LM741CN op-amp: specs and pinout
A general-purpose single operational amplifier in an 8-pin through-hole DIP package. The chip maker's data sheet covers the LM741 family; the LM741C grade (0 C to 70 C) is the one that matches the CN suffix. It is meant for a dual supply of about plus and minus 15 V and does not run rail to rail.
Specs
| Spec | Value | Source |
|---|---|---|
| Recommended supply voltage (LM741C) | plus and minus 10 V to plus and minus 18 V (nominal plus and minus 15 V) | source 6.3 Recommended Operating Conditions, p.4 |
| Operating temperature (LM741C) | 0 C to 70 C | source 6.3 Recommended Operating Conditions, p.4 |
| Supply current (LM741C, 25 C, supply plus and minus 15 V) | 1.7 mA typical, 2.8 mA maximum | source 6.7 Electrical Characteristics, LM741C, p.6 |
| Input offset voltage (LM741C, 25 C, RS up to 10 kOhm) | 2 mV typical, 6 mV maximum | source 6.7 Electrical Characteristics, LM741C, p.6 |
| Input bias current (LM741C, 25 C) | 80 nA typical, 500 nA maximum | source 6.7 Electrical Characteristics, LM741C, p.6 |
| Output voltage swing (LM741C, supply plus and minus 15 V) | plus and minus 12 V minimum with a 10 kOhm load; plus and minus 10 V minimum with a 2 kOhm load | source 6.7 Electrical Characteristics, LM741C, p.6 |
| Slew rate (LM741C, unity gain, 25 C) | 0.5 V/us typical | source 6.7 Electrical Characteristics, LM741C, p.6 |
| Large signal voltage gain (LM741C, 25 C) | 20 V/mV minimum, 200 V/mV typical | source 6.7 Electrical Characteristics, LM741C, p.6 |
| Output short-circuit current (LM741C, 25 C) | 25 mA typical | source 6.7 Electrical Characteristics, LM741C, p.6 |
| Absolute maximum supply voltage (LM741C) | plus and minus 18 V | source 6.1 Absolute Maximum Ratings, p.4 |
Power
| Value | Source | |
|---|---|---|
| Supply | plus and minus 10 V to plus and minus 18 V recommended for the LM741C (dual supply) | source 6.3 and 6.7, pp.4 and 6 |
| Current | 1.7 mA typical (supply plus and minus 15 V, 25 C) | source 6.3 and 6.7, pp.4 and 6 |
Pinout
This is a bare chip, not a module. The pin numbers are those of the 8-pin PDIP package in the chip maker's data sheet.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| 1 | OFFSET NULL | Offset null pin used to eliminate the offset voltage and balance the input voltages | source 5 Pin Configuration and Functions, p.3 (NAB package, 8-pin CDIP or PDIP, top view) | |
| 2 | INVERTING INPUT | Inverting signal input | source 5 Pin Configuration and Functions, p.3 (NAB package, 8-pin CDIP or PDIP, top view) | |
| 3 | NONINVERTING INPUT | Noninverting signal input | source 5 Pin Configuration and Functions, p.3 (NAB package, 8-pin CDIP or PDIP, top view) | |
| 4 | V- | Negative supply voltage | source 5 Pin Configuration and Functions, p.3 (NAB package, 8-pin CDIP or PDIP, top view) | |
| 5 | OFFSET NULL | Offset null pin | source 5 Pin Configuration and Functions, p.3 (NAB package, 8-pin CDIP or PDIP, top view) | |
| 6 | OUTPUT | Amplified signal output | source 5 Pin Configuration and Functions, p.3 (NAB package, 8-pin CDIP or PDIP, top view) | |
| 7 | V+ | Positive supply voltage | source 5 Pin Configuration and Functions, p.3 (NAB package, 8-pin CDIP or PDIP, top view) | |
| 8 | NC | No connect, should be left floating | source 5 Pin Configuration and Functions, p.3 (NAB package, 8-pin CDIP or PDIP, top view) |
Build with it
Project ideas for the LM741CN op-amp. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- Buffer for a light-level divider: The LDR and a fixed resistor make a divider from the Uno 5 V pin. The op-amp wired as a follower repeats that voltage into ADC input A0, so the divider is not loaded. Two 12 V battery holders in series with the middle joined to Uno ground give about plus and minus 12 V, inside the recommended supply range (it falls below plus and minus 10 V as the cells drain). Input stays between 0 and 5 V, below the supply. Decouple each supply pin with a 0.1 uF capacitor from the pack. Learning project.
- A dark detector with an Arduino Uno, an LDR, a potentiometer and an op-amp comparator: Run open loop, the LM741 can act as a comparator (section 7.4.1), and its output swings close to the supply, positive or negative: on about +/-12 V rails the output reaches roughly +10 V or more (the +12 V minimum is for +/-15 V rails). A 1N4148 from the diode pack blocks the negative swing. After the diode, divide the positive swing with 10 k (from the output side) over 5.6 k (to ground), a ratio of 0.36, which gives about 3.5 V at +9.8 V and about 4.6 V at +12.8 V, enough to read HIGH on the Uno (3.0 V threshold) and under 5 V. Add a second 1N4148 from the D2 node to the Uno 5 V pin as a clamp. Never connect the op-amp output directly to a Uno pin. Supply is two 12 V holders in series (about plus and minus 12 V). Learning project.
- Filtered PWM level read back through a buffer: A resistor and capacitor from the packs smooth a PWM pin into a slow DC level. The op-amp follower isolates the filter from the load, and the level is read back on A1 and shown on the I2C LCD (a 5 V part). The output only goes between 0 and 5 V because the input does. Supply is two 12 V holders in series. Learning project.
Common mistakes
- Running it from a 3.3 V or 5 V board rail: the recommended supply for the LM741C is plus and minus 10 V to plus and minus 18 V, so a single low rail is outside that range (source: link, section 6.3).
- Expecting the output to reach the supply rails: with plus and minus 15 V and a 10 kOhm load the guaranteed swing is only plus and minus 12 V, less with a heavier load (source: link, section 6.7).
- Leaving out supply decoupling: the data sheet recommends a 0.1 uF capacitor on the supply lines, placed close to the supply pins (source: link, section 9).
Not covered by the official source
- Only the plastic-DIP package pinout was used; the exact LM741CN grade table is the LM741C table in the same document.
- No module facts are claimed; this is a bare chip.
Sources
- link (LM741 Operational Amplifier, SNOSC25D, May 1998, revised October 2015; chip maker)