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Accecptable supply voltage

Hi,

I want to know what is the accecptable supply voltage range for the following devices as I have to choose negative 5 volts regulator which is hard to find for the required current rating (I need 2A current for these devices) :

1. ADA4412-3

2. ADV3225

3. AD8145

4. AD8146

5. AD8062

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  • All these devices list voltage rail limits and output current limits in their respective data sheets

    Each device has a quiescent current plus you must add in the load current.  Just looking at the ADA4412, the max. quiescent current is 56mA and for an absolute worst case load of 150 Ohms at 2V peak on each output pin, load current = 3 x 2/150 = 40mA.

    Without knowing your design I do not know how you came up with 2A current.

  • I am using these parts with following quantity:

    S.No. Part number Qty
    1 ADA4412-3 4
    2 ADV3225 3
    3 AD8145 13
    4 AD8146 7
    5 AD8062 1

    So that is how I have come up with a value closer to 2 Ampere. Let me know what is the tolerance of negative input voltage for these ICs?

  • With that many devices it is very likely the -5V rail will require 2A.

    For this application the rail voltage can be +-5V +- 10% and you should not see any issues.  Normally we design closer to +-2% tolerance.

    My suggestion is build a spread sheet with each device, their quantity, quiescent current and load current number.  Sum this all up and determine the required system rail currents.  

    For these loads I'd recommend going with a switching regulator.  We have many to choose from.

    These video parts have good PSRR numbers but it always best to keep the power rails as clean as possible.

  • Thanks. Based on your suggestions I have made a table with the values I could find in the datasheet. Kindly validate it & correct me if I am wrong.

    S.No component    CURRENT (in mA) page number in datasheet
    1 ADA4412-3ARQZ Linear Output Current per Channel (3 channels used) 90 3
    Quiescent Current 56 3
    Total current for 1 IC 146  
    Total current for 4 Ics 584  
             
    2 AD8145YCPZ-R7  Output Current 50 3
    Quiescent Current 52 4
    Total current for 1 IC 102  
    Total current for 13 Ics 1326  
             
    3 AD8146ACPZ-R7  load / output current     
    Quiescent Current 62 4
    Total current for 1 IC    
    Total current for 7 Ics    
             
    4 ADV3225ACPZ load / output current    4
    AVEE, outputs enabled, no load 70  
    Total current for 1 IC    
    Total current for 3 Ics    

    I am unable to find the required values in the respective fields of AD8146 & ADV3225 so kindly help me out.

    For your clear understanding kindly see the connectivity of these ICs below & help me with the current calculation:

    The above block represents the way in which each IC is connected.

    I want you to help me find the current requirement of the above 4 blocks alone individually & I will manage the rest of the current calculation by multiplying it with the number of ICs that I am using.

  • For ADV3225, enabled, 150 Ohm load, 1vpp signal total current is 70 + 6.66mA

    For ad8146, enable, 8-150 Ohm loads, 1vpp signal, total current is 62 + 8 * 1 / 150 oHms = 115 mA.  Worst case with all outputs loaded at 150 Ohms.

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