AMIS-30663 Datasheet, PDF (4/11 Pages) AMI SEMICONDUCTOR – High Speed CAN Transceiver

AMIS−30663
Functional Description
General
The AMIS−30663 is the interface between the CAN
protocol controller and the physical bus. It is intended for
use in automotive and industrial applications requiring baud
rates up to 1 Mbaud. It provides differential transmit
capability to the bus and differential receiver capability to
the CAN protocol controller. It is fully compatible to the
“ISO 11898−2” standard.
Table 4. Function Table (X = don’t care)
Pin
Mode
TxD
RxD
State
4.75 V < Vcc < 5.25 V
High
0
Speed
1
0
Dominant
1
Recessive
Vcc < PORL
−
X
1
Recessive
PORL < Vcc < 4.75 V
−
> V_IH
1
Recessive
Operating Modes
AMIS−30663 only operates in high−speed mode as
illustrated in Table 4.
The transceiver is able to communicate via the bus lines.
The signals are transmitted and received to the CAN
controller via the pins TxD and RxD. The slopes on the bus
lines outputs are optimised to give extremely low EME.
Bus
CANH
High
0.5 Vcc
0 < V_CANH < V_CC
0 < V_CANH < V_CC
CANL
Low
0.5 Vcc
0 < V_CANL < V_CC
0 < V_CANL < V_CC
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.
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 t_dom, the transmitter is
disabled, driving the bus into a recessive state. The timer is
reset by a positive edge on pin TxD.
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.
3.3 V Interface
AMIS−30663 may be used to interface with 3.3 V or 5 V
controllers by use of the V₃₃ pin. This pin may be supplied
with 3.3 V or 5 V to have the corresponding digital interface
voltage levels.
When the V₃₃ pin is supplied at 2.5 V, even interfacing
with 2.5 V CAN controllers is possible. See also Digital
Output Characteristics @ V₃₃ = 2.5 V, Table 8. In this case
a pull resistor from TxD to V₃₃ is necessary.
Electrical Characteristics
Definitions
All voltages are referenced to GND (pin 2). Positive
currents flow into the IC. Sinking current means that the
current is flowing into the pin. Sourcing current means that
the current is flowing out of the pin.
Absolute Maximum Ratings
Stresses above those listed in Table 5 may cause
permanent device failure. Exposure to absolute maximum
ratings for extended periods may effect device reliability.
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