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TPS731: Product Idea: Better than a PTC Fuse or eFuse – a very low short-circuit current TPS731xx LDO part

Part Number: TPS731

Multiple times, my designs have had switched power lines leaving an enclosure, going to Load Cells, I2C sensors on cables, and the like. These items require just tens of milli-amps of 5V power.

But I’ve never found ideal short-circuit protection solution to work at such low currents (25mA to 50mA). If external power wires inadvertently get shorted, it might hiccup the power system, affecting the micro-controller.

PTC fuses have too much resistance. Few of them are good for low currents and trip currents are variable.

I feel that an ideal solution might be a Very Low Drop-Out Regulator, such as the TPS731xx, but with a much lower short circuit current (50mA).

As such, the TPS731xx has a short circuit current far too high at 150mA to 300mA – that simply drags down everything on the 5V rail.

An ideal part for me would be a TPS731xx, with an output current of 35mA and a short circuit current of 50mA. Therefore, under short circuit conditions, a maximum of 50mA gets drawn - which won’t impact the main power supply.  

None of the eFuses appear to protect at these low currents (minimum appears to be 400mA).

Even better, the TPS731xx type part can also "switch" power - using the enable pin.

The other perfect feature is that it is a very low drop-out regulator. Having a low drop-out voltage of less than 50mV, means a 5V device can run off a 5V supply and still work properly.

Promote it as an Ultra low drop-out regulator, that can switch power and can act like a very low current PTC fuse – just far better than a PTC fuse solution.

Just take the TPS731xx design and reduce its current characteristics.

Could you please ask you product development people to have a think about this?


Peter Baxter

  • Hi Peter,

    We are reviewing your comments and will reply soon.  Please allow up to 2 business days for a reply.


    - Stephen

  • Hi Peter,

    I sent this information to our system engineering for consideration in future.  The issue with the current limit is that it is a protection circuit, which usually has a high tolerance.  A linear regulator, including the TPS731, would have to be designed to maintain lower than typical tolerance to meet this need.  It would require more than a current limit adjustment.

    If there is anything else I can assist with on the TPS731, please let me know.


    - Stephen