
NCV7357
www.onsemi.com
4
FUNCTIONAL DESCRIPTION
High speed CAN FD transceiver
NCV7357 implements high−speed physical layer CAN
FD transceiver compatible with ISO11898−2, implementing
following optional features or alternatives:
•Extended bus load range
•Transmit dominant timeout, long
•Support of bit rates up to 5 Mbps
•Normal Bus biasing
Operating Modes
NCV7357 provides two modes of operation as illustrated
in Table 2. These modes are selectable through pin S.
Table 2. OPERATING MODES
Pin S Mode Pin TxD BUS Pin RxD
Low Normal
0 Dominant 0
1 Recessive 1
High Silent
XDominant
(1) 0
X Recessive 1
1. CAN BUS driven by another transceiver on the BUS
2. ’X’ = don’t care
Power−off
This virtual mode is entered as soon as the VCC or VIO
undervoltage condition is detected. The internal logic is
reset and the transceiver is disabled. CAN bus pins are kept
floating. As soon as both VCC and VIO voltages rise above
corresponding undervoltage recovery thresholds, the device
proceeds to Normal or Silent mode, depending on S pin
state.
Normal Mode
In the normal mode, 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 optimized to
give low EME.
Silent Mode
In the silent mode, the transmitter is disabled. The bus pins
are in recessive state independent of TxD input. Transceiver
listens to the bus and provides data to controller, but
controller is prevented from sending any data to the bus.
Silent mode
Power−off
Normal mode
Any
mode CAN: off (no bias)
RxD: High−Z
TxD, S: High−Z
S = Low S = High
CAN: Tx/Rx
CAN bias: VCC/2
CAN: Rx only
CAN bias: VCC/2
S = Low
No UV
and S = High
Notes:
NCV7357−0
UV detected: VCC < VUVDVCC
No UV: VCC > VUVDVCC
S = High
No UV
and S = Low
UV
detected
NCV7357−3
UV detected: VCC < VUVDVCC and/or VIO < VUVDVIO
No UV: VCC > VUVDVCC and VIO > VUVDVIO
Overtemperature Detection
A thermal protection circuit protects the IC from damage
by switching off the transmitter if the junction temperature
exceeds TJ(sd) value. 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 the temperature
decreases below the shutdown threshold and pin TxD goes
high. The thermal protection circuit is particularly needed
when a bus line short circuits.
TxD Dominant Timeout Function
A TxD dominant timeout timer circuit prevents the bus
lines 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(TxD), the transmitter is disabled,
driving the bus into a recessive state. The timer is reset by a
positive edge on pin TxD.
This TxD dominant timeout time tdom(TxD) defines the
minimum possible bit rate to 17 kbps.
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.
Detection of undervoltage on supply pin (VCC or VIO)
causes switching off device. After supply voltage is
recovered TxD pin must be first released to high to allow
sending dominant bits again.
The pins CANH and CANL are protected from
automotive electrical transients (according to ISO 7637; see