TPS2511 Current limiter?

Set Rilim=44.2k for 5W and Rilim-22.1k for 10W apps.

Remember that it is the phone that regulates the charging current (below ILIM). TPS2511 only acts as a limiter (above the ILIM set point). Try completely discharging the batteries on the phones, then charge them up.

Thanks Eric,

Will this work with the circuit suggested within the data sheet on page 20? 

The current is max at 0.4A on all devices I have tried (Samsung Galaxy Nexus, Nexus 7 and iPod Touch)

Regards

Chris

Yes, the circuits on pg 20 are all valid and have been tested/validated with many, many phones including the ones you list. Are you using the EVM hardware or your own circuit? Make sure to check the hookup of the DM/DP lines from TPS2511 to USB connector as this hookup changes depending on whether you are configuring for 5 or 10W PD's (note the changes in each of the four figures on pg 20).

Thanks Eric,

I think i know what I have done wrong, I believe the DP and DM pins are mixed up. Thats the only part of the circuit I am still yet to check. I'll swap them over and see if that helps the situation. 

C

I have change RIlim to 22k however I am still having the same issue. Is there anything else you can suggest?

Regards

C

Eric Wright said:

Yes, the circuits on pg 20 are all valid and have been tested/validated with many, many phones including the ones you list. Are you using the EVM hardware or your own circuit? Make sure to check the hookup of the DM/DP lines from TPS2511 to USB connector as this hookup changes depending on whether you are configuring for 5 or 10W PD's (note the changes in each of the four figures on pg 20).

Hi Eric,

I am still having issues with the TPS2511, it still charges at no more than 500mA. i have also noticed that the Datapins have no effect on the charging of the device. What do you suggest?

Kindest Regards

Chris

Hi Chris,

From your description you have tried multiple PD's (phones/portable devices) using the same charging circuit, and in every case the charging current never exceeds 0.43A correct? If so, this seems to point to your charging setup. Please furnish the following information so we can dig into this further.

• How many samples does this occur on? If one, then maybe there is a damaged component. If more than one, then it points to a design problem.
• Detailed schematic of the entire test setup including the following:

• Power source: Lab supply? If so, what is the current limit set at? Wall adapter? If so, what is the current limit? PC or laptop source? What is the current limit? Many times if the power source is not sufficient, then the input voltage (to the charging circuit) droops (below UVLO) and resets the power switch.
• TPS2511 circuit schematic and PCB layout. Are you using the TI EVM or your own layout? If using your own layout/schematic, please provide any and all details. 
• Interconnect: How is the power source connected to the TPS2511 circuit? How long are the wires? Describe the connection to the portable device. is it a long cable or directly connected. Pictures are always nice.

• Test data - Provide annotated oscilloscope waveform data (the more detail you provide, the more we can help):

• Power switch current (this provides significant information about how much current the PD is requesting from the charging circuit). Measure this current as close to the IN pin (between IN capacitor and TPS2511 IN pin) as possible, or at the OUT pin (between TPS2511 and the output capacitors).
• Voltage activity on the DP and DM pins when the portable device is communicating it's status to the TPS2511. This is important as we can gather information about the transaction between the PD and the TPS2511 (how much charging current is the PD requesting). Since the transactions are fairly slow, you will have to adjust the timebase until you capture the activity (100's of milli-seconds). It may take several tries to sequence the events, but give it your best try.
• Power switch voltage at both IN and OUT pins during the course of the test. Try to capture events that could cause the IN voltage to droop below UVLO (will cause chip to reset). You may have to zoom in on events depending on the scope timescale. Your circuit must provide a stable IN voltage source.
• Are you using the CSb pin? If so, please provide information about activity on that signal. This could provide information about what the TPS2511 thinks the switch current is at.
• Is the EN pin being used? Please provide any significant detail about this connection. Noise on EN can also cause problems.

Good luck!

Hi Eric,

Thanks for your response, I will reply next week when I have had the chance to troubleshoot my circuit further then get back to you.

Kind Regards

Chris

Hi Eric,

I believe the problem lies in that the circuit is being supplied with an Emerson  ASA01A18-L  converter which only offers a max 1A output. So for example my Samsung galaxy nexus draws 500mA from the standard wall plug, and roughly the same from my circuit. 

Do you suppose this is the issue which is limiting the current? 

EN has a 1k reistor to the supply.

Regards

Chris

This could very well be the issue. If the input supply is folding back, the portable device may see the voltage droop and never use full charge current. The "i" products monitor Vbus very closely and will change their behavior when the voltage droops too low.

Can you try a lab supply with at least 3A current capabillity? When the OUT capacitor is charged, you can get inrush current up to the TPS2511 ILIM setting (could be over 2A for 10W mode).

Hi Eric,

I have isolated the USB charging part of the circuit and have hooked it up to a 2.5A max supply. Using a clamp meter connected to my oscilloscope I am getting a peak of 510mA.

The out capacitor is 22uF electrolytic - Is this the right one? 

Chris