ICS91730 Datasheet, PDF (3/11 Pages) Integrated Circuit Systems – Low EMI, Spread Modulating, Clock Generator

ICS91730
LOW EMI, SPREAD MODULATING, CLOCK GENERATOR
Table 1: Frequency Configuration (see I2C Byte0)
14in/27out
FS4
0
0
0
0
0
0
0
0
0
0
0
0
FS3
0
0
0
0
0
0
0
0
1
1
1
1
FS2
0
0
0
0
1
1
1
1
0
0
0
0
FS1
0
0
1
1
0
0
1
1
0
0
1
1
FS0
0
1
0
1
0
1
0
1
0
1
0
1
Sprd Type Sprd %
0.60
0.80
DOWN
1.00
SPR EAD
(-)
1.25
1.50
2.00
CENTER
SPD (+/-)
0.50
1.00
DOWN
SPR EAD
(-)
0.60
1.00
-0.80
CTR SPD +/-0.3
0
1
1
0
0
1.50
0
1
1
0
1
DOWN
1.75
14in/14out
0
1
1
1
0
SPREAD _2.00
(-)
27in/27out
0
1
1
1
1
2.50
1
0
0
0
0
3.00
1
0
0
0
1
1.25
1
0
0
1
0
0.40
1
0
0
1
1
0.50
1
0
1
0
0
CENTER 0.70
1
0
1
0
1
SPD (+/-) _1.00
1
0
1
1
0
1.20
1
0
1
1
1
1.50
1
1
0
0
0
0.60
1
1
0
0
1
DOWN
0.80
1
1
0
1
0
SPREAD ^1.00
48in/48out
1
1
0
1
1
1.25
(-)
66in/66out
1
1
1
0
0
1.50
1
1
1
0
1
2.00
1
1
1
1
0
CENTER 0.50
1
1
1
1
1
SPD (+/-) _1.00
Above is the hard coded 5 bit (32 entry) ROM table.
FS3:0 are ONLY accessible through I2C software programming bits (byte0 bits5:7). FS4 can also be decoded from FS_IN1
latched input hardware pins.
FS_IN1 → FS4. Upon power-up the default is to use hardware selection of FS_IN1 latched value.
FS3 = 0, FS2 = 0, FS1 = 0, FS0 = 1 upon power-up (refer to the functionality table on page 1).
To access non-default spread entries in the ROM, byte0 programming should be used. In order to change the power up
default of FS_IN1 = 1 (-1.25% down spread) to any other spread % entry, first change byte0bit 0 to software selection by
switching this bit to a ‘1’ and then program the desired percentage by changing byte0 bits 7:3.
IDT® LOW EMI, SPREAD MODULATING, CLOCK GENERATOR
3
ICS91730
REV F 061611