New Option for Multi-Channel Voltage Monitoring: Detailed Explanation of LM2901PWR Quad Comparator

^{October 19, 2025 — With the continuous growth in demand for multi-channel voltage monitoring in industrial control systems, highly integrated voltage comparators are becoming core components in complex system designs. The widely adopted industry-standard LM2901PWR quad differential comparator, with its wide voltage range (2V to 36V) and industrial-grade temperature characteristics (-40℃ to +125℃), provides an efficient multi-channel voltage detection solution for industrial automation, motor control, and power management systems.}

 

 

^{I. Chip Introduction: LM2901PWR}

 

^{The LM2901PWR is a monolithic integrated circuit that integrates four independent voltage comparators. Housed in a TSSOP-14 package, this device features low power consumption, high precision, and a wide power supply voltage range, while maintaining direct compatibility with TTL, CMOS, and MOS logic interfaces.}

 

 

^{Core Features and Advantages:}

^{Quad-Channel Integration: Four independent comparators integrated in a single chip}

^{Wide Operating Voltage Range: Single supply 2V to 36V, dual supply ±1V to ±18V}

^{Low Input Bias Current: Typically 25nA}

^{Low Input Offset Voltage: Typically ±2mV}

^{Low-Power Design: Quiescent current approximately 0.4mA per comparator}

 

^{Typical Application Fields:}

^{Industrial process control systems}

^{Multi-channel power monitoring and protection}

^{Motor drive control circuits}

^{Battery management systems}

 

^{Typical Application Fields:}

^{Industrial Process Control Systems}

^{Multi-channel Power Monitoring and Protection}

^{Motor Drive Control Circuits}

^{Battery Management Systems}

 

 

^{II. Pin Configuration and Functional Analysis}

 

^{Package Type Overview
The LM2901PWR offers two main package options:}

^{14-pin packages: SOIC, SSOP, PDIP, SOP, TSSOP}

^{16-pin WQFN package: With exposed thermal pad}

 

^{14-Pin Package Configuration (Top View)}

 

 

^{Detailed Pin Function Description}

 

^{Channel Configuration and Signal Distribution}

^{Channel 1 Comparator (1OUT)}

^{Pin 2 (1IN-): Channel 1 Inverting Input}

^{Pin 3 (1IN+): Channel 1 Non-inverting Input}

^{Pin 1 (1OUT): Channel 1 Output}

 

^{Channel 2 Comparator (2OUT)}

^{Pin 6 (2IN-): Channel 2 Inverting Input}

^{Pin 5 (2IN+): Channel 2 Non-inverting Input}

^{Pin 7 (2OUT): Channel 2 Output}

 

^{Channel 3 Comparator (3OUT)}

^{Pin 10 (3IN-): Channel 3 Inverting Input}

^{Pin 9 (3IN+): Channel 3 Non-inverting Input}

^{Pin 8 (3OUT): Channel 3 Output}

 

^{Channel 4 Comparator (4OUT)}

^{Pin 11 (4IN-): Channel 4 Inverting Input}

^{Pin 12 (4IN+): Channel 4 Non-inverting Input}

^{Pin 13 (4OUT): Channel 4 Output}

 

^{16-Pin WQFN Package Configuration (Top View)}

 

^{Power Supply and Ground}

^{Pin 14 (VCC): Positive power supply input (2V to 36V)}

^{Pin 4 (GND): Ground terminal}

 

^{Special Design Considerations}

^{WQFN Package Specific Features}

^{Exposed Thermal Pad: Must be directly connected to GND pin}

^{NC Pins: Internally unconnected, can be left floating}

^{Compact Layout: 16-pin design saves PCB space}

 

^{Electrical Characteristic Parameters}

^{Operating temperature range: -40℃ to +125℃}

^{Input offset voltage: Maximum ±5mV}

^{Response time: 1.3μs typical value}

 

^{PCB Layout Guidelines}

^{Place decoupling capacitors close to VCC pin}

^{Ensure thermal pad has full connection to ground plane}

^{Route sensitive input signals away from output lines}

 

^{Thermal Management Design}

^{WQFN package requires effective heat conduction through thermal pad}

^{Recommended use of thermal via arrays}

^{Ensure sufficient copper area for heat dissipation}

 

^{This pin configuration analysis provides comprehensive reference for proper application of the LM2901PWR in industrial control systems, ensuring full utilization of its quad-comparator performance advantages.}

 

 

 

^{III. In-Depth Analysis of Single Comparator Internal Schematic}

 

^{Core Architecture Overview
The LM2901PWR employs a fully differential bipolar transistor architecture, with each comparator containing a complete input stage, bias network, gain stage, and output stage, ensuring precise voltage comparison functionality across the industrial temperature range (-40℃ to +125℃).}

