SN65HVDA1040A-Q1

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SLLS995C

– FEBRUARY 2010 – REVISED FEBRUARY 2011

Protection Features

TXD Dominant State Timeout

During normal mode (only mode where CAN driver is active) the TXD dominant time-out circuit prevents the

transceiver from blocking network communication in event of a hardware or software failure where TXD is held

disabled freeing the bus for communication between other network nodes. The CAN driver is re-activated when a

recessive signal is seen on TXD pin, thus clearing the dominant state time out. The CAN bus pins will be biased

to recessive level during a TXD dominant state time-out and SPLIT will remain on.

APPLICATION NOTE: The maximum dominant TXD time allowed by the TXD Dominant state time out limits the

minimum possible data rate of the device. The CAN protocol allows a maximum of eleven successive dominant

bits (on TXD) for the worst case, where five successive dominant bits are followed immediately by an error

frame. This, along with the t(dom) minimum, limits the minimum bit rate. The minimum bit rate may be calculated

by:

Thermal Shutdown

If the junction temperature of the device exceeds the thermal shut down threshold the device will turn off the

CAN driver circuits, including SPLIT pin. This condition is cleared once the temperature drops below the thermal

shut down temperature of the device.

Undervoltage Lockout / Unpowered Device

force the device in standby mode (low power) if the pin floats.

The bus pins (CANH, CANL, and SPLIT) all have extremely low leakage currents when the device is un-powered

so it will not load down the bus but be an

“ideal passive” load to the bus. This is critical, especially if some nodes

of the network will be unpowered while the rest of the network remains in operation.

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