LM2903N - Dual Voltage Comparator, Open-Collector, 8-DIP | TI/STMicro/onsemi
MPN: LM2903N ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.58 | $0.58 |
| 10 | $0.5 | $5.00 |
| 100 | $0.39 | $39.00 |
| 500 | $0.32 | $160.00 |
| 1,000 | $0.27 | $270.00 |
LM2903N Overview
A voltage comparator is an analog building block that compares two input voltages and produces a binary digital output; when the non-inverting input exceeds the inverting input, the output switches state. The LM2903N belongs to the LM393/LM2903 family - a long-standing industry standard introduced for low-power single-supply sensing, and it sits in the hierarchy: comparator -> analog comparator -> signal conditioning IC -> integrated circuit. Its open-collector architecture requires an external pull-up resistor (typically 10 kohm to VCC), which lets multiple comparators be wire-ORed together and lets the output pull to a different rail than the supply voltage.
Key specifications include a 1.3 us typical response time at 5 V/2 mA, a 2.5 mV maximum input offset voltage (LM2903 grade), an input bias current of 25 nA typical, and ESD clamps on the inputs that tolerate human-body-model discharge. The device operates across the automotive-industrial -40 C to +125 C range (LM2903N suffix N designates the PDIP-8 package, not the temp grade).
The LM2903's architecture uses a PNP input stage that gives the inputs an exceptionally wide common-mode range that includes the negative rail (ground), which is why single-supply ground-referenced sensing is its dominant application. The open-collector NPN output stage isolates the comparator logic from the load voltage; only the pull-up rail sets the high-level output.
Typical applications include battery monitoring in 12 V/24 V automotive and industrial systems (window detectors, under-voltage cutoff), zero-crossing detectors for mains interfaces when paired with an optocoupler, line-receiver / level-shift interfaces between high-voltage analog and low-voltage logic, threshold alarms and signal-conditioning front-ends, and oscillator / relaxation-oscillator circuits.
When designing with the LM2903N, observe one trade-off: open-collector outputs use a pull-up resistor that adds RC delay to the rising edge - at 10 kohm with 100 pF of trace capacitance, rise time is about 1 us. For high-speed logic interfaces downstream, size the pull-up conservatively or use a discrete or integrated push-pull comparator when sub-microsecond edge rates are needed.
Drop-in alternatives for LM2903N — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with LM2903N (same form factor and footprint) — differing in Comparator Type, Output Type, Package, RoHS Status, Number of Comparators.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LM2903N/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
LM393N
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$0.18 / Unit
View Datasheet →LM293N
✅ Drop-In📋 Reference alternative (not in catalog)
LM2903N
✅ Drop-In✓ In Stock
$0.27 / Unit
View Datasheet →LM2903N
✅ Drop-In✓ In Stock
$0.27 / Unit
View Datasheet →LM2903N
✅ Drop-In✓ In Stock
$0.27 / Unit
View Datasheet →LM2903N
✅ Drop-In✓ In Stock
$0.27 / Unit
View Datasheet →LM2903N Maximum Ratings & Electrical Characteristics
| Comparator Type | Low Offset Voltage, Dual Differential |
| Number of Comparators | 2 (dual independent) |
| Output Type | Open-Collector / Open-Drain |
| Supply Voltage (Single Supply) | 2 V to 36 V |
| Supply Voltage (Dual Supply) | ±1 V to ±18 V |
| Input Offset Voltage (Max) | 2.5 mV (LM2903 grade) |
| Input Bias Current (Typ) | 25 nA |
| Input Common-Mode Range | Includes ground (negative rail) |
| Output Sink Current (Typ) | 16 mA typical, 6 mA min |
| Response Time (Typ) | 1.3 us at 5 V / 2 mA |
| Differential Input Voltage (Max) | 36 V |
| Operating Temperature Range | -40 C to +125 C |
| Package | 8-Pin PDIP (DIP-8, N suffix) |
| Mounting Type | Through-Hole |
| RoHS Status | Compliant (NOPB suffix); non-compliant original |
| Lead-Free / NOPB Option | Yes (LM2903N/NOPB) |
| Manufacturer Source Bases | TI, STMicroelectronics, onsemi, NXP |
LM2903N Pin Configuration
| Pin 1 | OUT1 — Open-collector output of comparator 1 |
| Pin 2 | IN1- — Inverting input of comparator 1 |
| Pin 3 | IN1+ — Non-inverting input of comparator 1 |
| Pin 4 | V- / GND — Negative supply (or ground for single-supply operation) |
| Pin 5 | IN2+ — Non-inverting input of comparator 2 |
| Pin 6 | IN2- — Inverting input of comparator 2 |
| Pin 7 | OUT2 — Open-collector output of comparator 2 |
| Pin 8 | V+ — Positive supply (2 V to 36 V) |
Typical Applications
LM2903N is suitable for 6 applications: 12 V / 24 V Battery Voltage Monitor, Zero-Crossing Detector for Mains Interface, Window Comparator (Dual-Threshold Detector), Line-Receiver / Logic Level Shifter, Relaxation Oscillator / Square-Wave Generator, Automotive Threshold Alarm and Sensor Interface.
