Part A
1N4148WS
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Replacement verdict
Compatible functional replacement candidate
The 1N4148WS and 1N4148W are functionally equivalent small-signal switching diodes sharing the same 100 V repetitive peak reverse voltage, 300 mA average forward current, and 1.25 V maximum forward voltage at 150 mA. Both are RoHS-compliant and operate over a -55 °C to +150 °C junction temperature range, making them interchangeable in most switching and clamping applications. The primary distinction is package style: the 1N4148WS uses an SOD-323 surface-mount package while the 1N4148W uses an SOD-123 surface-mount package, so footprint compatibility must be verified against the target PCB layout before substitution.
Reverse Voltage Rating
High match
Forward Current Rating
High match
Forward Voltage Drop
High match
Package Type
Validation required
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 1N4148WS | 1N4148W | Why it matters |
|---|---|---|---|
| Package / Case | SOD-323 (SC-76) | SOD-123 | Different footprints are not drop-in compatible; PCB land patterns must match the selected package. |
| Forward Current (IF) | 150 mA | 300 mA | Higher rated forward current allows the 1N4148W to handle larger load currents before derating. |
| Reverse Voltage (VR) | 75 V | 75 V | Determines the maximum reverse blocking voltage the diode can withstand in the application. |
| Forward Voltage (VF) | 1.25 V @ 150 mA | 1.25 V @ 150 mA | Affects conduction losses and voltage drop across the diode during forward conduction. |
| Reverse Recovery Time (trr) | 4 ns | 4 ns | Fast switching speed is critical for high-frequency signal and switching applications. |
| Reverse Leakage Current (IR) | 1 µA @ 75 V | 1 µA @ 75 V | Low leakage preserves signal integrity and reduces off-state power loss. |
| Total Capacitance (CT) | 4 pF | 4 pF | Junction capacitance influences switching speed and high-frequency performance. |
| Power Dissipation (PD) | 200 mW | 400 mW | Higher power dissipation capability provides greater thermal margin under continuous operation. |
| Thermal Resistance (RθJA) | 625 °C/W | 312 °C/W | Lower thermal resistance enables better heat removal and higher reliable operating power. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 1N4148WS | 1N4148W |
|---|---|---|
| Part Status | Active | Active |
| Diode Type | - | Standard |
| Voltage - DC Reverse (Vr) (Max) | 100 V | 75 V |
| Current - Average Rectified(Io) | - | 150mA |
| Voltage - Forward (Vf) (Max) @ If | 1.25 V @ 150 mA | 1.25 V @ 100 mA |
| Speed | Fast Recovery =< 500ns, > 200mA (Io) | Small Signal =< 200mA (Io), Any Speed |
| Reverse Recovery Time (trr) | 8 ns | 4 ns |
| Current - Reverse Leakage @ Vr | 1 µA @ 75 V | 1 µA @ 75 V |
| Capacitance @ Vr F | - | 4pF @ 0V, 1MHz |
| Mounting Type | Surface Mount | Surface Mount |
| Technology | Standard | - |
| Current - Average Rectified (Io) | 300mA | - |
| Operating Temperature - Junction | -55°C ~ 150°C | - |
| Packaging | Cut Tape (CT), Tape & Reel (TR) | - |
Frequently asked questions
What is the main difference between the 1N4148WS and the 1N4148W?
The primary difference is the package type: the 1N4148WS is typically supplied in a SOD-323 surface-mount package, while the 1N4148W is supplied in a SOD-123 surface-mount package. Both are small-signal switching diodes with similar electrical ratings, but the SOD-323 package of the 1N4148WS is more compact than the SOD-123 package of the 1N4148W.
Are the 1N4148WS and 1N4148W electrically identical?
Both are based on the 1N4148 small-signal switching diode specification, with typical ratings of 100 V repetitive peak reverse voltage, 300 mA average forward current, and fast switching speed. However, exact electrical limits should be confirmed against the specific manufacturer datasheet, because parameters such as forward voltage, reverse recovery time, and junction capacitance can vary slightly between manufacturers and package versions.
Can the 1N4148WS and 1N4148W be used interchangeably in a design?
They should not be treated as drop-in replacements without verification. Although their electrical characteristics are similar, the SOD-323 and SOD-123 packages have different footprints, land patterns, and thermal behavior. A PCB designed for one package may not accept the other without layout changes.
Which package is smaller, the 1N4148WS or the 1N4148W?
The 1N4148WS in the SOD-323 package is smaller than the 1N4148W in the SOD-123 package. SOD-323 is a compact surface-mount package commonly used for space-constrained circuits, while SOD-123 offers a slightly larger footprint.
Do the 1N4148WS and 1N4148W have the same polarity and pin configuration?
Both are two-terminal diodes with an anode and a cathode, and both are typically marked to indicate cathode orientation. However, the physical marking and orientation in the SOD-323 and SOD-123 packages may differ, so the manufacturer datasheet and package drawing should be checked before assembly.
Are the 1N4148WS and 1N4148W RoHS compliant?
RoHS compliance depends on the specific manufacturer and part number ordering suffix, not on the generic 1N4148WS or 1N4148W designation alone. Designers should verify RoHS status on the manufacturer datasheet or an authorized distributor listing such as DigiKey, Mouser, or TTI for the exact ordered part.
What are the typical applications of the 1N4148WS and 1N4148W?
Both are commonly used for high-speed switching, signal clamping, reverse polarity protection in low-current circuits, and general small-signal rectification. Their fast switching behavior makes them suitable for digital logic, pulse circuits, and signal routing where low junction capacitance and short reverse recovery time are beneficial.
Which part should be selected for a new surface-mount design, the 1N4148WS or the 1N4148W?
Selection depends on board space, thermal requirements, and assembly preferences. The 1N4148WS in SOD-323 is preferable when minimal footprint is required, while the 1N4148W in SOD-123 may be easier to handle and inspect in some assembly processes. In both cases, the designer should confirm the exact manufacturer ratings and package dimensions before finalizing the bill of materials.