ELM327 Demonstration Board

2 (RxD)

X14.00MHz

C427pF

RS232Interface(DB9F)

OBDInterface

R27-30470Ω

+5V

C327pF

+5V

+5V

+5V

3 (TxD)

5 (SG)

1 (DCD)

4 (DTR)

6 (DSR)

7 (RTS)

8 (CTS)

+5V

317L

+12V

ELM327pin 14

R154.7KΩ

toR15

+5V

(DB9M)

J1850 Bus +7

J1850 Bus -6

Q5

toR21

n.c.

+5V

+5V

CAN-H3

CAN-L5

1 2 3 4

5678

MCP2551

PWR

Vbat Vbat

ISO-L8

ISO-K4

ELM327pin 12

Vbat

327

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1516171819202122232425262728

U1

BatteryPositive

9 78L05

Vbat +12V

SignalGround

1

+5V

R1470Ω

C60.1µF

C10.1µF

D1

R264.7KΩ

R2410KΩ

R2510KΩ D4D5

C5

0.1µF

R234.7KΩ

R2210KΩ

Q8

Q9

L1-L4

L5R32

100ΩR33

100Ω

C8560pF

C9560pF

R314.7KΩ

C70.1µF

R19510Ω

R17510Ω

R16 2.2KΩ

R18 2.2KΩ

R2047KΩ R21

22KΩ

R3447KΩ

R3510KΩ C2

0.1µF

R5240Ω R3 470Ω

R4470Ω

R2470Ω

R810KΩ

R74.7KΩ Q1

Q2R64.7KΩ R10

22KΩ

R9 10KΩ

R1110KΩ

R12100KΩD3

Q4

R1310KΩ

R144.7KΩ

Q3

D2

Q6

Q7

U2

U3

U4