RM0082
Miscellaneous registers (Misc)
Doc ID 018672 Rev 1
219/844
PLL programming sequence
After reset both PLLs must be firstly configured in normal mode waiting for the PLL lock valid
status, than these can be optionally reconfigured in dithered mode through an additional
specific programming sequence.
Two different output frequency equations are provided for the above PLL operating mode:
●
PLL Normal Mode:
●
PLL Dithered or fractional-N mode
.
Table 160.
PLL 1/2_CTR register bit assignments
PLL_CTR Register
PLL2_CTR
0x008
0x014
Bit
Name
Reset
Value
Description
[31:09]
RFU
-
Reserved for future use (Write don’t care - Read return zeros).
[08:03]
pll_control1
6’h0
PLL Main Configuration Table
Control Bit
Description
Pll_control1(8)
1’b0
1’b1
External feedback enable:
Internal feedback
External feedback (dithered mode)
Pll_control(7:6)
2’b00
2’b01
1X
Sigma Delta Order:
1
st
Order
2
nd
Order
N.A. (not applicable for current silicon
version)
Pll_control1(5:4)
2’b00
2’b01
2’b10
2’b11
Dither mode:
Normal mode (non dithered)
Fractional-N
Dithering (double side modulation)
Dithering (single side modulation)
Pll_control1(3)
1’b0
1’b1
PLL sample program parameters:
No action.
Sample program parameters (
.
)
[02]
pll_enable
1’h0
Enable PLL:
1’b0: Disable PLL (power-down mode).
1’b1: Enable PLL
F
out
2
M
158
[
]
×
N
--------------------------
F
in
2
P
-------
×
=
F
out
2
M
×
256XN
-------------------
F
in
2
P
-------
×
=