Programmable-gain instrumentation amplifier – Rainbow Electronics MAX1329 User Manual
Page 69
MAX1329/MAX1330
12-/16-Bit DASs with ADC, DACs, DPIOs, APIOs,
Reference, Voltage Monitors, and Temp Sensor
______________________________________________________________________________________
69
AIN1
AGND
2N3904
MUX
REFADC
PGA
AIN1
AIN2
OUT1
OUTB/OUT2
FBB/IN2-
IN1-
DV
DD
/4
REFADC
REFDAC
OUTA/OUT3
FBA/IN3-
ADC FIFO
DITHER
ACCUMULATOR
12-BIT ADC
A
V
= 1, 2, 4, 8
ALARM
MUX
REFADJ
REFADC
2.5V
REF
A
V
= 0.5, 0.82, 1
AIN2
AGND
2N3904
REFDAC
TEMP
SENSOR
TEMP1
A
V
= 0.5, 0.82, 1
*FOR BEST RESULTS, LIMIT C
AIN1
AND C
AIN2
TO 10pF.
AV
DD
/4
TEMP1
AGND
C
AIN1
*
TEMP2
TEMP3
C
AIN2
*
1
μF
0.01
μF
1
μF
MAX1329
MAX1330
Figure 31. Temperature Measurement with Two Remote Sensors
Programmable-Gain Instrumentation
Amplifier
Two op amps and two SPDT switches are configured
as a programmable-gain instrumentation amplifier in
Figure 32. It includes a differential input and a single-
ended output. SPDT1 and SPDT2 are configured as
single-pole, double-throw switches. The gain is set by
the following equations:
for switch position 1, and
for switch position 2.
V
R
R
R
V
V
OUT
IN
IN
=
+
+
⎛
⎝
⎜
⎞
⎠
⎟
−
+
−
3
1
2
1 (
)
V
R
R
R
V
V
OUT
IN
IN
=
+
+
⎛
⎝
⎜
⎞
⎠
⎟
−
+
−
2
3
1
1 (
)