CY28346-2
Byte 7: Watchdog Time Stamp Register
Bit
7
@Pup
Name
Description
0
0
0
0
0
0
0
0
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
6
5
4
3
2
1
0
Byte 8: Dial-a-Frequency Control Register N (all bits are read and write functional)
Bit
7
@Pup
Name
Description
0
0
0
0
0
0
0
0
N7, MSB
N6
6
5
N5
4
N4
3
N3
2
N2
1
N3
0
N0, LSB
Byte 9: Dial-a-Frequency Control Register R (all bits are read and write functional)
Bit
7
@Pup
Name
Description
0
0
0
0
0
0
0
0
R6 MSB
R5
6
5
R4
4
R3
3
R2
2
R1
1
R0, LSB
0
R and N register load gate 0 = gate closed (data is latched), 1 = gate open
(data is loading from SMBus registers into R and N)
Dial-a-Frequency Feature
Dial-a-dB Features
SMBus Dial-a-Frequency feature is available in this device via
Byte8 and Byte9. See our App Note AN-0025 for details on our
Dial-a-Frequency feature.
SMBus Dial-a-dB feature is available in this device via Byte8
and Byte9.
Spread Spectrum Clock Generation (SSCG)
P is a large value PLL constant that depends on the frequency
selection achieved through the hardware selectors (S1, S0).
P value may be determined from Table 3.
Spread Spectrum is a modulation technique used to
minimizing EMI radiation generated by repetitive digital
signals. A clock presents the greatest EMI energy at the center
frequency it is generating. Spread Spectrum distributes this
energy over a specific and controlled frequency bandwidth
therefore causing the average energy at any one point in this
band to decrease in value. This technique is achieved by
modulating the clock away from its resting frequency by a
certain percentage (which also determines the amount of EMI
reduction). In this device, Spread Spectrum is enabled by
setting specific register bits in the SMBus control Bytes.
Table 4 is a listing of the modes and percentages of Spread
Spectrum modulation that this device incorporates.
Table 3. P Value
S(1:0)
0 0
P
32005333
48008000
96016000
64010667
0 1
1 0
1 1
Rev 1.0,November 20, 2006
Page 6 of 19
SPECTRALINEAR [ SPECTRALINEAR INC ]
