Maxim Integrated MAX12527 - Manual (Page 19)

externally isolates it from heavy capacitive loads. Refer
to the MAX12527 EV Kit schematic for recommendations
of how to drive the DAV signal through an external buffer.
Data Out-of-Range Indicator
The DORA and DORB digital outputs indicate when the
analog input voltage is out of range. When DOR_ is high,
the analog input is out of range. When DOR_ is low, the
analog input is within range. The valid differential input
range is from (V
REF_P - V REF_N ) x 2/3 to (V REF_N -
V
REF_P
) x 2/3. Signals outside of this valid differential
range cause DOR_ to assert high as shown in Table 1.
DOR is synchronized with DAV and transitions along
with the output data D11–D0. There is an 8 clock-cycle
latency in the DOR function as is with the output data
(Figure 5). DOR_ is high impedance when the
MAX12527 is in power-down (PD = high). DOR_ enters
a high-impedance state within 10ns after the rising edge
of PD and becomes active 10ns after PD’s falling edge.
Digital Output Data and Output Format Selection
The MAX12527 provides two 12-bit, parallel, tri-state
output buses. D0A/B–D11A/B and DORA/B update on
the falling edge of DAV and are valid on the rising edge
of DAV.
The MAX12527 output data format is either Gray code
or two’s complement depending on the logic input G/T.
With G/T high, the output data format is Gray code.
With G/T low, the output data format is set to two’s com-
plement. See Figure 8 for a binary-to-Gray and Gray-to-
binary code conversion example.
The following equations, Table 3, Figure 6, and Figure 7
define the relationship between the digital output and
the analog input.
Gray Code (G/T = 1):
V
IN_P
- V
IN_N
= 2/3 x (V
REF_P
- V
REF_N
) x 2 x
(CODE
10
- 2048) / 4096
Two’s Complement (G/T = 0):
V IN_P - V IN_N = 2/3 x (V REF_P - V REF_N ) x 2 x
CODE 10 / 4096
where CODE 10 is the decimal equivalent of the digital
output code as shown in Table 3.
MAX12527
Dual, 65Msps, 12-Bit, IF/Baseband ADC
______________________________________________________________________________________ 19
GRAY-CODE OUTPUT CODE
(G/T = 1)
TWO’S COMPLEMENT OUTPUT CODE
(G/T = 0)
BINARY
D11A–D0A
D11B–D0B DOR
H EXA D ECIM A L
EQUIVALENT
OF
D11A–D0A
D11B–D0B
DECIMAL
EQUIVALENT
OF
D11A–D0A
D11B–D0B
(CODE 10 )
BINARY
D11A–D0A
D11B–D0B DOR
HEXADECIMAL
EQUIVALENT
OF
D11A–D0A
D11B–D0B
DECIMAL
EQUIVALENT
OF
D11A–D0A
D11B–D0B
(CODE 10 )
V IN_P - V IN_N
V
REF_P
= 2.418V
V REF_N = 0.882V
1000 0000 0000 1 0x800 +4095 0111 1111 1111 1 0x7FF +2047
>+1.0235V
(DATA OUT OF
RANGE)
1000 0000 0000 0 0x800 +4095 0111 1111 1111 0 0x7FF +2047 +1.0235V
1000 0000 0001 0 0x801 +4094 0111 1111 1110 0 0x7FE +2046 +1.0230V
1100 0000 0011 0 0xC03 +2050 0000 0000 0010 0 0x002 +2 +0.0010V
1100 0000 0001 0 0xC01 +2049 0000 0000 0001 0 0x001 +1 +0.0005V
1100 0000 0000 0 0xC00 +2048 0000 0000 0000 0 0x000 0 +0.0000V
0100 0000 0000 0 0x400 +2047 1111 1111 1111 0 0xFFF -1 -0.0005V
0100 0000 0001 0 0x401 +2046 1111 1111 1110 0 0xFFE -2 -0.0010V
0000 0000 0001 0 0x001 +1 1000 0000 0001 0 0x801 -2047 -1.0235V
0000 0000 0000 0 0x000 0 1000 0000 0000 0 0x800 -2048 -1.0240V
0000 0000 0000 1 0x000 0 1000 0000 0000 1 0x800 -2048
<-1.0240V
(DATA OUT OF
RANGE)
Table 3. Output Codes vs. Input Voltage