MAX1426 Datasheet, PDF (13/16 Pages) Maxim Integrated Products – 10-Bit, 10Msps ADC

10-Bit, 10Msps ADC
octal D-latched flip-flop (74ALS374), or use octal
buffers such as the 74ALS541.
Typical Application Using an
External Reference
Figure 7 shows an application circuit that shuts down
the internal reference, allowing an external reference to
be used for selecting a different common-mode volt-
age. This added flexibility also allows for ratiometric
conversions, as well as for calibration.
CMLP
5.5k
INP
INN
5.5k
TO T/H INPUT
Using Transformer Coupling
A small transformer (Figure 8) provides isolation and
AC-coupling to the ADC’s input. Connecting the trans-
former's center tap to CML provides a +2.25VDC level
shift to the input. Transformer coupling reduces the
need for high-speed op amps, thereby reducing cost.
Although a 1:1 transformer is shown, a step-up trans-
former may be selected to reduce the drive require-
ments.
Single-Ended DC-Coupled Input Signal
Figure 9 shows an AC-coupled, single-ended applica-
tion. The MAX4106 quad op amp provides high speed,
high bandwidth, low noise, and low distortion to main-
tain the integrity of the input signal.
4.5k
4.5k
CMLN
Figure 6. Analog Input DC Bias Circuit
V_DD
R
R
MAX4284
50Ω
( ) CML
V_DD
2
0.1µF
V_DD
2
50Ω
MAX4284
( ) REFP
V_{DD + 1V}
2
0.1µF
R
R
V_DD
2
MAX1426
V_DD
4
R
50Ω
R
MAX4284
( ) REFN VDD - 1V
2
0.1µF
V_DD ^R
4
REFIN
AGND
R
+1V
Figure 7. Using an External Reference for REFP, REFN, and CML (internal reference shut down)
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