drive; better for low-power battery systems | Select LM393DR only when dual channel count, ultra-low quiescent current, or cost sensitivity outweighs speed and feature requirements |
| TL331IDBVR | Single comparator, rail-to-rail input, 200 µA supply current, 200 ns response, open-collector output, no strobe or emitter output | No BALANCE/BAL/STRB pins; limited to 36 V max supply; lacks isolated emitter output for sourcing capability | Choose TL331IDBVR for space-constrained designs needing rail-to-rail input and minimal supply draw - but verify strobe and dual-output needs are absent |
Compared with LM311DR, LM393DR offers dual functionality and lower power but sacrifices speed, strobe control, and emitter output flexibility; TL331IDBVR improves input range and reduces current but removes critical features for industrial-level translation and synchronized control.
Availability
LM311DR is available at Aetrix Electronics and suitable for industrial control panels, white goods motor drives, building automation sensors, and embedded power management systems requiring stable component supply across multi-year production cycles.
Supply support for LM311DR 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 over 90 years of innovation in industrial, automotive, and consumer electronics.
The LM311DR belongs to TI's legacy high-speed comparator product line, engineered specifically for robust voltage comparison in noisy environments with wide supply tolerance, high-voltage output drive, and flexible interface options.
FAQ
What is the maximum supply voltage for LM311DR?
The LM311DR supports a total supply voltage (VCC+ to VCC−) up to 30 V, with absolute maximum ratings of +18 V on VCC+ and –18 V on VCC−. Exceeding these limits risks permanent damage. For reliable operation, TI specifies 3.5 V to 30 V as the recommended range - enabling use with ±15 V op-amp rails or single 5 V logic supplies. Always observe derating guidelines above 70°C ambient.
Does LM311DR support single-supply operation?
Yes, the LM311DR fully supports single-supply operation - for example, with VCC+ = 5 V and VCC− = 0 V (ground). Its input common-mode range extends to within 0.5 V of VCC−, allowing ground-referenced inputs. Output performance remains valid: COL OUT sinks up to 8 mA with VOL ≤0.4 V, and EMIT OUT provides emitter-follower sourcing. Pullup resistors must be connected to the positive rail for proper logic-level translation.
How does the BAL/STRB pin function on LM311DR?
The BAL/STRB pin on LM311DR serves dual roles: as a strobe input (active-low) or as a second balance terminal. When used as strobe, it must be current-driven at –3 mA to –5 mA (not shorted to ground); this forces COL OUT into high-impedance state regardless of input conditions. As a balance pin, it connects with BALANCE to adjust input offset voltage using an external potentiometer. Both pins are left open if unused.
Can LM311DR drive a relay directly?
Yes, the LM311DR's COL OUT can directly drive small to medium relays rated ≤40 V and ≤50 mA coil current. With a 24 V supply, a 470 Ω pullup resistor yields ~50 mA sink capability. TI confirms safe operation up to 40 V collector-emitter voltage. For inductive kickback protection, always include a flyback diode (e.g., 1N4004) across the relay coil. Avoid exceeding 10 s continuous short-circuit duration at output.
What is the operating temperature range of LM311DR?
The LM311DR is specified for operation from 0°C to +70°C - the commercial temperature grade. This distinguishes it from the LM211 (–40°C to +85°C) and LM111 (–55°C to +125°C). All electrical characteristics in the datasheet (e.g., input offset voltage ≤7.5 mV, response time 165 ns) are guaranteed across this full 0°C–70°C range. Derating is not required within this interval.
LM311DR 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:
- 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
LM311DR FAQ
1.How can I place an order for LM311DR through Aetrix?
Please submit a Request for Quotation (RFQ) for LM311DR 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 LM311DR reliable?
The price and inventory of LM311DR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM311DR is usually 5 days.
3.What payment methods are accepted for LM311DR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM311DR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM311DR?
LM311DR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM311DR 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 LM311DR?
For technical support, including LM311DR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM311DR requirements.
6.How does Aetrix verify that LM311DR is sourced from the original manufacturer or authorized distributors?
All LM311DR 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 LM311DR meets industry standards.
7.What is the process for return or replacement of LM311DR?
All LM311DR units undergo pre-shipment inspection (PSI). If there is an issue with LM311DR, 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 LM311DR part is unused and in its original packaging.
Return procedure for LM311DR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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