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TIC10024-Q1: Information on Multi Switch Detection devices

Warren Muir
Intellectual 515 points
Part Number: TIC10024-Q1
Other Parts Discussed in Thread: TIC12400, , TIC12400-Q1

To whom it may concern

I have a few queries related to Multi Switch Detection devices and specifically the TIC10024

1. Does TI have any integrated solution for switch-to-battery (STB) only inputs - the TIC10024 only has 10 configurable inputs and 24 switch-to-ground (STG). Our application requires 20 STB with limited PCB real estate. 

2. Can the STG input be configured to detect a STB, and if so how?

3. Can the TIC10024 be used in a 24V application?

4. When will production of the TIC10024 re-commence?

Many Thanks

Warren Muir

  • 0
    TI__Guru 68492 points

    Warren,

    An engineer has been assigned this thread and will reply by end of business CST on 01/26/2023.

    Regards,

    Eric Hackett 

  • 0 in reply to Eric Hackett
    TI__Mastermind 24110 points

    Hello Warren,

    1. No, all of TI's Multiple Switch Detection Interface (MSDI) devices only have 10 STB inputs.  (TIC10024-Q1, TIC12400-Q1, and TIC12400)

    2. The 10 STB/STG inputs have the ability to either sink, or source wetting current through the switch while making a voltage measurement on the INx pin. The other 14 STG only inputs only have the ability to source wetting current while making the voltage measurement on the INx pin. 

    However, all Inputs can have the wetting current disabled (set to 0mA) and the INx pin can be used only for a voltage measurement.  If the wetting current through the switch can flow to GND through an external current limiting resistance, then an STG only INx pin can be used to make a voltage measurement and determine the state of the switch.

    3. The TIC10024 is tolerant of 24V, but was designed to work in a 12V application where the battery is less than 16V for normal operation.  Prolonged exposure to higher voltages will not cause it to immediately fail, but it can reduce the lifespan of device. See this Application Brief discussing how to protect the 12-V MSDI Devices in a 24-V System. https://www.ti.com/lit/pdf/scpa061

    4. This device is currently in production with high demand.

    Does your application need an automotive qualified (Q1) device, or is it an Industrial application? 

    Do you need the device to supply the wetting current, or can this be supplied to the switches external to the detection device?

    For Automotive applications the TIC10024-Q1 and TIC12400-Q1 MSDI devices are our best options.  However, for industrial applications that do not require wetting current, the SN65HVS88x family of 8-channel Digital Input Serializers are often used such as the SN65HVS883.  These devices support a daisy-chain architecture for scalability as well as can work directly in 24V applications.  But they do not provide wetting current or programmable thresholds.  So they may or may not be an option for your application but you might want to check them out.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    Intellectual 515 points

    Thanks very much for the response Jonathan and the relevant information.

    I have considered the SN65HVS88x family, but the versatility of the TIC1xxxx range is more suitable for our application. I will review the application brief on the higher voltage use and make the call. I currently use a MAX16127 to control the voltage input, so am able to protect against over voltage.

    If a STG input is configured to read the input voltage, will the ADC value be proportional to the input. The reason for asking this, is that we currently use the MC33975 and were informed that we would be able to determine a switch-to-battery by just measuring the input voltage. However, the ADC is limited to 3V on that IC, and if an input is left floating, the op-amp outputs the max voltage. 

    Many Thanks

    Warren

  • +1 in reply to Warren Muir
    TI__Mastermind 24110 points

    Hello Warren,

    The ADC has a 0-6V range as measured at the INx pin.  There is an internal resistor voltage divider at the input of the ADC to scale the voltage down to safe level for the ADC so that an Input pin with an abs max voltage of 40V will not damage the ADC.  This voltage divider is made up of two 120k resistors for a total of 240k (typ) resistance between the INx pin and GND at the moment of sampling.  There is only one divider that sits between the MUX and the ADC so only the pin actively connected to the ADC will see the resistance and it will be disconnected from the INx pin for the rest of the polling cycle.

    This 240k resistance also limits current flow through the device during measurement, but does become part of the overall load being measured and in parallel to the external load.  For very accurate measurements such as an analog temp sensor, this would need to be considered.

    But the ADC is calibrated to report the voltage as applied to the INx pin and not on the ADC side of this divider. 

