Fairchild Semiconductor 1N4730A-T50A-FS
Full Technical Specifications
9 Parameters| Parameter / Attribute | Specification / Value |
|---|---|
| Mounting | Through Hole |
| Voltage - zener (Nom) | 3.9 V |
| Current - reverse leakage @ vr | 50 µA @ 1 V |
| Power - max | 1 W |
| Operating temperature | -65°C ~ 200°C |
| Package | Bulk |
| Tolerance | ±5% |
| Case | DO-204AL, DO-41, Axial |
| Impedance (Max) | 9 Ohms |
Need Stock or a Drop-in Second-Source for 1N4730A-T50A-FS?
Package: DO-41 (DO-204AL) glass · Pin-compatible replacements with immediate Shenzhen spot stock
The 1N4728A to 1N4764A row is the general-purpose 1-watt zener drawer of every repair bench: 37 voltage steps from 3.3V to 100V in the DO-41 glass body, with the 5.1V 1N4733A the most ordered of them all. Two letters carry all the grading a buyer needs - the suffix letter is the tolerance (A = 5 percent, none = 10, C = 2, D = 1) and the middle digits are the voltage - and one lookalike carries the trap: the European BZX55 family covers the same voltages at HALF the dissipation in a smaller DO-35 body. The page exists for the swap where a 500mW part quietly replaces a 1W one and the rail drifts hot.
Verified Pin-Compatible Replacements (3 verified alternatives)
The European 500mW Counterpart
Shenzhen Spot Stock (24-48h Dispatch)
The European naming of the same voltage range: 5.1V nominal in a DO-35 body rated at 500 milliwatts - half the dissipation class of the 1N47xx row, with its own tolerance letters on its own datasheet scale.
Same voltage, different power: the substitution is a dissipation decision before it is a pin decision.
The Same Die for SMD Boards
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The surface-mount form of the same family: the same 1W 5.1V grade in the MELF body, for boards built after the through-hole era and for rework on them.
Identical electricals across the through-hole and MELF rows.
The 2 Percent and 1 Percent Grades
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The precision grades of the same voltage: C at 2 percent and D at 1 percent tolerance against the 5 percent of the common A suffix - exact drop-ins where accuracy was the design point.
Same nominal, tighter window: the grade buys certainty, not headroom.
Buyer & Quality Checklist for Sourcing Alternatives
- The suffix is the business letter: A is 5 percent, no suffix is 10 percent, C is 2 percent, D is 1 percent. The 1N4733A 5.1V window is 4.84V to 5.36V - a 10 percent stand-in widens that to nearly a volt of legal span.
- Voltage lives in the digits: 1N4728A is 3.3V and 1N4764A is 100V - 37 steps of the same glass body, sold in adjacency. Read the whole number; the drawer mix-up between neighboring voltages is the most common zener repair error there is.
- Power class is the body, not the name: this row is 1W DO-41; the European BZX55 line is 500mW DO-35 and the BZX85 line 1.3W. Substituting downward in power is legal only after the series-resistor current is computed against the smaller rating.
- The regulating current sets the resistor, not just the voltage: this family specifies its test current (49mA for the 5.1V part) - a repair that changes voltage but keeps the old series resistor can push the new diode out of regulation or into thermal drift.
- The 5.x V zeners sit near the temperature-coefficient sweet spot (around 5.6V): the near-zero drift is why designs picked them for reference-ish duty - moving the voltage away changes behavior beyond the nominal value.
- Glass bodies fail loudly and innocently: a cracked DO-41 from lead-forming stress reads open weeks later. Inspect and strain-relieve leads when replacing, and prefer MELF (AUR/MLL rows) only where the footprint exists.
Frequently Asked Technical Questions
Q: What does the A mean in 1N4733A?
A: Tolerance: A is plus or minus 5 percent. No suffix letter is 10 percent, C is 2 percent and D is 1 percent. The 5.1V 1N4733A therefore operates in a 4.84V to 5.36V window.
Q: Can I use a BZX55C5V1 instead of a 1N4733A?
A: The voltage matches but the power class does not: BZX55 is a 500mW DO-35 part against the 1W DO-41 of the 1N47 row. It works where the original ran cool, and drifts or fails where the series-resistor current actually used the watt.
Q: What is the voltage of a 1N4733A?
A: 5.1V nominal at a 49mA test current, with the 5 percent window spanning 4.84V to 5.36V, dynamic resistance around 7 ohms at that current. It is the most-ordered member of the 1N4728A-1N4764A 1W ladder.