AK8126 Datasheet, PDF (5/8 Pages) Asahi Kasei Microsystems – Spread Spectrum Clock Generator

The brand name
of AKEMD’s IC’s
AK8126
Spread Spectrum Modulation Characteristics
All specifications at VDD: over 3.0 to 3.6V, Ta: -10 to +85 , Input Frequency: over 16MHz to 128MHz,
unless otherwise noted
Parameter
Symbol
Conditions
MIN TYP MAX Unit
Modulation Frequency⁽⁵⁾
Modulation Ratio
@ Center Spread
Modulation Ratio
@ Down Spread
Average Modulation
Frequency Offset⁽⁶⁾
@ Down Spread
fmod
Mod C
Mod D
fmod-off
Ratio Selection Pin S[1:0]=LH
Ratio Selection Pin S[1:0]=LL
Ratio Selection Pin S[1:0]=HL
Ratio Selection Pin S[1:0]=HH
Ratio Selection Pin S[1:0]=LH
Ratio Selection Pin S[1:0]=LL
Ratio Selection Pin S[1:0]=HL
Ratio Selection Pin S[1:0]=HH
Ratio Selection Pin S[1:0]=LH
Ratio Selection Pin S[1:0]=LL
Ratio Selection Pin S[1:0]=HL
Ratio Selection Pin S[1:0]=HH
38.46
76.92 kHz
±0.25
±0.5
±1.0
%
±1.5
-0.5
-1.0
-2.0
%
-3.0
-0.36
-0.6
-1.2
%
-1.8
(5) Modulation frequency is determined by input frequency range. Following equations provide the
theoretical modulation frequency of AK8126.
Output Frequency Range 16-32MHz: fmod(KHz) = 38.46KHz x fin(MHz) / 16MHz
32-64MHz:
fmod(KHz) = 38.46KHz x fin(MHz) / 32MHz
64-128MHz: fmod(KHz) = 38.46KHz x fin(MHz) / 64MHz
64-128MHz, x4 Output mode: fmod(KHz) = 38.46KHz x fin(MHz) / 16MHz
Where, fin is an input frequency of crystal or reference clock input.
(6) The average output frequency in the mode of down spread modulation is intentionally offset against the
ideal average frequency. The offset is specified by percentage to the target output frequency as shown
in Figure 1.
fmod-ave: Average Output
Frequency
fmod-ideal: Frequency of
½ Modulation Ratio
fo: Target Output
Frequency
fmod-off: Average
Frequency Offset
Modulation Ratio
Figure 1: Offset in the mode of down spread modulation
MS0548-E-01
-5-
Nov-07