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BQ25798: 使用Type C连接器时其D+、D-是接DP、DM还是需要使用单独的CC控制逻辑器件?

Part Number: BQ25798
Other Parts Discussed in Thread: TPS25750, , BQ25792, TUSB422

我们的应用场景是太阳能和Type C双输入,Type C优先,同时会存在内置电池和扩展的备用电池,有几点疑问:

1.BQ25798的D+、D-支持BC1.2的检测,使用Type C时是直接连接连接器的DP、DM Pin,还是需要单独使用CC控制逻辑芯片来使用,比如TPS25750?但使用TPS25750 则BQ25798上的USB PD功能就浪费了,增加了成本。

2.BQ25798的D+、D-做USB PD检测的同时,是否还可以作为数据通道传输数据,应用上MCU的USB D+、D-会接到USB连接器上,PC可以给设备供电的同时也可以进行usb数据传输。

3.太阳能输入和Type C双输入时,每个通路上均使用背靠背的MOS管,在同时有电压输入是是否会存在电流倒灌,比如太阳能的21.7V将电流倒灌到Type C的5V里面了?

4.BQ25798电池的部分,2串内置电池是系统默认带的,扩展电池2串是可以插拔的,是否可以按照2S2P的方式设计,插拔扩展电池对BQ25798是否有影响?

  • 您好,正在查询,稍后回复。

  • 您好,请问有进展了吗?另外,目前BQ25798的供货周期是多久?

  • 您好,参考下面内容,BQ25798的供货周期建议您与sales联系。

    Regarding 1, I recommend using the TPS25750 but it will depend on the TPS25750 firmware.  That's how our reference design appears to do it per the block diagram.

    Regarding 2, no.  During the first 2 seconds after power up at VBUS, the charger needs complete control of the D+/D- lines.

    Regarding 3, no.  Only one input source at a type is allowed by the ACDRVx logic and the back-to-back FETs block back flow.

    Regarding 4, those batteries will try to self balance at plug in.  So the charger may not work as configured for a few seconds until the self balancing completes.  The safety timer and/or charge current may need to increase in order to complete the charge cycle in the desired time.

  • 如何联系你们的Sales呢?

    关于问题1,有以下疑问:

    a)TPS25750还需要单独的固件?这个我看介绍是无需固件开发的,如下。

    • 独立式 USB Type-C PD 解决方案

      • 无需固件开发或外部微控制器

    b)如过是Type C不推荐使用BQ25789的BC 1.2功能,那么Type A是不是就可以使用起来其BC1.2特性?

    c)如果不使用BQ25798的USB供电功能,是否有更合适的带MPPT功能的Charger+TPS25750的芯片组合?具有较低的静态功耗

    d)Type C连接器中是不是仅CC做电压控制,DP、DM不再进行电压协商?

    e)是否有CC控制逻辑芯片,在接入Type C后协商成Slink设备,Type C的VBUS作为BQ25798的双输入的1路?TPS25750的功能还是比较全,与BQ25798配合使用时其USB Source的能力用不上,浪费了。

    关于问题2:这2s内控制的D+、D-对MCU有影响吗?如果在协商过程中会占用D+、D-,在协商完成后是否可以正常使用,我们的场景是接受2s后操作的。

    感谢!

  • 您好,正在询问更了解这款芯片的TI工程师,稍后回复。

  • 您好,请参考下面答复:

    Regarding 1a. TPS25750 requires firmware.  The PSIL team has already developed the firmware and it has been loaded to the TPS25750.  If it works for your application, then no changes to the firmware are needed. 

    Regarding 1b, The TPS25750 firmware writes to the charger's input current limit after USB C negotiation.  So, I suppose you could use the D+/D- feature on the charger but the TPS25750 might overwrite the value. Actually, you will need to ask the firmware team if the TPS25750 firmware disables auto D+/D- detection. If so, then you can't use it.

    Regarding 1c, the original firmware was written for BQ25792 which does not have MPPT.  There is no TPS25750 firmware version that has been optimized for use with MPPT and BQ25798. So, if you use that firmware, another host will need to enable MPPT on BQ25798.

    Regarding 1d, CCx lines are used for output current and voltage negotiation.

    Regarding 1e, you will have to ask the USB team.  The only other TI type C non-port controller, communication devices that I know are the TUSB422 and TUS32x. 

    Regarding 2, yes.  The charger's D+/D-, if enabled, goes HiZ after power up negotiation completes.