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TS5A3154: High current consumption

Expert 1435 points
user4725373

Replies: 7

Views: 722

Part Number: TS5A3154

Hi,

I have this circuit that I've found consumes 20 mA where it should consume 1-2 uA.

  • CONN_DETECT, CONN_VIN1, CONN_VIN2 are floating
  • Vcc = 3.3V
  • P1 is a header that I can short two pins together

When the P1 connector's P$2 pin = Vcc, there is an increase of 10 mA. I removed U2 and U3 and there was a decrease in current consumption of 20 mA. I've seen an E2E thread where the user was powering a switch with 10V, but controlling it with a 3.3V signal. Here, the switches are powered with 5.6V and controlled with 3.3V. Would that be the problem? The datasheet says that 2.4V < VIH < 5.5V, so it should be good.

Thank you,

Fred

Expert 1435 points
user4725373
  • Mastermind 43715 points
    Adam Torma

    Fred,

    Please see note 2 from the TS5A3154 datasheet.  If the digital control logic signals are floating or not at V+ or ground there will be excess current consumption through Icc.  If you place the logic at Vcc of the switch does this fix the issue?

    More information can be found in the application note.

    Thank you,

    Adam

  • Expert 1435 points
    user4725373

    In reply to Adam Torma:

    Hi Adam,

    Thanks for the answer. The control pins (EN, IN) are already either Vcc or GND, so that wouldn't be the case. As mentioned in my previous post, P1 is a header in which I'll short the P$2 pin either to Vcc or GND.
  • Mastermind 43715 points
    Adam Torma

    In reply to user4725373:

    Fred,

    Sorry for my confusion. I meant to ask what is the result if you control the IN and EN pins with the same voltage you are supplying to the switch IC.

    In the schematic above I'm interpreting that the switch supply voltage is a 5.6 V and the IN and EN pins are at 3.3V. Since 3.3V is not at the same level as the "Vcc of the switch 5.6V" I would expect some extra current consumption. Does the current consumption improve if you set the IN and EN pins to 5.6 V?

    If that doesn't explain the extra current, the next place I would look is U2 connection C2 to A1. It might be possible that signal path is connecting Vcc to CONN_VIN1 that could be connect to something drawing the extra current.

    Thank you,
    Adam
  • Expert 1435 points
    user4725373

    In reply to Adam Torma:

    Hi Adam,

    I can't really test that without removing parts or cutting traces on the PCB. However, I don't think your second guess is this, as CONN_V1 (pin A1 of U2) is floating.

    The internal schematic is not in the datasheet. From your perspective, is the more plausible cause of this extra current is the delta in voltage between IN/EN and V+?

  • Mastermind 43715 points
    Adam Torma

    In reply to user4725373:

    Fred,

    Unfortunately we don't give out our internal IC schematics to protect our IP.

    I think its plausible that the extra current is the delta in voltage between IN/EN and V+ but 20mA seems high to me. I can probably find out by ordering some ICs and putting them on the bench to see how much current they consume with a delta between V+ and IN/EN voltages.

    Thank you,
    Adam
  • Mastermind 43715 points
    Adam Torma

    In reply to Adam Torma:

    Fred,

    I have confirmed the extra current consumption is due to phenomenon stated in the app note above. For these types of devices we recommend setting the control voltage to Vcc or GND.

    I set Vcc = 5.5 V and IN =3.3 V
    I measured Icc = 4.7mA.

    If I set IN = Vcc
    I measure Icc = <1uA

    Since you are only passing 3.3 V signals through the switch could you set the switch V+ pin to 3.3 V? This will eliminate the extra current consumption.

    thank you,
    Adam
  • Expert 1435 points
    user4725373

    In reply to Adam Torma:

    Thank you for taking the time to do that.

    These switches were powered at 5.6V because they were used to route a signal that could go up to 5.5V. I'll think of something else on the next revision.

    Have a great day,

    Fred

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