MAX1438 Datasheet, PDF (16/22 Pages) Maxim Integrated Products – Octal, 12-Bit, 65Msps, 1.8V ADC with Serial LVDS Outputs Serial LVDS Outputs

Octal, 12-Bit, 65Msps, 1.8V ADC
with Serial LVDS Outputs
Table 2. Output Code Table (V_REFIO = 1.24V)
TWO’S-COMPLEMENT DIGITAL OUTPUT CODE
(T/B = 0)
BINARY
D11 → D0
HEXADECIMAL DECIMAL
EQUIVALENT EQUIVALENT
OF D11 → D0 OF D11 → D0
OFFSET BINARY DIGITAL OUTPUT CODE
(T/B = 1)
BINARY
D11 → D0
HEXADECIMAL DECIMAL
EQUIVALENT EQUIVALENT
OF D11 → D0 OF D11 → D0
V_IN__P - V_IN__N (mV)
(V_REFIO = 1.24V)
0111 1111 1111
0x7FF
+2047
1111 1111 1111
0xFFF
+4095
+699.66
0111 1111 1110
0x7FE
+2046
1111 1111 1110
0xFFE
+4094
+699.32
0000 0000 0001
0000 0000 0000
1111 1111 1111
0x001
0x000
0xFFF
+1
1000 0000 0001
0x801
0
1000 0000 0000
0x800
-1
0111 1111 1111
0x7FF
+2049
+2048
+2047
+0.34
0
-0.34
1000 0000 0001
0x801
-2047
0000 0000 0001
0x001
+1
1000 0000 0000
0x800
-2048
0000 0000 0000
0x000
0
-699.66
-700.00
1 LSB =2 ^{x FSR}
4096
FSR
0x7FF
0x7FE
0x7FD
FSR = 700mV xVREFIO
1.24V
FSR
1 LSB =2 ^{x FSR}
4096
FSR
0xFFF
0xFFE
0xFFD
FSR = 700mV xVREFIO
1.24V
FSR
0x001
0x000
0xFFF
0x801
0x800
0x7FF
0x803
0x802
0x801
0x800
-2047 -2045
-1 0 +1
+2045 +2047
DIFFERENTIAL INPUT VOLTAGE (LSB)
Figure 6. Two’s-Complement Transfer Function (T/B = 0)
Output Data Format (T/B) Transfer Functions
The MAX1438 output data format is either offset binary
or two’s complement, depending on the logic-input T/B.
With T/B low, the output data format is two’s comple-
ment. With T/B high, the output data format is offset
binary. The following equations, Table 2, and Figures 6
and 7 define the relationship between the digital output
and the analog input. For two’s complement (T/B = 0):
V_{IN_P}
−
V_{IN_N}
=
FSR
×
2
×
CODE₁₀
4096
0x003
0x002
0x800
0x000
-2047 -2045
-1 0 +1
+2045 +2047
DIFFERENTIAL INPUT VOLTAGE (LSB)
Figure 7. Binary Transfer Function (T/B = 1)
and for offset binary (T/B = 1):
V_{IN_P}
−
V_{IN_N}
=
FSR
×
2
×
CODE₁₀ −
4096
2048
where CODE₁₀ is the decimal equivalent of the digital
output code as shown in Table 2.
Keep the capacitive load on the MAX1438 digital out-
puts as low as possible.
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