Datasheet

Data Sheet ADF4158
Rev. E | Page 23 of 36
STEP REGISTER (R6) MAP
With Register R6 DB[2:0] set to [1, 1, 0], the on-chip step
register is programmed as shown in Figure 29.
Reserved Bits
All reserved bits should be set to 0 for normal operation.
Step SEL
Setting DB23 to 0 chooses Step Word 1. Setting DB23 to 1
chooses Step Word 2.
20-Bit Step Word
DB[22:3] determine the step word. Step word is a number of
steps in the ramp.
DB31
20-BIT STEP WORDRESERVED
CONTROL
BITS
DB30 DB29 DB28 DB27 DB26 DB25 DB24 DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
0 0 0 0 0 0 0 0 SSE1 S20 S19 S18 S17 S16 S15 S14 S13 S12 S11 S10 S9 S8 S7 S6 S5 C3(1) C2(1) C1(0)
08728-117
S20 S19 .......... S2 S1 CLOCK DIVIDER VALUE
0 0 .......... 0 0 0
0 0 .......... 0 1 1
0 0 .......... 1 0 2
0 0 .......... 1 1 3
. . .......... . . .
. . .......... . . .
. . .......... . . .
1 1 .......... 0 0 1048572
1 1 .......... 0 1 1048573
1 1 .......... 1 0 1048574
1 1 .......... 1 1 1048575
S4 S3
S1
S2
STEP SEL
SSE1 STEP SEL
0 STEP WORD 1
1 STEP WORD 2
Figure 29. Step Register (R6) Map