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TCAN4550: IIH of WAKE terminal in sleep mode

Hiroaki Yuyama TED
Expert 1720 points
Part Number: TCAN4550

Tool/software:

Dear, Interface Support team.

If I set WAKE = VSUP (same as the power supply voltage), will IIH be close to 0uA?
According to the datasheet, IIH is -15uA (TYP) at WAKE=VSUP-1V.

I would like to reduce the leakage current of the WAKE terminal when the TCAN4550 is set to SLEEP.
The current circuit pulls up the WAKE terminal to VSUP with 33kΩ,

and includes a transistor that sinks to GND via a 3kΩ resistor.
The customer circuit is the same as the recommended circuit.

・Application: Cycle computer Can communication unit Battery powered
・Target product: TCAN4550RGYR

Best Regards,
Hiroaki Yuyama

  • 0
    TI__Mastermind 33030 points

    Hi Hiroaki-san,

    I suspect the IIH current will be close to 0uA, but I don't have direct current data for WAKE=VSUP condition and I only have data that matches the datasheet test conditions (WAKE=VSUP-1V).  I will have to look into this before confirming.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    TI__Mastermind 33030 points

    Hi Hiroaki-san,

    hank you for your patience, I have been able to make some measurements in the lab and there are essentially three different regions.

    Using a power supply and current meter connected directly to the WAKE pin, I swept the voltage on the WAKE pin while monitoring the current.

    The WAKE pin input current is essentially static, or unchanging, when the WAKE pin voltage is within 500mV of either GND or VSUP. 

    0.5V < WAKE Pin Voltage < VSUP - 0.5V

    In this configuration, I measured 16.5uA in this static region (0.5V to 11.5V) using a 12V supply.

    I noticed the current reduced as the WAKE pin voltage was increased above 11.5V and became 0uA when the voltage became 12V (equal to VSUP), and also as the voltage was reduced below 0.5V and also became 0uA as the voltage became 0V (equal to GND).

    The datasheet test condition limits of VSUP-1V and 1V were likely set based on this static region where I am assuming the transistors are operating in a linear mode and not in a saturated mode that results when the voltage difference between VSUP and WAKE, or GND and WAKE becomes small.

    Before removing the 33k resistor (R44) on the TCAN4550EVM I used for this test with an external power supply, I measured the voltage on the WAKE pin and the drop across the R44 resistor to be 0.011V, which calculates out to approximately 0.33uA of input current to the WAKE pin.

    I hope that this addresses your questions.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    Expert 1720 points

    Dear Jonathan-san,

    Thank you for your support on my question.
    What was particularly important to my customer was that when the WAKE pin voltage and VSUP were the same, the IIH of the WAKE pin was 0uA.
    This was met, and when VSUP was 12V, the IIH was 16.5uA even though the WAKE pin was 0.5V to 11.5V. Thank you for the measurement results.
    Best Regards,
    Hiroaki Yuyama
  • +1 in reply to Hiroaki Yuyama TED
    TI__Mastermind 33030 points

    Hi Hiroaki-san,

    You're welcome.  I'm glad I could help.

    Best Regards,

    Jonathan