1N4478US

Single Zener Diodes Overview

The Microchip Technology 1N4478US is a surface mount Zener voltage regulator with a nominal breakdown voltage of 36 V and a maximum power dissipation of 1.5 W at 25 °C ambient temperature. It features a standard voltage tolerance of ±5% and a maximum dynamic impedance of 27 Ohms at the test current of 7.0 mA. The device operates within a junction and storage temperature range of -65 °C to +175 °C, utilizing a hermetically sealed void-less glass package.

Single Zener Diodes Feature Summary

• Hermetically sealed construction using void-less hard glass with an internal metallurgical bond for high reliability.
• Military qualification per MIL-PRF-19500/406 standards suitable for applications where failure cannot be tolerated.
• Inherently radiation hard design as described in Microsemi MicroNote 050.
• Triple-layer passivation and extremely robust physical construction.

Single Zener Diodes Applications

• Voltage regulation over broad operating current and temperature ranges
• High-reliability military and aerospace electronic circuits
• Radiation-hardened system designs

Single Zener Diodes Procurement Notes

Verify that the specific ordering suffix matches the required reliability level (JAN, JANTX, JANTXV, or JANS) and tolerance code. Confirm RoHS compliance status if applicable, noting that compliant versions are available on commercial grade only. Ensure the package type corresponds to the D-5A MELF surface mount configuration specified for this part number.

Single Zener Diodes Selection Notes

Select this component when a 36 V Zener reference is required in a surface mount form factor. Consider the 1.5 W steady-state power dissipation limit and the thermal resistance characteristics for heat management. Verify that the ±5% standard tolerance meets circuit requirements, or select tighter tolerance variants if necessary.

Single Zener Diodes Part Context

This device belongs to the 1N4460US through 1N4496US series of industry-recognized 1.5 watt Zener voltage regulators. These components serve as surface mount equivalents to popular JEDEC registered axial-lead series, offering similar electrical performance in a compact SQ-MELF package.

Single Zener Diodes Replacement Considerations

Equivalent parts include JAN1N4478US, JANTX1N4478US, JANTXV1N4478US, and JANS1N4478US from Microchip Technology. Other manufacturers may offer compatible 1N4478 devices, but verify MIL-PRF-19500/406 qualification and package dimensions for direct replacement.

Single Zener Diodes FAQ

What is the maximum continuous Zener current for the 1N4478US?

The maximum continuous regulator current (IZM) is 40 mA.

How is polarity indicated on the 1N4478US package?

Polarity is indicated by a band marking on the cathode end of the device.

Is the 1N4478US sensitive to electrostatic discharge?

No, the device is non-sensitive to ESD per MIL-STD-750 method 1020.