Datasheet

AD9974
Rev. A | Page 43 of 52
Address
Data Bit
Content
Default
Value Update Name Description
0x0C [27:0] 0 VD TESTMODE Test Operation Only. Set to 0 if this register is accessed.
0x0D [0] 0 VD CLIDIVIDE
CLI Divide.
1 = divide CLI input frequency by 2.
[3:1] 0 TESTMODE Test Operation Only. Set to 0.
[27:4] Unused Set unused bits to 0.
0x0E [27:0] SCK Unused Set unused register to 0 if accessed.
0x0F [27:0] SCK Unused Set unused register to 0 if accessed.
Table 23. Miscellaneous Registers
Address
Data Bit
Content
Default
Value
Update Name Description
0x10 [0] 0 SCK SW_RST
Software Reset. Bit self-clears to 0 when a reset occurs.
1 = reset Address 0x00 to Address 0xFF to default values.
[27:1] Unused Set unused bits to 0.
0x11 [0] 0 VD OUT_CONTROL
Output Control.
0 = make all outputs dc inactive.
1 = enable outputs at next VD edge.
[27:1] Unused Set unused bits to 0.
0x12 [1:0] 0 SCK TESTMODE Test Operation Only. Set to 0.
[27:2] Unused Set unused bits to 0.
0x13 [0] 0 SCK TESTMODE Test Operation Only. Set to 0.
[27:1] Unused Set unused bits to 0.
0x14 [0] 0 SCK TGCORE_RST
Timing Core Reset Bar.
0 = hold in reset.
1 = resume operation.
[27:1] Unused Set unused bits to 0.
0x15 [0] 0 SCK CLI_BIAS
Enable bias for CLI input (see Figure 11).
0 = disable bias (CLI input is dc-coupled).
1 = enable bias (CLI input is ac-coupled).
[27:1] Unused Set unused bits to 0.
0x16 [0] 0 SCK TESTMODE Test Operation Only. Set to 0.
[27:1] Unused Set unused bits to 0.
0x17 [12:0] 0 SCK UPDATE
Serial Interface Update Line. Sets the line (HD) within the field to
update the VD-updated registers. Disabled when PREVENTUP = 1.
[13] 0 PREVENTUP
Prevents normal update of VD-updated registers.
0 = normal update at VD.
1 = prevent update of VD-updated registers.
[27:14] Unused Set unused bits to 0.
0x18 [27:0] 0 TESTMODE Test Operation Only. Set to 0 if this register is accessed.
0x19 [27:0] 0 TESTMODE Test Operation Only. Set to 0 if this register is accessed.
0x1A to
0x1F
[27:0] Unused Set unused bits to 0.
Table 24. VD/HD Registers
Address
Data Bit
Content
Default
Value Update Name Description
0x20 [0] 0 SCK TESTMODE Test Operation Only. Set to 0.
[27:1] Unused Set unused bits to 0.
0x21 [0] 0 SCK VDHDPOL
VD/HD Active Polarity.
0 = active low.
1 = active high.
[2:1] 0 TESTMODE Test Operation Only. Set to 0.
[27:3] Unused Set unused bits to 0.
0x22 [27:0] 0 TESTMODE Test Operation Only. Set to 0 if this register is accessed.