Datasheet

AD9974
Rev. A | Page 44 of 52
Table 25. I/O Control Registers
Address
Data Bit
Content
Default
Value Update Name Description
0x23 [0] 0 SCK TESTMODE Test Operation Only. Set to 0.
[1] 0 TESTMODE Test Operation Only. Set to 0.
[2] 0 IO_NVR
IOVDD Voltage Range for VD, HD, SCK, SDATA, and SL.
0 = 1.8 V.
1 = 3.3 V.
The I/Os are 3 V tolerant, so there is no problem having higher
than 1.8 V inputs at start-up, but this register should be set to 1
at initialization if using higher than 1.8 V supplies.
[3] 0 DATA_NVR DRVDD Voltage Range.
[4] 0 TESTMODE Test Operation Only. Set to 0.
[7:5] 1 HCLKMODE Selects HCLK output configuration (see Table 9).
[27:8] Unused Set unused bits to 0.
0x24 [27:0] 0 TESTMODE Test Operation Only. Set to 0 if this register is accessed.
0x25 [27:0] 0 TESTMODE Test Operation Only. Set to 0 if this register is accessed.
0x26 [27:0] 0 TESTMODE Test Operation Only. Set to 0 if this register is accessed.
0x27 [27:0] 0 TESTMODE Test Operation Only. Set to 0 if this register is accessed.
Table 26. Mode Registers
Address
Data Bit
Content
Default
Value Update Name Description
0x28 [4:0] 0 VD HPATNUM Total Number of H-Pattern Groups.
[27:5] Unused Set unused bits to 0.
0x29 [27:0] Unused Set unused register to 0 if accessed.
0x2A [2:0] 0 VD FIELDNUM Total Number of Fields. Set to 1 for single-field operation.
[27:3] Unused Set unused bits to 0.
0x2B [4:0] 0 VD FIELD_SEL1 Selected First Field.
[9:5] 0 VD FIELD_SEL2 Selected Second Field.
[14:10] 0 FIELD_SEL3 Selected Third Field.
[19:15] 0 FIELD_SEL4 Selected Fourth Field.
[24:20] 0 FIELD_SEL5 Selected Fifth Field.
[27:25] Unused Set unused bits to 0.
0x2C [4:0] 0 VD FIELD_SEL6 Selected Sixth Field.
[9:5] 0 FIELD_SEL7 Selected Seventh Field.
[27:10] Unused Set unused bits to 0.
0x2D [27:0] SCK Unused Set unused register to 0 if this register is accessed.
0x2E [27:0] SCK Unused Set unused register to 0 if this register is accessed.
0x2F [27:0] SCK Unused Set unused register to 0 if this register is accessed.