L5951

4/13

high pulse identified by a pulse width of about t = 200

µs.

DATA - Total number of bytes that can be transmitted (from SOF to EOF) is 12 bytes.

Cyclic Redundancy Check (CRC) - A method for determining if the message received is the same as the mes-

sage transmitted. If an invalid CRC number is detected, then an error will be detected. The SOF signal is not

used to determine the CRC. All bits in the CRC are initially "ones" to avoid confusion with a data stream that are

all "zeros".

End of Data (EOD) - Used to signal the receiver about the end of data transmission. If there is a IRF signal, the

sender of the frame will expect one or more bytes in the IFR following the EOD. If there is no IFR used, then the

bus would stay in a logic level low state resulting in a EOF. EOD signal is recognized by a logic level low pulse

for a duration of about 200

µs.

Normalization Bit (NB) - The sole reason for the NB is to define the start of the in-frame response. The first bit

the the IFR is passive, therefore it is necessary to have a signal that follows EOD. There are two forms to the

NB. First of all, the NB is a logic level high pulse. The two forms are distinguished by thier pulse widths. The first

form has a pulse width of about 64

µs and indicates if the IFR contains a CRC or not. The second form has a

longer pulse width of about 128

µs and also indicates if there is a CRC in the IFR or not. The manufacturer can

manipulate the NB to any of the two methods.

In-Frame Response (IFR) - Response bytes are sent by the receiver of the transmission and start after the

EOD. If the IFR stays at a logic level low for a period of time then the frame must be considered to be complete.

IFR bytes can be used to send a signal back to the originator indicating the correct CRC number to confirm the

correct message was sent.

End of Frame (EOF) - Indicates the end of a frame. Once the last byte is transmitted, the bus will be in a logic

level low state for a period of time indicating the end of the frame. EOF signal is recognized by a low pulse for

a width of about 280

µs.

Inter-Frame Separation (IFS) - IFS is used to synchronize the receivers at various nodes.

ABSOLUTE MAXIMUM RATINGS

* denotes active low

THERMAL DATA

(*) With 6cm2 on board heat sink area.

Symbol

Parameter

Value

Unit

DC Operating Supply Voltage

-0.6 to 26.5

V

Diagnostic output voltage

-0.6 to 5.5

V

Input Control Voltage (EN, Sleep, 4X, Loop, TX)

-0.6 to 5.5

V

Output Control Voltage (Reset *)

-0.3 to 5.5

V

Peak Supply Voltage t = 50ms

34

V

Operating Temperature Range

-40 to 85

°C

Storage Temperature Range

-40 to 150

°C

Symbol

Parameter

Value

Unit

Thermal resistance junction to ambient (*)

50

°C/W