ICS1524

8

ICS1524 Rev C 01/31/2003

Name:

Feedback Divider 0 Register / Feedback Divider 1 Register

Register:

2h, 3h

Index:

Read / Write*

Bit Name

Index

Bit #

Reset Value

Description

FBD 0-7

2

0 -7

FF

PLL Feedback Divider LSBs (0 -7).* When Bit 0 = 0, then the total

number of clocks per line is even. When Bit 0 = 1, then the total

number of clocks is odd.

FBD 8 -11

3

0 -3

F

PLL Feedback Divider MSBs (8 -11)*

Reserved

3

4 -7

Reserved

Feedback Divider Modulus

=

See Register 8h for details.

Name:

DPA Offset Register

Register:

4h

Index:

Read / Write

Bit Name

Bit # Reset Value

Description

DPA_OS0-5

0 - 5

0

Dynamic Phase Adjust Offset

Reserved

6

0

Reserved

Fil_Sel

7

0

Loop Filter Select

Bit

Name

Description

0-5

DPA_OS0-5

Dynamic Phase Adjust Offset.

Selects clock edge offset in discrete steps from zero to one clock period minus one step.

Resolution (number of delay elements per clock cycle) is selected by DPA_Res0-1 (Reg 5:0-1).

Note: Offsets equal to or greater than one clock period are neither recommended nor supported.

Example: For DPA_Res0-1=01H, the clock can be delayed from 0 to 31 steps.

7

Fil_Sel

Selects external loop filter (0) or internal loop filter (1).

The use of an external loop filter is strongly recommended for all designs. Typical loop filter

values are 6.8K Ohms for the series resistor, 3300 pF RF-type capacitor for the series capacitor,

and 33 pF for the shunt capacitor.

12

≤ Feedback Divider Modulus ≤ 4103

The value that is programmed into these two registers, plus a value of 8, defines the total number of clock periods that the ICS

1524 generates between HSYNCs. Program these registers with the total number of horizontal clocks per line minus 8.

3

g

e

R2

g

e

R

32

1

0

7

6

5

4

32

1

0

+8