TPS25750: Technical questions for TPS25750 + BQ25792

Jonathan,

Here are my answers in line.

1. Are there any Linux drivers avaiable for chipset TPS25750 and BQ25792?
   1. We do not provide linux drivers
2. Which GPIO mapped event of TPS25750 can be used as OTG ID signal for iMX7 USB OTG Controller?
   1. enablesource_port1 (31) will provide this
3. When working as a Host/Power provider we want to use BQ25792 OTG mode and avoid using extra 5V DC/DC Power and leave PP5V unconnected. Is it possible? Which configuration select in TPS25750_Application_Customization_Tool Are you a power source (provider) and a power sink (consumer)?  Section? There are no such  configuration without 5V DC/DC.
   1. This is not possible.  The TPS25750 uses the PP5V power path when operating at 5V and it is required for internal analog signaling as well
4. What select in TPS25750_Application_Customization_Tool “What is the maximum power that can be sourced?”  when we want to source USB2.0 default power 5V/500mA only?
   1. The TPS25750 is configured to support 5V/3A only currently.  
5. Do the BQ25792 registers contain information that could be used to continuously indicate the percentage of battery charge? If yes can you provide a guide and a formula?
   
   1. I will have to follow up with the BQ25792 team to get this answer
6. In TPS25750 Application Customization Tool I miss some configuration features for BQ25792:
   1. I will have to follow up with the BQ25792 team to get this answer.  I know some of them, but I want to answer them all at once.

1. Setting of V_SYSMIN
2. Setting of V_RECHG  
3. I_OTG and V_OTG
4. PRECHG_TMR
5. Is it possible to setup V_{BAT_UVLOZ} for 1S,2S,3S 4S cells?

7. Does BQ25792 affect USB data lines D+, D-? Can D+ and D- be connected directly  to BQ25792 and to USB controller?
   
   1. You should connect the USB lines to the TPS25750.  It will take the B1.2 negotiation into account when setting the current limits
8. How and where following parameters of TPS25750 can be set?
   
   1. We are working to document to describe the events and register updates that the TPS25750 executes and then you can supplement with your MCU.

Hi Chuck,

I have suplementary questions:

Ad1. Are you going to provide Linux drivers in the future?

Ad2. I do not believe that enablesource_port1 (31) will provide OTG ID signal function. First, such an event 31 doesn’t exist in SLVUC05 – NOVEMBER 2020 TPS25750 Host Interface Technical Reference Manual. If you meant event 73 enablesource (73) which is described below in Italic, then I think it will not work with a non USB Power Delivery Device (e.g. Flash disc) or Host(e.g.old PC)  as there will be no PD communication and contract. Can you please explain in more detail how it will work as ID signal?

When the PD controller sends an Accept message to start

sourcing VBUS under a high-power contract this GPIO is

asserted high. It will remain high as long as the high-power

contract is active. If the contract transitions from a high-power

contract to a low-power contract, this GPIO will have a highto-

low transition after the PS_Rdy message is sent.

Second, Events 32:30 are reserved in SLVUC05, however there is event 31 tbt_mode_selection_event_port1 (31) in TPS25750 Application Customization Tool which meaning is not clear to me. If you meant this one you need to explain in more detail how it will work as ID signal. If you didn’t mean this one I would like to know the description of this event anyway.

Third, I have personaly considered event 75 attachedassink (75), however I am not sure. What is your opinion?

To help you understand what function I need I would mension TI TUSB320LAI USB Type-C Configuration Channel Logic and Port Control Chip and its ID pin 9. I want one TPS25750 GPIO to behave the same way. Can you please look on it again and advise?

Ad3: Isn’t it restriciton of functionality. When exactly I can use BQ25792 OTG mode? Note: In datasheet I can see that PP5V is used only for VBUS or VCON on CC which I do not need.

Ad4: First, in SLVUC05 is mentioned that TPS25750 is USB Type-C specification complaint which means it has to be able to advertise 3 current modes according to the USB Type-C specification: default, 1.5A and 3A – I would expect that it is somehow configurable. Then, if the connected device supports power delivery a contract can be agreed according USB PD 3.0.

Second, what  about the advanced configuration when I can specify source PDO and I can select  maximum current 500mA? Then I would expect I deliver only 2.5W with a current protection (e.g. 700mA) against short on VBUS.

Ad 5, 6: When I can get the answer?

Ad 8: When I can get it?

9. Can USB2ANY be used instead of Aardvark I2C/SPI Host Adapter to dowload the configuration to USB-PD-CHG-EVM-01? (of couse with an adapter to adopt to J5 connector pinout)

Vlad,

Here are the rest of the original answers from the Charger team

5. Do the BQ25792 registers contain information that could be used to continuously indicate the percentage of battery charge? If yes can you provide a guide and a formula?
The BQ25792 has an ADC that can measure battery voltage, battery current, input voltage, input current and other values. If you would like a percentage of battery charge, you will need a battery gauge for that.
6. 1. VYSMIN is set by the by the PROG pin according to the following table: Table 9-2. Charging Parameters Dependent on Battery Cell Count
6. 2. VRECHG is the default value of 200 mV.
6. 3. IOTG and VOTG are set by the firmware we made.
6.4. The PRECHG_TMR is enabled by default and is set to the default value of 2 hours.
6.5. VBAT_UVLOZ is a fixed specification.

====

Second set of questions:

1.  We do not plan to provide linux drivers at this time

2.  The TPS25750 and BQ25792 integration will handle all of the necessary OTG switching within the I2C events, so no GPIO is used

3.  The PP5V has to be powered in order for any of the source path to work and it must be used to source 5V, so if you are not supplying VCONN, you will still need a 3.5A buck from the battery voltage.

4.  The section of the spec that you are referring to is the type C values.  They are 900mA, 1.5A, and 3A.  If you add in PD functionality, then you are able to program current between 0 and 3A for voltages other than 20V and up to 5A for 20V.

8.  I will provide the Events table tomorrow.  I need to remove some things from the model to make it public

9.  For the USB-Pd-CHG-EVM-01, the Aardvark is used to program the EEPROM for the TPS25750 and the USB2ANY is used to interface with the charger GUI.  There is currently no implementation to support EEPROM programming with the USB2ANY, so both interfaces are required.

Chuck,

Thanks for promt answer, however :

Ad2. Can you please answer my question anyway. I want OTG ID signal and not I2C communiction!

Ad4. Sorry, havent you only repeated what I had written in my question? I have asked how Type-C current advertisement (default, 1.5A, and 3A.)  can be configured. I suppose when I_LIM5V can be set (see 8 A) then current advertisement has to be configurable as well.

General Note: Maybe TPS25750 Application Customization Tool doesn’t provide full configuration which can be achieved via register setting by AP over I2Cs interface. Then it is necessary to explain or describe as I am as a user often confused what is possible and how.

2. From a PD standpoint, the enablesource_port1 event will transition high when the data port is configured as a UFP and low when it is configured as a DFP.  This will match the OTG EN as closely as type C allows.

4.  The TPS25750 is currently only available as a 3A advertisement for type C only connections.