7 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification, and

TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining

suitability of components for their purposes. Customers should validate and test their design

implementation to confirm system functionality.

7.1 Application Information

The ISO7842 device is a high-performance, quad-channel digital isolator with a 5.7kVRMS isolation voltage per

UL 1577. The device comes with enable pins on each side that can be used to put the respective outputs

in high impedance for multi-master driving applications and reduce power consumption. The ISO7842 device

uses single-ended CMOS-logic switching technology. The supply voltage range is from 2.25V to 5.5V for both

supplies, VCC1 and VCC2. When designing with digital isolators, keep in mind that because of the single-ended

design structure, digital isolators do not conform to any specific interface standard and are only intended for

isolating single-ended CMOS or TTL digital signal lines. The isolator is typically placed between the data

controller (that is, μC or UART), and a data converter or a line transceiver, regardless of the interface type or

standard.

7.2 Typical Application

Figure 7-1 shows the typical isolated RS-232 interface implementation.

VCC1

VCC2

GND1

GND2

16

14

12

2, 8

9, 15

P3.1

P3.0

UCA0TXD

UCA0RXD

11

15

16

12

4

XOUT

XIN

5

6

2

MSP430F2132

INA

OUTD

1

3

5

4

6

ISO7842

DVss

DVcc

0.1 F

0.1 F

0.1 F

EN1

EN2

7

10

INB

13

11

OUTB

INC

IND

16

0.1 F

OUTC

Vcc

GND

15

T1IN

9

11

12

10

C2±

3

R1OUT

T2IN

14

13

5

7

8

VS±

6

4

2

1

R2OUT

VS+

C1+

C1±

C2+

TRS232

4.7 k

4.7 k

R1IN

T1OUT

R2IN

T2OUT

1 F

1 F

1 F

1 F

TxD

RxD

RST

CST

ISOGND

10 F 0.1 F

MBR0520L

MBR0520L

1:2.1

0.1 F

3

1

D2

SN6501

D1

Vcc

4, 5

2

GND

3.3 V

IN

ON

GND

OU

T

1

5

4

3

LP2985-50

3.3 F

10 F

Isolation

Barrier

VIN

5 VISO

2

BP

10 nF

OUTA

Copyright © 2016, Texas Instruments Incorporated

Figure 7-1. Isolated RS-232 Interface

ISO7842, ISO7842F

SLLSEJ0H – OCTOBER 2014 – REVISED MARCH 2024

www.ti.com

22

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Product Folder Links: ISO7842 ISO7842F