26

LTC1096/LTC1096L

LTC1098/LTC1098L

S

APPLICATI

TYPICAL

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

50

µA 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

0.1

µF

1N5817

0.022

µF

47

µF

1N5817

1N5817

0.001

µF

2kV

5MHz

100k

300

Ω

10k

500k

ANALOG

INPUT

FLOATING SYSTEM

CLK

DATA

100k

LTC1096/8 • F16

2N3904

+