ELM327P Ver la hoja de datos (PDF) - Elm Electronics

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ELM327P

OBD to RS232 Interpreter

Elm Electronics 

Pin Descriptions (continued)

Example Applications section for more information).

If unused, pin 24 must be connected to a logic high

(VDD) level.

RS232 Rx LED (pin 25), RS232 Tx LED (pin 26),

OBD Rx LED (pin 27) and OBD Tx LED (pin 28)

These four output pins are normally high, and are

driven to low levels when the ELM327 is transmitting

or receiving data. These outputs are suitable for

directly driving most LEDs through current limiting

resistors, or interfacing to other logic circuits. If

unused, these pins may be left open-circuited.

Note that pin 28 can also be used to turn off all of the

Programmable Parameters, if you can not do so by

using the normal interface - see page 69 for details.

ELM327

Unused Pins

When people only want to implement a portion of what the ELM327 is capable of, they often ask what to do with the

unused pins. The rule is that unused outputs may be left open-circuited with nothing connected to them, but unused

inputs must be terminated. The ELM327 is a CMOS integrated circuit that can not have any inputs left floating (or

you might damage the IC). Connect unused inputs as follows:

Pin

1

Level H

2

5

6

7

11

12

13

15

18

24

H*

H*

H*

H*

H*

L*

L*

H

H

H

Note that the inputs that are shown with an asterisk (*) may be connected to either a High (VDD) or a Low (VSS)

level, but the level shown is preferred.

Absolute Maximum Ratings

Storage Temperature....................... -65°C to +150°C

Ambient Temperature with

Power Applied....................................-40°C to +85°C

Voltage on VDD with respect to VSS..... -0.3V to +7.5V

Voltage on any other pin with

respect to VSS........................... -0.3V to (VDD + 0.3V)

Note:

These values are given as a design guideline only.

The ability to operate to these levels is neither

inferred nor recommended, and stresses beyond

those listed here will likely damage the device.

ELM327DSJ

Elm Electronics – Circuits for the Hobbyist

www.elmelectronics.com

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