How to Read Op-Amp and Comparator Part Numbers — LM358 · LM324 · LM393 · TL072: Channel Count Digits and Package Letters

Illustration: At an electronic parts shop counter, a customer holds up two 8-pin chips printed LM358 and LM393 and asks, "They both have 8 pins, so they're the same, right?" A female staff member in a red apron points at the two chips and answers, "One's an op amp, the other's a comparator!"

An op amp is an amplifier that boosts or filters small signals, while a comparator checks which of two voltages is higher and switches its output on or off. Part numbers like LM358 · LM324 · LM393 · TL072 are short and look alike, but the digits in the part number tell you the channel count and temperature grade, and the trailing letters tell you the package and packing. In particular, even with the same pin count, op amps and comparators have different output types, and 14-pin and 5-pin chips have different pinouts depending on the maker and series, so in many cases you cannot simply swap one for another.

All values were checked against TI · ST · onsemi · Analog Devices · Microchip · Nisshinbo (NJR) datasheets. Click a part number to look up stock in eGuro Part Search.

1. Decoding one part number (LM358DR)

Part numbers in this family follow the order [prefix] + temperature grade digit + function digits + package + packing. LM358DR is TI · 0~70℃ grade · dual op amp · SOIC-8 · 2,500-piece reel. Changing only the leading digit for the same function changes the temperature grade: LM158 (−55~125℃) · LM258 (−25~85℃) · LM358 (0~70℃) (per TI). Comparators follow the same rule, so LM193 · LM293 · LM393 are one family.

2. Channel count from the digits — 1 · 2 · 4

How many op amps are in one chip is built into the part number digits. Many series split them by the last digit 1 · 2 · 4, like TL07x (TI documents say "x is the channel count"), while others such as LM358 · LM324 use entirely different numbers. onsemi documents describe the LM358 as "half of an LM324". Some have separate numbers for automotive and wide-temperature versions: LM2904 = wide-temperature version of the LM358, LM2902 = wide-temperature version of the LM324, and for comparators LM2903 = LM393, LM2901 = LM339.

3. Op amps vs comparators — same outside, different output

The TI datasheet explains that the LM393 output is open-collector, so "a pull-up resistor can be connected to the desired logic voltage to match the level". The output transistor only sinks at least 6mA when Low, and almost no current flows when High, so without a pull-up resistor you get no High output. The LM358, by contrast, can also source current from its output (at least 20mA with a 15V supply). The two chips have identical 8-pin pinouts, so you cannot tell them apart on the board — always check the part number. The LM393's response time is about 1.3µs (TI · ST · onsemi typ).

4. Leading digits and grade letters — temperature · performance

Even with the same leading digit, the temperature range differs by maker. For the same LM2904, onsemi rates it −40~105℃, and only LM2904VDR2G with a V reaches 125℃. The supply range also differs: TI LM2904 is 3~26V, ST LM2904 is 3~30V.

• A — Grade with lower offset voltage. TI LM358 7mV → LM358A 3mV, LM393 9mV → LM393A 4mV (max)
• B (TI LM358B · LM393B, etc.) — New-generation version. Supply up to 36V (LM358B) · 38V (LM393B absolute max), ESD 2kV, LM358B GBW 1.2MHz
• V (TI LM2903V · LM2904V) — Version with a higher maximum supply (LM2903V 32V, LM2904V 30V)
• W (ST LM2904W · LM393W) — Enhanced-ESD version (HBM 2kV)
• E (onsemi LM358E) — ESD 2000V. The onsemi LM358DR2G is 250V, an 8x difference
• Y (ST) · NCV (onsemi prefix) · -Q1 (TI) — automotive (AEC-Q100)
• C · I · M (TL072, etc.) — 0~70℃ · −40~85℃ · −55~125℃ (TI). ST TL072I is −40~125℃

5. Package letters — different for each maker

At TI, 8-pin DIP is P and 14-pin DIP is N. But the NS in LM324NSR is not DIP but an SOP-14 reel, so judging by the N alone will mislead you. ST has dropped DIP from its current documents (SO8 is D/DT, TSSOP8 is PT, MiniSO8 is ST, DFN8 is QT), and onsemi writes D (SOIC) + R2 (reel) + G (lead-free), as in LM358DR2G. Microchip uses the order T (reel) · I/E (temperature) · /MS (MSOP-8), as in MCP6002T-I/MS, and NJR uses NJM4558M (DMP8) · E (SOP8) · V (SSOP8); the trailing -D is not a package but a grade selected for low noise.

