Datasheet

Normal CAN
communication
CAN
Bus
Signal
Bus Fault stuck dominant , example CANH
short to supply =5V and CAN L short to GND .
RXD output is returned recessive (high)
and FAULT is signaled to μP and link
layer / protocol.
RXD
(reciever)
RXD
(receiver)
t
RXD_DTO
FAULT
CAN PHY With RXD
DTO AND FAULT
SN65HVD257
CAN PHY
SN65HVD255
SN65HVD256
Fault is repaired and normal
communication returns
FAULT cleared signal
is given
RXD mirrors
bus
RXD will also be “stuck dominant” blocking
alternative communication paths
CAN BUS
Normal CAN
communication
CAN
Bus
Signal
TXD fault stuck dominant, example PCB
failure or bad software
Fault is repaired & transmission
capability restored
TXD
(driver)
%XVZRXOGEH³VWXFNGRPLQDQW´EORFNLQJFRPPXQLFDWLRQIRUWKH
whole network but TXD DTO prevents this and frees the bus for
communication after the time t
TXD_DTO
.
t
TXD_DTO
Communication from
local node
Communication from
repaired node
RXD
(receiver)
Communication from
other bus node(s)
Communication from
repaired local node
FAULT
(HVD257)
Fault indication is removed.
FAULT is signaled to link layer / protocol.
Communication from
other bus node(s)
t
TXD_DTO
Driver disabled freeing bus for other nodes
SN65HVD255
SN65HVD256, SN65HVD257
www.ti.com SLLSEA2C –DECEMBER 2011–REVISED SEPTEMBER 2013
Figure 6. Example Timing Diagram for TXD DTO and FAULT Pin
Figure 7. Example Timing Diagram for Devices With and Without RXD DTO and FAULT Pin
Copyright © 2011–2013, Texas Instruments Incorporated Submit Documentation Feedback 7
Product Folder Links: SN65HVD255 SN65HVD256 SN65HVD257