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ADG419 Asymmetric Supply

Hello,

can I safely use the ADG419BR or BRZ analog switch with:

Option 1:

 - asymmetric +5V and -22V supplies and VL = 5V, or

Option 2:

 - asymmetric +3V and -22V supplies and VL = 3V

The data sheet specifies the part for +/-15V and +12V. I know, that for other supply voltage values parameters can change, that's why my question is about safe use of that part.

Is it possible use the part with VL=2.7V?

Many thanks in advance.

Best regards.

Parents
  • Hi, PaulZ.

    I am checking with the team about the asymmetric supply and I will give you an answer as soon as possible.

    Regarding VL, you can indeed operate the device with different VL values. Please, refer to this Application Note for more insight on how it can affect the device's operation: https://www.analog.com/media/en/technical-documentation/application-notes/5480454737347503205AN680_0.pdf

    Yours sincerely,

    Igor Ono.

  • Many thanks for Your first reply. According to the AN-680 You mentioned, It looks that using +3V (against GND) as VL voltage is somewhat at the edge of VL specification. For this reason I consider an additional usage scenario, so here an additional question:

    It looks like I have to change my mind regarding the allowable negative supply measured to the GND pin of the ADG419. The new idea is to use +2.7V and -22V as supplies and connect the GND pin of the ADG419 to -2.7V. The control signal would be shifted to +/-2.7V. Do You see any problems with such usage scenario for the ADG419?

    Best regards.

  • Hi, PaulZ.

    I have a few questions about your application:

    • Is it possible to change the supply values? Or are those also the value of your signal range?
    • VSS as -22 V might be too high for the ADG419, so we cannot guarantee functionality at this voltage. Could you increase VDD to +9 V so you could use the ADG5419 and still maintain the VSS as -22 V?
    • Regarding this last scenario, would the +2.7 V and -22 V be measured to ground thus when measuring them to the new ground in the switch (-2.7 V), it would effectively be VDD = +5.4 V and VSS = -19.3 V?
    • What would be the voltage in the VL pin then?

    Yours sincerely,

    Igor Ono.

  • Hi Igor,

    many thanks for Your response,

    Regarding Your questions:

     - I unfortunately cannot change the VSS=-22V, but I have some headroom for changing the VDD.

     - I already looked at ADG5419, but compared with the ADG419 it dissipates a substantial amount of power (it draws something like 50 to 70 uA from VDD) an I have to count every uA.

     - Yes, in the last case the VDD against ground would be +5.4V and VSS against ground -19.3V (GND pin connected to -2.7V). The signal I intend to switch would be well within VDD and VSS.

    Best regards.

    Paul

  • Oh, I forgot the last question:

     - The VL pin would be supplied with the same voltage as VDD, which would also give the value of +5.4V measured against the GND pin of the ADG419, The control signal at the IN pin would be level-shifted to be at -2.7V (LOW logic level) and +2.7V (HIGH logic level).

    Best regards.

    Paul

  • Hi, Paul.

    Apologies for the delayed response.

    Regarding the ADG419, in this last configuration (ADG419 ground pin connected to -2.7 V), VDD and VL should not be a problem for this device, however, as VSS is still below -16.5 V, I do not have enough data that confirms that this device should be operational as seen in the datasheet.

    If you can increase VDD to +9 V and keep VSS above -22 V, then, I would recommend that you look at the ADG5419 for your application, as both supplies are within our tested range, thus, should be operational and reliable for you.

    With respect to power dissipation/current consumption, at the conditions presented in the datasheet, the ADG419 indeed has a lower current consumption. However, at your application supply voltages, this might change. Therefore, I recommend again to use the ADG5419.

    I hope this helps!

    Yours sincerely,

    Igor.

  • Hello Igor,

    many thanks for Your response.

    Unfortunately the ADG5419 power rating makes it impossible to use it.

    Regarding the ADG419, as I understand, I should not exceed 16.5V as the voltage between GND and VSS. This would be possible to me in a following way:

     - connect -22V to the VSS pin (actually it is enough for me to adjust this voltage to -21V)

     - apply -5.5V to the GND pin

     - apply +5.5V to the  VDD pin

     - apply +5.5V to the VL pin

     - provide a level shifted control signal to the IN pin being between -5.5V (GND pin potential) and +5.5V (VL pin potential).

    In this configuration VDD-GND = +11V, VSS-GND = -21V-(-5.5V)=-15.5V, VL = +11V

    Could You confirm that it would be safe to use the ADG1419 in this configuration?

    Best regards.

    Paul

  • Hi, Paul.

    Using a voltage lower than -16.5 V at the ADG419 VSS pin might work, however, we do not have any data to corroborate this, which is why I do not recommend using it at that condition.

    This last voltage setup should hit all the marks regarding the device's operability. I will talk to the team just to be sure and I will get back to you.

    Just to confirm, you are still referring to the ADG419 and not the ADG1419, correct?

    In this condition, you could look at the ADG1419. As long as your logic input HIGH is equal to VDD, then, your current consumption will be low as well, with the max consumption lower than the ADG419.

    Yours sincerely,

    Igor.

  • Hi Igor,

    many thanks for Your response.

    Yes, I am talking about the ADG419.

    However, I also could consider the ADG1419. I simply do not need the very low channel resistance of the ADG1419.

    Best regards.

    Paul

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