Datasheet

AD9780/AD9781/AD9783 Data Sheet
Rev. B | Page 22 of 32
SPI REGISTER DESCRIPTIONS
Reading these registers returns previously written values for all defined register bits, unless otherwise noted.
Table 12.
Register Address Bit Name Function
SPI Control 0x00 7 SDIO_DIR 0, operate SPI in 4-wire mode. The SDIO pin operates as an input only pin.
1, operate SPI in 3-wire mode. The SDIO pin operates as a bidirectional data line.
6 LSBFIRST 0, MSB first per SPI standard.
1, LSB first per SPI standard.
Only change LSB/MSB order in single-byte instructions to avoid erratic behavior
due to bit order errors.
5
RESET
0, execute software reset of SPI and controllers, reload default register values
except Register 0x00.
1, set software reset, write 0 on the next (or any following) cycle to release the reset.
Data Control 0x02 7 DATA 0, DAC input data is twos complement binary format.
1, DAC input data is unsigned binary format.
4 INVDCO 1, inverts the data clock output. Used for adjusting timing of input data.
Power-Down 0x03 7 PD_DCO 1, power down data clock output driver circuit.
6 PD_INPT 1, power down input.
5 PD_AUX2 1, power down AUX2 DAC
4 PD_AUX1 1, power down AUX1 DAC.
3 PD_BIAS 1, power down voltage reference bias circuit.
2 PD_CLK 1, power down DAC clock input circuit.
1 PD_DAC2 1, power down DAC2.
0 PD_DAC1 1, power down DAC1.
Setup and Hold 0x04 7:4 SET[3:0] 4-bit value used to determine input data setup timing.
3:0 HLD[3:0] 4-bit value used to determine input data hold timing.
Timing Adjust 0x05 4:0 SAMP_DLY[4:0] 5-bit value used to optimally position input data relative to internal sampling clock.
Seek 0x06 2 LVDS low One of the LVDS inputs is above the input voltage limits of the IEEE reduced link
specification.
1 LVDS high One of the LVDS inputs is below the input voltage limits of the IEEE reduced link
specification.
0 SEEK Indicator bit used with LVDS_SET and LVDS HLD to determine input data timing
margin.
Mix Mode 0x0A 3:2 DAC1MIX[1:0] 00, selects normal mode, DAC1.
01, selects return-to-zero mode, DAC1.
10, selects return-to-zero mode, DAC1.
11, selects mix mode, DAC1.
1:0 DAC2MIX[1:0] 00, selects normal mode, DAC2.
01, selects return-to-zero mode, DAC2.
10, selects return-to-zero mode, DAC2.
11, selects mix mode, DAC2.
DAC1 FSC
0x0B
7:0
DAC1FSC[9:0]
DAC1 full-scale 10-bit adjustment word.
0x0C 1:0 0x3FF, sets DAC full-scale output current to the maximum value of 31.66 mA.
0x200, sets DAC full-scale output current to the nominal value of 20.0 mA.
0x000, sets DAC full-scale output current to the minimum value of 8.66 mA.