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Texas Instruments LM397MFX
- Part No.:
- LM397MFX
- Manufacturer:
- Texas Instruments
- Category:
- Comparators
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM397MFX.pdf
- Description:
- IC COMPARATOR 1 GEN PUR SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,704
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Product details
Overview
LM397MFX from Texas Instruments is a single general-purpose voltage comparator with bipolar input stage, open-collector NPN output, and industrial temperature range (−40°C to +85°C). It operates from 5 V to 30 V single or dual supply, draws only 300 µA typical supply current, and delivers 440 ns propagation delay at 50-mV overdrive - used in A/D converter front-ends, pulse generators, and peak detectors.
For engineers reviewing the LM397MFX datasheet, LM397MFX pinout, LM397MFX application, or LM397MFX equivalent, key selection criteria include input common-mode range (0 V to VS − 1.5 V), ±2 mV input offset voltage, 7 nA input bias current, open-collector interface flexibility, and SOT-23 (DBV) package compatibility with TL331.
Technical Context
The LM397MFX implements a bipolar-input comparator architecture with rail-to-rail-capable input common-mode range down to ground and up to VS − 1.5 V. Its open-collector output requires an external pull-up resistor and supports TTL/CMOS logic interfacing across multiple voltage domains.
It features low input bias current (7 nA typ), low input offset current (±1 nA), and stable propagation delay performance across supply voltages (5–30 V) and temperature (−40°C to +85°C), enabling reliable threshold detection in noisy industrial environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 5 V to 30 V - supports direct integration into 5 V microcontroller systems or high-voltage industrial rails without level-shifting. |
| Input Offset Voltage | ±2 mV (typ) - enables accurate threshold detection within ±2 mV of reference, critical for precision analog-to-digital conversion interfaces. |
| Supply Current | 300 µA (typ) - allows battery-powered or energy-constrained applications to maintain long operational life without sacrificing speed. |
| Propagation Delay | 440 ns (tPLH/tPHL, 50-mV overdrive) - ensures fast response for pulse shaping, zero-crossing detection, and timing-critical edge generation. |
| Input Bias Current | 7 nA (typ) - minimizes loading error on high-impedance sensor sources such as thermistors or photodiodes. |
| Common-Mode Input Range | 0 V to VS − 1.5 V - permits direct sensing of ground-referenced signals (e.g., current-sense shunts) without input-level translation circuitry. |
| Output Type | Open-collector NPN - enables wired-OR logic, multi-comparator sharing of pull-up, and flexible logic-level translation (e.g., 3.3 V logic driven from 12 V supply). |
Pinout & Package
LM397MFX is housed in a 5-pin SOT-23 (DBV) package measuring 2.90 mm × 1.60 mm, with 1.45 mm max height and JEDEC MO-178 compliant footprint. The package supports tape-and-reel delivery (3000 pcs/reel) and Level-1 moisture sensitivity rating (260°C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN− (Pin 1) | Inverting Input | Accepts reference or feedback signal; differential comparison against VIN+ determines output state. |
| GND (Pin 2) | Ground Reference | Primary return path for supply and input signals; must connect to low-impedance PCB ground plane. |
| VIN+ (Pin 3) | Noninverting Input | Accepts sensed or variable signal; comparator asserts high-Z output when VIN+ exceeds VIN− by > VOS. |
| OUTPUT (Pin 4) | Open-Collector Output | Sinks up to 13 mA; requires external pull-up to define logic-high level and drive load (TTL/CMOS compatible). |
| VS (Pin 5) | Positive Supply | Provides power for internal circuitry; supports single-supply operation from 5 V to 30 V or split supplies (±15 V max). |
Key Features
| Feature | Design Value |
|---|---|
| Single-supply operation | Operates from 5 V to 30 V with inputs referenced to ground - eliminates need for negative rail in sensor monitoring circuits. |
| Open-collector output | Enables level translation, wired-OR logic, and direct interface to 3.3 V, 5 V, or 12 V logic families using appropriate pull-up voltage. |
| Low input bias current | 7 nA typical - preserves accuracy when driving from high-impedance sources like RC filters or piezoelectric sensors. |
| Industrial temperature range | −40°C to +85°C - qualified for deployment in motor controls, PLC I/O modules, and outdoor instrumentation without derating. |
| Fast propagation delay | 440 ns at 50-mV overdrive - supports kHz-range pulse generation and real-time overvoltage/undervoltage fault detection. |
Applications
| Overvoltage Protection Circuit | Pulse Width Modulation (PWM) Generator |
|---|---|
|
Use Scenario: Monitors DC bus voltage in power supplies and shuts down switching stages if voltage exceeds safe threshold. IC Role / Device Role / Timing Role: Voltage comparator detecting excursion above programmable reference; triggers latch or gate driver disable. Use Value: Prevents MOSFET avalanche failure by responding within 440 ns to overvoltage events while drawing only 300 µA quiescent current. |
Use Scenario: Generates fixed-frequency, variable-duty-cycle square waves using hysteresis-based relaxation oscillator topology. IC Role / Device Role / Timing Role: Core timing element in inverting hysteresis configuration; sets frequency via RC time constant and threshold levels. Use Value: Delivers stable PWM output across 5–30 V supply range with minimal external components - no external op-amp or timer IC required. |
| Peak Detector Interface | ADC Input Conditioning Stage |
|
Use Scenario: Captures and holds maximum amplitude of analog sensor outputs (e.g., vibration or audio envelope) before digitization. IC Role / Device Role / Timing Role: Threshold detector triggering sample-and-hold enable; compares instantaneous signal to stored peak value. Use Value: Low 7 nA input bias current avoids discharge error in hold capacitor; wide common-mode range accepts signals near ground or rail. |
Use Scenario: Converts analog sensor outputs (e.g., temperature, pressure) into clean digital transitions for successive-approximation ADC sampling. IC Role / Device Role / Timing Role: Front-end signal conditioner providing noise-immune threshold decision prior to ADC clocking. Use Value: ±2 mV offset voltage ensures sub-LSB decision accuracy for 12-bit ADCs; 440 ns delay enables >1 MHz sampling control rates. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage comparator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL331IDBVR | Pin-compatible SOT-23 single comparator; identical pinout and electrical specs but slightly higher input offset voltage (±3 mV max vs ±2 mV for LM397MFX). | Same industrial operating range and open-collector output; suitable for drop-in replacement where ±3 mV offset is acceptable. | Select TL331IDBVR when sourcing TI's newer production-binned comparator with identical layout and qualification. |
| LMV331IDBVR | Rail-to-rail input/output CMOS comparator; lower supply current (17 µA), wider temp range (−40°C to +125°C), but incompatible pinout (non-pin-compatible) and no bipolar input stage. | Better for ultra-low-power or extended-temp designs; requires PCB redesign due to different pin assignment and supply requirements (2.7–5.5 V only). | Choose LMV331IDBVR only when upgrading to CMOS process benefits and redesigning layout for new footprint and supply constraints. |
Compared with TL331IDBVR and LMV331IDBVR, the LM397MFX offers superior input offset voltage (±2 mV) and full 5–30 V supply flexibility in a proven industrial SOT-23 package - making it optimal for legacy-compatible, medium-speed, high-voltage threshold detection without layout change.
