2
\$\begingroup\$

I am using the TPS61236P from Texas Instruments to charge a phone from a 3.7V Li-ion battery. I have gotten it working to the point where I have a ~5.1V output through a USB port, going into the phone. The phone recognizes that it is charging, but AIDA64 outputs a very low charging current (20-100mA).

I am wondering if the problem is the fact that I am using the constant current mode of the boost converter, which I have set to 2A. I have used the TPS2514 from Texas Instruments as a USB port controller (2.7V to D+ and D-), and have even shorted the D+ and D- lines (after removing the TPS2514), with no better result. Is the constant current mode causing this issue, or would that not be a problem?

If not, is there anything else that could be related to the USB port/controller itself that would limit the amount of current the phone can draw?

EDIT: I should note I am using a Nexus 6P as the phone to charge, with the cable being a USB-A to USB-C M/M cable. I have had no problems with the cable when used with a commercial grade phone charger.

Schematic:Schematic

\$\endgroup\$
9
  • \$\begingroup\$ 100mA is the maximum un-enumerated USB current. Make sure the charger is recognized by the phone. Or maybe the phone is full? \$\endgroup\$ – Jeroen3 Jun 2 '17 at 5:34
  • \$\begingroup\$ With my charger disconnected, the phone discharges at a noticeable rate (~200-300mA). With my charger connected, it charges as stated above (~20-100mA). With a commercial 2A charger connected, it charges at around 1600mA. \$\endgroup\$ – Benjamin Owen Jun 2 '17 at 5:36
  • 1
    \$\begingroup\$ "I am wondering if the problem is the fact that I am using the constant current mode of the boost converter, which I have set to 2A" - 2A is just the maximum it will do (any attempt to draw more will cause it to lower the voltage so current doesn't exceed 2A). Since the phone won't draw more than 2A anyway, this should never happen. \$\endgroup\$ – Bruce Abbott Jun 2 '17 at 5:43
  • \$\begingroup\$ I am using the TPS61236P from Texas Instruments to charge a phone from a 3.7V Li-ion battery. What you write is not what the TSP6123P is intended for ! It is for charging a battery (which is not in a phone) from a power source, for example 5 V from USB. Include a schematic of what you made to confirm this or not. \$\endgroup\$ – Bimpelrekkie Jun 2 '17 at 5:46
  • 1
    \$\begingroup\$ @AngryCupcake274 - "AIDA64 outputs a very low charging current". I recommend not to use a mobile phone app like that, to report the current. I have used it when investigating mobile phone charging and found that it can report incorrect values. To prevent you being misled with potentially incorrect information from AIDA64, I recommend using one of the external USB current / power meters (test its accuracy using a lab PSU, multimeter and some known loads first, to get confidence in whatever you use). \$\endgroup\$ – SamGibson Jun 2 '17 at 12:26
4
\$\begingroup\$

Try placing a resistive load on the output of the converter that would draw a 1 amp load (about a 5 ohm, 10 watt resistor). This will tell you if it is a phone or converter issue.

If it doesn't output sufficient current under test, check your input supply voltage to make sure it is holding up under load. If this is OK, start checking your wiring and component values.

If the converter checks out under load, then the issue is with your phone. Many phones follow the USB protocols to check the supply's capability. If it fails to communicate with the supply, it will default to a minimum current to protect the supply.

\$\endgroup\$
5
  • \$\begingroup\$ It seems I don't have any 5-ohm power resistors on hand, but will order one and edit the main post with the result. \$\endgroup\$ – Benjamin Owen Jun 2 '17 at 5:56
  • \$\begingroup\$ you can use a few other power resistors to get 5, but anything under 50 will tell you if it can deliver more than the reported 100ma; do the math... \$\endgroup\$ – dandavis Jun 2 '17 at 6:09
  • 2
    \$\begingroup\$ I have read somewhere about some chargers having different resistor dividers on the D+ and D- pins to tell it at what rate to charge at (from 100mA up to 1.5A I believe) and it can vary with different phones. I done a project exactly like this for my college project last year and found my charging current issues to be down to this. \$\endgroup\$ – MCG Jun 2 '17 at 7:44
  • \$\begingroup\$ @MCG That's why I tried the TPS2514, but it seems that the Nexus 6P doesn't like 2.7V to D+ and D-. I will just have to play around with different dividers. \$\endgroup\$ – Benjamin Owen Jun 2 '17 at 17:18
  • 1
    \$\begingroup\$ @AngryCupcake274 there is information out there somewhere. A good starting point is shove a 200 ohm resistor across the D+ and D- pins with no voltage source. For the majority of phones (except apple) that will usually set them to charge at around 1A or 500mA depending on the phone. That should help as an indicator as to whether it is the divider or not. \$\endgroup\$ – MCG Jun 2 '17 at 17:28

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.