NCV7441
Dual High Speed Low
Power CAN Transceiver
The NCV7441, dual CAN transceiver offers two fully independent
high−speed CAN transceivers which can be individually connected to
two CAN protocol controllers. The CAN channels can be separately
put to normal or to standby mode, in which remote wakeup detection
from the bus is possible.
Due to the shared auxiliary circuitry and common package, this
circuit version can replace two standard high−speed CAN transceivers
while saving board space.
Features
14
1
SOIC−14 NB
CASE 751A
XXXXX
A
WL
Y
WW
G
1
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MARKING
DIAGRAM
14
NCV7441−0
AWLYWWG
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Compatible with the ISO 11898 Standard (ISO 11898−2, ISO
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11898−5 and SAE J2284)
Low Quiescent Current
High Speed (up to 1 Mbps)
Ideally Suited for 12 V and 24 V Industrial and Automotive
Applications
Extremely Low Current Standby Mode with Wakeup Via the Bus
Low EME without Common−mode Choke
No Disturbance of the Bus Lines with an Un−powered Node
Predictable Behavior Under All Supply Circumstances
Transmit Data (TxD) Dominant Time−out Function
Thermal Protection
Bus Pins Protected Against Transients in an Automotive
Environment
Power Down Mode in Which the Transmitter is Disabled
Bus and V
SPLIT
Pins Short Circuit Proof to Supply Voltage and
Ground
Input Logic Levels Compatible with 3.3 V Devices
Up to 110 Nodes can be Connected to the Same Bus in Function of
Topology
Pb−Free Packages are Available
= Specific Device Code
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb−Free Package
PIN CONNECTIONS
TxD1
RxD1
GND
VCC
GND
RxD2
TxD2
1
2
3
Dual CAN
NCV7441
4
5
6
7
14
13
12
11
10
9
8
STB1
CANH1
CANL1
TEST/GND
CANH2
CANL2
STB2
Typical Applications
•
Automotive
•
Industrial Networks
ORDERING INFORMATION
See detailed ordering and shipping information in the
package dimensions section on page 9 of this data sheet.
©
Semiconductor Components Industries, LLC, 2011
August, 2011
−
Rev. 0
1
Publication Order Number:
NCV7441/D
NCV7441
BLOCK DIAGRAM
V
CC
CANH1
Transmitter
NCV7441
Dual CAN
Transmitter
CANH2
CHANNEL 1
CONTROL LOGIC
Receiver
CHANNEL 2
CONTROL LOGIC
CANL1
CANL2
Receiver
SUPPLY
MONITOR
THERMAL
MONITOR
Low−power
receiver
Low
−
power
receiver
V
CC
V
CC
V
CC
V
CC
PD20100615.01
TEST/
GND
STB1
STB2
RxD1
RxD2
TxD1
Figure 1. NCV7441 Dual CAN: Block Diagram
Table 1. PIN FUNCTION DESCRIPTION
Pin
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Pin
Name
TxD1
RxD1
GND
V
CC
GND
RxD2
TxD2
STB2
CANL2
CANH2
TEST /
GND
CANL1
CANH1
STB1
Pin Type
digital input;
internal pull−up
digital output
ground
supply input
ground
digital output
digital input;
internal pull−up
digital input;
internal pull−up
high−voltage analog
input/output
high−voltage analog
input/output
test/ground
high−voltage analog
input/output
high−voltage analog
input/output
digital input;
internal pull−up
Description
transmit data for the 1
st
CAN channel in normal mode; ignored in standby
mode
received data from the 1
st
CAN channel in normal mode; 1
st
CAN channel
remote wakeup indication in standby mode
ground connection
5 V supply connection
ground connection
received data from the 2
nd
CAN channel; 2
nd
CAN channel remote wakeup
indication in standby mode
transmit data for the 2
nd
CAN channel
mode control input for the 2
nd
CAN channel; STB2 = High puts the 2
nd
CAN
channel into standby mode
CANL−wire connection of the 2
nd
CAN channel
CANH−wire connection of the 2
nd
CAN channel
The pin is used for test purposes during device production. It’s recommended
to connect to ground in the end−application.
CANL−wire connection of the 1
st
CAN channel
CANH−wire connection of the 1
st
CAN channel
mode control input for the 1
st
CAN channel;
STB1 = High puts the 1
st
CAN channel into standby mode
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2
TxD2
GND
NCV7441
TYPICAL APPLICATION DIAGRAM
VBAT
LDO
5V
STB1
MCU + CAN ctrl.
