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TPS61391: TPS61391 power consomption at no load

ziad jabbour
Prodigy 100 points
Part Number: TPS61391

Tool/software:

hello 

i am working on a design where i should boost from 3V to 35 or 45VDC

i am using TPS61391, the load current is null ( less than 20µA) 

i tested the TPS61391-eval board and i noticed that the current consumprion of the evaluation board is 15mA at no load, 

i am operating on a very small battery that can't allow that current, 

the Iq of the tps61391 in the datasheet is <1mA

I did not found an explication for that, can you help to understand why the dev board is consumming 15mAon the 3V side ?

best regards

Ziad

  • 0
    TI__Mastermind 18940 points

    Hi Ziad,

    The TPS61391EVM has many additional function blocks, such as a positive charge pump to 70V, a negative charge pump to -35V, and APD power.

    If you use the boost function only, please try the modifications shown below and then measure the current consumption at no load again.

    Thank you.

      

    We have a long holiday here from Oct 1st to 7th, sorry the response may be delayed.

    Regards

    Lei

  • 0 in reply to Lei Zhong
    Prodigy 100 points

    Hello Lei 

    Thanks for your feedback 

    i desoldered the requested component, we passed to 10mA over 3V on the input 

    it still not acceptable for our design 

    do you have any idea why it is overconsuming ?

    best regards

    Ziad

  • 0 in reply to ziad jabbour
    TI__Mastermind 18940 points

    Hi Ziad,

    Let me double check on EVM after the holiday (back to work on Oct. 8th).

    Regards

    Lei

     

  • 0 in reply to Lei Zhong
    Prodigy 100 points

    Thanks Lei, enjoy your holiday and waiting for your feedback 

    best regards

  • 0 in reply to ziad jabbour
    TI__Guru 65450 points

    Thank you Ziad,

    Best regards,
    Brigitte

  • 0 in reply to ziad jabbour
    TI__Mastermind 18940 points

    Hi Ziad,

    I verified on EVM and observed similar input current when no load.

    The Rdson of TPS61391 is big. When Vin = 3V and Vout = 48V (For the EVM I verified, the Vout = 48V. When Vout = 45V or 35V, there should be the similar behavior) even there is no load, the device still works in DCM mode with frequency around 700kHz. So the efficiency is very low.

    That's why with a 0.34mA(from datasheet) internal Vout leakage, there will still be around 15mA input current was consumed.

    Will it be available to add a EN/disable signal in your application and disable the TPS61391 when there is no load?

    Regards

    Lei 

  • 0 in reply to Lei Zhong
    Prodigy 100 points

    Thanks Lei for your feedback 

    in fact i am using it at no load( 50µA load) 

    so i am interested to optimize the no load current 

    is there any solution from your point of view?

    best regards

  • 0 in reply to ziad jabbour
    TI__Mastermind 18940 points

    Hi Ziad,

    Is the 35V or 45V Vout needed all the time for the load? If the 35V or 45V Vout is needed only to active the load in short time, you may use an EN signal to enable/disable the device.

    If the device should be enabled all the time, sorry there may be no effective ways to decrease the input current.

    Other possible solution is to use a boost with pulse-skipping PFM mode and a charge pump to generate the 45V Vout. Following is an example. Could you provide more accurate for your Vin range? So I can search more suitable device if this solution is acceptable.

    Regards

    Lei

  • 0 in reply to Lei Zhong
    Prodigy 100 points

    Thanks Lei

    allow me to explain my need

    i have a small system powered by a 3V battery (so input voltage (2,5 to 3,5) nominal at 3

    48 times a day, for 5 seconds each time, i need to polarize an elctrode with high Voltage, the electrode current consumption <50µA

    so i need to creat a 40 or 60V with optimized power consumption at no load 

    can you help please

    best regards

    Ziad

  • +1 in reply to ziad jabbour
    TI__Mastermind 18940 points

    Hi Ziad,

    Thank you for your detailed information.

    If my understanding is correct, the real time that the 40V or 60V is needed to polarize the electrode is very short. Then in your system, will a IO signal be available to control the EN pin of TPS61391?

    If yes then I think the IO signal can be pulled low to disable the TPS61391 most of the time to save the battery power. The shut down current of TPS61391 is very small, 1μA max.  And only enable the TPS61391 "48 times a day, for 5 seconds each time". Or even the 48 x 5 = 240s per day high input current (~15mA) will be the concern?

    Regards

    Lei

  • 0 in reply to Lei Zhong
    Prodigy 100 points

    hello Lei, 

    i want to have a system with 3mA operational current max

    is that possible ?

    best regards

  • 0 in reply to ziad jabbour
    TI__Mastermind 18940 points

    Hi Ziad,

    When the EN is pulled down to disable the TPS61391, as my measurement on EVM, the total shut down current from the Vin supply is 16μA (7.5μA caused by the feedback resistors and the other major ones come from the input capacitor).

    That should meet your requirement.

    Regards

    Lei