12 V / 24 V Battery Voltage Monitor
The LM2903N is widely used as the comparator core in 12 V and 24 V battery-monitoring modules because its 2 V-36 V supply range accepts automotive and industrial battery rails directly without pre-regulation, and its open-collector output can drive an LED or alarm transistor directly. Wire a resistor divider from the battery plus a stable reference (such as a TL431 or LM4040) into the inverting input; the divided battery voltage goes into the non-inverting input; when the battery sags below the threshold, the output goes low. The LM2903N operates across -40 C to +125 C, covering under-hood and outdoor-cabinet environments, and the 2.5 mV max offset contributes only ~0.04 percent threshold error for a 6 V trip point.
Recommended
Zero-Crossing Detector for Mains Interface
Use the LM2903N at the front end of an optocoupled mains interface: attenuate the 230 V/115 V mains with a high-impedance resistor divider and use a small filter capacitor to limit dV/dt, then feed the attenuated sinewave into one LM2903N input with a low-voltage reference on the other. The open-collector output drives an optocoupler LED through a current-limit resistor, providing galvanic isolation for a downstream timer, MCU, or triac-control logic. The LM2903N's ground-sensing input allows a single low-voltage supply rail (for example 5 V) to power the comparator, even though the input network is referenced near ground; this avoids needing a negative rail just to bias the comparator inputs.
Recommended
Window Comparator (Dual-Threshold Detector)
Two cascaded LM2903N comparators (one IC, since the part contains two) build a window comparator for detecting whether an analog signal lies inside or outside a programmable voltage window. Set the upper and lower thresholds with external resistor dividers and reference; wire the inputs so that OUT goes low when Vsig falls below the lower threshold or rises above the upper threshold. Typical use is supervising a 4-20 mA loop signal or a sensor supply rail; the LM2903N's 1.3 us response time is more than adequate for fault detection bandwidths in the kHz range. Wire-OR the two open-collector outputs together for a single 'out-of-range' flag.
Recommended
Line-Receiver / Logic Level Shifter
The LM2903N is the classic solution for shifting a higher-voltage analog or digital signal down to a lower-voltage logic domain: feed the signal into one input and connect a divided reference to the other, then use the open-collector output with a pull-up to the lower-voltage rail so the output logic-high follows the downstream logic supply rather than the comparator's VCC. This approach is robust for interfaces between a ±15 V op-amp world and a 3.3 V microcontroller, between 24 V industrial sensors and 5 V logic, or between unregulated mains-synchronous signals and a low-voltage counter.
Recommended
Relaxation Oscillator / Square-Wave Generator
A single LM2903N comparator plus an RC timing network and two resistors forms a textbook relaxation oscillator (also called an astable multivibrator) that generates square waves from a few Hz to ~50 kHz depending on RC values. The LM2903N's wide supply range (2-36 V) makes the oscillator amplitude programmable from a few volts up to about 33 V p-p, while the open-collector output with a pull-up resistor to any desired rail provides flexibility in output level. This topology is common in test-and-measurement fixtures, low-cost clock generators, PWM modulators, and tone generators; typical 10 kHz designs use 10 kohm + 0.01 uF for approximately 7 kHz output frequency.
Recommended
Automotive Threshold Alarm and Sensor Interface
Inside an automotive ECU, the LM2903N acts as a rugged threshold detector for low-speed analog sensor signals (temperature sensors via NTC/PTC thermistor dividers, fluid-level sensors, switch-bounce debouncing, and generic over-temperature alarms). Its -40 C to +125 C operating range, ESD-robust inputs, and tolerance of supply transients (within the 36 V abs-max envelope) are well-matched to 12 V automotive electrical environments. For AEC-Q100-qualified alternatives, TI recommends the TLV1702-Q1 or LM2903-Q1 in SOIC-8; the through-hole PDIP-8 LM2903N remains popular for development kits, hobby automotive projects, and industrial-grade (not automotive-qualified) designs.
