4.1 Reset and Initialization
Once power is applied, the device begins an initialization period where it downloads default register values and configuration data from
internal non-volatile memory (NVM) and performs other initialization tasks. Communicating with the device through the serial interface
is possible once this initialization period is complete. No clocks will be generated until the initialization is complete.
There are two types of resets available. A hard reset is functionally similar to a device power-up. All registers will be restored to the
values stored in NVM, and all circuits will be restored to their initial state including the serial interface. A hard reset is initiated using the
RST pin or by asserting the hard reset bit. A soft reset bypasses the NVM download. It is simply used to initiate register configuration
changes.
NVM
2x
OTP
RAM
Figure 4.2. Si5397/96 Memory Configuration
Table 4.1. Reset Control Registers
Setting Name
Hex Address
[Bit Field]
Function
Si5397
Si5396
HARD_RST
001E[1]
001E[1]
Performs the same function as power cycling the de-
vice. All registers will be restored to their default val-
ues.
SOFT_RST_ALL
001C[0]
001C[0]
Resets the device without re-downloading the regis-
ter configuration from NVM.
SOFT_RST_PLLA
001C[1]
001C[1]
Performs a soft reset on DSPLL A only.
SOFT_RST_PLLB
001C[2]
001C[2]
Performs a soft reset on DSPLL B only.
SOFT_RST_PLLC
001C[3]
—
Performs a soft reset on DSPLL C only.
SOFT_RST_PLLD
001C[4]
—
Performs a soft reset on DSPLL D only.
Power-Up
Serial interface
ready
RST
pin asserted
Hard Reset
bit asserted
Initialization
NVM download
Soft Reset
bit asserted
Figure 4.3. Initialization from Hard Reset and Soft Reset
The Si5397/96 is fully configurable using the serial interface (I
2
C or SPI). At power up the device downloads its default register values
from NVM. Application specific default configurations can be written into NVM allowing the device to generate specific clock frequencies
at power-up. Writing default values to NVM is in-circuit programmable with normal operating power supply voltages applied to its VDD
(1.8 V) and VDDA (3.3 V) pins. Neither VDDOx or VDDS supplies are required to write the NVM.
Si5397/96 Reference Manual
Modes of Operation
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