LM2903Dual voltage comparator
Two threshold decisions across an extended temperature range.
LM2903 contains two independent voltage comparators with open-collector outputs. Each channel compares its positive input with its negative input and either sinks output current or releases the collector. An external pull-up resistor supplies the HIGH state. This page selects classic TI LM2903P in PDIP-8 and LM2903DR in SOIC-8, rated for −40 to +125°C. It uses the non-B electrical table; LM2903B and V/AV variants have different limits. All eight physical pins keep the same function when switching between these two packages. The 5 V example compares a 1.50 V signal with a nominal 2.00 V resistor-divider reference. A 10 kΩ output pull-up and 100 nF supply bypass complete the first channel; the unused channel is tied to defined inputs. Offset, input current, resistor tolerance and noise affect the real threshold. The interactive explorer marks uncertainty near equality rather than pretending the decision is exact.
8Physical pins
LM2903PPDIP-8
Manufacturer-referencedTexas Instruments
Pin diagram
Select a pin to explore its connection
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LM2903PPDIP-8Top view
LM2903DRSOIC-8Top view
Click a lead or use the arrow keys. Top view
PIN 1 · Open-collector outputs
Open-collector outputOUT1
Function
Channel A sinks current when IN1− is above IN1+.
How to connect
Add a 10 kΩ pull-up to +5 V; read this node with a high-impedance input.
Electrical note
The IC does not actively drive HIGH.
PIN 2 · Comparison inputs
Inverting inputIN1−
Function
Channel A reference input in the illustrated circuit.
How to connect
Connect the 2.00 V divider node.
Electrical note
Keep both example inputs within 0–3 V at a 5 V supply.
PIN 3 · Comparison inputs
Non-inverting inputIN1+
Function
Channel A measured signal.
How to connect
Connect VIN and a common ground.
PIN 4 · Ground
Supply returnGND
Function
Ground reference for both comparators.
How to connect
Connect the supply return and bypass capacitor.
PIN 5 · Comparison inputs
Non-inverting inputIN2+
Function
Channel B positive input.
How to connect
Tie to GND when unused in this example.
PIN 6 · Comparison inputs
Inverting inputIN2−
Function
Channel B negative input.
How to connect
Connect to the same 2 V reference to give the unused channel a defined state.
PIN 7 · Open-collector outputs
Open-collector outputOUT2
Function
Channel B current-sinking output.
How to connect
Leave unconnected in the single-channel example.
Electrical note
Use a separate pull-up when using channel B.
PIN 8 · Supply
Positive supplyVCC
Function
Shared positive supply for both comparators.
How to connect
Apply +5 V; place 100 nF between pins 8 and 4.
Electrical note
Classic LM2903 recommended supply: 2–30 V.
Key specifications
An open-collector output needs a pull-up resistor. It sinks current instead of sourcing a HIGH level.
Recommended supply2–30 V · classic LM2903
Independent channels2 Open-collector outputs
Ambient range−40–125 °C
Typical response1.3 µs · specified small-signal test
Package details
LM2903P · PDIP-8
| Property | Details |
|---|---|
| Manufacturer | Texas Instruments |
| Part number | LM2903P |
| Package | PDIP-8 |
| Connections | 8 pins |
| Mounting | Through-hole |
| Lead pitch | 2.54 mm |
| Package code | dip |
| Thermal reference | Board and package dependent; see manufacturer data |
Select the exact family member
This page uses classic LM2903 limits
Manufacturer specifications 6 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Through-hole order | LM2903P | PDIP-8 P |
| SMD order | LM2903DR | SOIC-8 D |
| Temperature grade | −40 to +125°C | Selected classic LM2903 orders |
| B revision | Not substituted here | Lower offset/bias and a different recommended maximum supply |
| V / AV versions | Not substituted here | Different voltage or accuracy limits |
| Reference section | TI SLCS005AH section 5.10 | Non-B LM2903 column; section 5.11 for switching |
No specifications match. Try a parameter name or a unit.
Part-family similarity does not make every electrical rating interchangeable.
Supply and input conditions
Classic LM2903, not LM2903B
Manufacturer specifications 6 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Recommended supply | 2–30 V | Example uses 5 V |
| Ambient range | −40 to +125°C | Manufacturer operating range |
| Input range at 25°C | 0 to VCC−1.5 V | Electrical table |
| Full-temperature input range | 0 to VCC−2 V | Use 0–3 V for this 5 V example |
| Input negative limit | Do not go below −0.3 V | Parasitic current can produce an incorrect output |
| Output HIGH | External pull-up required | Output transistor off does not itself create a voltage |
No specifications match. Try a parameter name or a unit.
