Why tja1145 switch to sleep mode after power-on

[aiweixin]

Hi,

   According to datasheet,  tja1145 will be in standby mode after power-on.

    But, i debug the tja1145, after power-on, read mode control register (address 01h) by spi, the value is 0x01 (Sleep mode), and INH pin is not Vbat level.

    Why does tja1145 switch to sleep mode after power-on, not standby mode?

Best regards!

[guoweisun]

Have your ever written this MC bits after power on?

[aiweixin · Accepted solution]

Hi @guoweisun,

    Thank you for your reply. I have found out the reason.

    In hardware design, we use PMIC, the power of Vcc and Vio lag behind Vbat, the time is longer than undervoltage detection delay time, so tja1145 switch to sleep mode.

    We will optimize the design of hw and sw.

Best regards!

[aiweixin]

Hi @guoweisun ,

    I don't write any data after power on. 

    The first operation by spi is reading mode control register (address 01h).

Best regards!