Datasheet

26
LTC1096/LTC1096L
LTC1098/LTC1098L
U
SA
O
PP
L
IC
AT
ITY
P
I
CA
L
Remote or Isolated Systems
Figure 16 shows a floating system that sends data to a
grounded host system. The floating circuitry is isolated by
two optoisolators and powered by a simple capacitor
diode charge pump. The system has very low power
requirements because the LTC1096 shuts down between
conversions and the optoisolators draw power only when
data is being transferred. The system consumes only
50µA at a sample rate of 10Hz (1ms on-time and 99ms off-
time). This is easily within the current supplied by the
charge pump running at 5MHz. If a truly isolated system
is required, the system’s low power simplifies generating
an isolated supply or powering the system from a battery.
Figure 16. Power for This Floating A/D System Is Provided by a Simple Capacitor Diode Charge Pump. The Two Optoisolators
Draw No Current Between Samples, Turning On Only to Send the Clock and Receive Data
LTC1096

+IN
–IN
D
OUT

CS

CLK
V
CC
GND
V
REF


75k
LT1004-2.5
1k
20k
0.1µF
1N5817
0.022µF
47µF
1N5817
1N5817
0.001µF
2kV
5MHz
100k
300Ω
10k
500k
ANALOG
INPUT
FLOATING SYSTEM
CLK
DATA
100k
LTC1096/8 • F16
2N3904
+