    If the voltage on the INxpin exceeds 6V, the ADC will return the max code of 0x3ff, or 1023 decimal.  This is twice the 3V from the MC33975, but an external divider could be used to scale this down to a 0-6V range.

    I will note that the device does also have a small amount of leakage current in the MUX circuit (+/-110uA max) that comes from the supply voltage which can cause an open or floating pin to output the max voltage code in the 0mA configuration. 

    This leakage current is only applied to the INx pin that is actively connected to the ADC which is typically only 24us out of the overall polling time (2ms to 4096ms).  This will mix with the current flowing from the external load and can result in a slight voltage offset in the ADC reading.  Without an external load or any pin capacitance to absorb this current, the ADC will effectively see the supply voltage on an open pin and report the max code.

    To prevent an open switch from reading a High voltage, a weak path to GND would be needed for this leakage current to flow out the INx pin along with a cap on the INx pin to stabilize the voltage on the INx pin.  A series resistor and cap are already recommended for ESD protection, but a weak pulldown resistor may be needed as well to discharge the charge the capacitor receives from this 24us pulse of current during the idle portion of the polling cycle.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    Intellectual 515 points

    Thanks very much for your response Jonathan. Wish we had received such detailed information from NXP before we decided to use their solution and waste over US$10k on boards and components.

    Two last little issues - do you know where I can get samples of the TIC10024 and when production will commence.

    Regards

    Warren

  • 0 in reply to Warren Muir
    TI__Mastermind 24110 points

    Hi Warren,

    You're welcome, I'm glad to help.  These devices are actually in production and have a high demand.  Unfortunately the global supply chain issues didn't help reduce the lead times on orders placed.

    I can check internally with the team to see if we have some samples.  How many samples would you need?

    Are you interested in the TIC10024-Q1, or the TIC12400-Q1?  The TIC12400-Q1 is the full-featured version with the ADC, and the TIC10024-Q1 is the reduced feature version without the ADC.

    You've asked for samples of the TIC10024-Q1, but it doesn't have the ADC.  Since you asked about the ADC I wanted to make sure you don't really want the TIC12400-Q1 instead.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    TI__Mastermind 24110 points

    Hi Warren,

    I checked the TI.com inventory and both the TIC10024-Q1 and TIC12400-Q1 are in stock so you should be able to order some sample devices of either type.

    Regards,

    Jonathan

  • +1 in reply to Jonathan Nerger
    Intellectual 515 points

    Hi Jonathan

    I would prefer the TIC12400-Q1 with the ADC, as that is crucial to our application. I would only need two samples to test on a proto PCB.

    Thanks

    Warren

  • 0 in reply to Jonathan Nerger
    Intellectual 515 points

    Hi Jonathan

    Unfortunately, timing is everything in the current silicon crisis. Just checked now, and there is no stock. Please let me know if there is anyone I could just get two samples (TIC12400-Q1) from to evaluate.

    Kind Regards

    Warren

  • 0 in reply to Warren Muir
    Intellectual 515 points

    I will keep checking the site periodically to see if stock appears.

  • 0 in reply to Warren Muir
    TI__Mastermind 24110 points

    Hi Warren,

    Interesting.  I don't see what you are seeing and instead see a positive TI.com inventory  for the TIC12400QDCPRQ1.  I will inquire with our marketing team about this.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    Intellectual 515 points

    Hi Jonathan

    Have been checking for last few days but still not stock - must be a function of my login.

    I have also tried to request samples, but says my organisation does not qualify. Quite frustrating since I have religiously used TI for the last 30 years, and buy quite a lot via the online store!

    Will keep checking. 

    Rgds

    Warren

  • 0 in reply to Warren Muir
    TI__Mastermind 24110 points

    Hi Warren,

    I'm sorry for the frustration.  I am not sure why you are not seeing the online stock, and I think you should.  I have brought this thread to the attention of our marketing team and asked them how we can get some samples to you. 

    I don't know if there is an issue with the system that can be corrected to allow you to see the inventory and order samples, or if they have an alternative preferred method to get some samples to you.

    I will keep you updated and hopefully have a solution very soon.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    TI__Mastermind 24110 points

    Hi Warren,

    Were you able to receive the samples?

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    TI__Mastermind 24110 points

    Hi Warren,

    Thank you for confirming through email that you received the samples.  I will now close this thread.  If you have any additional questions, please feel free to reach back out to us.

    Regards,

    Jonathan