AK8126 Datasheet, PDF (6/8 Pages) Asahi Kasei Microsystems – Spread Spectrum Clock Generator

AK8126
The brand name
of AKEMD’s IC’s
Operation Clock Frequency Range Selection
The AK8126 operates at a wide frequency rage to support clocking in most of Home AV products. The
operation frequency range applying to the AK8126 is required to select by pin-setting of FR0 (Pin8) and
FR1 (Pin9), as shown in Table 1.
Table 1: Operation Clock Frequency Setting
Pin Setting
FR1
FR0
L
L
L
H
H
L
H
H
Input
Frequency (MHz)
16 – 32
32 – 64
64 – 128
16 – 32
Output
Frequency (MHz)
16 – 32
32 – 64
64 – 128
64 – 128
Input Frequency
Scaling
x1
x4
Applicable Input
Crystal Clock






Spread Spectrum Modulation Selection
The AK8126 operates in two modes of spread spectrum modulation. One is “Center Spread Modulation” in
which the frequency deviation from the target output frequency is equal to the lower side and the upper
side. The other one is “Down Spread Modulation”, which will be used in applications where the target
clock is providing at a maximum frequency rate of that system. In this mode, the maximum spread
frequency is equal to the target frequency, and the frequency deviation is provided in the lower side. The
AK8126 can provide a variable modulation ratio with the AKEMD’s original spread profile for both
modulation modes, offering appropriate tune for EMI elimination without degradation of system
performance.
The modulation mode and the modulation ration are selectable by pin setting of C/D/OFF (Pin 10) and
S[1:0] (Pin 4 and 5), as defined in Table 2 and Table 3, respectively.
Table 2: Spread Spectrum Modulation Mode Setting
Pin Setting
C/D/OFF
Modulation Mode
L
Down Spread
M
No Modulation
H
Center Spread
Table 3: Modulation Ratio Setting
Pin Setting
Modulation Ratio (%)
S1
S0
Center Spread Mode
Down Spread Mode
L
L
± 0.5
-1.0
L
H
± 0.25
- 0.5
H
L
± 1.0
-2.0
H
H
± 1.5
- 3.0
Nov-07
MS0548-E-01
-6-