How to Read Diode Part Numbers — 1N4007 · S1M · SS34 · MBR · KBP · BZT52 · TVS part numbers explained
Picture: A customer holds an axial leaded diode 1N4007 in one hand and a small SMD diode M7 in the other and asks, “Are the 1N4007 and the M7 the same?” The staff member raises a finger and answers, “Both are 1000V 1A — only the shape is different.”
Diodes are the most common components, but their part numbering differs by family. In some part numbers the digits are the current and voltage directly (SS34 = 3A 40V), in others they are just a registration number (1N4007), and the same number can mean different things depending on the family (P6KE15A vs. SMBJ15A). Here is how to read the families you will meet most often in the field.
Values were checked against the manufacturer tables in the eGuro Semiconductor Library (WTE datasheets · Samyang diodes · Jingheng diodes). Click a part number to find stock in eGuro Part Search.
1. 1N part numbers (1N4007 · 1N5819 · 1N4148)
2. SMD rectifier diodes (S1M · ES1J · M7)
3. Schottky (SS34 · SB560 · MBR1045)
4. Bridge (KBP210 · GBU806 · KBPC3510)
5. Zener (BZT52C5V1 · 1N4733A)
6. TVS (P6KE · SMAJ · SMBJ) — the biggest trap
7. SOT-23 small-signal (BAT54A·C·S · BAV99)
1. 1N part numbers (1N4007 · 1N5819 · 1N4148)
| Part numbers | Current | Voltage VRRM |
|---|---|---|
| 1N4001 | 1A | 50V |
| 1N4002 | 1A | 100V |
| 1N4004 | 1A | 400V |
| 1N4007 | 1A | 1000V |
| 1N5400 | 3A | 50V |
| 1N5408 | 3A | 1000V |
| Part numbers | Type | Key point |
|---|---|---|
| 1N5817~19 | Schottky 1A | 20 · 30 · 40V |
| 1N4148 | Switching | 75V fast |
| 1N4728A | Zener 1W | 3.3V |
| 1N4733A | Zener 1W | 5.1V |
| 1N4764A | Zener 1W | 100V |
1N means a diode registered with JEDEC in the US, and the number after it is the registration number. You cannot calculate specs from the number, but within the same family, a higher number means a higher voltage: 1N4001 (1A 50V) → 1N4007 (1A 1000V), 1N5400 (3A 50V) → 1N5408 (3A 1000V). 1N5819 is a 1A Schottky (20 · 30 · 40V), 1N4148 is a fast switching diode, and the 1N4733A family are 1W Zeners.
2. SMD rectifier diodes (S1M · ES1J · M7)
| Part numbers | Breakdown |
|---|---|
| S1M | S (standard rectifier) · 1 (1A) · M (1000V) — SMD version of 1N4007 |
| S1J | 1A · 600V |
| ES1J | ES (super fast) · 1A · 600V |
| RS1M · US1M | RS fast · US ultrafast, 1A · 1000V |
| M1 ~ M7 | SMA (SMD) version of 1N4001–1N4007, M7 = 1A · 1000V |
For SMD rectifier diodes, the prefix = type, the number = current, the suffix = voltage. The voltage letters are A 50V · B 100V · D 200V · G 400V · J 600V · K 800V · M 1000V. So S1M = 1A 1000V, the SMD version of the 1N4007. The prefix indicates recovery speed: S (standard) · RS (fast) · US (ultrafast) · ES (superfast). M1 ~ M7 are part numbers that move the 1N4001~1N4007 directly into the SMA package.
※ Fast types with only a number, such as HER · FR · UF, differ by family: HER107 = 800V, HER108 = 1000V, UF4007 = 1000V. Always check the table.
3. Schottky (SS34 · SB560 · MBR1045)
The SS series is 1 digit of current + voltage (×10V): SS14 = 1A 40V, SS34 = 3A 40V, SS16 = 1A 60V, SS110 = 1A 100V. The axial SB series works the same way: SB560 = 5A 60V, SB360 = 3A 60V.