Availability
LM397MFX is available at Aetrix Electronics and suitable for overvoltage protection circuits, PWM generator designs, peak detector interfaces, and ADC input conditioning stages requiring stable component supply across industrial temperature ranges and long product lifecycles.
Supply support for LM397MFX 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.
The LM397MFX belongs to TI's general-purpose analog comparator product line, designed specifically for robust, cost-effective threshold detection in industrial control, power management, and signal conditioning applications.
FAQ
What is the maximum supply voltage for LM397MFX?
The LM397MFX supports a maximum supply voltage of 30 V under recommended operating conditions. Absolute maximum rating is ±15 V for dual supplies or 30 V for single supply. Exceeding 30 V risks permanent damage per TI's absolute maximum ratings table in SNOS977F Rev F. Always limit VS to ≤30 V in LM397MFX designs.
Does LM397MFX require a negative supply rail?
No, the LM397MFX does not require a negative supply rail. It is fully specified for single-supply operation from 5 V to 30 V, with input common-mode range extending down to 0 V (ground). Dual-supply use (e.g., ±15 V) is supported but optional - the LM397MFX functions correctly with GND as the negative reference.
What pull-up resistor value should be used with LM397MFX output?
A 5.1 kΩ pull-up resistor to VS is commonly used with LM397MFX, as validated in TI's typical application curves (Figure 10–11, SNOS977F). This value balances speed (440 ns delay) and power (≤6 mA sink current) while ensuring VOL ≤ 400 mV at 4 mA. For 3.3 V logic interfacing, pull to 3.3 V instead of VS - LM397MFX output remains compatible.
Is LM397MFX pin-compatible with TL331?
Yes, LM397MFX is pin-compatible with TI's TL331 in the SOT-23 (DBV) package. Both share identical pin 1 (VIN−), pin 2 (GND), pin 3 (VIN+), pin 4 (OUTPUT), and pin 5 (VS) assignments and mechanical footprint. LM397MFX datasheet explicitly states "pin-compatible to TI's TL331" - enabling direct substitution in existing layouts.
What is the input common-mode voltage range of LM397MFX?
The input common-mode voltage range of LM397MFX is 0 V to VS − 1.5 V at 25°C, and 0 V to VS − 2 V across the full −40°C to +85°C temperature range. This allows direct sensing of ground-referenced signals (e.g., shunt voltage) and accommodates most industrial sensor outputs without level-shifting circuitry in LM397MFX applications.
LM397MFX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- SC-74A, SOT-753
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- General Purpose
- Number of Elements:
- 1
- Output Type:
- Open-Collector, Rail-to-Rail
- Voltage - Supply, Single/Dual (±):
- 5V ~ 30V, ±2.5V ~ 15V
- :
- 7mV @ 30V
- Voltage - Input Offset (Max):
- 0.25µA @ 5V
- Current - Input Bias (Max):
- 13mA @ 5V
- Current - Output (Typ):
- 2mA
- Current - Quiescent (Max):
- -
- CMRR, PSRR (Typ):
- -
- Propagation Delay (Max):
- -
- Hysteresis:
- -40°C ~ 85°C
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- Surface Mount
- :
- SOT-23-5
LM397MFX FAQ
1.How can I place an order for LM397MFX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM397MFX 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 LM397MFX reliable?
The price and inventory of LM397MFX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM397MFX is usually 5 days.
3.What payment methods are accepted for LM397MFX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM397MFX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM397MFX?
LM397MFX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM397MFX 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 LM397MFX?
For technical support, including LM397MFX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM397MFX requirements.
6.How does Aetrix verify that LM397MFX is sourced from the original manufacturer or authorized distributors?
All LM397MFX 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 LM397MFX meets industry standards.
7.What is the process for return or replacement of LM397MFX?
All LM397MFX units undergo pre-shipment inspection (PSI). If there is an issue with LM397MFX, 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 LM397MFX part is unused and in its original packaging.
Return procedure for LM397MFX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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