Serial Interface Illustrative Applications

NVE Corporation

(952) 829-9217

iso-apps@nve.com

www.IsoLoop.com

www.nve.com

Isolating Standard CAN Transceivers

Isolating CANbus allows higher speed and more reliable operation by eliminating ground

loops and reducing noise susceptibility. This simple circuit works with any CAN transceiver

with a TxD dominant timeout, which includes all of the current-generation transceivers

including the ubiquitous Philips/NXP TJA1050. Propagation delay is critical for CANbus, and

the IL712 and IL721 bidirectional isolators have best-in-class propagation delay of 10 ns.

IL712/IL721

TxD

RxD

CANH

CANL

Tx0

Rx0

TJA1050

ADR 0...7, CS

XTAL1

XTAL2

SJA1000

7

6

2

1

4

3

1

2

3

4

8

7

6

5

2

DD2

Isolated USB UART Using an IL712 or IL721

Isolating the input to a USB controller (rather than the bus lines) requires fewer isolation

channels and is therefore usually the simplest solution, as shown above. The Microchip

MCP2200 is a USB 2.0 to UART protocol converter.

0.1µF

12 MHz

5V

1

VDD

OSC1

4

OSC2

RST

T

MCP2200

VSS

20

D+

19

D-

18

VUSB

17

CTS 13

R

10

IL712/IL721

GND_USB

3.3V

GN D

3

2

12

D+

D-

VBUS

GN D

USB_P

USB_N

1

5

2

3

T

R

4.7k

Visit www.IsoLoop.com for more illustrative IsoLoop Isolator applications.