MAX114 Datasheet, PDF (9/12 Pages) Maxim Integrated Products – +5V, 1Msps, 4 & 8-Channel, 8-Bit ADCs with 1μA Power-Down

+5V, 1Msps, 4 & 8-Channel,
8-Bit ADCs with 1µA Power-Down
Pipelined Operation
Besides the two standard write-read-mode options,
pipelined operation can be achieved by connecting
WR to RD (Figure 6). With CS low, driving WR and RD
low initiates a conversion and concurrently reads the
result of the previous conversion.
_____________Analog Considerations
Reference
Figures 7a, 7b, and 7c show typical reference connec-
tions. The voltages at REF+ and REF- set the ADC’s
analog input range (see Figure 10). The voltage at REF-
defines the input that produces an output code of all
zeros, and the voltage at REF+ defines the input that
produces an output code of all ones.
The internal resistance from REF+ to REF- can be as
low as 1kΩ, and current will flow through it even when
the MAX114/MAX118 are shut down. Figure 7d shows
how an N-channel MOSFET can be connected to REF-
CS
RD, WR
A0–A2
INT
tCSS
tCSH
tWR
tACQ
tAH
ADDRESS
VALID (N)
tIHWR
tINTL
D0–D7 OLD DATA (N - 1)
tACQ
ADDRESS
VALID (N + 1)
tID
NEW DATA (N)
Figure 6. Pipelined Mode Timing (WR = RD) (MODE = 1)
VIN+
VIN-
+5V
4.7µF
0.1µF
IN_
GND
MAX114
VDD MAX118
REF+
REF-
Figure 7a. Power Supply as Reference
VIN+
+5V
4.7µF ^0.1µF
+2.5V
VIN-
R* 0.1µF
* CURRENT PATH MUST STILL
EXIST FROM V_IN- TO GND
IN_
GND
VDD _MAX114
MAX118
REF+
REF-
0.1µF
Figure 7c. Input Not Referenced to GND
+5V
4.7µF
0.1µF
VIN+
VIN-
MX584
IN_
GND
C1
0.1µF
VDD _MAX114
REF+ ^MAX118
REF-
+5V
MAX874
0.1µF
C1
3.3µF
V_DD
MAX114
MAX118
REF+
PWRDN
* IRML2402
N-FET*
REF-
0.1µF
PWRDN
Figure 7b. External Reference, 4.096V Full Scale
Figure 7d. An N-channel MOSFET switches off the reference
load during power-down
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