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TPS2066A Absolute Max Current Draw

SSF
Intellectual 2025 points
Other Parts Discussed in Thread: TPS2066A, TPS2066C

Hi Team,

We have a customer who is trying to determine what the absolute max current draw TPS2066A would allow. They are trying to see if they can drive the +5V line of two USB 3.0 ports (not going supporting high current charging) with it.

Early in the datasheet it is stated that the IC has a continuous current rating of 1.0 A, with a 1.6 A current limit per channel. But on page 3 min/typ/max values for various scenarios show higher limits.

Of greatest interest is the "Ganged overcurrent trip threshold" that has a max value of 4.9 A. What does this represent? They understand that OUT1 and OUT2 are tied together to drive a single load greater than 1.0 A; but then assume that a 2.0 A load would be the max that this chip would drive. So they are unsure of where the 4.9 A value comes from. Is it the absolute max, instantaneous current the chip is capable of supplying (assuming enough bypass caps nearby to supply the instantaneous current flow)? Or is there a possibility that it could  supply the 4.9 A for a period of time (seconds or even minutes)?

Appreciate your feedback here!

Regards,
Steve

  • 0
    TI__Mastermind 42795 points

    Hi Steve,

    Generally, the values given in the recommended operating conditions table define conditions over which the device can operate continuously for the duration of the device lifetime. Operating above these conditions will in general shorten the life. For this device, a continuous current of 1A max per channel is allowed (2A for ganged operation or putting two channels in parallel).

    The current limit of this device has two parameters, Ios and Ioc. The diagram below shows these two parameters graphically.

    The electrical characteristics table provides the guaranteed min, typ, max values per the test conditions as shown.

    Ios and Ioc define what happens when the load current exceeds the normal operating condition. For example, as the load resistance decreases, the current will rise until it hits Ioc and then will reduce to Ios as the device regulates current. Ios_g and Ioc_g are the values for both channels in parallel. 4.9A is the maximum ganged Ioc trip point.

    Load currents exceeding the recommended value but lower than Ioc can flow for extended duration's but are beyond the recommended rating of the device. This condition is not normally encountered in the routine application but could occur.

  • 0 in reply to SSF
    TI__Mastermind 42795 points

    Steve,

    I would recommend using the "C" family of devices which do not exhibit the peaking type of current limit. These have a nice flat current limit. See TPS2066C datasheet for examples.