Rainbow Electronics MAX1208 - Manual (Page 18)

MAX1208
for two’s complement (G/T = 0)
where CODE 10 is the decimal equivalent of the digital
output code as shown in Table 2.
Digital outputs D11–D0 are high impedance when the
MAX1208 is in power-down (PD = high). D11–D0 transi-
tion high 10ns after the rising edge of PD and become
active 10ns after PD’s falling edge.
Keep the capacitive load on the MAX1208 digital outputs
D11–D0 as low as possible (<15pF) to avoid large digital
currents feeding back into the analog portion of the
MAX1208 and degrading its dynamic performance. The
addition of external digital buffers on the digital outputs
isolates the MAX1208 from heavy capacitive loading. To
improve the dynamic performance of the MAX1208, add
220
Ω resistors in series with the digital outputs close to
the MAX1208. Refer to the MAX1211 evaluation kit
schematic for an example of the digital outputs driving a
digital buffer through 220
Ω series resistors.
Power-Down Input (PD)
The MAX1208 has two power modes that are controlled
with the power-down digital input (PD). With PD low, the
V V V V
CODE
INP INN REFP REFN
( )
− = − Ч Ч
2
4096
10
12-Bit, 80Msps, 3.3V ADC
18 ______________________________________________________________________________________
GRAY CODE OUTPUT CODE (G/ T = 1) TWO’S-COMPLEMENT OUTPUT CODE (G/ T = 0)
BINARY
D11 ➝D0
DOR
HEXADECIMAL
EQUIVALENT
OF
D11 ➝D0
DECIMAL
EQUIVALENT
OF
D11 ➝D0
(CODE 10 )
BINARY
D11 ➝D0
DOR
HEXADECIMAL
EQUIVALENT
OF
D11 ➝D0
DECIMAL
EQUIVALENT
OF
D11 ➝D0
(CODE 10 )
V INP - V INN
V REFP = 2.162V
V
REFN
= 1.138V
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 2. Output Codes vs. Input Voltage
( )