Datasheet

RXD
V /2
CC
A
B
A: Normal Mode
B: Low Power Standby Mode
CANH
CANL
Recessive Dominant Recessive
Time, t
Typical Bus Voltage
Low Power
Standby Mode
CANL
CANH
V
diff
V
diff
Normal & Silent Mode
SN65HVDA1040A-Q1
www.ti.com SLLS995C –FEBRUARY 2010– REVISED FEBRUARY 2011
FUNCTIONAL DESCRIPTION
Operating Modes
The device has two main operating modes: normal mode and standby mode. Operating mode selection is made
via the STB input pin.
Table 1. Operating Modes
STB PIN MODE DRIVER RECEIVER RXD PIN
LOW NORMAL Enabled (On) Enabled (On) Mirrors CAN bus
Low-power wake-up receiver and bus Low = wake-up request received
HIGH STANDBY Disabled (Off)
monitor enabled (On) High = no wake-up request received
Bus States by Mode
The CAN bus has three valid states during powered operation depending on the mode of the device. In normal
mode the bus may be dominant (logic LOW) where the bus lines are driven differentially apart or recessive (logic
HIGH) where the bus lines are biased to V
CC
/2 via the high-ohmic internal input resistors R
IN
of the receiver. The
third state is low power standby mode where the bus lines will be biased to GND via the high-ohmic internal input
resistors R
IN
of the receiver.
Figure 1. Bus States (Physical Bit Representation) Figure 2. Simplified Common Mode Bias and
Receiver Implementation
Normal Mode
This is the normal operating mode of the device. It is selected by setting STB low. The CAN driver and receiver
are fully operational and CAN communication is bi-directional. The driver is translating a digital input on TXD to a
differential output on CANH and CANL. The receiver is translating the differential signal from CANH and CANL to
a digital output on RXD. In recessive state the bus pins are biased to 0.5 × V
CC
. In dominant state the bus pins
(CANH and CANL) are driven differentially apart. Logic high is equivalent to recessive on the bus and logic low is
equivalent to a dominant (differential) signal on the bus.
The SPLIT pin is biased to 0.5 × V
CC
for bus common mode bus voltage bias stabilization in split termination
network applications (see application information).
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