±18-Bit ADC with Serial Interface
_________________________________________________Pin Description (continued)
PIN
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
NAME
P2
P3
EOC
DGND
V-
IN HI
IN LO
AGND
REF-
REF+
CREF+
CREF-
INT IN
INT OUT
BUF OUT
V+
FUNCTION
User-programmable output bit 2—programmed through the serial port.
User-programmable output bit 3—programmed through the serial port.
End of Conversion Output goes high at end of conversion.
Digital Ground—power-supply return
Negative Supply, nominally -5V
Positive Analog Input
Negative Analog Input
Analog Ground
Negative Reference Input
Positive Reference Input
Positive Reference Capacitor connection
Negative Reference Capacitor connection
Integrator Input. Connect the integration capacitor between INT IN and INT OUT.
Integrator Output. To minimize noise, this pin should drive the capacitor’s outside foil (negative end).
Buffer-Amplifier Output drives the integrator resistor.
Positive Supply, nominally +5V
MAX132
0.1µF
20
CREF-
1
4
11
2
3
CS
SCLK
EOC
DIN
DOUT
REF+
REF-
7
8
9
10
19
CREF+
V+
24
23
22
21
18
17
16
15
14
13
12
+5V
2.5V
602k
120k
MAX872
BUF OUT
INT OUT
INT IN
4.7nF
100k
40.2k
MAX132
P0
P1
P2
P3
OSC1
6
AGND
IN LO
IN HI
V-
DGND
OSC2
5
15pF
512mV INPUT
-5V
32,768Hz
15pF
Figure 1. Test and Typical Application Circuit
_______________________________________________________________________________________
5
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