The high-current MBR follows IR (Infineon) part numbering rules, with current + voltage written directly: MBR1045 = 10A 45V, MBR20100CT = 20A 100V dual. The CT suffix means a center-tap (dual) type with 2 diodes inside, and B · F · D after MBR indicate the package (D²Pak · Full-pak · D-Pak).
4. Bridge (KBP210 · GBU806 · KBPC3510)
| Part numbers | Breakdown |
|---|---|
| KBP210 | KBP · 2(2A) · 10(1000V) |
| GBU806 | GBU · 8(8A) · 06(600V) |
| KBPC3510 | KBPC · 35(35A) · 10(1000V) |
| DF10S | DF · 10 (1000V) · S (SMD type) — 1A |
| MB10S | MB · 10 (1000V) · S (SMD) — compact |
For bridge diodes, the prefix = package (shape), the number = current + voltage code. The voltage code is 005 = 50V, 01 = 100V … 10 = 1000V. KBP210 = 2A 1000V, GBU806 = 8A 600V, KBPC3510 = 35A 1000V, DF10S = 1A 1000V (S is the SMD type). Even with the same current and voltage, KBP · GBU · KBU · KBPC differ in size and lead layout, so they cannot be swapped directly.
5. Zener (BZT52C5V1 · 1N4733A)
Zeners use V as the decimal point: 5V1 = 5.1V, 3V3 = 3.3V. The C in BZT52C5V1 is a voltage tolerance of ±5% (B is ±2%: BZT52B5V1). Even at the same 5.1V, size and power differ: 1N4733A (1W axial), MMSZ5231B (0.5W SMD), BZX84C5V1 (SOT-23).
6. TVS (P6KE · SMAJ · SMBJ) — the biggest trap
Picture: A customer holds a P6KE15A bag and an SMBJ15A bag and excitedly asks, “They’re both 15V, so they’re the same, right?” The staff member holds out both palms to stop him and answers, “The number 15 means something different!”
| Part numbers | Peak power | What 15 means | Breakdown voltage VBR | Working voltage VRWM |
|---|---|---|---|---|
| P6KE15A | 600W | VBR (breakdown) | 14.25 ~ 15.75V | 12.8V |
| 1.5KE15A | 1500W | VBR (breakdown) | 14.25 ~ 15.75V | 12.8V |
| SMBJ15A | 600W | VRWM (working) | 16.7 ~ 18.5V | 15V |
| SMAJ15A | 400W | VRWM (working) | 16.7 ~ 18.5V | 15V |
The number in P6KE · 1.5KE is the breakdown voltage (VBR), while the number in SMAJ · SMBJ · SMCJ is the working voltage (VRWM). P6KE15A starts conducting at 14.25~15.75V, but SMBJ15A does not conduct at all up to 15V and starts at 16.7V. Swapping one for the other shifts the protection voltage by about 2V.
- Prefix = peak power: P4 400W · P6 600W · 1.5KE 1500W, SMA(J) 400W · SMB(J) 600W · SMC(J) 1500W
- A suffix = narrow breakdown voltage range (P6KE15A 14.25~15.75V; P6KE15 without A is 13.5~16.5V)
- C · CA suffix = bidirectional (P6KE15CA). Without it, the part is unidirectional and must be mounted in the right direction
7. SOT-23 small-signal (BAT54A·C·S · BAV99)
A SOT-23 contains 1 or 2 diodes, and the suffix letter indicates the connection: BAT54 single · BAT54A common anode · BAT54C common cathode · BAT54S series. BAV99 is also a series type. Even if they look identical, a different suffix means a different circuit, so they are not interchangeable.
Sources: Won-Top (WTE) product specification tables · Samyang diode product tables · International Rectifier Schottky MBR Part Numbering System. Part numbering rules have exceptions in each family, so check the datasheet before actual use.