PLL Control Registers
384
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Oscillator and PLL
10.6 PLL Control Registers
The clock module has two registers (PLLCTL1 and PLLCTL2) located within the System and Peripheral
Control Registers, plus it has four bits located in other System and Peripheral Control Registers.
The FM-PLL is off at power-on. The clock source is enabled by clearing the appropriate bit in the Clock
Source Disable Register (CSDIS) or setting the appropriate bit in the Clock Source Disable Clear Register
(CSDISCLR) of the System and Peripheral Control Registers. [CSDISCLR and Clock Source Disable Set
Register (CSDISSET) also enable/disable the PLL and oscillator (and other clock sources).]
The LPOCLKDET module generates the OSCFAIL flag in the Global Status Register (GLBSTAT), of the
System and Peripheral Control Registers, if a problem with the reference oscillator is detected. The slip
signals are also registered in the RFSLIP and FBSLIP status flags in the Global Status Register
(GLBSTAT), of the System and Peripheral Control Registers, in order to indicate the source of a clock
failure.
The appropriate CLKSRnV bit for the PLL is set in the Clock Source Valid Status Register (CSVSTAT) of
the System and Peripheral Control Registers.
The following sections describe the PLL registers used in the system module. These registers support 8,
16, and 32-bit write accesses. The reset values for these registers are configured so that an input
frequency in the range from 5MHz to 20MHz generates a valid clock.
Table 10-4. PLL Module Registers
Offset
Acronym
Register Description
Section
FFFF FF30h
CSDIS
Clock Source Disable Register
FFFF FF34h
CSDISSET
Clock Source Disable Set Register
FFFF FF38h
CSDISCLR
Clock Source Disable Clear Register
FFFF FF54h
CSVSTAT
Clock Source Valid Status Register
FFFF FF70h
PLLCTL1
PLL Control 1 Register
FFFF FF74h
PLLCTL2
PLL Control 2 Register
FFFF E100h
PLLCTL3
PLL Control 3 Register
FFFF FFA0h
GPREG1
General Purpose Register
FFFF FFECh
GLBSTAT
Global Status Register
FFFF E170h
CLKSLIP
PLL Clock Slip Control Register
FFFF FF24h
SSWPLL1
PLL Modulation Depth Measurement Control Register
FFFF FF28h
SSWPLL2
SSW PLL BIST Control Register 2
FFFF FF2Ch
SSWPLL3
SSW PLL BIST Control Register 3
Table 10-5. LPOCLKDET Module Registers
Offset
Acronym
Register Description
Section
FFFF FF88h
LPOMONCTL
LPO/Clock Monitor Control Register
FFFF FF8Ch
CLKTEST
Clock Test Register