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TPS62260: Short circuit protection behaviour for TPS62260

Part Number: TPS62260
Other Parts Discussed in Thread: , TPS62170, TPS62175, TPS62821, TPS62147

Hi Sir,

I verified TPS62260 short circuit protection behaviour under the following condition.

DUT : TPS62260EVM-229 Rev.A

VIN : 6V, VOUT : 3.3V

Once I shorten this output (Vout to GND) while running, the short current (about 1.1A) draws continuously as below and it looks like the short protection circuit does not work at all.

Is this behaviour normal to tps62260?

I would like to turn the output off or hi-cup the output in this case, are there any way to solve this behaviour?

Moreover in terms of short circuit protection, tps62170/tps62175 are same behaviour?

Regards,

  • Hi User,

    Yes, this agrees with the current limit behavior described in section 8.4.4 of the D/S. Hiccup or latch off is not mentioned, so it should not be expected to behave this way.

    The TPS62821 is a newer, smaller, and more efficient device and it has hiccup current limit.

    For the higher Vin TPS621 devices, please see the newer, smaller TPS62147 with hiccup protection.
  • Hi Chris,

    Thank you for your quick reply.

    So you mean that it is normal behavior for TPS62260, isn't it? If so, how about TPS62170 and TPS62175?

    Unfortunately TPS62821 does not meet my spec, VIN=6V. Also I need "MODE" pin to switch PFM and FPWM manually.

    TPS62147 is too expensive for me. Any other devices you recommend?

    Regards,

  • Hi User,

    Yes, the behavior that you show is what the D/S describes for the TPS62260. It is limiting the output current. This is current limit and it is working. You should be able to look at the input current drawn and see it is very low since the output power (Vout (shorted) * Iout) is also low.

    You can read the other D/S to see if they meet your current limit needs. TPS62170 behaves similar, while TPS62175 operates with the current returning to 0 during each switching cycle. There is even a waveform showing you what the current limit operation looks like. Neither device has a MODE pin.

    What input power source gives you 6V? Or is this the maximum tolerance of the input source?

    TPS6209733 is 6Vin with a MODE pin and hiccup.
  • Dear  Chris,

    Thank you for your kind explanation.

    I understood those short circuit protection behavior for each devices.

    My 6V input power source is an another DCDC, so it's output tolerance is very small.

    It is still expensive for me to use TPS6209733, even it has a MODE pin.

    Regards,

  • Hi User,

    Why do you need hiccup current limit? What does this achieve in your system?

    What is your minimum load current? If it is high enough, you may not need a device with forced PWM mode.
  • Dear Chris,

    Sorry for late reply.
    I think hiccup current limit is more safer than this device's short circuit protection, but it depends on the system as you said.
    Anyway I will verify this feature in my system later.

    I need forced PWM mode in my system because this is more stable (less ripple) output even though it is not good efficiency.

    Regards,