 

^{Detailed Circuit Module Analysis}

^{1. Input Differential Amplifier Stage}

^{Core Structure:}

^{Q1 and Q2 form PNP differential input pair}

^{Symmetrical design ensures high CMRR}

 

^{Bias Circuit:}

^{Q15 constitutes precision constant current source (Itail)}

^{Provides stable operating current bias}

 

^{Protection Mechanism:}

^{D3 and D4 implement input clamp protection}

^{VCM Clamp limits common-mode voltage range}

 

^{Performance Characteristics:}

^{Input impedance: >1MΩ}

^{Input bias current: 25nA (typical)}

^{Input offset voltage: ±2mV (maximum)}

 

 

^{2. Precision Bias Network}

^{Current Mirror Structure:}

^{Q9-Q12 and Q14 form multi-output current mirror}

^{Provides precise current matching}

 

^{Temperature Compensation:}

^{Built-in temperature tracking compensation network}

^{Ensures stability across full -40℃ to +125℃ temperature range}

 

^{Reference Generation:}

^{D1 and D2 establish stable voltage reference}

 

^{3. Intermediate Gain Stage}

^{Voltage Amplification:}

^{Q3 and Q4 form high-gain common-emitter amplifier}

^{Provides primary voltage gain (typically 200V/mV)}

 

^{Signal Conversion:}

^{Implements differential-to-single-ended signal conversion}

^{Level shifting adapts to output stage requirements}

 

^{4. Output Driver Stage}

^{Output Structure:}

^{Q13 serves as open-collector output transistor}

^{Requires external pull-up resistor (1kΩ to 10kΩ)}

 

^{Protection Circuit:}

^{Integrated ESD protection structure}

^{Overcurrent protection mechanism}

 

^{Output Characteristics:}

^{Saturation voltage: Typically 130mV (at Isink=4mA)}

^{Maximum sink current: 16mA}

^{Response time: 1.3μs (typical)}

 

^{Signal Path Analysis}

^{Non-inverting Input → Q2 (Differential Pair) → Level Shifting → Gain Stage (Q3, Q4) → Output Driver (Q13) Inverting Input → Q1 (Differential Pair) → Level Shifting → Gain Stage (Q3, Q4) → Output Driver (Q13)}

 

^{Key Performance Indicators}

^{Precision Parameters}

^{Voltage gain: 200V/mV (typical)}

^{Response time: 1.3μs (at Vcc=5V)}

^{Propagation delay: <300ns}

 

^{Reliability Specifications}

^{Operating voltage: 2V to 36V}

^{Temperature range: -40℃ to +125℃}

^{ESD protection: >2kV (HBM)}

 

^{Design Advantages Detailed Explanation}

 

^{1. High Precision Assurance}

^{Precision current mirror ensures bias stability}

^{Symmetrical differential structure provides high common-mode rejection}

^{Temperature compensation network guarantees accuracy across full temperature range}

 

^{2. Robustness Design}

^{Comprehensive input protection mechanism}

^{ESD protection enhances system reliability}

^{Wide supply voltage adaptation capability}

 

^{3. System-Friendly Features}

^{Open-collector output supports "wired-AND" connection}

^{Compatible with TTL/CMOS logic levels}

^{Low-power design (0.8mA/comparator)}

 

^{This internal architecture demonstrates the core technical advantages of the LM2901PWR as an industrial-grade quad comparator, providing a solid hardware foundation for high-reliability system design, making it particularly suitable for industrial control applications requiring multi-channel voltage monitoring.}

 

 

^{IV. Analysis of Typical Application Circuits}

 

Single-Ended Comparator Configuration (Left Diagram)

 

 

 

 

 

^{Operating Characteristics}

^{Configuration Mode: Input signal Vin is compared with a fixed reference voltage Vref}

^{Output Logic:}

^{When Vin > Vref: Output low level (close to GND)}

^{When Vin < Vref: High-impedance state (level determined by pull-up resistor)}

^{Key Components:}

^{Rpullup: Pull-up resistor, determines output high-level voltage}

^{Vref: Sets comparison threshold voltage}

 

^{Application Scenarios}

^{Voltage threshold detection}

^{Overvoltage/undervoltage protection}

^{Level conversion circuits}

 

^{Differential Comparator Configuration (Right Diagram)}
 

 

 

^{Operating Characteristics}

^{Configuration Mode: Compares the relative magnitudes of two input signals Vin+ and Vin-}

