ICL7126_14 Datasheet, PDF (12/15 Pages) Intersil Corporation – 3 1/2 Digit, Low Power, Single Chip A/D Converter

ICL7126
Typical Applications (Continued)
OSC 1 40
OSC 2 39
OSC 3 38
TEST 37
REF HI 36
V+ 35
C_REF 34
C_REF 33
COMMON 32
IN HI 31
IN LO 30
A-Z 29
BUFF 28
INT 27
V - 26
G2 25
C3 24
A3 23
G3 22
GND 21
†
50pF
SET V_REF
= 100mV
+5V
20kΩ 100kΩ 27kΩ
0.1µF
1.2V (ICL8069)
1MΩ
+
0.01µF
IN
0.33µF
-
180kΩ
†
TO DISPLAY
TO BACK PLANE
V+
OSC 1 40 _†
OSC 2 39
OSC 3 38
TEST 37 ^50pF
REF HI 36
V+ 35
C_REF 34
C_REF 33
COMMON 32
0.1µF
IN HI 31
IN LO 30
A-Z 29
BUFF 28
0.33µF
R_INT
INT 27
V - 26
†
G2 25
C3 24
A3 23
TO DISPLAY
G3 22
GND 21
TO BACK PLANE
An external reference must be used in this application, since the
voltage between V+ and V- is insufficient for correct operation of the
internal reference. † indicates values depend on clock frequency.
FIGURE 14. ICL7126 OPERATED FROM SINGLE +5V SUPPLY
The resistor values within the bridge are determined by the desired
sensitivity. † indicates values depend on clock frequency.
FIGURE 15. ICL7126 MEASURING RATIOMETRIC VALUES OF
QUAD LOAD CELL
OSC 1 40
OSC 2 39
†
OSC 3 38
TEST 37
REF HI 36
50pF
SCALE
FACTOR
ADJUST
V+ 35
C_REF
34
0.1µF
C_REF 33
COMMON 32
100kΩ 1MΩ
200kΩ 470kΩ
IN HI 31
IN LO 30
A-Z 29
BUFF 28
0.01µF
0.33µF
ZERO
ADJUST
390kΩ
INT 27
V - 26
†
G2 25
C3 24
A3 23
TO DISPLAY
G3 22
BP 21
TO BACKPLANE
100kΩ
SILICON NPN
MPS 3704 OR
SIMILAR
9V
A silicon diode-connected transistor has a temperature coefficient of about -2mV/^oC. Calibration is achieved by placing the sensing transistor in
ice water and adjusting the zeroing potentiometer for a 000.0 reading. The sensor should then be placed in boiling water and the scale-factor
potentiometer adjusted for a 100.0 reading.
FIGURE 16. ICL7126 USED AS A DIGITAL CENTIGRADE THERMOMETER
12
FN3084.5