This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

  • TI Thinks Resolved

SN65HVDA1040A-Q1: CAN Driver TVS diode maximum Clamping voltage and Junction Capacitance

Prodigy 20 points
Arvind Munde

Replies: 2

Views: 58

Part Number: SN65HVDA1040A-Q1

We are using SN65HVDA1040A-Q1 with maximum data rate of 1Mbps. At bus terminals(CANH, CANL) we are using SMAJ24CA-E3 TVS diodes for protection. This diode have maximum clamping voltage of 39.8 V and Junction Capacitance above 2000pF to 3000pF.

1. The CAN Driver support maximum -27 V to 40 V Voltage on bus terminals(CANH, CANL).  So is there any problem in negative transient as maximum voltage is -27 V and clamping voltage is -39.8V.

2. The CAN driver is operating at 1Mbps, Is there any problem due to diode Junction Capacitance (2000pF to 3000pF).

3.  Also let me know typical Capacitor value in Split Termination

Prodigy 20 points
Arvind Munde
  • Mastermind 20850 points
    Eric Hackett

    Arvind,

    1. Yes, this may present issues with the delta in the absolute maximum rating and the clamping of the diode. The device pin will likely be damaged in the event of a negative transient greater than -27V, so the diode clamping at -40V won't help.
    2. This much capacitance added will distort the waveform but at 1Mbps the communication should still be okay. The problem is you're going to be severely limited on added capacitance on the rest of the CAN bus. I looked up this diode's datasheet and it looks like the junction capacitance is around 200-250pF, not 2000pF. Where was the 2000-3000pF value found?
    3. Typical capacitor value for SPLIT capacitance is 4.7nF, but it range from 4.7nF to 100nF. 

    Is there a particular reason the SN65HVDA1040A-Q1 was chosen? The TCAN1042-Q1 has the same pinout (minus the SPLIT pin, which isn't necessary for the TCAN1042), higher absolute maximum ratings on the CAN bus pins, higher ESD protection, and several other benefits. 

    Also, if you wanted to look into a TVS diode that had the same clamping voltage but lower capacitance, PESD1CAN is typically recommended.

    Regards,

    Eric Hackett

    Texas Instruments | INT-TRX| Applications Engineer

  • Prodigy 20 points
    Arvind Munde

    In reply to Eric Hackett:

    Thank you Eric for replay.

    Yes it is 250pF to 300pF. I will check possibility TCAN1042-Q1 and PESD1CAN.

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.


All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.

Content on this site may contain or be subject to specific guidelines or limitations on use. All postings and use of the content on this site are subject to the Terms of use of the site; third parties using this content agree to abide by any limitations or guidelines and to comply with the Terms of use of this site. TI, its suppliers and providers of content reserve the right to make corrections, deletions, modifications, enhancements, improvements and other changes to the content and materials, its products, programs and services at any time or to move or discontinue any content, products, programs, or services without notice.

TI worldwide | Contact us | myTI login | Corporate citizenship

TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs and
embedded processors, along with software, tools and the industry’s largest sales/support staff.

© Copyright 1995-2021 Texas Instruments Incorporated. All rights reserved.
Trademarks | Privacy policy | Terms of use