TPS546D24AEVM: Controlling the output current.

Hi Amanda,

You shouldn't need to update anything to get more than 5A out of the EVM. The first thing to check is to make sure it is not related to the setup. My first suspicion would be the load or the wires to the load. If the voltage across the electronic load is to low, it will not be able to sink it's full current capability. This EVM also has a relatively low output of 0.8 V so it doesn't take much voltage drop across the wires to start hitting the limits of electronic loads. When I was first testing this EVM, I had trouble myself getting the full 80-A out of it due to the drop across the wires to the electronic load.

Also make sure the input supply is not becoming current limited.

Hope this helps.

Anthony

Amanda Lasko 

It may help Anthony and I assist you if we know more about what you are doing and what you are seeing.

The TPS546D24A is a voltage regulating controller, it is designed to produce a fixed, regulated output voltage.  The TPS546D24AEVM uses 2 of the TPS546D24A converters in a stacked configuration such that they are phase shifted and current share in order to supply upto 80A of load current.

As Anthony points out, the output voltage of the default EVM configuration is only 0.8V, so your load may not be capable of drawing more than 5A of load current from the 0.8V output.  If that is the issue, you will likely see the load current simply stop increasing, but the output voltage will remain steady at the programmed voltage.  You can test that by trying to increase VOUT from 0.8V to as high as 1.5V using the VOUT_COMMAND function.  If the issue is the compliance voltage of the load, that should allow you to draw more current.  A lot of electronic loads also have remote sense leads that connect to the load point rather than their input, this helps them sense the voltage without the drop of the connecting wires.  Sometimes connecting up those sense leads will allow the load to draw more current than it could with the voltage sense leads connected at the load's input.

If the issue is the sourcing (VIN) supply voltage, you will typically the sourcing supply drop out and an interruption in the output voltage as the sourcing supply drops out and recovers.  Similarly, if the converter is reaching it's own current limit, the output voltage will also collapse as the converter shuts down and then restarts.  Make sure the 5V input is connected to the green terminal blocks using wire that can handle the input current without allowing the supply voltage to drop out due to losses in the wires.

Hi Amanda Lasko, were you able to get this working?

Hi, 

I was able to get it working! I ended up having to shorten the length of the my wires on the output to minimize the voltage drop! I also had to increase the output voltage to 1V like you recommended because as you stated the load wouldn't change because the input voltage to the load was so low. 

Thanks for the help! 

Great! Glad to see you got this working. Thanks for the quick update.