Recommended
Recommended Products Summary
Engineering reference data for LM2903N — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LM2903N/NOPB | LM393N | LM293N | LM2903N (STMicro) | LM2903N (onsemi) |
|---|---|---|---|---|---|---|
| Package | 8-Pin PDIP (DIP-8, N suffix) | 8-Pin PDIP (DIP-8) - same | 8-Pin PDIP (DIP-8) - same | 8-Pin PDIP (DIP-8) - same | 8-DIP - same | 8-DIP - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | STMicroelectronics | onsemi |
| Number of Comparators | 2 | 2 | 2 | 2 | 2 | 2 |
| Output Type | Open-Collector | Open-Collector | Open-Collector | Open-Collector | Open-Collector | Open-Collector |
| Supply Voltage (Single) | 2 V - 36 V | 2 V - 36 V | 2 V - 36 V | 2 V - 36 V | 2 V - 36 V | 2 V - 36 V |
| Operating Temperature | -40 C to +125 C | -40 C to +125 C | 0 C to +70 C | -40 C to +85 C | -40 C to +125 C | -40 C to +125 C |
| RoHS Compliant | Yes (NOPB suffix) | Yes | Yes (NOPB) | Yes (NOPB) | Yes | Yes |
Key Differentiators
- Quad-source legacy dual comparator with 36 V supply range (vs LM393N (TI 0-70C version))
- Tighter input offset at the same price point (vs LM393N)
- Pin-to-pin second-source availability across multiple manufacturers (vs Proprietary comparator pinouts (e.g. TLV3202 in SOIC-8))
- Through-hole PDIP-8 package (DIP-8) for prototyping and breadboards (vs Surface-mount-only comparators (LM2903DR SOIC-8))
Design Notes
The LM2903N open-collector output requires an external pull-up resistor to any desired voltage rail up to 36 V, even when running the comparator itself on a separate supply. Choose pull-up values from 1 kohm to 100 kohm based on speed vs current trade-off: at 1 kohm the rise time is fast but quiescent current when low is 5 mA; at 100 kohm, rise time is ~10 us and on-current is 50 uA. Bypass V+ (pin 8) with a 0.1 uF ceramic capacitor placed physically close to the IC, since the comparator draws sharp switching transients from the rail during output transitions.
The LM2903N input common-mode range is specified from V- up to roughly (V+ - 1.5 V), so at a 5 V supply the inputs are only linear to ~3.5 V - do not present input voltages near the positive rail. Differential input voltage must not exceed 36 V, even if both inputs are within the common-mode range; clamping with back-to-back diodes or series resistors is advised if transients are expected. Note that the LM2903N suffix 'N' designates the PDIP-8 package, not the temperature grade - identical electrical behavior applies to other packages (SOIC-8, DSBGA) of the same die.
Layout tips for the LM2903N: keep input traces short and parallel to avoid injecting switching noise into the high-impedance comparator inputs; route output traces away from input traces to prevent feedback. For through-hole PDIP-8 designs use a single-point ground star at the LM2903N GND pin (pin 4) to avoid ground-loop-induced input offset. If the system uses high-impedance (>100 kohm) input dividers, add 10 pF to 100 pF bypass capacitors across the inputs to suppress RF rectification and stray switching noise pickup.
The LM2903N's open-collector topology is an excellent noise-margin asset, but it interacts with capacitive loads - the rise time is governed by R_pullup x C_load. A scope measurement on the OUT pin will show a slow ramp rather than a clean edge when driving >50 pF. For best signal integrity into downstream CMOS, size R_pullup for rise times below 1 us; for driving relays or LEDs directly, a slow ramp is acceptable. Add a 100 pF speed-up capacitor in parallel with R_pullup if you need sub-microsecond rising edges without sacrificing the pull-up's DC bias current.
Compliance Information
LM2903N/NOPB (TI lead-free version) is fully RoHS compliant. The non-NOPB LM2903N uses lead terminations and is not RoHS compliant - choose NOPB for new designs. AEC-Q100 qualification not available in PDIP-8 form factor; the AEC-Q100 option for LM2903 family is the LM2903-Q1 in SOIC-8.
