TJA1051_2

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 02 — 1 July 2009

4 of 18

NXP Semiconductors

TJA1051

High-speed CAN transceiver

6.

Functional description

The TJA1051 is a high-speed CAN stand-alone transceiver with Silent mode. It combines

the functionality of the TJA1050 transceiver with improved EMC and ESD handling

capability. Improved slope control and high DC handling capability on the bus pins

provides additional application flexibility.

The TJA1051 is available in two versions, distinguished only by the function of pin 5:

supply voltages down to 3 V

6.1 Operating modes

The TJA1051 supports two operating modes, Normal and Silent, which are selectable via

pin S. See Table 3 for a description of the operating modes under normal supply

conditions.

[1]

LOW if the CAN bus is dominant, HIGH if the CAN bus is recessive.

[2]

X = don't care

6.1.1 Normal mode

A LOW level on pin S selects Normal mode. In this mode, the transceiver is able to

transmit and receive data via the bus lines CANH and CANL (see Figure 1 for the block

diagram). The differential receiver converts the analog data on the bus lines into digital

data which is output to pin RXD. The slope of the output signals on the bus lines is

controlled and optimized in a way that guarantees the lowest possible ElectroMagnetic

Emission (EME).

6.1.2 Silent mode

A HIGH level on pin S selects Silent mode. In Silent mode the transmitter is disabled,

releasing the bus pins to recessive state. All other IC functions, including the receiver,

continue to operate as in Normal mode. Silent mode can be used to prevent a faulty CAN

controller from disrupting all network communications.

6.2 Fail-safe features

6.2.1 TXD dominant time-out function

A ‘TXD dominant time-out’ timer is started when pin TXD is set LOW. If the LOW state on

lines to recessive state. This function prevents a hardware and/or software application

Table 3.

Operating modes

Mode

Inputs

Outputs

Pin S

Pin TXD

CAN driver

Pin RXD

Normal

LOW

LOW

dominant

active[1]

LOW

HIGH

recessive

active[1]

Silent

HIGH

X[2]

recessive

active[1]