MAX1425_11 Datasheet, PDF (12/16 Pages) Maxim Integrated Products – 10-Bit, 20Msps ADC Separate Digital Supply Input for 3V Logic Compatibility

10-Bit, 20Msps ADC
heavy loads, as they are specified to deliver only
200µA for TTL compatibility. If an application needs
output buffering, use 74LS74s or 74ALS541s as
required.
Applications Information
Figure 5 depicts a typical application circuit containing
a single-ended to differential converter. The internal ref-
erence provides a +2.25V output for level shifting. The
input is buffered and then split to a voltage follower and
inverter. The op amps are followed by a lowpass filter
to remove some of the wideband noise associated with
high-speed op amps. In this application, the amplifier
outputs are directly coupled to the inputs. This configura-
tion can also be modified for AC-coupled applications.
The MAX1425 includes a DC level-shifting circuit internal
to the part, allowing for AC-coupled applications. The
level-shifting circuit is shown in Figure 6.
The circuit in Figure 6 can accept a 1Vp-p maximum
input voltage. With a maximum clock frequency of
20MHz, use 50Ω termination to minimize reflections.
Buffer the digital outputs with a low-cost, high-speed,
INPUT
50Ω
300Ω
300Ω
0.1μF
600Ω
+5V
MAX4108
0.1μF
BAS16
0.1μF
-5V
0.1μF
300Ω
50Ω
600Ω
+5V
2.5k
0.1μF
MAX473A
+5V
0.1μF
MAX4108
-5V
0.1μF
25Ω
25Ω
0.1μF
0.1μF
2.5k
50Ω
600Ω
+5V
300Ω
0.1μF ^0.1μF
300Ω
300Ω
MAX4108
50Ω
BAS16
-5V
0.1μF
600Ω
INP
22pF
MAX1425
CML
INN
22pF
Figure 5. Typical Application Circuit Using the Internal Reference
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