6. Same "op amp", different performance

They are all "op amps", but their operating voltages and performance are completely different. The LM358 works up to 30V but its output does not swing all the way to the supply rail, while low-voltage types such as LMV321 · MCP6002 swing to the rail but must not exceed 5.5~6V. TL072 · NE5532 suit circuits with dual ± supplies. Don't substitute just because the part numbers look alike — check the supply range first.

7. Pinouts — the most dangerous trap

Dual-channel 8-pin parts share the same pinout regardless of op amp · comparator · maker, so plugging them in is easy (which is why the output difference in section 3 is even more of a trap). But for quad-channel 14-pin parts, the LM324 and LM339 have different power pins. If you plug an LM339 into an LM324 socket, power goes into the wrong pins from the start. Also, don't assume pin 4 of a 14-pin chip is ground out of 8-pin habit — on the LM324, pin 4 is the + supply.

The most dangerous is the single-channel 5-pin SOT-23. Even within TI, LMV321IDBVR has IN+ on pin 1, while TL071H · OPA333 have OUT on pin 1. Microchip has three versions of the same MCP6001 with different pinouts (MCP6001 · R · U), and in particular the MCP6001R has + supply on pin 2 and − supply on pin 5, so the power is reversed. For TL071H · OPA333, the SOT-23 and SC70 pinouts also differ from each other. For 5-pin op amps, check the pin diagram in the datasheet down to the last letter of the part number.

Illustration: A customer is about to plug an LM339 into a 14-pin socket on a board and asks, "I just pull out the LM324 and plug this in, right?" A female staff member holds out her palm to stop him and answers, "The power pins are in different places!"

8. Top markings on the chip

Large chips such as SOIC · DIP are printed with text resembling the part number, but small chips such as VSSOP · SOT-23 · DFN carry only short codes like M9P · RC1F · K5B, which you have to look up in that maker's datasheet marking table. TI's new LM358BIDDFR also has LM358 on top, the same as the old LM358DR, so you cannot tell from the marking alone whether it is the B version, and onsemi's NCV2903 (automotive) is also marked 2903V on top, so it cannot be distinguished by the surface alone.

9. Commonly searched part numbers explained

All of these part numbers appear letter for letter in the ordering information of each maker's datasheet. Even for the same LM358 SOIC reel, the ending differs: DR at TI, DT at ST, and DR2G at onsemi.

10. What to check when substituting

• Op amp or comparator — LM358 ↔ LM393 have the same pins but different outputs (comparators need a pull-up resistor)
• Channel count and pinout — 14-pin LM324 ↔ LM339 have different power pins; for 5-pin SOT-23, check down to the last letter of the part number
• Supply range — don't put a low-voltage type rated up to 6V in place of an LM358 used up to 30V
• Input/output range — whether the circuit needs the output to swing all the way to the supply (rail-to-rail)
• Temperature grade — even the same LM2904 · LM2903 is rated 105℃ or 125℃ depending on the maker
• Package and packing — go by the package name (SOIC-8 · TSSOP8 …) rather than the letter (D · P · N · ST), and check reel · tube quantities

Sources: TI LM358 (SLOS068AB) · LM324 (SLOS066AE) · TL072 (SLOS080W) · NE5532 (SLOS075K) · LMV321 (SLOS263Y) · OPA2333 (SBOS351E) · LM393 (SLCS005AH) · LM339 (SLCS006Z), ST LM358 · LM2904 · TL072 · LM393, onsemi LM358/D · LM393/D, Analog Devices OP07, Microchip MCP6001/2/4 (DS20001733L), Nisshinbo NJM4558 datasheets. Grades · packages · markings may differ by maker and product, so check the relevant datasheet before placing an actual order.