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High current drawn randomly by TPS63000

Sriram V S
Prodigy 30 points
Other Parts Discussed in Thread: TPS63000, TPS63001

Hi,

i am using TPS63000 adjustable regulator to down-convert 3V from AAA battery (2 in series) to 2.7V for circuit operation. The circuit is designed exactly like the one in datahseet page#11 (http://www.ti.com.cn/cn/lit/ds/symlink/tps63001.pdf).

I am seeing high currents (more than 400mA to 1.2A) drawn by the regulator.. This behavior is very random since the current at most times is just 5mA. Since this is battery operated application, the cells heat up very quickly when this scenario occurs. The steel wire attaching the battery from holder to PCB heats up and has started melting the plastic enclosure.

As I said, this behavior is seen very random - happens once every 25 or so times. But, when this happens, the current stays high as long as the input is powered.

Another question was regarding R3 and C3 in the circuit in page#11. What is the use of this circuit? Can it cause the MOS gates to turn-on randomly during input transients? Is it only for power-on reset, similar to other devices which use this approach?

Regards,

Sriram V S

  • 0
    TI__Expert 7110 points

    The RC-Tank R3/C3 stabilize the voltage at the pin VINA in addition. The VINA-rail is the supply for the control stage and therefore very sensitive.

    Besides the Schematic, the Layout is a very important part of the power stage design. It's important to keep the passive components as close to the IC as possible. The EVM is a good starting point to make sure your layout is proper. This is where the files can be found: http://www.ti.com/product/TPS63000/toolssoftware

    Did you make sure to follow this approach?

    Do you see the behavior on the same physical board, or is it one out of several?

    Do you have any chance to observe the output of the device (voltage current)?

  • 0 in reply to Florian Feckl
    Prodigy 30 points

    1. This random behavior is seen on all boards (15 nos).

    2. The components values are selected as per datasheet.

    3. Passives are very close to the regulator pins and we have followed guidelines.

    4. I am getting the designed output voltage and the output current is consistent with my target device consumption.

    5. Only the input current shoots high randomly on power-on, even with no-load operation.

    - Sriram

  • 0 in reply to Sriram V S
    TI__Expert 5055 points

    Hi, 

    • can you explain your application in more detail? Do you enable/disable the device continuously?     (" 5. Only the input current shoots high randomly on power-on, even with no-load operation. ")
    • PS/SYNC Pin is connected to Vina as in datasheet page#11, right?