Datasheet

Data Sheet AD9284
Rev. A | Page 21 of 24
MEMORY MAP REGISTER DESCRIPTIONS
For more information about functions controlled in Register 0x00
to Register 0xFF, see the AN-877 Application Note, Interfacing
to High Speed ADCs via SPI.
Voltage Reference (Register 0x18)
Bits[7:5]—Reserved
Bits[4:0]—Voltage Reference
Bits[4:0] scale the internally generated voltage reference and,
consequently, the full scale of the analog input. Within this register,
the reference driver can be configured to be more easily driven
externally by reducing the capacitive loading.
The relationship between the V
REF
voltage and the input full scale
is described by Equation 1. See Table 13 for a complete list of
register settings.
Input_Full_Scale = V
REF
× 1.2 (1)
Table 13. V
REF
and Input Full Scale (Register 0x18)
Value V
REF
(V) Full Scale (V)
0x14 0.844 1.013
0x15 0.857 1.028
0x16 0.87 1.044
0x17 0.883 1.060
0x18 0.896 1.075
0x19 0.909 1.091
0x1A 0.922 1.106
0x1B 0.935 1.122
0x1C 0.948 1.138
0x1D
0.961
1.153
0x1E 0.974 1.169
0x1F 0.987 1.184
0x00 1 1.200
0x01 1.013 1.216
0x02 1.026 1.231
0x03 1.039 1.247
0x04 1.052 1.262
0x05 1.065 1.278
0x06 1.078 1.294
0x07 1.091 1.309
0x08 1.104 1.325
0x09 1.117 1.340
0x0A 1.13 1.356
0x0B 1.143 1.372
0x0C 1.156 1.387
0x0D 1.169 1.403
0x0E
1.182
1.418
0x0F 1.195 1.434
0x10 1.208 1.450
0x11 1.221 1.465
0x12 1.234 1.481
0x13
External
External x 1.2