FS6520 VAUX for 5V no output

[LyncLin]

Hi NXP team,

I have an issue with FS6520 VAUX output that need your help.  The hardware schametics are attached.

The select pin-31 is connected a 24 kohm resistor. The DEBUG mode is enabled by connecting Pin-15 DEBUG to a voltage divided from VPRE 6.5V. SW_CORE is confirmed to output around 1.25V.

VCCA and VAUX are both connected to an external PNP transistor (BCP52-16,115). On output of VCCA, an 3.28V output voltage can be measured on Pin-43 VCCA, and it's around 5.9V on VCCA_B and 6.6V on VCCA_E. However, on pin-38 VAUX, it's close to 0V, and it's around 7.8V on VAUX_B and 8.2V on VAUX_E.It looks FS0B is also pulled down LOW.

Currently there's no SPI or software available. It will be appreciated if you can provide any suggestions to debug this issue. Thanks a lot in advance!

Regards,

Lync

[guoweisun]

VPRE/VCORE都是正常的吗？只有VAUX/VCCA有问题吗？

[LyncLin]

你好！

VPRE测得大约6.4V, VCORE1.25V, VCCA 3.28V. VAUX的三极管看起来处于截止状态，B级E级电压见问题描述。 VAUX和VCCA是同款三极管。外部电源输入12V，试过上升到18V，VAUX仍不工作。

[guoweisun]

你是学生？这个是学校的项目？还是什么？

[LyncLin]

Spoiler

我们是家方案公司，一个客户的项目

[guoweisun]

方便告知什么公司吗？以后提问题尽量用公司的邮箱，这样优先级很高，用自己的邮箱我们认为是C 客户就是可以支持但是如果我们很忙就会忽略掉C客户的问题。

[LyncLin]

论坛上不太方便，麻烦留个邮箱，稍后给您发个邮件吧。

[guoweisun]

Home (nxp.com)

用公司的邮箱上面的链接提问题，我们会回复的，私人、公司的问题不会被public post。 

[LyncLin · Accepted solution]

用公司邮箱注册的账号开了一个新的问题，我将关闭这个问题，请在新的ticket下提供支持，感谢！

[LyncLin]

Spoiler

我们是企业，这是一个客户的项目。