Nexperia Augments its Line of CAN-FD Protection Diodes With New Leadless Additions

The AEC-Q101 qualified ESD protection diodes take up as little as 20% of the board space when compared to traditional SOT23 and SOT323 packages. 

 

Image courtesy of Nexperia

 

The new, leadless members of Nexperia’s PESD2CANFDx series sport a large internal lead frame that features a heat sink and a thermal pad. These enhancements enable improved thermal behavior despite the devices’ overall smaller size.

The PESD2CANFDx diodes feature a clamping voltage of 33 volts for a 8/20 μs pulse with an IPP of one amp. These electrostatic discharge (ESD) protection devices are specced for a mixed mode insertion loss of +20 dB at 300 MHz, leading to excellent signal integrity. 

 

The CAN-FD Bus

A look under the hood of a modern auto reveals that most of the mechanical signaling is gone, replaced with electric cables, which function as the vehicle’s “nervous system”. The present iteration is the CAN-FD (Flexible Data), which conveys information at speeds of up to 12 Mbit/s.

 

Image courtesy of Nexperia

 

High data speeds and an extremely “noisy” electrical environment add up to severe data integrity challenges. The PESD2CANFDx series of diodes are specifically tailored to provide the ESD/EMI protection needed by the CAN-FD bus to protect its vital data.

 

The Advantages Afforded by Leadless Diodes

An obvious advantage is smaller size. With a leadless component making direct electrical connection to the PCB under its body, the board space otherwise required by the leads is eliminated..

 

Image courtesy of Nexperia

 

The smaller size and the more intimate connection that a leadless package makes with a PCB also reduces parasitic capacitances, and thereby improves signal integrity.

 

Side Wettable Flanks Make Visual Inspection Possible

If the solder connection between the device and the board is made under the device, there is a problem in that the soundness of the connection is not directly observable, making inexpensive automatic optical inspection (AOI) impossible. The problem is solved by covering the vertical surfaces of the electrical contact pads with the same material used on the bottom pads.

The construct is described in an article describing another Nexperia device that employs it. The complete side pad surface is wetted with solder during the reflow soldering process. Thus, the success (or not) of the soldering step is easily observable. 

Commented Nexperia’s product manager Lukas Droemer: “CAN-FD is an important bus in automotive in-vehicle networks but devices must be protected against ESD. Another essential requirement for automotive applications is the ability to use AOI. Our new devices in leadless packages meet both these requirements, providing a high-performance alternative to leaded SMD packages. The PESD2CANFDx series fulfills all CAN (FD) specification requirements and exceeds the requirements of AEC-Q101 by two times.” 

 

Variations

There are twenty members of the PESD2CANFDx series. Eight of them are of the new leadless variety. Of those, four are housed in the DFN1110D-3 package, and the other four in the DFN1412D-3 package. The parametric search page provides easy access to all data sheets.

 

Physical 

The DFN1110D-3 and DFN1412D-3 are both plastic packages featuring side wettable flanks (SWF) for easy AOI

• The DFN1110D-3 features 0.65 mm pitch with a 1.1 mm x 1 mm x 0.48 mm body
• The DFN1412D-3 features 0.8 mm pitch with a 1.4 mm x 1.2 mm x 0.48 mm body