^{Output Logic:}

^{When Vin+ > Vin-: Output low level}

^{When Vin+ < Vin-: High-impedance state}

^{Signal Characteristics:}

^{Differential inputs suppress common-mode noise}

^{Suitable for weak signal detection}

 

^{Application Scenarios}

^{Differential signal detection}

^{Window comparator}

^{Motor current detection}

^{Sensor bridge circuits}

 

^{Core Design Parameters}

^{Power Supply Configuration}

^{Operating voltage range: 2V to 36V (single supply)
Quiescent current: Typically 0.4mA per comparator (at Vcc=5V)
Recommended decoupling: 0.1μF ceramic capacitor near Vcc pin}

 

^{Output Configuration}

^{Pull-up Resistor Selection:}

^{Calculation formula: Rpullup = (Vlogic - Vol) / Iol_sink}

^{Recommended range: 1kΩ to 10kΩ}

^{Typical application: 4.7kΩ (when Vlogic=5V)}

 

^{Output Characteristics:}

^{Saturation voltage: Typically 130mV (at Isink=4mA)}

^{Maximum sink current: 16mA}

 

^{Performance Parameters}

^{Response time: 1.3μs typical (at Vcc=5V)}

^{Input offset voltage: Maximum ±2mV}

^{Input bias current: Typically 25nA}

 

^{Design Key Points Summary}

 

^{Single-Ended Mode Advantages}

^{Simple circuit structure}

^{Fixed and well-defined threshold voltage}

^{Suitable for standard voltage monitoring}

 

^{Differential Mode Advantages}

^{Strong common-mode noise rejection}

^{Ideal for weak signal comparison}

^{High flexibility with dynamically adjustable thresholds}

 

^{General Design Recommendations}

^{Keep sensitive input signals away from noise sources}

^{Maintain short and direct signal paths}

^{Pay attention to thermal management in high-temperature applications}

 

^{These application circuits demonstrate the flexible configuration capability of the LM2901PWR as an industrial-grade quad comparator. Through simple single-ended or differential connections, it can meet various voltage detection requirements, providing a reliable signal comparison solution for system design.}

 

 

 

^{V. Package Dimension Specification Analysis}

 

 

 

 

 

 

^{Main Outline Dimension Parameters}

 

^{Package Outline Dimensions}

^{Total length: 7.4mm (typical)}

^{Total width: 6.5mm (Note 3 range 5.9-6.5mm)}

^{Package height: 2.0mm (maximum)}

^{Lead span: 8.2mm}

 

^{Pin Layout Specifications}

^{Number of pins: 14 pins}

^{Pin pitch: 0.65mm (12× standard spacing)}

^{Pin width: 0.38mm (14× uniform size)}

^{Pin length: 0.95mm (range 0.55-0.95mm)}

 

^{Key Mechanical Characteristics}

^{Mounting Reference Plane}

^{Seating plane: Device mounting reference plane}

^{Datum plane: Dimensional measurement reference plane}

^{Lead angle: 0°-8° outward expansion design}

 

^{Tolerance Control}

^{Main dimensional tolerance: ±0.15mm}

^{Pin position tolerance: ±0.05mm}

^{Outline profile tolerance: ±0.25mm}

 

^{Manufacturing and Inspection Requirements}

^{Geometric Features}

^{Lead coplanarity: 0.1mm maximum}

^{Lead thickness: 0.22mm (range 0.09-0.25mm)}

^{Corner radius: 0.05mm minimum}

 

^{Identification Area}

^{Pin 1 identification area: Clear polarity recognition}

^{Package marking: Clear device model identification}

^{Orientation indicator: Facilitates automated optical inspection}

 

^{PCB Design Adaptation Guidelines}

 

^{Pad Design Recommendations}

^{Pad width: 0.45mm (based on 0.38mm pin width)}

^{Pad length: 1.5mm (provides sufficient soldering area)}

^{Pad spacing: Maintain 0.2mm clearance}

 

^{Stencil Aperture Parameters}

^{Aperture width: 0.4mm (105% of pin width)}

^{Aperture length: 1.2mm}

^{Stencil thickness: 0.1-0.15mm}

 

^{Process Control Standards}

^{Manufacturability Requirements}

^{Lead coplanarity: ≤0.1mm}

^{Pad alignment accuracy: ±0.05mm}

^{Solder quality standard: IPC-A-610 Class 2}

 

^{Reliability Verification}

^{Thermal cycle testing: -40℃ to 125℃}

^{Mechanical strength: Passes vibration and shock tests}

^{Solder integrity: Meets J-STD-020 standard}

 

^{This package dimension specification provides complete technical basis for PCB design, SMT production, and quality inspection of the LM2901PWR, ensuring reliable mechanical fixation and electrical connections in industrial-grade applications.}