BQ25756: BQ25756

Hello Dante,

Thanks for working with us on this.

The BQ25672 is a buck only charger with integrated FETs. The max Vin is 24V.

The BQ25756E is a buck boost charger with external FETs. The max Vin is 36V.

I have a few questions about the part.

Does the customer need any qualifications like AEC-Q100?
What's the charge current for the battery?

At the moment, I think the BQ25756E might be a better choice, but I think the BQ25672 would be a way better choice if the VIN voltage was lowered to 24V

Best Regards,
Ethan Galloway

Hi Ethan,

Thanks for responding. 

There are not AEC-Q100 qualifications needed.

Can you tell me why the EVM for the BQ25756E does not support 1S battery configuration?

In my design we have a 1 cell design.

Hello Dante,

The EVM can support a 1 cell design. However, the IC enters into trickle charge mode for battery voltages below 3V. You can get the range of trickle charge from the Electrical Characteristics table in the datasheet. Trickle Charge mode charges the battery at 150mA

The BQ25762 enters into trickle charge when the voltage is above 2.3V. Trickle charge mode here charges the battery at 100mA. An Li-Ion battery should not go below 2.3V however.

Also, the BQ25756E does not have a power path. The BQ25762 does have an NVDC power path.

Let me know if you have any more questions about the differences between the two parts.

Best Regards,
Ethan Galloway

Hello Dante,

The power flows through the full bridge.

For the USB PD controller, you can use the TPS25751. This is a newer part that can handle USB power standards up to 20V at 5A.

I can also loop you into the USB PD experts if you would like.

Best Regards,
Ethan Galloway

I don't see stock for the TPS25751, do you expect it to be available in a couple of months?

Also, if there a sample design with a 1 cell Li battery and the TPS25756?

Hi Ethan, follow-up questions.

1) The TIDMBT8 is a 4S-1-S design. What needs to change to convert this to a 1S design?

2) Am I correct in saying the TPS25751 EVM supports 1S?

3) If I buy the TPS25751EVM and the BQ25756EEVM, do you think I can connect them together and get a 1S design with a PD?

Dan

Hi Ethan,

Sorry for all the questions.

We have to support USB-C PD 3.1, upto 36V.

I don't think the PD you recommended, the TPS25751S, is suitable.

VBUS max is only 28V?

Is that correct?

Dan

It seems the PD controller I want is the TPS26750, still in development?

Hello Dante,

1. I can't find the TIDMBT8 design. Can you send me a link to the design?

2. The TPS25751 EVM is a USB-PD controller. It can support 1S when paired with a battery charger.

3. Yes, you can connect these EVMs together. These EVMs are designed to plug into each other. The TPS25751 EVM User's Guide describes how to do this.

Let me loop in one of the USB-PD expert to answer your question about the TPS26750.

Best Regards,
Ethan Galloway

Hi Ethan,TIDMBT8.PDF

There were several other questions, let me  tell you all the modes of operation and specs we need:

The design I referenced is attached.

Hi Dante,

I was looped in by Ethan to support the USB-C PD questions.

Could you share a block diagram of your power architecture? I'm a little confused on how you are planning to handle the two power inputs.

Dante Fasano said:

• Nominally we run on aircraft power of 28V, but if USB-C is the source it can be upto 36V per USB-C PD 3.1 spec profile 6

If you are using any voltage above 20-V for USB-C, you will need to use the TPS26750. It is still in development though. What is your timeline for your project? The TPS26750 is planned to release later in the year, and there is a required companion part that is still in development.

Dante Fasano said:

The board must control a USB ID line going to a SOM

Can you elaborate what you mean here?

Dante Fasano said:

Where are the 15K and 1.5K USB 2.0 resistors used to set speed and identify host/device modes, in the SOM USB transceiver?

The PD controller will only provide support for detection of BC1.2 if the D+/D- lines are connected. You may need a USB2 endpoint for USB2.0 speeds.

Dante Fasano said:

The board must be able to accept voltage surges upto 60V?

For the USB-C receptacle side, we have a port protection part in development that may fit your needs. Is there a TI FAE that you are in contact with? I cannot share additional information for this part on a public thread.

From the system side, you may need to implement discrete protection if you are expecting 60-V generated internally.

The other requirements related to USB-C PD seem fine. I am not sure about the BQ requirements, Ethan will have to comment.

Thanks and Regards,

Chris

Hi Ethan and Christopher,

I have a couple of related questions.

1) In the datasheet for the BQ25756 it shows the TPS2663 eFuse being in figure 9-19. So, the eFuse can be used in a bidirectional mode?

I have a mode of operation where my board is the host and needs to supply power.

2) I will provide a block diagram shortly for discussion. 

Hello Dante,

Can you start a new thread for the TPS2663 questions? That way we can keep the threads organized better.

Best Regards,
Ethan Galloway