LTC1096/LTC1096L

LTC1098/LTC1098L

29

10968fc

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

CS

CLK

GND

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

10968 F16

2N3904

+