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TPS54386 quiescent current

Tuan Pham
Intellectual 645 points
Other Parts Discussed in Thread: TPS54386, CC2540, TPS54240, TPS54260

Hi all,

I got problem with Iq (no load current) of TPS54386, I measured and the input current is too high: 20mA with no load in both 2 output pin, input voltage = 12V.

I used SwitcherPro to design this circuit with input = 12V ~ 25V, output1 = 4V/3A, output2 = 3.3V/2A. From datasheet I see the quiescent current is 5mA with open circuit of output inductors, I can confirm that this is right, 5mA with L1 and L2 are not mounted. But it becomes 20mA with L1 and L2 mounted and no load.

How can I reduce this no-load-current? I expect it is less than 5mA. Or can any one suggest me another switching regulator with low quiescent and dual 2.5A output?

Thank you.

  • 0
    TI__Guru**** 191445 points

    No load current is different than quiescent current.  You will still accrue switching losses at no load conditon so 20 mA seems about right.  You probaly want to consider a part with eco-mode or forced skip mode.  I do not think we have a dual converter available with Vin above 18 V.

  • 0 in reply to JohnTucker
    Intellectual 645 points

    Thanks JohnTucker,

    So I'm looking for another Step-down IC with ECO-mode.

    In my application, I have 1 GSM module (ON current is about 100mA/2.0A peak, sleep current = 2mA), and 1 BLE CC2540 (ON current is about 20mA, Sleep current is less than 1mA). GSM and BLE can work on same power supply 3.5V.

    There are 3 modes: full ON (GSM and BLE are ON), sleep1 (GSM sleep, BLE ON), sleep2 (GSM and BLE are sleep).

    Is there any Step-down device can supply on all 3 mode with consume current on it is less than 3mA? Is TPS54240 meet this requirement?

  • 0 in reply to Tuan Pham
    TI__Guru**** 191445 points

    TPS54240 may potentially meet your needs.  If I recall correctly there is an application note on GSM supply for TPS54260.  You can use the same approach for TPS54240.  There is one drawback to TPS54240; the eco-mode threshold is not very predictable.  At 3 mA load current you should be in eco-mode, but there is no guarantee of it.

  • 0 in reply to JohnTucker
    Intellectual 645 points

    Thank you JohnTucker,

    So I will try TPS54240 and feedback here later :)