Datasheet

APPLICATION INFORMATION
DIAGNOSTIC LOOPBACK (SN65HVD233)
Ω
120
Ω
120
CANH
CANL
TMS320LF243
SN65HVD251
D R
Rs
Vref
CANTX CANRX
Sensor, Actuator, or Control
Equipment
TMS320F2812
SN65HVD233
D R
0.1µF
Vcc
GND
Rs
LBK
CANTX CANRX
Sensor, Actuator, or Control
Equipment
TMS320LF2407A
SN65HVD230
D R
Rs
Vref
CANTX CANRX
Sensor, Actuator, or Control
Equipment
3.3 V
0.1µF
Vcc
GND
5 V
0.1
µ
F
Vcc
GND
3.3 V
Stub Lines -- 0.3 m max
Bus Lines -- 40 m max
GPIO
ISO 11898 COMPLIANCE OF SN65HVD230 FAMILY OF 3.3-V CAN TRANSCEIVERS
Introduction
Differential Signal
SN65HVD233-EP
SLLS944 – NOVEMBER 2008 ............................................................................................................................................................................................ www.ti.com
The loopback function of the SN65HVD233 is enabled with a high-level input to LBK. This forces the driver into a
recessive state and redirects the data (D) input at pin 1 to the received-data output (R) at pin 4. This allows the
host controller to input and read back a bit sequence to perform diagnostic routines without disturbing the CAN
bus. A typical CAN bus application is displayed in Figure 25 .
If the LBK pin is not used it may be tied to ground (GND). However, it is pulled low internally (defaults to a
low-level input) and may be left open if not in use.
Figure 25. Typical HVD233 Application
Many users value the low power consumption of operating their CAN transceivers from a 3.3 V supply. However,
some are concerned about the interoperability with 5-V supplied transceivers on the same bus. This report
analyzes this situation to address those concerns.
CAN is a differential bus where complementary signals are sent over two wires and the voltage difference
between the two wires defines the logical state of the bus. The differential CAN receiver monitors this voltage
difference and outputs the bus state with a single-ended output signal.
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Product Folder Link(s): SN65HVD233-EP