DreamCity Innovations

WCH CH340G Datasheet

5.2. Example: Optically isolated USB to UART adapter

This adapter provides optically isolated inputs and outputs with 4 PC817 optoisolators.

Respect the isolation border when laying out the board, and if possible, cut slots under the

optoisolators. The two 74LVC1G06 is optional, but helpful when the input pins cannot source

too many current.

PN61729-S

GND

10µ

10n

22p

22p

12M

GND

PC817

PC817

PC817

PC817

74LVC1G06DBV

74LVC1G06DBV

510

10k

510

10k

GNDIO

GNDIO

VDD

GNDIO

10µ

10k

510

10k

510

GND

VCC

16

GND

1

R232

15

V3

4

XI

7

XO

8

D+

5

D-

6

TXD

2

RXD

3

RTS#

14

DTR#

13

DCD#

12

RI#

11

DSR#

10

CTS#

9

IC2

X1

1

2

3

4

C1

C2

C3

C4

Q1

OK1

1

2

3

4

OK2

1

2

3

4

OK3

1

2

3

4

OK4

1

2

3

4

JP1

DTR

RXI

TXO

VCC

CTS

GND

IC1G$1

2

4

IC1G$2

IC3G$1

2

4

IC3G$2

R1

R2

R3

R4

C5

R5

R6

R7

R8

D-

D-

D+

D+

RXD

RXD

DCD

RI

DSR

CTS

CTS

TXD

TXD

DTR

DTR

RTS

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WCH CH340G Datasheet