The emitter-base junction of a bipolar NPN transistor behaves as a zener diode, with breakdown voltage at about 6.8 V for common bipolar processes and about 10 V for lightly doped base regions in BiCMOS processes. Older processes with poor control of doping characteristics had the variation of Zener voltage up to +-1 V, newer processes using ion implantation can achieve no more than +-0.25 V. The NPN transistor structure can be employed as a surface zener diode, with collector and emitter connected together as its cathode and base region as anode. In this approach the base doping profile usually narrows towards the surface, creating a region with intensified electric field where the avalanche breakdown occurs. The hot carriers produced by acceleration in the intense field sometime shoot into the oxide layer above the junction and become trapped there. The accumulation of trapped charges can then cause Zener walkout, a corresponding change of the Zener voltage of the junction. The same effect can be achieved by radiation damage.
The emitter-base zener diodes can handle only smaller currents as the energy is dissipated in the base depletion region which is very small. Higher amount of dissipated energy (higher current for longer time, or a short very high current spike) will cause thermal damage to the junction and/or its contacts. Partial damage of the junction can shift its Zener voltage. Total destruction of the Zener junction by overheating it and causing migration of metallization across the junction ("spiking") can be used intentionally as a Zener zap antifuse.
| Part Nnmber | Manufacturer | Description |
|---|---|---|
| SMBG5356B | Micro Commercial Components | Watt Surface Mount Silicon Zener Diodes |
| SMBJ5356B | Micro Commercial Components | Watt Surface Mount Silicon Zener Diodes |
| ZMM10 | Diotec Semiconductor | Surface mount Silicon Planar Zener Diodes |
| MLL957B | Microsemi Corporation | LEADLESS GLASS ZENER DIODE SURFACE MOUNT |
| 1SMB5953BT3 | Motorola, | PLASTIC SURFACE MOUNT ZENER DIODES WATTS 3.3.200 VOLTS |
| CMZ5953B | Central Semiconductor Corp | SURFACE MOUNT SILICON ZENER DIODE WATT, THRU VOLTS TOLERANCE |
| ZMM27 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM2V7 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZM4744A | Diodes Incorporated | 1.0W SURFACE MOUNT ZENER DIODE |
| ZMM9.1 | Diotec Semiconductor | Surface mount Silicon Planar Zener Diodes |
| ZMM8V2 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM3.3 | Diotec Semiconductor | Surface mount Silicon Planar Zener Diodes |
| ZMM11 | Diotec Semiconductor | Surface mount Silicon Planar Zener Diodes |
| ZM4735A | Diodes Incorporated | 1.0W SURFACE MOUNT ZENER DIODE |
| ZM4746A | Diodes Incorporated | 1.0W SURFACE MOUNT ZENER DIODE |
| ZM4741A | Diodes Incorporated | 1.0W SURFACE MOUNT ZENER DIODE |
| ZMM3V3 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM12 | Diotec Semiconductor | Surface mount Silicon Planar Zener Diodes |
| ZMM13 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM16 | Diotec Semiconductor | Surface mount Silicon Planar Zener Diodes |
| ZMM33 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM3V6 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM4.3 | Diotec Semiconductor | Surface mount Silicon Planar Zener Diodes |
| ZMM43 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM4V3 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5223B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5224B | Jinan Gude Electronic Device | SURFACE MOUNT ZENER DIODES/MINI MELF |
| ZMM5225B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5227B | Jinan Gude Electronic Device | SURFACE MOUNT ZENER DIODES/MINI MELF |
| ZMM5228B | Jinan Gude Electronic Device | SURFACE MOUNT ZENER DIODES/MINI MELF |
| ZMM5230B | Jinan Gude Electronic Device | SURFACE MOUNT ZENER DIODES/MINI MELF |
| ZMM5231B | Jinan Gude Electronic Device | SURFACE MOUNT ZENER DIODES/MINI MELF |
| ZMM5232B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5234B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5237B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5240B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5241B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5242B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5243B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5247B | Jinan Gude Electronic Device | SURFACE MOUNT ZENER DIODES/MINI MELF |
| ZMM5248B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5249B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5250B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5254B | Jinan Gude Electronic Device | SURFACE MOUNT ZENER DIODES/MINI MELF |
| ZMM5256B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5257B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5258B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5259B | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5V1 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM5V6 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM6.8 | Diotec Semiconductor | Surface mount Silicon Planar Zener Diodes |
| ZMM6V2 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM6V8 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| ZMM9V1 | Diodes Incorporated | 500mW SURFACE MOUNT ZENER DIODE |
| CZRM27C200P | Comchip Technology | Surface Mount Zener Diode |
| CZRM27C20P | Comchip Technology | Surface Mount Zener Diode |
| 1SMA110Z | TRSYS | SURFACE MOUNT SILICON ZENER DIODE |
| MMBZ52 | Jinan Gude Electronic Device | SURFACE MOUNT ZENER DIODES/SOT-23 |
| MMBZ5221B | International Inc. | SURFACE MOUNT SILICON ZENER DIODES |
| MMBZ5221BS | Diodes Incorporated | 200mW SURFACE MOUNT ZENER DIODE |
| MMBZ5221BT | Diodes Incorporated | 150mW SURFACE MOUNT ZENER DIODE |
| MMBZ5221BTS | Diodes Incorporated | TRIPLE SURFACE MOUNT ZENER DIODE ARRAY |
| MMBZ5221BW | International Inc. | SURFACE MOUNT SILICON ZENER DIODES |
| MMBZ5222BW | International Inc. | SURFACE MOUNT SILICON ZENER DIODES |
| MMBZ5223B | Diodes Incorporated | 350mW SURFACE MOUNT ZENER DIODE |
| MMBZ5223BS | Diodes Incorporated | 200mW SURFACE MOUNT ZENER DIODE |
| MMBZ5223BT | Diodes Incorporated | 150mW SURFACE MOUNT ZENER DIODE |
| MMBZ5223BTS | Diodes Incorporated | TRIPLE SURFACE MOUNT ZENER DIODE ARRAY |
| MMBZ5223BW | Diodes Incorporated | 200mW SURFACE MOUNT ZENER DIODE |
| MMBZ5225B | Diodes Incorporated | 350mW SURFACE MOUNT ZENER DIODE |
| MMBZ5225BS | Diodes Incorporated | 200mW SURFACE MOUNT ZENER DIODE |
| MMBZ5225BT | Diodes Incorporated | 150mW SURFACE MOUNT ZENER DIODE |
| MMBZ5225BTS | Diodes Incorporated | TRIPLE SURFACE MOUNT ZENER DIODE ARRAY |
| MMBZ5225BW | Diodes Incorporated | 200mW SURFACE MOUNT ZENER DIODE |
| MMBZ5226BS | Diodes Incorporated | 200mW SURFACE MOUNT ZENER DIODE |
| MMBZ5226BT | Diodes Incorporated | 150mW SURFACE MOUNT ZENER DIODE |
| MMBZ5226BTS | Diodes Incorporated | TRIPLE SURFACE MOUNT ZENER DIODE ARRAY |
| MMBZ5226BW | Diodes Incorporated | 200mW SURFACE MOUNT ZENER DIODE |
| MMBZ5227B | Diodes Incorporated | 350mW SURFACE MOUNT ZENER DIODE |
| MMBZ5227BS | Diodes Incorporated | 200mW SURFACE MOUNT ZENER DIODE |
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