Discrete
Zener Diodes
Precision voltage references and clamping diodes for regulation and protection.
What is it?
A Zener diode is a heavily-doped diode designed to reverse-breakdown at a precise voltage and hold that voltage stable across a range of currents. Two main uses: (1) voltage reference / regulator, small Zener with a series resistor creates a simple regulated rail, and (2) over-voltage clamping on a signal or gate input, similar to a TVS but smaller and lower current.
When do you need it?
- Simple low-current voltage references (e.g., 3.3 V / 5.1 V) where an LDO is overkill.
- Gate-source protection on MOSFETs (clamping VGS during fault).
- Adjustable voltage offsets in op-amp circuits.
- Power-on bias for current-mode converters.
- Clipping or level-shifting in analogue signal paths.
How to pick the right one
- Zener voltage (VZ)
- The breakdown / regulation voltage. Magnias offers 2.4 V to 200 V.
- Tolerance
- The letter in the Magnias part number shows it: B = ±2% (e.g. PZD05B5V1-D2), C = ±5% (e.g. PZD03C5V1L). Some series use other codes, so check VZ min / max in the datasheet. For precision references go with the tightest tolerance.
- Power rating
- 100 mW (DFN0603-2L), 150 mW (SOD523), 200 mW (SOD323), 250 mW (DFN1006-2L), 300 mW (SOT23), 500 mW (SOD123-2L, SOD123-FL), 1 W and 2.3 W (SOD123-FL), 1 W and 1.5 W (SMA), 3 W (SMB). Match to your worst-case current × VZ.
- Temperature coefficient
- Zeners below 5.5 V have negative TC, above 5.5 V positive TC. At ~5.6 V the TC crosses zero, best for precision references.
What Magnias offers
Magnias offers Zeners from 2.4 V to 200 V, 100 mW to 3 W, in DFN0603-2L, DFN1006-2L, SOD523, SOD323, SOT23 (single and dual), SOD123-2L, SOD123-FL, SMA and SMB packages, with ±5% and ±2% tolerance. AEC-Q101 versions are available for several series (see the -A ordering code in each datasheet).
Common questions
Zener or LDO for a small reference rail?
Zener if load current is low (<5 mA) and noise / accuracy aren't critical. LDO if you need >5 mA, low noise, or tight regulation under load changes.
Can I parallel Zeners for more power?
Not directly, VZ has manufacturing spread, so one Zener will hog all the current. Use a current-sharing resistor in series with each, or pick a higher-power single device.
What's the difference between Zener and TVS?
Zeners are general-purpose, optimised for steady-state regulation. TVS are tuned for fast transients and high surge current, they have faster response and much higher peak current rating.