AD9211-170EB AD [Analog Devices], AD9211-170EB Datasheet - Page 17

• Manufacturer Part Number: AD9211-170EB
• Description: 10-Bit, 170/200/250 MSPS 1.8 V A/D Converter
• Manufacturer: AD [Analog Devices]

Preliminary Technical Data
By asserting the PDWN pin high, the AD9211 is placed in
standby mode. In this state, the ADC typically dissipates
1 mW even if the CLK and analog inputs are static. During
standby, the output drivers are placed in a high impedance state.
Reasserting the PDWN pin low returns the AD9211 into its
normal operational mode.
An additional stand by mode is supported by means of varying
the clock input. When the clock rate falls below 20MHz, the
AD9211 will assume a standby state. In this case, the biasing
network and internal reference remain on but digital circuitry is
powered down. Upon reactivating the clock, the AD9211 will
resume normal operation after allowing for the pipeline latency.
DIGITAL OUTPUTS
The AD9228’s differential outputs conform to the ANSI-644
LVDS standard on default power up. The LVDS driver current
is derived on-chip and sets the output current at each output
equal to a nominal 3.5 mA. A 100 Ω differential termination
resistor placed at the LVDS receiver inputs results in a nominal
350 mV swing at the receiver.
The AD9211’s LVDS outputs facilitate interfacing with LVDS
receivers in custom ASICs and FPGAs that have LVDS capa-
bility for superior switching performance in noisy environ-
ments. Single point-to-point net topologies are recommended
with a 100 Ω termination resistor placed as close to the receiver
as possible. It is recommended to keep the trace length no
longer than 12 inches and to keep differential output traces
close together and at equal lengths.
Figure 14. AD9211-250, Supply Current vs. f
SAMPLE
for f
IN
= 10.3 MHz
Rev. PrA | Page 17 of 21
The format of the output data is offset binary. An example of
the output coding format can be found in Table 7.
Table 7. Digital Output Coding
Code
1024
512
511
0
As detailed in Interfacing to ADC SPI , the data format can be
selected for either offset binary or twos complement, or Gray
code (SPI access only).
Out-of-Range (OTR)
An out-of-range condition exists when the analog input voltage
is beyond the input range of the ADC. OTR is a digital output
that is updated along with the data output corresponding to the
particular sampled input voltage. Thus, OTR has the same
pipeline latency as the digital data. OTR is low when the analog
input voltage is within the analog input range and high when
the analog input voltage exceeds the input range as shown in
Figure 15. OTR will remain high until the analog input returns
to within the input range and another conversion is completed.
By logically AND-ing OTR with the MSB and its complement,
over-range high or under-range low conditions can be detected.
TIMING
The AD9211 provides latched data outputs with a pipeline delay
of five clock cycles. Data outputs are available one propagation
delay (t
Figure 15. OTR Relation to Input Voltage and Output Data for
PD
(VIN+) − (VIN−),
Input Span =
1.252 V p-p (V)
1.000
0
−0.000488
−1.00
) after the rising edge of the clock signal.
AD9230/AD9211
Digital Output
Offset Binary
(D9 ... D0)
11 1111 1111
10 0000 0000
01 1111 1111
00 0000 0000
AD9211