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TPS65281: latching of buck controller, current control for buck controller

Schroedinger Karl
Prodigy 160 points
Part Number: TPS65281
Other Parts Discussed in Thread: TPS55330,

I am using only the buck circuit of this device (as I use it with about 10V output voltage). It seems  there is a latching also in the buck circuit (e.g at an overload, also sometimes at power up), which can be reset by toggling the EN (buck). In the data sheet it seems the latching is located in the switch (only). 

Is there any application for a current output using  for the buck circuit only, at about 10V output voltage? I plan to do it using an external OPAMP, using the COMP as an input. (I did this with the TPS55330 and it worked). I probably will use TPS65281-1. 

Thanks.  

  • 0
    TI__Expert 6425 points
    Hi Kaschroed,
    I'm a little confused about your question. Can you explain it in detail?
    BRs,
    Edwin.
  • 0
    TI__Mastermind 19080 points
    Hi,

    Are you going to build an external EA loop with an OPAMP? I think it's OK to do so.
    Can you post your schematic here or send it to me? I'd like to check the schematic first. My email is sam.zhang@ti.com. Thanks!

    Regards,
    Hao
  • 0 in reply to Edwin Zang
    Prodigy 160 points
    o.k., regarding TPS25281:
    1. question: does the buck controller have a Current Latch-Off Protection or only the switch? I recognized for the buck controller something like a latch functionality during over current similar to what was describes for the switch in the data sheet.
    2. question: Is it better to used the TPS25281-1 to avoid the latch (although there should be no latch)?
    3. question: Is there a simple current limit application or poposal for the buck only (no using the switch)?
    BR kaschroed
  • 0 in reply to Schroedinger Karl
    TI__Genius 15135 points

    Hi, Sir 

    1. When buck converter of TPS65281/-1 triggers over current protection, it will work in hiccup mode: buck will shut down for 10msec, then try to startup......IC repeats this process untill over current condition is removed, so IC can resume to normal working. See the details in datasheet page21: Short Circuit Protection, and Figure16. 

    The SWITCH of TPS65281 is over current Latch-Off Protection. 

    The SWITCH of TPS65281-1 is over current Auto-Recovery, see the Figure 24~26. --> it is similar as buck over current hiccup mode. 

    2. Yes, recommend to use TPS25281-1, its SWITCH is no latch(Auto-Recovery). 

    3. Buck peak inductor current limit is fixed at 4A(typical). 

    The resistor connected to Rlim is for setting current limit for SWITCH. 

    If you no use SWTICH, you can float its related pins except EN_SW set to low.