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ISO1042-Q1: sleep mode

user5789841
Intellectual 285 points
Part Number: ISO1042-Q1

Hello TI Experts,

I have some questions about isolated CAN transceiver :

  • There is no "Wake PIN" OR "Inhibit Pin" available for ISO1042-q1, how to realize low quiescent current of system?
  • Can ISO1042-Q1 realize remote message wakeup? if yes, how to realize ? 
  • There is no "sleep mode" available for ISO1042-Q1, I would like to know how much current consumed in standby mode?
  • Why isolated CAN transceiver don't need consider quiescent current issue , as far as I know the most ECU has system sleep current requirement , for example , less than 100uA， but the isolated CAN transceiver has no sleep mode , I don't know how satisfy system sleep current issue ? Do you have any suggestion about sleep current issue for isolated CAN transceiver? 

Thank you!

  • 0
    TI__Expert 8030 points

    Hello,

    Thanks for reaching out.

    user5789841 said:
    There is no "Wake PIN" OR "Inhibit Pin" available for ISO1042-q1, how to realize low quiescent current of system?

    Since the ISO1042-Q1 is an isolator, the current consumption of Side 1 and Side 2 of the device will be independent from each other. As shown by the electrical characteristics section of the datasheet below, both Side 1 and Side 2 of the device will consume the lowest amount of current whenever the TXD pin of the transceiver is set to a logic high, and the CAN bus transitions to a recessive state. When the transceiver is in this state, Side 1 will consume a maximum of 2.1 mA and Side 2 will consume a maximum of 4.1 mA. 

    user5789841 said:
    Can ISO1042-Q1 realize remote message wakeup? if yes, how to realize ? 

    The ISO1042-Q1 does not have standby mode or a remote message wakeup feature. 

    user5789841 said:
    There is no "sleep mode" available for ISO1042-Q1, I would like to know how much current consumed in standby mode?

    As previously mentioned, there is no standby mode available for the ISO1042-Q1. The smallest amount of current that the device will consume will be when the transceiver is in the recessive state.

    user5789841 said:
    Why isolated CAN transceiver don't need consider quiescent current issue , as far as I know the most ECU has system sleep current requirement , for example , less than 100uA， but the isolated CAN transceiver has no sleep mode , I don't know how satisfy system sleep current issue ? Do you have any suggestion about sleep current issue for isolated CAN transceiver? 

    We believe that the current consumption of the ISO1042-Q1 is around the same as the current consumption as other isolated CAN transceivers in the industry that have a standby pin.

    Additionally, I would also like to point out that in order to maintain isolation, the ISO1042-Q1 needs to be powered by an isolated power supply. In some instances, an isolated DC/DC converter may consume more current than the ISO1042-Q1, and it also may not have any current saving mode similar to the "sleep" mode of a non-isolated CAN transceiver. As a result, even if an isolated CAN transceiver did have a low current consumption mode, the overall current consumption may still be large when you consider the potentially larger and continuous current consumption of the isolated DC/DC converter. Therefore, we believe that the ISO1042-Q1 current consumption should be low enough for most applications where an isolated CAN interface is required. 

    Regards,

    Kenneth

  • 0 in reply to Kenneth Arnold
    Intellectual 285 points

    Hello，

    Thanks for the feedback!

    The below picture shows the concept what I did, but issue is sleep current , I don't know how control the sleep current. because there no INH and Wakeup PIN available ... please give me some suggestion...

    To be honest I am not sure whether the isolated CAN transceiver really needed , because I only saw those requirements from customer specification:

     1.with galvanic isolation , (min.1500Vrms)

     2. Max.boot up time 1000ms

    3. CAN FD / CANopen /CAN 2.0b

    4. .....

    Thank you!

  • 0 in reply to user5789841
    TI__Expert 8030 points

    Hello,

    While the ISO1042-Q1 does not have a STB pin or "sleep mode" feature, it can have a low current consumption when compared with the typical current consumption of some isolated DC/DC converter. Additionally, isolated DC/DC converters usually do not have a current saving mode, so having an isolated CAN transceiver with this capability usually does not help reduce the overall current consumption of the system.

    Since the ISO1042-Q1 does not have a STB pin or "sleep mode" feature, you will need to consider another solution for reducing the systems current consumption during sleep mode, such as using an isolated DC/DC converter with a low current consumption mode, or using a load switch to turn off the power connected to this part of the system when it is not being used. 

    Regards,

    Kenneth