Question on TJA1043

[nadeem_syed]

In our application, pins VBAT (pin 10) and WAKE (pin 9) are tied together. Our application matches with the information shown in Section.12 Example Application diagram of datasheet.

I have following question

1. When we provide VBATT (12V) to our application we are observing "INH" signal turns on.
I believe TJA1043 device considers this as a local wake-up event and turns on "INH" signal. Is my understanding correct ?

2. What will be the operating mode of TJA1043 device when VBATT is turned off ?

[PetrS]

Hi,

1) when Vbat is applied, transceiver goes to Standby mode, INH pin is pulled up to Vbat. Once EN and STBN pins becomes driven by the MCU, a mode is determined by their level, for example if driven high transceiver enters Normal mode.

2) if there is undervoltage only on Vbat then device is in Standby mode. If there is undervoltage on Vio or Vcc then device go to Sleep mode.

See more in AH1014; https://www.nxp.com/documents/report/AH1014_v1_4_Application_Hints_TJA1042_43_48_51.pdf

BR, Petr

[nadeem_syed]

Can you please explain a little bit more detail about why the device pulls INH pin up to VBAT when the VBAT is applied ?

Is this because the pins VBatt & Wake are tied together ? Is the device considering this as a local wake-up event ?

[PetrS · Accepted solution]

Hi,

transceiver's behavior after Vbat connection is described in chapter "Software flow for an ECU cold start" of AH1014 (page 67).

BR, Petr