NCV7380
http://onsemi.com
9
The receive threshold values V
BUS_CNT_max
and
V
BUS_CNT_min
are symmetrical to 0.5*V
S
with a hysteresis
of 0.16*V
S
(typ). The LIN specific receive threshold is
between 0.4*V
S
and 0.6*V
S
.
The received BUS signal will be output to the RxD pin:
BUS < V
BUS_CNT
– 0.5 * V
HYS
→ RxD = low (BUS dominant)
BUS > V
BUS_CNT
+ 0.5 * V
HYS
→ RxD = high, floating (BUS recessive)
RxD is a buffered open drain output with a typical load
of:
Resistance: 2.7 k
Capacitance: < 20 pF
Data Rate
The NCV7380 is a constant slew rate transceiver. The
bus driver operates with a fixed slew rate range of 1.0 V/ s
v V/T v 3.0 V/s. This principle provides very good
symmetry of the slope times between recessive to dominant
and dominant to recessive slopes within the LIN bus load
range (C
BUS
, R
term
).
The NCV7380 guarantees data rates up to 20 kBit within
the complete bus load range under worst case conditions.
The constant slew rate principle holds appropriate voltage
levels and can operate within the LIN Protocol
Specification for RC oscillator systems with a matching
tolerance up to 2%.
Operating Under Disturbance
Loss of Battery
If V
S
and V
CC
are disconnected from the battery, the bus
pin is in high impedance state. There is no impact to the bus
traffic.
Loss of Ground
In case of an interrupted ground connection from V
S
and
V
CC
, there is no influence to the bus line.
Short Circuit BUS to Battery
The transmitter output current is limited to 200 mA
(max) in case of short circuit to battery.
Short Circuit BUS to Ground
Negative voltages on the bus pin are limited to current
through the internal 30 k resistor and series diode from V
S
.
Thermal Overload
The NCV7380 is protected against thermal overloads. If
the chip temperature exceeds the thermal shutdown
threshold, the transmitter is switched off until thermal
recovery. The receiver continues to work during thermal
shutdown.
Undervoltage V
CC
The V
CC
undervoltage lockout feature disables the
transmitter until it is above the undervoltage lockout
threshold to prevent undesirable bus traffic.
Application Hints
LIN System Parameter
Bus Loading Requirements
Parameter Symbol Min Typ Max Unit
Operating Voltage Range V
BAT
8.0 − 18 V
Voltage Drop of Reverse Protection Diode V
Drop_rev
0.4 − 1.0 V
Voltage Drop of Bus Decouple Diode in the Master Node V
Drop_dec
0.4 − 1.0 V
Battery Offset Voltage V
batoff
− − 0.1 V
BAT
Ground Offset Voltage V
goff
− − 0.1 V
BAT
Master Termination Resistor R
pu_master
900 1000 1100
Slave Termination Resistor R
pu_slave
20 30 60 k
Number of System Nodes N 2 − 16 −
Network Distance between any two ECU Nodes B
US_length
− − 40 m
Line Capacitance C
LINE
− 100 150 pF/m
Capacitance of Master Node C
Master
− 220 − pF
Capacitance of Slave Node C
Slave
195 220 300 pF
Network Total Capacitance C
t1
1.0 4.0 10 nF
Network Total Resistance R
t1
537 − 863
Time Constant of Overall System net 1.0 − 5.0 s
