Datasheet

MAX1183
where f
IN
represents the analog input frequency and
t
AJ
is the time of the aperture jitter.
Clock jitter is especially critical for undersampling
applications. The clock input should always be consid-
ered as an analog input and routed away from any ana-
log input or other digital signal lines.
The MAX1183 clock input operates with a voltage thresh-
old set to V
DD
/2. Clock inputs with a duty cycle other
than 50% must meet the specifications for high and low
periods as stated in the Electrical Characteristics.
System Timing Requirements
Figure 3 depicts the relationship between the clock
input, analog input, and data output. The MAX1183
samples at the rising edge of the input clock. Output
data for channels A and B is valid on the next rising
edge of the input clock. The output data has an internal
latency of five clock cycles. Figure 4 also determines
the relationship between the input clock parameters
and the valid output data on channels A and B.
Digital Output Data, Output Data Format
Selection (T/B), Output Enable (
OE )
All digital outputs, D0A–D9A (Channel A) and D0B–D9B
(Channel B) are TTL/CMOS logic-compatible. There is a
five-clock-cycle latency between any particular sample
and its corresponding output data. The output coding
can be chosen to be either straight offset binary or
two’s complement (Table 1) controlled by a single pin
(T/B). Pull T/B low to select offset binary and high to
activate two’s complement output coding. The capaci-
tive load on the digital outputs D0A–D9A and D0B–D9B
should be kept as low as possible (<15pF) to avoid
large digital currents that could feed back into the ana-
log portion of the MAX1183, thereby degrading its
dynamic performance. Using buffers on the digital out-
puts of the ADCs can further isolate the digital outputs
from heavy capacitive loads. To further improve the
dynamic performance of the MAX1183, small-series
resistors (e.g., 100Ω) may be added to the digital out-
put paths close to the MAX1183.
Dual 10-Bit, 40Msps, 3V, Low-Power ADC with
Internal Reference and Parallel Outputs
12 ______________________________________________________________________________________
N - 6
N
N - 5
N + 1
N - 4
N + 2
N - 3
N + 3
N - 2
N + 4
N - 1
N + 5
N
N + 6
N + 1
5-CLOCK-CYCLE LATENCY
ANALOG INPUT
CLOCK INPUT
DATA OUTPUT
D9A–D0A
t
DO
t
CH
t
CL
N - 6 N - 5 N - 4 N - 3 N - 2 N - 1 N N + 1
DATA OUTPUT
D9B–D0B
Figure 3. System Timing Diagram