User's Manual l TQMa8XxS UM 0101 l © 2022, TQ-Systems GmbH
Page 17
3.2.3.2
RTC PCF85063
In addition to the i.MX 8X-internal RTC, TQMa8XxS variants with discrete RTC at I2C0 are available, see Table 8.
The accuracy of the RTC is primarily determined by the characteristics of the quartz used. The type CM7V used on the TQMa8XxS
has a standard frequency tolerance of ±20 ppm at +25 °C. (Parabolic coefficient: max.
–
0.04 x 10
–6
/ °C
2
)
The RTC PCF85063 is only supplied directly by LICELL when the PMIC is switched off or the module supply is switched off. During
runtime the PMIC takes over the supply via the module supply with 3.3 V.
SMARC-Pins
PMIC
Level-
Translator
VDD_RTC
Coin-Cell
Li-Coin-Cell
Super-Cap
(typ. 3 V)
PCF85063A
LDO3OUT
I2C
VDD
VDD_IN
3…5,25 V
VIN
i.MX 8X
I2C0
Figure 9:
Block diagram RTC supply (TQMa8XxS with discrete RTC)
Note: SNVS domain supply
The SNVS domain is not buffered by LICELL for TQMa8XxS variants with assembled discrete RTC.
The SNVS functions of the i.MX 8X can therefore only be used when the TQMa8XxS supply is present.
The charging function of the PMIC at pin LICELL is not available for TQMa8XxS variants with
assembled discrete RTC.
The following table shows the current consumption at the LICELL pin for TQMa8XxS variants with discrete RTC:
Table 10:
Current consumption V_VDD_RTC with discrete RTC
Voltage LICELL
Current consumption LICELL
Remark
3.25 V
typ. 0,173 µA; max. 0,450 µA
V_3V3_IN = typ. 0 V
T
amb
= +25 °C
3.00 V
typ. 0,171 µA; max. 0,450 µA
2.40 V
typ. 0,164 µA ; max. 0,450 µA
The RTC PCF85063 has I
2
C address
The interrupt of the RTC (RTC_INT#) is routed to the i.MX 8X pin MIPI_DSI1_GPIO0_01.
