LM393 dual comparator: specs and pinout
Two independent voltage comparators in one 8-pin chip, run from a single supply. The outputs are open-collector, so each output needs a pull-up resistor to the voltage the input stage expects. The numbers here are for the plain LM393 (0 C to 70 C) in the chip maker's data sheet, not the improved B version.
Specs
| Spec | Value | Source |
|---|---|---|
| Supply voltage (LM393, non-B) | 2 V to 30 V | source 5.2 Recommended Operating Conditions, p.4 |
| Ambient temperature (LM393) | 0 C to 70 C | source 5.2 Recommended Operating Conditions, p.4 |
| Supply current (LM393, VCC = 5 V, no load) | 0.45 mA typical, 1 mA maximum for both comparators | source 5.8 Electrical Characteristics, p.8 |
| Supply current (LM393, VCC = 30 V, full temperature range) | 2.5 mA maximum | source 5.8 Electrical Characteristics, p.8 |
| Input common-mode voltage range (LM393, 25 C) | 0 V to VCC minus 1.5 V (0 V to VCC minus 2 V over temperature) | source 5.8 Electrical Characteristics, p.8 |
| Input offset voltage (LM393, 25 C) | 2 mV typical, 5 mV maximum | source 5.8 Electrical Characteristics, p.8 |
| Input bias current (LM393, 25 C) | minus 25 nA typical, minus 250 nA maximum | source 5.8 Electrical Characteristics, p.8 |
| Output type | Open-collector (output sinks current; needs a pull-up resistor) | source 6.1 Overview, p.17 |
| Low-level output voltage (LM393, IOL = 4 mA, 25 C) | 130 mV typical, 400 mV maximum | source 5.8 Electrical Characteristics, p.8 |
| Response time (VCC = 5 V, 5.1 kOhm pull-up, 100 mV step with 5 mV overdrive) | 1.3 us typical | source 5.11 Switching Characteristics, p.10 |
Power
| Value | Source | |
|---|---|---|
| Supply | 2 V to 30 V single supply (LM393) | source 5.2 and 5.8, pp.4 and 8 |
| Current | 0.45 mA typical at VCC = 5 V (both comparators) | source 5.2 and 5.8, pp.4 and 8 |
Pinout
This is a bare chip, not a module. Pin numbers are for the 8-pin DIP/SOIC package in the chip maker's data sheet.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| 1 | 1OUT | Output of comparator 1 | source 4 Pin Configuration and Functions, p.3 (8-pin SOIC, VSSOP, PDIP, SO or TSSOP, top view) | |
| 2 | 1IN- | Negative input of comparator 1 | source 4 Pin Configuration and Functions, p.3 (8-pin SOIC, VSSOP, PDIP, SO or TSSOP, top view) | |
| 3 | 1IN+ | Positive input of comparator 1 | source 4 Pin Configuration and Functions, p.3 (8-pin SOIC, VSSOP, PDIP, SO or TSSOP, top view) | |
| 4 | GND | Ground | source 4 Pin Configuration and Functions, p.3 (8-pin SOIC, VSSOP, PDIP, SO or TSSOP, top view) | |
| 5 | 2IN+ | Positive input of comparator 2 | source 4 Pin Configuration and Functions, p.3 (8-pin SOIC, VSSOP, PDIP, SO or TSSOP, top view) | |
| 6 | 2IN- | Negative input of comparator 2 | source 4 Pin Configuration and Functions, p.3 (8-pin SOIC, VSSOP, PDIP, SO or TSSOP, top view) | |
| 7 | 2OUT | Output of comparator 2 | source 4 Pin Configuration and Functions, p.3 (8-pin SOIC, VSSOP, PDIP, SO or TSSOP, top view) | |
| 8 | VCC | Positive supply | source 4 Pin Configuration and Functions, p.3 (8-pin SOIC, VSSOP, PDIP, SO or TSSOP, top view) |
Build with it
Project ideas for the LM393 dual comparator. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- Dark detector with a comparator: Power the LM393 from the 3.3 V pin and keep both input voltages below about 1.3 V (VCC minus 2 V) by sizing the LDR divider and the reference divider from the resistor pack. The open-collector output needs a pull-up resistor to 3.3 V and goes to an ESP32 input; the OLED shows light or dark. Learning project.
- A voltage window checker with an Arduino Uno, a potentiometer and an LM393 dual comparator: One comparator watches for the voltage going above a low limit and the other for going below a high limit. Open-collector outputs can be tied together (they act as an AND), with one pull-up resistor and an LED through a resistor. Keep limits below about 3 V with a 5 V supply. Learning project.
- Comparator driving an indicator LED: The output sinks current, so an LED with a resistor from 5 V to the output lights when the output is low; size the resistor for about 4 mA or less, the condition at which the data sheet gives the output low voltage. A fixed resistor in series with the potentiometer's 5 V end keeps the reference below about 3 V, within the input range. Learning project.
Common mistakes
- No pull-up on the output: the outputs are open-collector, so they can only pull low; add a pull-up resistor to the voltage your input expects (source: link, section 6.1).
- Putting an input above the common-mode range: it is 0 V to VCC minus 1.5 V at 25 C (VCC minus 2 V over temperature), and an input may not go more than 0.3 V below ground (source: link, section 5.8 and its note 2).
- Using it outside 0 C to 70 C: the plain LM393 is specified only over that range; the B version has a wider range (source: link, sections 5.2 and 5.8).
Not covered by the official source
- The product page does not name the chip maker; the maker's sheet that matches the LM393 part number was used.
- The plain LM393 table was used, not the B-version table.
Sources
- link (LM393B, LM2903B, LM193, LM293, LM393 and LM2903 Dual Comparators, SLCS005AH, October 1979, revised April 2025; chip maker)