Datasheet

CAN
Transceiver
CANL
CANH
C
SPLIT
CAN
Transceiver
R
TERM
Standard Termination
Split Termination
CANL
CANH
R /2
TERM
R /2
TERM
MCU or DSP
CAN
Controller
CAN
Transceiver
Node 1
MCU or DSP
CAN
Controller
CAN
Transceiver
Node 2
MCU or DSP
CAN
Controller
CAN
Transceiver
Node 3
MCU or DSP
CAN
Controller
CAN
Transceiver
Node n
(with termination)
R
TERM
R
TERM
SN65HVD255
SN65HVD256, SN65HVD257
www.ti.com SLLSEA2C –DECEMBER 2011–REVISED SEPTEMBER 2013
CAN TERMINATION
The ISO11898 standard specifies the interconnect to be a twisted pair cable (shielded or unshielded) with 120 Ω
characteristic impedance (Z
O
). Resistors equal to the characteristic impedance of the line should be used to
terminate both ends of the cable to prevent signal reflections. Unterminated drop lines (stubs) connecting nodes
to the bus should be kept as short as possible to minimize signal reflections. The termination may be on the
cable or in a node, but if nodes may be removed from the bus the termination must be carefully placed so that it
is not removed from the bus.
Figure 18. Typical CAN Bus
Termination may be a single 120 Ω resistor at the end of the bus, either on the cable or in a terminating node. If
filtering and stabilization of the common mode voltage of the bus is desired, then split termination may be used.
(See Figure 19). Split termination improves the electromagnetic emissions behavior of the network by eliminating
fluctuations in the bus common-mode voltages at the start and end of message transmissions.
Figure 19. CAN Bus Termination Concepts
Copyright © 2011–2013, Texas Instruments Incorporated Submit Documentation Feedback 19
Product Folder Links: SN65HVD255 SN65HVD256 SN65HVD257