MAX114 Maxim, MAX114 Datasheet - Page 9

• Manufacturer Part Number: MAX114
• Description: +5V / 1Msps / 4 & 8-Channel / 8-Bit ADCs with 1A Power-Down
• Manufacturer: Maxim

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
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-
Figure 7a. Power Supply as Reference
Figure 7b. External Reference, 4.096V Full Scale
+5V
4.7µF
+5V
4.7 F
0.1µF
0.1 F
_______________________________________________________________________________________
V
V
IN+
IN-
MX584
V
V
IN+
IN-
Pipelined Operation
REF+
REF-
IN_
GND
V
DD
C1
0.1µF
MAX114
MAX118
8-Bit ADCs with 1µA Power-Down
REF+
REF-
IN_
GND
V
DD
MAX114
MAX118
Reference
+5V, 1Msps, 4 & 8-Channel,
Figure 6. Pipelined Mode Timing (WR = RD) (MODE = 1)
Figure 7c. Input Not Referenced to GND
Figure 7d. An N-channel MOSFET switches off the reference
load during power-down
RD, WR
* CURRENT PATH MUST STILL
A0–A2
D0–D7
+5V
4.7µF
EXIST FROM V
INT
* IRML2402
CS
PWRDN
OLD DATA (N - 1)
0.1µF
ADDRESS
VALID (N)
+5V
t
IN-
ACQ
t
CSS
t
TO GND
AH
MAX874
t
WR
V
IN-
t
N-FET*
R*
t
IHWR
CSH
+2.5V
t
V
INTL
0.1µF
IN+
0.1µF
C1
3.3µF
0.1µF
t
VALID (N + 1)
t
ACQ
ID
ADDRESS
0.1µF
V
REF+
REF-
PWRDN
REF-
IN_
GND
V
REF+
DD
NEW DATA (N)
DD
MAX114
MAX118
MAX114
MAX118
9