Keep the example inputs in the full-temperature common-mode range.
Input accuracy and supply current
5 V and 25°C unless stated
Manufacturer specifications 7 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Input offset | 2 mV typical; 7 mV maximum | VCC = 5–30 V; specified common-mode/output condition |
| Offset over temperature | 15 mV maximum | −40 to +125°C |
| Input bias-current magnitude | 25 nA typical; 250 nA maximum | 500 nA maximum over temperature; source uses negative sign |
| Input offset current | 5 nA typical; 50 nA maximum | 200 nA maximum over temperature |
| Total supply current | 0.8 mA typical; 1 mA maximum | 5 V, no load, 25°C |
| Total current over temperature | 2.5 mA maximum | VCC = 30 V, no load |
| Large-signal gain | 25 V/mV minimum; 100 V/mV typical | VCC 15 V, output 1.4–11.4 V, RL ≥15 kΩ |
No specifications match. Try a parameter name or a unit.
Typical offset and bias values are not worst-case error bounds.
Collector output and response
Loading and overdrive matter
Manufacturer specifications 7 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| LOW voltage at 4 mA | 150 mV typical; 400 mV maximum | 25°C; VID = −1 V |
| LOW voltage over temperature | 700 mV maximum | Same 4 mA condition |
| Output sink capability test | 6 mA minimum | VOL = 1.5 V; VID = −1 V; 25°C |
| HIGH leakage at 5 V | 0.1 nA typical; 50 nA maximum | 25°C; VID = 1 V |
| HIGH leakage over temperature | 1 µA maximum | Output at maximum supply |
| Small-signal response | 1.3 µs typical | 100 mV step, 5 mV overdrive; 5.1 kΩ pull-up, 15 pF |
| TTL-step response | 0.3 µs typical | Same manufacturer switching fixture |
No specifications match. Try a parameter name or a unit.
The DC explorer does not model propagation time, parasitic capacitance or output slew.
A 2 V threshold detector
Nominal 5 V teaching circuit
Manufacturer specifications 7 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Reference divider | 30 kΩ upper / 20 kΩ lower | 5 × 20/(30+20) = 2.00 V before loading |
| VIN | 1.50 V | IN+ pin 3; output initially LOW |
| External pull-up | 10 kΩ from OUT1 to +5 V | Output pin 1 |
| Illustrative LOW current | 0.485 mA | (5−0.15)/10 kΩ |
| Supply bypass | 100 nF | Between pins 8 and 4, locally |
| Unused comparator | IN+5 to GND; IN−6 to VREF | OUT2 pin 7 left open |
| Near-equality band | ±15 mV input offset allowance | Teaching uncertainty band, not hysteresis or complete error budget |
No specifications match. Try a parameter name or a unit.
Divider tolerance, bias current and supply error move the threshold.
Pins, layout and stress limits
LM2903P · PDIP-8
Manufacturer specifications 8 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Lead pitch | 2.54 mm | Through-hole; top view |
| Channel 1 | 3 IN+; 2 IN−; 1 OUT | Separate open collector |
| Channel 2 | 5 IN+; 6 IN−; 7 OUT | Separate open collector |
| Power | 8 VCC; 4 GND | Shared by both channels |
| Absolute supply maximum | 36 V | Stress rating; recommended maximum is 30 V |
| Absolute output voltage | −0.3 to +36 V | Observe current and thermal limits |
| Absolute output current | 20 mA | Not a recommended design current |
| Absolute junction / storage | 150°C / −65 to +150°C | Thermal design still depends on board and package |
No specifications match. Try a parameter name or a unit.
Follow manufacturer layout guidance and verify the actual package before fabrication.
Connections by function
Select a pin for its function, connection guidance and electrical notes.
Open-collector outputs2 pins
Comparison inputs4 pins
Ground1 pin
Supply1 pin
Open-collector outputs2 pins
Comparison inputs4 pins
Ground1 pin
Supply1 pin
LM2903 at a glance
Follow the labeled connections and functional stages
How it works
3 stages · Explore one step at a time
Compare the two inputs
The differential input stage responds to IN+ minus IN−. No analog-to-digital converter or firmware is needed.
Sink current or release the node
A negative input difference turns the output transistor on. A positive difference turns it off. The external pull-up supplies the HIGH level.
