TUSB320: Unusual Charging Behavior

Hi Hamza,

Thanks for reaching out. Can you share the schematic as a PDF? Its difficult to see the details and net names in the image you show.

I have a couple questions to get a better idea of the issue:

Hamza Alpiyal said:

Some of the phones shows charging status but they give an option of slow charging. while the other phone do not even give the charging status

1. In your case some of the phones will charge and some will not when the CURRENT MODE is set to 1.5A?

Hamza Alpiyal said:

when I change them to 3A then none of the device shows the charging status

2. When you configure the CURRENT_MODE for 3A, then your phone does not charge from the port at all?

3. How do you control the Type-C VBUS? The VBUS should only be enabled when ID on the TUSB320 goes low.

Best,

Shane

Hello, Thanks for your time. Yes I am sharing my schematic in PDF so you can view it.

CO_Detector.PDF

The answers to your questions are below.

Shane Hauser said:

In your case some of the phones will charge and some will not when the CURRENT MODE is set to 1.5A?

1. Yes, I have set the CURRENT MODE to 1.5A (Code snippet attached below for configuring the current mode). Actually I was testing my circuit so I connected a phone from Xiaomi Redmi Note 12. While the other phone was from Apple which is Iphone15. When I connect the cable, Xiaomi  phone shows the status of charging but after around 1 min it shows a message which says that "Phone charging slowly. Check your cable or charger". While on the other hand Apple device doesn't even shows the charging status. I have also connected a Samsung Phone it was also showing slow charging status. However I have checked the voltages at VBUS they are around 5.07V.

Shane Hauser said:

When you configure the CURRENT_MODE for 3A, then your phone does not charge from the port at all?

2. As I have mentioned earlier that the phone was showing the slow charging status for that purpose I have set CURRENT MODE to 3A but now when I have set that I have connected the Xiaomi device but it wasn't charging. I have also connected some other devices as well but no sign of charging at all. I can also understand that TPS61023 couldn't provide 3A current but it does provide 1.5A so why TUSB320 couldn't provide the desired current to charge the phone.

Shane Hauser said:

How do you control the Type-C VBUS? The VBUS should only be enabled when ID on the TUSB320 goes low.

3. Well currently in my design I have pulled up the ID pin. So it is high. I am controlling the VBUS by using the CC pins.

Thanks

Hi Hamza,

From your schematic, I don't see a VBUS switch between your 5V power rail and the Type-C VBUS:

In a type-C port, VBUS should only be applied after a connection is made on the CC lines. When this connection is made, our TUSB320 will pull the ID pin low. When ID is low your VBUS switch should apply the VBUS. Here is a good resource on how to control the VBUS on a type-C port with the TUSB320.

Hamza Alpiyal said:

why TUSB320 couldn't provide the desired current to charge the phone.

The TUSB320 does not supply current to the Type-C port. The CURRENT_MODE pin will only tell the connected device what current to expect on the VBUS. The actual VBUS would be provided through your VBUS switch and power supply.

Can you show a block diagram of the power path from your supply to the Type-C VBUS? I want to be sure I didn't miss anything in the schematic.

Best,

Shane

Hi Shane,

Thanks for your assistance but I need to make some of the things easier for you that at the moment R59 is DNP. While P1 is configuration PAD which makes a selection between 5V_1.5A and 5V_3A source. For the time being I am using 5V_1.5A so source and 5V_1.5A  are soldered. Picture is attached for better understanding.

Shane Hauser said:

I don't see a VBUS switch between your 5V power rail and the Type-C VBUS:

The switching is performed in the software using TUSB320 registers. But a small circuit is also added which shows that when does VBUS will be provided. The external device only charges(VBUS provided ) if the EXT_DEV_CHRG_EN pin is set to high.  I am attaching a code snippet and switching circuit so you can review it. Thanks.

Please let me know if you find any errors in schematic or in the code. So I can fix it. Currently my issue is that some devices are charging and some or not. However I have read the DEVICE_ID and its working fine.

Hi Hamza,

I didn't realize D7 was not populated. Thank you for clarifying.

Looking at the VBUS switch circuit, your EXT DEV CHRG EN will drive T4 when it goes high. This will pull the gate on T5 to GND and enable the VBUS switch. I assume this means that the EXT DEV CHRG EN signal is active high (VBUS provided when signal is high). Can you confirm?

If this is the case, I don't see how the gate of T5 gets pulled up to disable the switch after the device is disconnected. When the EXT DEV CHRG EN signal goes low and disables T4, the gate of T5 would be a floating node. Can you check the following:

1. When you plug in a device do you see T5 (and VBUS) get enabled?

2. When you detach the device do you see T5 (and VBUS) get disabled?

Best,

Shane

Hi Shane

Shane Hauser said:

EXT DEV CHRG EN signal is active high

Yeah  EXT DEV CHRG EN is an active high signal.

Shane Hauser said:

the gate of T5 would be a floating node

Yeah you got it right that once the device is connected (VBUS is enabled) but when the device is detached the due to floating state at the gate of T5 (VBUS is still enabled). I think that's the issue from my side regarding power switching !!.

Any suggestions how can make the current circuit work properly regarding charging. I will revise the schematic in near future. Thanks