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TPS61241: Output Current - Maximum and Short Circuit

Ryan.Bishop
Expert 3900 points
Part Number: TPS61241
Other Parts Discussed in Thread: TPS61240

Hi! I have two questions regarding the TPS61241:

1. If there is a hard short on the output, what is the expected behavior?

-How much current will the device supply?

-Will it run continuously in current limiting mode?

-Will the device only shutdown if it reaches 140C junction temperature thermal shutdown?

2. Figure 1 of the datasheet shows the maximum output current vs input voltage. At Vin=3V, the maximum output current is listed as ~300mA. However, using equation 1 on page 10 with the following parameters, I calculate an output current of 516mA. (Vin=3V, Vout=5V, L=1uH, f=3.75MHz, Ivalley=.7A)

-Which limit should I use for the design?

Thank you!

-Ryan

  • 0
    TI__Mastermind 46905 points
    1. the device continuously limit the input current and don't switching at short circuit condition. but i need to further check the limiting value.
    2. the figure is the data from TPS61240, not TPS61241. i would suggest using the minimum value 600mA, not typical 0.7A, to calculate the maximum output current.
  • 0
    TI__Mastermind 46905 points
    the current limit value is approximately 90mA, and the device will stay at this mode if it is not thermal shutdown
  • 0 in reply to Jasper Li
    TI__Expert 3900 points
    Hi Jasper,

    Thank you for helping on this issue.

    1. On the TPS61241, the soft start current limit is 300mA. How does the device differentiate between a short and start up in order to have different current limits?

    2. To restate my question, sometimes the formula will give different max output currents than the datasheet figures. Which should I use as my design constraint?

    Regards,
    Ryan
  • 0 in reply to Ryan.Bishop
    TI__Mastermind 46905 points
    1. the startup of a boost converter divide into pre-charge phase and boost phase. the 300mA is the pre-charge current. the pre-charge current is related to the output voltage level. it is typical 90mA at VOUT=0 condition.
    2. the figure is normally measured in the EVM. we need to use the formula to calculate the worst condition with the data in the EC table.