Make a stable decision
Keep inputs in their common-mode range. Add positive-feedback hysteresis when a slowly changing or noisy signal would chatter around the threshold.
Step 1 of 3
Find the switching threshold
Adjust VIN and the reference. Remove the pull-up to see why it matters.
IN+ − IN−—
Output state—
Pull-up current—
Enable JavaScript to explore the comparator.
Violet: offset-sensitive transition · Amber: input outside the recommended range.
DC teaching model for channel A. The ±15 mV band uses the full-temperature maximum input-offset magnitude, not hysteresis or a complete error budget. LOW uses an illustrative 0.15 V estimate. Input bias, leakage, noise, timing and capacitance are omitted.
LM2903 in a circuit
A physical IC, a resistor reference and a clearly defined output.
Connect it, step by step
Follow the component values and pin connections
Build the reference
30 kΩ above and 20 kΩ below produce a nominal 2 V reference from 5 V.
Compare VIN
Connect the measured voltage to IN1+ and VREF to IN1−. VIN below 2 V makes OUT1 LOW.
Add the pull-up
Connect 10 kΩ from OUT1 to 5 V. Without it, the released output is floating rather than HIGH.
Inside LM2903
Two differential channels with independent open-collector outputs.
Explore the circuit
Select a stage to see its role and connections
Differential input
Compare the two input voltages while respecting their valid range.
Open-collector switch
The collector is exposed at OUT. A LOW state sinks current; an off transistor releases the node.
Shared supply
Both channels use VCC pin 8 and GND pin 4, but each has its own inputs and output.
Selected packagePDIP-8LM2903P
Physical connections8 pinsPackage-specific numbering
Reference collection7 tables41 parameters & pin functions
Pin reference
Signal names, electrical functions and connection guidance
Physical pin numbers8 pins
Scroll within the table to see all columns and rows.
| Pin | Signal | Type | Function & connection |
|---|---|---|---|
| OUT1 | Open-collector output | Channel A sinks current when IN1− is above IN1+.Connection guidanceAdd a 10 kΩ pull-up to +5 V; read this node with a high-impedance input. The IC does not actively drive HIGH. | |
| IN1− | Inverting input | Channel A reference input in the illustrated circuit.Connection guidanceConnect the 2.00 V divider node. Keep both example inputs within 0–3 V at a 5 V supply. | |
| IN1+ | Non-inverting input | Channel A measured signal.Connection guidanceConnect VIN and a common ground. | |
| GND | Supply return | Ground reference for both comparators.Connection guidanceConnect the supply return and bypass capacitor. | |
| IN2+ | Non-inverting input | Channel B positive input.Connection guidanceTie to GND when unused in this example. | |
| IN2− | Inverting input | Channel B negative input.Connection guidanceConnect to the same 2 V reference to give the unused channel a defined state. | |
| OUT2 | Open-collector output | Channel B current-sinking output.Connection guidanceLeave unconnected in the single-channel example. Use a separate pull-up when using channel B. | |
| VCC | Positive supply | Shared positive supply for both comparators.Connection guidanceApply +5 V; place 100 nF between pins 8 and 4. Classic LM2903 recommended supply: 2–30 V. |
No pins match these filters. Try another signal name or reset the filters.
Select the exact family member
This page uses classic LM2903 limits
Manufacturer-referenced values6 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Through-hole order | LM2903P | PDIP-8 P |
| SMD order | LM2903DR | SOIC-8 D |
| Temperature grade | −40 to +125°C | Selected classic LM2903 orders |
| B revision | Not substituted here | Lower offset/bias and a different recommended maximum supply |
| V / AV versions | Not substituted here | Different voltage or accuracy limits |
| Reference section | TI SLCS005AH section 5.10 | Non-B LM2903 column; section 5.11 for switching |
No specifications match. Try a parameter name or a unit.
Part-family similarity does not make every electrical rating interchangeable.
Supply and input conditions
Classic LM2903, not LM2903B
Manufacturer-referenced values6 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Recommended supply | 2–30 V | Example uses 5 V |
| Ambient range | −40 to +125°C | Manufacturer operating range |
| Input range at 25°C | 0 to VCC−1.5 V | Electrical table |
| Full-temperature input range | 0 to VCC−2 V | Use 0–3 V for this 5 V example |
| Input negative limit | Do not go below −0.3 V | Parasitic current can produce an incorrect output |
| Output HIGH | External pull-up required | Output transistor off does not itself create a voltage |
No specifications match. Try a parameter name or a unit.
