TJA1051T-E 데이터 시트보기 (PDF) - Philips Electronics

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TJA1051T-E

High-speed CAN transceiver

Philips Electronics 

NXP Semiconductors

TJA1051

High-speed CAN transceiver

7.1.3 Off mode

A LOW level on pin EN of TJA1051T/E selects Off mode. In Off mode the entire

transceiver is disabled, allowing the microcontroller to save power when CAN

communication is not required. The bus pins are floating in Off mode, making the

transceiver invisible to the rest of the network.

7.2 Fail-safe features

7.2.1 TXD dominant time-out function

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

pin TXD persists for longer than tto(dom)TXD, the transmitter is disabled, releasing the bus

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

failure from driving the bus lines to a permanent dominant state (blocking all network

communications). The TXD dominant time-out timer is reset when pin TXD is set HIGH.

The TXD dominant time-out time also defines the minimum possible bit rate of 40 kbit/s.

7.2.2 Internal biasing of TXD, S and EN input pins

Pin TXD has an internal pull-up to VIO and pins S and EN (TJA1051T/E) have internal

pull-downs to GND. This ensures a safe, defined state in case one or more of these pins

is left floating.

7.2.3

Undervoltage detection on pins VCC and VIO

Should VCC or VIO drop below their respective undervoltage detection levels (Vuvd(VCC)

and Vuvd (VIO); see Table 7), the transceiver will switch off and disengage from the bus

(zero load) until VCC and VIO have recovered.

7.2.4 Overtemperature protection

The output drivers are protected against overtemperature conditions. If the virtual junction

temperature exceeds the shutdown junction temperature, Tj(sd), the output drivers will be

disabled until the virtual junction temperature falls below Tj(sd) and TXD becomes

recessive again. Including the TXD condition ensures that output driver oscillations due to

temperature drift are avoided.

7.3 VIO supply pin

There are three versions of the TJA1051 available, only differing in the function of a single

pin. Pin 5 is either an enable control input (EN), a VIO supply pin or is not connected.

Pin VIO on the TJA1051T/3 and TJA1051TK/3 should be connected to the microcontroller

supply voltage (see Figure 6). This will adjust the signal levels of pins TXD, RXD and S to

the I/O levels of the microcontroller. For versions of the TJA1051 without a VIO pin, the VIO

input is internally connected to VCC. This sets the signal levels of pins TXD, RXD and S to

levels compatible with 5 V microcontrollers.

TJA1051

Product data sheet

All information provided in this document is subject to legal disclaimers.

Rev. 6 — 25 March 2011

© NXP B.V. 2011. All rights reserved.

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