AMIS-30663 Datasheet, PDF (4/12 Pages) AMI SEMICONDUCTOR – High Speed CAN Transceiver

AMIS-30663 High Speed CAN Transceiver
Data Sheet
Table 3: Function Table (X = don’t care)
4.75 < VCC < 5.25V
Mode
Pin
TxD
RxD
0
0
High Speed
1
1
STATE
Dominant
Recessive
Bus
CANH
High
0.5 VCC
CANL
Low
0.5 VCC
VCC < PORL
Mode
Pin
TxD
RxD
-
X
1
STATE
Recessive
Bus
CANH
0 < VCANH < VCC
CANL
0 < VCANL < VCC
PORL < VCC < 4.75V
Mode
Pin
TxD
RxD
-
> VIH
1
STATE
Recessive
Bus
CANH
0 < VCANH < VCC
CANL
0 < VCANL < VCC
7.3 Over-temperature Detection
A thermal protection circuit protects the IC from damage by switching off the transmitter if the junction temperature exceeds a value of approximately
160°C. Because the transmitter dissipates most of the power, the power dissipation and temperature of the IC is reduced. All other IC functions continue
to operate. The transmitter off-state resets when pin TxD goes HIGH. The thermal protection circuit is particularly needed when a bus line short circuits.
7.4 TxD Dominant Time-out Function
A TxD dominant time-out timer circuit prevents the bus lines from being driven to a permanent dominant state (blocking all network communication) if
pin TxD is forced permanently LOW by a hardware and/or software application failure. The timer is triggered by a negative edge on pin TxD. If the duration
of the LOW-level on pin TxD exceeds the internal timer value tdom, the transmitter is disabled, driving the bus into a recessive state. The timer is reset by a
positive edge on pin TxD.
7.5 Fail-safe Features
A current-limiting circuit protects the transmitter output stage from damage caused by accidental short circuit to either positive or negative supply voltage -
although power dissipation increases during this fault condition.
The pins CANH and CANL are protected from automotive electrical transients (according to "ISO 7637"; see Figure 4). Should TxD become disconnected,
this pin is pulled high internally. When the VCC supply is removed, pins TxD and RxD will be floating. This prevents the AMIS-30663 from being supplied
by the CAN controller through the I/O pins.
7.6 3.3V Interface
AMIS-30663 may be used to interface with 3.3V or 5V controllers by use of the V33 pin. This pin may be supplied with 3.3V or 5V to have the corresponding
digital interface voltage levels.
When the V33 pin is supplied at 2.5V, even interfacing with 2.5V CAN controllers is possible. See also Digital Output Characteristics @ V33 = 2.5V, Table 7.
In this case a pull resistor from TxD to V33 is necessary.
AMI Semiconductor - Rev. 1.4, Oct. 04
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