Keep the example inputs in the full-temperature common-mode range.
Input accuracy and supply current
5 V and 25°C unless stated
Manufacturer-referenced values7 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Input offset | 2 mV typical; 7 mV maximum | VCC = 5–30 V; specified common-mode/output condition |
| Offset over temperature | 15 mV maximum | −40 to +125°C |
| Input bias-current magnitude | 25 nA typical; 250 nA maximum | 500 nA maximum over temperature; source uses negative sign |
| Input offset current | 5 nA typical; 50 nA maximum | 200 nA maximum over temperature |
| Total supply current | 0.8 mA typical; 1 mA maximum | 5 V, no load, 25°C |
| Total current over temperature | 2.5 mA maximum | VCC = 30 V, no load |
| Large-signal gain | 25 V/mV minimum; 100 V/mV typical | VCC 15 V, output 1.4–11.4 V, RL ≥15 kΩ |
No specifications match. Try a parameter name or a unit.
Typical offset and bias values are not worst-case error bounds.
Collector output and response
Loading and overdrive matter
Manufacturer-referenced values7 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| LOW voltage at 4 mA | 150 mV typical; 400 mV maximum | 25°C; VID = −1 V |
| LOW voltage over temperature | 700 mV maximum | Same 4 mA condition |
| Output sink capability test | 6 mA minimum | VOL = 1.5 V; VID = −1 V; 25°C |
| HIGH leakage at 5 V | 0.1 nA typical; 50 nA maximum | 25°C; VID = 1 V |
| HIGH leakage over temperature | 1 µA maximum | Output at maximum supply |
| Small-signal response | 1.3 µs typical | 100 mV step, 5 mV overdrive; 5.1 kΩ pull-up, 15 pF |
| TTL-step response | 0.3 µs typical | Same manufacturer switching fixture |
No specifications match. Try a parameter name or a unit.
The DC explorer does not model propagation time, parasitic capacitance or output slew.
A 2 V threshold detector
Nominal 5 V teaching circuit
Manufacturer-referenced values7 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Reference divider | 30 kΩ upper / 20 kΩ lower | 5 × 20/(30+20) = 2.00 V before loading |
| VIN | 1.50 V | IN+ pin 3; output initially LOW |
| External pull-up | 10 kΩ from OUT1 to +5 V | Output pin 1 |
| Illustrative LOW current | 0.485 mA | (5−0.15)/10 kΩ |
| Supply bypass | 100 nF | Between pins 8 and 4, locally |
| Unused comparator | IN+5 to GND; IN−6 to VREF | OUT2 pin 7 left open |
| Near-equality band | ±15 mV input offset allowance | Teaching uncertainty band, not hysteresis or complete error budget |
No specifications match. Try a parameter name or a unit.
Divider tolerance, bias current and supply error move the threshold.
Pins, layout and stress limits
LM2903P · PDIP-8
Manufacturer-referenced values8 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Lead pitch | 2.54 mm | Through-hole; top view |
| Channel 1 | 3 IN+; 2 IN−; 1 OUT | Separate open collector |
| Channel 2 | 5 IN+; 6 IN−; 7 OUT | Separate open collector |
| Power | 8 VCC; 4 GND | Shared by both channels |
| Absolute supply maximum | 36 V | Stress rating; recommended maximum is 30 V |
| Absolute output voltage | −0.3 to +36 V | Observe current and thermal limits |
| Absolute output current | 20 mA | Not a recommended design current |
| Absolute junction / storage | 150°C / −65 to +150°C | Thermal design still depends on board and package |
No specifications match. Try a parameter name or a unit.
Follow manufacturer layout guidance and verify the actual package before fabrication.
No matching rowsTry a pin name, parameter, unit or test condition, or reset the filters.
Threshold and level detection
Compare a sensor voltage with a reference and feed the result to logic. Choose a pull-up voltage compatible with that logic.
Manufacturer application guideWindow detectors
Use both comparators for upper and lower limits. The output circuit determines how the two decisions combine.
Manufacturer application guideSlow sensor signals
Convert a temperature, light or position voltage into an alarm state. Hysteresis prevents noisy repeated transitions.
Manufacturer application guideTake it into ProTech
Find LM2903 in the Components Library to place its schematic symbol and connect its pins.
Reference page · circuit simulation model not yet availableOpen ProTech