SLLSEB6 – JULY 2012
Typical Application Circuit
V
S
3.3V
0.1μF
2
Vcc D2 3
1:2.2
MBR0520L
10μF 0.1μF
1
10μF
MBR0520L
5V
ISO
10μF
2
1Ω
9
10
1
SDA
ADDR
8
VDD
1
3
IN
ON
OUT
GND
5
0.1μF
4
4 Analog
Inputs
AIN3
7
SN6501
GND D1
4,5
LP2981-50
AIN0
SCL
ADS1115
GND RDY
3
2
6
22μF
SCL
ISO-BARRIER
5V
ISO
0.1μF
1.5k
2
5
6
DVcc
XOUT
MSP430
XIN
SDA
SCL
9
8
1.5k
1
8
VCC1
VCC2
2
7
SDA1
SDA2
ISO1541
3
6
SCL1
SCL2
GND1
GND2
4
5
0.1μF
1.5k
1.5k
SDA
5V
ISO
0.1μF
V
OUT
REF5040
5V
ISO
2
V
IN
1μF
4
0.1μF
G2132
DVss
4
15 4 12
3
A2 VDD IOV
DD
V
REF
H
11
1
SDA
V
OUT
A
10
SCL
DAC8574
9
LDAC
14
A1
V
OUT
D
8
A0 A3 GND V
REF
L
13 16
6
5
GND
4 Analog
Outputs
Figure 11. Isolated I
2
C Data Acquisition System
In
the ultra low-power micro controller, MSP430G2132, controls the I
2
C data traffic of configuration
data and conversion results for the analog inputs and outputs. Low-power data converters build the analog
interface to sensors and actuators. The ISO1541 provides the necessary isolation between different ground
potentials of the system controller, remote sensor, and actuator circuitry to prevent ground loop currents that
otherwise may falsify the acquired data.
The entire circuit operates from a single 3.3 V supply. A low-power push-pull converter, SN6501, drives a center-
tapped transformer whose output is rectified and linearly regulated to provide a stable 5 V supply for the data
converters.
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