CY28312B-2T SPECTRALINEAR [SpectraLinear Inc], CY28312B-2T Datasheet - Page 12

• Manufacturer Part Number: CY28312B-2T
• Manufacturer: SPECTRALINEAR [SpectraLinear Inc]

Rev 1.0, November 21, 2006
Table 5. Register Summary (continued)
How to Program CPU Output Frequency
When the programmable output frequency feature is enabled
(Pro_Freq_EN bit is set), the CPU output frequency is deter-
mined by the following equation:
Fcpu = G * (N + 3)/(M + 3).
“N” and “M” are the values programmed in Programmable
Frequency Select N-Value Register and M-Value Register,
respectively.
Table 6. Examples of N and M Value for Different CPU Frequency Range
WD_TIMER[4:0]
WD_PRE_SCALER
RST_EN_WD
RST_EN_FC
Frequency Ranges
130 MHz–248 MHz
50 MHz–129 MHz
Name
These bits store the time-out value of the Watchdog timer. The scale of the timer is determine by the
prescaler.
The timer can support a value of 150 ms to 4.8 sec when the pre-scaler is set to 150 ms. If the pre-scaler
is set to 2.5 sec, it can support a value from 2.5 sec to 80 sec.
When the Watchdog timer reaches “0”, it will set the WD_TO_STATUS bit.
0 = 150 ms
1 = 2.5 sec
This bit will enable the generation of a Reset pulse when a Watchdog timer time-out occurs.
0 = Disabled
1 = Enabled
This bit will enable the generation of a Reset pulse after a frequency change occurs.
0 = Disabled
1 = Enabled
Gear Constants
48.00741
48.00741
M-Value Register
Fixed Value for
93
48
“G” stands for the PLL Gear Constant, which is determined by
the programmed value of FS[4:0] or SEL[4:0]. The value is
listed in Table 4. The ratio of (N + 3) and (M + 3) needs to be
greater than “1” [(N + 3)/(M + 3) > 1].
Table 6 lists set of N and M values for different frequency
output ranges.This example use a fixed value for the M-Value
Register and select the CPU output frequency by changing the
value of the N-Value Register.
Description
for Different CPU Frequency
Range of N-Value Register
127–245
97–255
CY28312B-2
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