Bidirectional Minimum Zener Diode Overview

Zener diodes are voltage-stabilizing diodes. They are semiconductor devices that have a high resistance until the critical reverse breakdown voltage. When the critical breakdown point is reached, the reverse resistance decreases to a very small value. Renesas Technology Corporation has introduced two new Zener diodes, the RKZ7.5TKP and RKZ7.5TKL, to protect the circuits of portable devices from internal or external electrostatic discharge (ESD) voltage deviations. The RKZ7.5TKP has a package size of only 0.6 × 0.3 mm, which is one of the smallest packages in the industry, and the RKZ7.5TKL also offers more package options. Samples of both products will be available in Japan from June 9, 2009. Below we introduce this bidirectional Zener diode with the smallest package in the industry.


I. Product Background
In portable devices such as mobile phones, the development trend of power supplies is to be compact, small and thin, and have more functions. The high mounting density required for mobile phones makes them more sensitive to static electricity generated internally or externally. Therefore, effective measures must be taken to prevent malfunctions or damage caused by electrostatic discharge (ESD). Since compactness is also a critical factor, Renesas has focused on reducing the size of Zener diodes, a component that is closely related to handling ESD, and has developed and mass-produced bidirectional Zener diodes that can do the work of two conventional diodes. The newly developed bidirectional Zener diode products are among the world's smallest packages while providing excellent ESD absorption capabilities.


II. Product Details
The main product features of the RKZ7.5TKP and RKZ7.5TKL are as follows:
(1) Among the smallest packages in the industry (RKZ7.5TKP)
The RKZ7.5TKP achieves a package size of 0.6 mm × 0.3 mm, 0.3 mm thick (typical), making it one of the smallest packages for bidirectional Zener diodes by using a base configuration in which the electrical contacts are located on the bottom of the device. This package is 70% smaller than Renesas' previous bidirectional Zener diodes, allowing customers to create even more compact products.
(2) Protecting devices from forward and reverse ESD by providing the same function as two Zener
diodes Bidirectional Zener diodes have some electronic properties that are different from conventional Zener diodes. They have Zener breakdown characteristics in both directions, making one bidirectional Zener diode equivalent to two conventional Zener diodes.
They are also able to protect current from both forward and reverse bias ESD. This means that a single bidirectional Zener diode can be used to protect an LED matrix circuit, for example, from reverse biased surround current, replacing two conventional Zener diodes. This reduces the total number of components and, therefore, the combined mounting area.
(3) Excellent ESD protection Superior ESD protection
has been achieved while maintaining excellent ESD protection through optimization of PN junction information processing conditions. The new bidirectional Zener diode meets the requirements of the electrostatic discharge protection test standard of Level 4 (contact discharge) in IEC61000-4-2.
(4) Environmentally friendly lead-free and halogen-free versions (RKZ7.5TKP)
The RKZ7.5TKP is packaged in MO6 (Micro Package 6), which uses a base electrode configuration and occupies a footprint of only 0.6 mm × 0.3 mm. The base (lead-free) is formed by gold plating, and the package body is made of halogen-free resin. This reduces the environmental impact of the product in both production and handling.
The RKZ7.5TKL is packaged in an EFP (Extra Small Flat Lead Package) (Renesas package code) with leads, size 1.0 (body size: 0.8 mm² × 0.6 mm). It is also a lead-free package, and Renesas plans to release a version using halogen-free resin material as the package body in the future.
Customers can choose from the above two package categories to match the characteristics and requirements of their respective products.
Renesas will continue to develop new bidirectional Zener diodes with lower Zener voltages to expand its product lineup for low-voltage portable devices. At the same time, Renesas is also actively working to reduce the variation in electronic characteristics of products to provide diode products with more flexibility.


III. Typical Applications
(1) Mobile phones, portable DVD players, game consoles, etc.
(2) LED protection


IV. Conclusion
This new Zener diode from Renesas plays an important role in improving the compactness of our products and reducing product failures and damage. Its smallest package and ESD absorption function technology will surely make this diode have a wide range of applications!