V
CC
CANH1
CANL1
1
TxD1
RxD1
STB2
MCU + CAN ctrl.
NCV7441−
0
Dual CAN
CANH2
CANL2
CAN1
2
TxD2
RxD2
TEST/
GND
GND
CAN2
Comment
The entire chip in
under−voltage
CAN1/2 in standby
mode
CAN1/2 in normal
mode
GND
PD20100615.03
Figure 2. NCV7441 Dual CAN: Example Application Diagram
FUNCTIONAL DESCRIPTION
Dual CAN device behaves identically to two independent CAN transceivers. The representative signal dependencies are
shown in Figure 4 and further functional description is given in Table 2.
Table 2. FUNCTIONAL DESCRIPTION
V
CC
< V
CC_UV
> V
CC_UV
STB1/2
X
High
TxD1/2
X
X
RxD1/2
HZ
Low−power receiver
output
Indicates the signal
received on CAN1/2
Transceiver on CANH1/2/CANL1/2
Deactivated; unbiased
Transmitter deactivated;
Bus biased to GND through the input circuitry;
Receiver monitoring CAN1/2 wakeup
Recessive signal transmitted on CAN1/2;
Bus biased to V
CC
/2 through the input circuitry
Dominant signal transmitted on CAN1/2;
Bus biased to V
CC
/2 through the input circuitry
Low
Low
High
Low
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3
NCV7441
If the main power supply V
CC
(nominal 5 V) is above its under−voltage (V
CC_UV
) level, each CAN channel can enter either
normal mode (when the corresponding STB1/2 digital input is pulled Low) or standby mode (when the corresponding STB1/2
signal is left High):
•
In the normal mode:
♦
The bus transceiver is ready to transmit and receive CAN bus signals with the full CAN communication speed (up to
1 Mbps) and thus interconnect the CAN bus with the corresponding CAN controller through digital pins TxD1/2 and
RxD1/2
♦
The bus pins are internally biased to typically V
CC
/2 through the input circuitry
♦
TxD1/2 input pin is monitored by a timeout in order to prevent a permanent dominant being forced to the bus thus
preventing other nodes from communicating. If TxD1/2 is Low for longer than t
cnt(timeout)
, the transmitter switches
back to recessive. Only when TxD1/2 returns to High, the timeout counter is reset and the transmitter is ready to
transmit dominant symbols again. The TxD1/2 timeout protection is implemented individually for both CAN
transceivers.
♦
A common thermal monitoring circuit compares the circuit junction temperatures with threshold T
J(sd)
. If the thermal
shutdown level is exceeded, dominant transmission is disabled. The circuit remains biased and ready to transmit but
the logical path from TxD1/2 pin(s) is blocked. The transmission is again enabled when the junction temperature
decreases below the shutdown level and the TxD1/2 pin returns to the High level, thus avoiding thermal oscillations.
•
In the standby mode:
♦
The respective transmitter is disabled and the current consumption of the channel is fundamentally reduced. Only the
low−power receiver on the channel remains active in order to detect potential CAN bus wakeups. The logical signal
on TxD1/2 input is ignored.
♦
The bus pins are biased to GND through the input circuitry
♦
Digital output RxD1/2 signals the output of the low−power receiver and can be used as a wakeup signal in the
application. A filtering time
td
BUS
is applied between the bus activity and the RxD1/2 signal in order to ensure that
only sufficiently long dominant signals on the bus will be propagated to the digital output. In addition, dominant bus
signals are ignored in case they were present during normal−to−standby mode transition; in this way unwanted
wakeups are avoided in case of permanent dominant failure on the bus. Example waveforms illustrating bus activity
detection in standby mode are shown in Figure 3.
In order to ensure a safe device state, the digital inputs STB1/2 and TxD1/2 are connected through internal pull−up resistors
to V
CC
thus ensuring that both channels remain in standby mode and/or no dominant can be transmitted in case any of the digital
inputs gets disconnected.
STB1
< t
dbus
w
t
dbus
w
t
dbus
< t
dbus
CANH/L1
RxD1
STB2
< t
dbus
w
t
dbus
CANH/L2
RxD2
PD20100209.08
Figure 3. NCV7441 Dual CAN: Bus Activity Detection in Standby Mode
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4
TxD1
STB1
CANH/L1
RxD1
Re mo te
wakeup
TxD2
STB2
Re mo te
wakeup
NCV7441
Figure 4. NCV7441 Dual CAN: Functional Graphs
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5
CANH/L2
RxD2
PD20100209.03
Legend:
received
dominant
transmitted
dominant
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