tja1049 NXP Semiconductors, tja1049 Datasheet - Page 5

• Manufacturer Part Number: tja1049
• Description: Tja1049 High-speed Can Transceiver With Standby Mode
• Manufacturer: NXP Semiconductors

NXP Semiconductors
7. Functional description
TJA1049
Product data sheet
7.1.1 Normal mode
7.1.2 Standby mode
7.2.1 TXD dominant time-out function
7.1 Operating modes
7.2 Fail-safe features
The TJA1049 is a HS-CAN stand-alone transceiver with Standby mode. It combines the
functionality of the PCA82C250, PCA82C251 and TJA1040 transceivers and offers
improved EMC and ESD handling capability and quiescent current performance.
Improved slope control and high DC handling capability on the bus pins provide additional
application flexibility.
The TJA1049 is 100 % backwards-compatible with the TJA1040, and can be used in
existing PCA82C250 and PCA82C251 applications.
The TJA1049 supports two operating modes, Normal and Standby, which are selectable
via pin STB. See
conditions.
Table 4.
A LOW level on pin STB selects Normal mode. In this mode, the transceiver can transmit
and receive data via the bus lines CANH and CANL (see
The differential receiver converts the analog data on the bus lines into digital data which is
output on pin RXD. The slope of the output signals on the bus lines is controlled and
optimized in a way that guarantees the lowest possible EME.
A HIGH level on pin STB selects Standby mode. In Standby mode, the transceiver is not
able to transmit or correctly receive data via the bus lines. The transmitter and
Normal-mode receiver blocks are switched off to reduce supply current, and only a
low-power differential receiver monitors the bus lines for activity. The wake-up filter on the
output of the low-power receiver does not latch bus dominant states, but ensures that only
bus dominant and bus recessive states that persist longer than t
pin RXD.
In Standby mode, the bus lines are biased to ground to minimize the system supply
current. When pin RXD goes LOW to signal a wake-up request, a transition to Normal
mode will not be triggered until STB is forced LOW.
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 t
lines to recessive state. This function prevents a hardware and/or software application
Mode
Normal
Standby
Operating modes
All information provided in this document is subject to legal disclaimers.
Table 4
Pin STB
LOW
HIGH
Rev. 2 — 23 March 2011
for a description of the operating modes under normal supply
to(dom)TXD
High-speed CAN transceiver with Standby mode
, the transmitter is disabled, releasing the bus
Pin RXD
LOW
bus dominant
wake-up request
detected
Figure 1
fltr(wake)bus
for the block diagram).
HIGH
bus recessive
no wake-up request
detected
TJA1049
© NXP B.V. 2011. All rights reserved.
are reflected on
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