RTC & Power-Button
------------------

+-----+-------------+-------------------------------------------------------------------------------------------------------------+-------+-----+
| Pin | Signal      | Description                                                                                                 | type  | I/O |
+=====+=============+=============================================================================================================+=======+=====+
|     |             | DS1339 RTC backup power supply. Supply voltage must be held between                                         |       |     |
|     |             | 1.3V and 3.7V for proper RTC operation. This pin can be connected to                                        |       |     |
|     |             | a primary cell such as a lithium button cell. Additionally, this pin                                        |       |     |
|     |             | can be connected to a rechargeable cell or a super cap when used with                                       |       |     |
|     |             | the trickle charge feature.                                                                                 |       |     |
|     |             | Refer to DS1339 datasheet for details.                                                                      |       |     |
+ 13  + VBACKUP     +------------------------------+------+-----------------------+-----------------------------------------------+ power + I   +
|     |             | **Module**                          | **Remark**                                                            |       |     |
+     +             +------------------------------+------+-----------------------+-----------------------------------------------+       +     +
|     |             |                                     | Connected to BAT_VDD                                                  |       |     |
|     |             | TX25                                | DRYICE backup power supply input, max. 1.55V                          |       |     |
|     |             |                                     | The i.MX25 internal RTC is not supported                              |       |     |
+     +             +-------------------------------------+-----------------------------------------------------------------------+       +     +
|     |             | TX6 without DS1339                  | i.MX6 RTC backup power supply. Supply voltage must be held between    |       |     |
|     |             |                                     | 2.9V and 3.3V for proper RTC operation.                               |       |     |
+-----+-------------+-------------------------------------+-----------------------------------------------------------------------+-------+-----+
|     |             | PMIC dependent Function. Leave unconnected if not used.                                                     |       |     |
+     +             +--------------------------------+----+----------------------+------------------------------------------------+       +     +
|     |             | **Module**                          | **Remark**                                                            |       |     |
+     +             +--------------------------------+----+----------------------+------------------------------------------------+       +     +
|     |             | TX25                                | No PMIC onboard - Not connected                                       |       |     |
+     +             +-------------------------------------+-----------------------------------------------------------------------+       +     +
|     |             | TX28                                | PSWITCH - Used for chip power on or recovery. PSWITCH is at MID level |       |     |
|     |             |                                     | by default. Refer to i.MX28                                           |       |     |
|     |             |                                     | reference manual for details.                                         |       |     |
+ 14  + PMIC_PWR_ON +-------------------------------------+-----------------------------------------------------------------------+       + I   +
|     |             | TX27, TX51                          | This is an active high push button input which can be used to signal  |       |     |
|     |             |                                     | PWR_ON and PWR_OFF events to the CPU by controlling the PMIC          |       |     |
|     |             |                                     | EXT_WAKEUP. Refer to LP3972 datasheet, page 49 for details.           |       |     |
+     +             +-------------------------------------+-----------------------------------------------------------------------+       +     +
|     |             | TX48, TX53                          | Connected to LTC3589 WAKE. To power down, drive this pin LOW.         |       |     |
|     |             |                                     | Refer to LTC3589 datasheet, page 29 for details.                      |       |     |
+     +             +-------------------------------------+-----------------------------------------------------------------------+       +     +
|     |             | TX6                                 | Connected to PMIC ON.                                                 |       |     |
|     |             |                                     | Refer to PMIC datasheet for details.                                  |       |     |
+-----+-------------+-------------------------------------+-----------------------------------------------------------------------+-------+-----+

.. figure:: ../images/rtc_powerbutton.png
   :align: center