AMIS LIN Transceiver Application Note EMC Conducted Susceptibility, IEC , Direct Power Injection

Transcription

1 1.0 Introduction The EMC conducted immunity can be significantly improved by terminating the LIN bus with a capacitor to ground. On one hand it will load the bus so the maximum value is limited to ensure τ < µs (see LIN Physical Layer Spec Rev..0, paragraph.1 LINE characteristics). On the other hand the higher the capacitor level, the more power can be injected in the system. Terminating the LIN output with a capacitor CL to ground improves the EMC conducted susceptibility to the levels indicated in Table 1. Table 1: Measured Levels of EMC Conducted Susceptibility CL Power Injected Frequency Range 1nF W 1MHz 00MHz > W 17MHz 90MHz.nF W 6MHz 00MHz > W 8MHz 00MHz.0 Measurement Set-up + V Vbat 100 nf 100 nf V CC V BB 7 8 INH DPI Anayzer TxD RxD 1 AMIS LIN R L,7 nf 0 pf EN GND C L PC Figure 1: Schematic Diagram DUT 1

2 Figure : DPI Analyzer Details Table : List of Measurement Instruments Used Instrument RF generator Switch unit Switch unit module RF amplifier Switch box RF power meter RF attenuator URV probes Accessories Description Rohde & Schwarz signal generator khz; 1.GHz SMT0 Agilent data acquisition / switch unit 970A HP 0 channel actuator / general-purpose switch 90A Amplifier research worldwide directional coupler MODEL DC010 (10KHz-1000MHz, 0W CW/0dB) Amplifier research worldwide microwave switches 8761A (DC-18GHz, 10W) Power load termination Narda MOD76BNM (DC-1.GHz, 0Ohm/0W) Amplifier research worldwide model A0A Wats 10kHz; 0MHz Amplifier research worldwide model 0A1000B 0Wats 10kHz; 1000MHz Power switch AMIS including directional coupler amplifier research Rohde & Schwarz power meter NRVD Rohde & Schwarz 6dB, input max. 0W, DC-GHz Rohde & Schwarz URV-Z

3 .0 Measurement Results Power injected in dbm and W in function of frequency with termination capacitor CL as a parameter EMC susceptibility - disturbance on LIN bus 0 0 Power [dbm] C_LIN = NA C_LIN = 1n C_LIN =,n Frequency [MHz] Figure : Power Injected in dbm

4 EMC susceptibility - disturbance on LIN bus.. Power [W] C_LIN = NA C_LIN = 1n C_LIN =,n Frequency [MHz] Figure : Power Injected in W.0 Recommendation At the master node a capacitor CL can be connected between LIN and ground still fulfilling the maximum time-constant of the bus. Giving next equations: As an example, one can calculate the maximum value for CL: 1 master slaves Line length = 10m C line = 100pF/m Cslave = 0pF Rslave = 0kΩ Rmaster = 1kΩ τ µs This yields in CL =.7nF. Click here for the Cmaster calculator. CBUS = CMASTER + n CSLAVE + C LINE LengthBUS τ = CBUS RBUS RBUS = RMaster RSlave1 RSlave... RSlave_n

5 .0 Company or Product Inquires For more information about AMI Semiconductor s CAN/LIN transceivers, send an to /sales. For more information about AMI Semiconductor s products or services visit our Web site at Revision History Revision Date Modification.0 Apr. 00 Initial release.0 Sept. 007 Devices sold by AMIS are covered by the warranty and patent indemnification provisions appearing in its Terms of Sale only. AMIS makes no warranty, express, statutory, implied or by description, regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. AMIS makes no warranty of merchantability or fitness for any purposes. AMIS reserves the right to discontinue production and change specifications and prices at any time and without notice. AMI Semiconductor's products are intended for use in commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment, are specifically not recommended without additional processing by AMIS for such applications. Copyright 007 AMI Semiconductor, Inc.