Artesyn ATCA-7480 Installation and Use (February 2015) - Manual (Page 95)

Functional Description
ATCA-7480 Installation and Use (6806800T17A) 95
4.19 Real Time Clock
An external 32.768 kHz clock sources the internal real time clock inside Intel DH8900CC PCH
with a frequency tolerance of 20 PPM. The RTC is fully DS1287, MC14618, PC87911, and Y2K
compliant and provides 256 bytes of backed up CMOS RAM (of which 14 bytes contain the RTC
time and date information and RTC configuration). During power down, the RTC consumes
0.9uA/hr.
 Default power-down backup solution is an external +3V lithium battery with a capacity of
200mAh, which provides 3 years of backup.
 Optional power-down backup method uses a Super CAP with a 1 Farad capacity. This
provides 300 hours of RTC/SRAM backup.
4.20 SMBus
Intel C612 PCH (Wellsburg) provides six SMBus interfaces. Only four interfaces are used on
ATCA-7480 as described in the following table:
The Master SMBus interface of the Intel C612 PCH is connected to on-board devices like Clock
PLLs, temperature sensors and so on. An I2C Bus Repeater of type PCA9515 is used for load
distribution and buffering.
Additionally, both CPUs provide 2x SMBus to connect to the SPD PROMs of the DDR4 memory
system.
Table 4-4 SMBus Interface
Device / SMBus Description
Intel C612
B0:D31:F3 Host SMBus (Master/Slave)
SMLINK0 Connection to external IPMC to report thermal information via PCH
internal PECI bridge to CPU
SMLink1 Reserved
ME SMBus Optional connection