1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

INA

INB

OUTC

NC

OUTA

OUTB

INC

NC

GND2

0.1 µF

EN2

GND2

EN1

GND1

GND1

0.1 µF

ISO7831, ISO7831F

www.ti.com

SLLSEP8A – JULY 2015 – REVISED SEPTEMBER 2015

Typical Application (continued)

9.2.1 Design Requirements

For ISO7831, use the parameters shown in Table 2.

Table 2. Design Parameters

PARAMETER

VALUE

Supply voltage

2.25 to 5.5 V

0.1 µF

0.1 µF

9.2.2 Detailed Design Procedure

Unlike optocouplers, which need external components to improve performance, provide bias, or limit current,

ISO7831 only needs two external bypass capacitors to operate.

Figure 17. Typical ISO7831 Circuit Hook-up

9.2.2.1 Electromagnetic Compatibility (EMC) Considerations

Many applications in harsh industrial environment are sensitive to disturbances such as electrostatic discharge

(ESD), electrical fast transient (EFT), surge and electromagnetic emissions. These electromagnetic disturbances

are regulated by international standards such as IEC 61000-4-x and CISPR 22. Although system-level

performance and reliability depends, to a large extent, on the application board design and layout, the ISO7831

incorporate many chip-level design improvements for overall system robustness. Some of these improvements

include:

•

Robust ESD protection for input and output signal pins and inter-chip bond pads.

•

Low-resistance connectivity of ESD cells to supply and ground pins.

•

Enhanced performance of high voltage isolation capacitor for better tolerance of ESD, EFT and surge events.

•

Bigger on-chip decoupling capacitors to bypass undesirable high energy signals through a low impedance

path.

•

PMOS and NMOS devices isolated from each other by using guard rings to avoid triggering of parasitic

SCRs.

•

Reduced common mode currents across the isolation barrier by ensuring purely differential internal operation.

Copyright © 2015, Texas Instruments Incorporated

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