説明

The SZ/NUP2105L has been designed to protect the CAN transceiver in high−speed and fault tolerant networks from ESD and other harmful transient voltage events. This device provides bidirectional protection for each data line with a single compact SOT−23 package, giving the system designer a low cost option for improving system reliability and meeting stringent EMI requirements.

 

特徴

350 W Peak Power Dissipation per Line (8/20 sec Waveform)
Low Reverse Leakage Current (< 100 nA)
Low Capacitance High−Speed CAN Data Rates
IEC Compatibility:
− IEC 61000−4−2 (ESD): Level 4, 30 kV
− IEC 61000−4−4 (EFT): 40 A – 5/50 ns
− IEC 61000−4−5 (Lighting) 8.0 A (8/20 s)
ISO 7637−2 Pulse 2a: Repetitive Load Switch Disconnect, 9.5 A
ISO 7637−3 Pulse 3a,b: Repetitive Load Switching Fast Transients, 50 A
Flammability Rating UL 94 V−0
SZ Prefix for Automotive and Other Applications Requiring Unique Site and Control Change Requirements; AEC−Q101 Qualified and PPAP Capable
これらのデバイスは鉛フリー、ハロゲンフリー/BFRフリーで、RoHSに準拠しています。

 

アプリケーション

Industrial Control Networks
– Smart Distribution Systems (SDS)
– DeviceNet™
Automotive Networks
– Low and High−Speed CAN
– Fault Tolerant CAN

 

アプリケーション

Background

The Controller Area Network (CAN) is a serial communication protocol designed for providing reliable high speed data transmission in harsh environments. surge protection diodes provide a low cost solution to conducted and radiated Electromagnetic Interference (EMI) and Electrostatic Discharge (ESD) noise problems. The noise immunity level and reliability of CAN transceivers can be easily increased by adding external surge protection diodes to prevent transient voltage failures. The NUP2105L provides a surge protection solution for CAN data communication lines. The NUP2105L is a dual bidirectional surge protection device in a compact SOT−23 package. This device is based on Zener technology that optimizes the active area of a PN junction to provide robust protection against transient EMI surge voltage and ESD. The NUP2105L has been tested to EMI and ESD levels that exceed the specifications of popular high speed CAN networks.

CAN Physical Layer Requirements

The ISO 11898−2 physical layer specification forms the baseline for most CAN systems. The transceiver requirements for the Honeywell Smart Distribution Systems (SDS) and Rockwell (Allen−Bradley) DeviceNet™ high speed CAN networks are similar to ISO 11898−2. The SDS and DeviceNet transceiver requirements are similar to ISO 11898−2; however, they include minor modifications required in an industrial environment.

EMI Specifications

The EMI protection level provided by the surge protection device can be measured using the International Organization for Standardization (ISO) 7637−2 and −3 specifications that are representative of various noise sources. The ISO 7637−2 specification is used to define the susceptibility to coupled transient noise on a 12 V power supply, while ISO 7637−3 defines the noise immunity tests for data lines. The ISO 7637 tests also verify the robustness and reliability of a design by applying the surge voltage for extended durations.
The IEC 61000−4−X specifications can also be used to quantify the EMI immunity level of a CAN system. The IEC 61000−4 and ISO 7637 tests are similar; however, the IEC standard was created as a generic test for any electronic system, while the ISO 7637 standard was designed for vehicular applications. The IEC61000−4−4 Electrical Fast Transient (EFT) specification is similar to the ISO 7637−3 pulse 3a and b tests and is a requirement of SDS CAN systems. The IEC 61000−4−5 test is used to define the power absorption capacity of a surge protection device and long duration voltage transients such as lightning.

Surge protection Diode Protection Circuit

surge protection diodes provide protection to a transceiver by clamping a surge voltage to a safe level. surge protection diodes have high impedance below and low impedance above their breakdown voltage. A surge protection Zener diode has its junction optimized to absorb the high peak energy of a transient event, while a standard Zener diode is designed and specified to clamp a steady state voltage.