Philips Semiconductors
Product data
Single wire CAN transceiver
AU5790
FEATURES
•
Supports in-vehicle class B multiplexing via a single bus line with
ground return
DESCRIPTION
The AU5790 is a line transceiver, primarily intended for in-vehicle
multiplex applications. The device provides an interface between a
CAN data link controller and a single wire physical bus line. The
achievable bus speed is primarily a function of the network time
constant and bit timing, e.g., up to 33.3 kbps with a network
including 32 bus nodes. The AU5790 provides advanced
sleep/wake-up functions to minimize power consumption when a
vehicle is parked, while offering the desired control functions of the
network at the same time. Fast transfer of larger blocks of data is
supported using the high-speed data transmission mode.
•
33 kbps CAN bus speed with loading as per J2411
•
83 kbps high-speed transmission mode
•
Low RFI due to output waveshaping
•
Direct battery operation with protection against load dump, jump
start and transients
•
Bus terminal protected against short-circuits and transients in the
automotive environment
•
Built-in loss of ground protection
•
Thermal overload protection
•
Supports communication between control units even when
network in low-power state
•
70
µA
typical power consumption in sleep mode
•
8- and 14-pin small outline packages
•
±8
kV ESD protection on bus and battery pins
QUICK REFERENCE DATA
SYMBOL
V
BAT
T
amb
V
BATld
V
CANHN
V
T
t
TrN
t
TfN
t
DN
I
BATS
PARAMETER
Operating supply voltage
Operating ambient temperature range
Battery voltage
Bus output voltage
Bus input threshold
Bus output delay, rising edge
Bus output delay, falling edge
Bus input delay
Sleep mode supply current
load dump; 1s
3.65
1.8
3
3
0.3
70
CONDITIONS
MIN.
5.3
–40
13
TYP.
MAX.
27
+125
+40
4.55
2.2
6.3
9
1
100
V
°C
V
V
V
µs
µs
µs
µA
UNIT
ORDERING INFORMATION
DESCRIPTION
SO8: 8-pin plastic small outline package
SO14: 14-pin plastic small outline package
TEMPERATURE RANGE
–40
°C
to +125
°C
–40
°C
to +125
°C
ORDER CODE
AU5790D
AU5790D14
DWG #
SOT96–1
SOT108–1
2001 May 18
2
853-2237 26343
Philips Semiconductors
Product data
Single wire CAN transceiver
AU5790
SO8 PIN CONFIGURATION
SO14 PIN CONFIGURATION
TxD
1
8
GND
GND
1
14
GND
NSTB (Mode 0)
2
7
CANH (BUS)
TxD
2
13
N.C.
AU5790
EN (Mode 1)
3
6
RTH (Load)
NSTB (Mode 0)
3
12
CANH (BUS)
RxD
4
SO8
5
BAT
EN (Mode 1)
4
AU5790
11
RTH (Load)
RxD
5
10
BAT
SL01198
N.C.
6
9
N.C.
GND
7
SO14
8
GND
SO8 PIN DESCRIPTION
SYM-
BOL
TxD
NSTB
(Mode 0)
EN
(Mode 1)
RxD
PIN
1
2
DESCRIPTION
Transmit data input:
high = transmitter passive;
low = transmitter active
Stand-by control:
high = normal and
high-speed mode; low = sleep and wake-up
mode
Enable control:
high = normal and wake-up
mode; low = sleep and high-speed mode
Receive data output:
low = active bus condition
detected; float/high = passive bus condition
detected
Battery supply input
(12 V nom.)
Switched ground pin:
pulls the load to ground,
except in case the module ground is
disconnected
Bus line transmit input/output
Ground
N.C.
GND
GND
N.C.
BAT
RTH
(LOAD)
SL01251
SO14 PIN DESCRIPTION
SYM-
BOL
GND
TxD
NSTB
(Mode 0)
EN
(Mode 1)
RxD
PIN
1
2
3
Ground
Transmit data input:
high = transmitter passive;
low = transmitter active
Stand-by control:
high = normal and
high-speed mode; low = sleep and wake-up
mode
Enable control:
high = normal and wake-up
mode; low = sleep and high-speed mode
Receive data output:
low = active bus condition
detected; float/high = passive bus condition
detected
No connection
Ground
Ground
No connection
Battery supply input
(12 V nom.)
Switched ground pin:
pulls the load to ground,
except in case the module ground is
disconnected
Bus line transmit input/output
No connection
Ground
DESCRIPTION
3
4
BAT
RTH
(LOAD)
CANH
(BUS)
GND
5
6
4
5
7
8
6
7
8
9
10
11
CANH
(BUS)
12
13
14
N.C.
GND
2001 May 18
4
Philips Semiconductors
Product data
Single wire CAN transceiver
AU5790
FUNCTIONAL DESCRIPTION
The AU5790 is an integrated line transceiver IC that interfaces a
CAN protocol controller to the vehicle’s multiplexed bus line. It is
primarily intended for automotive “Class B” multiplexing applications
in passenger cars using a single wire bus line with ground return.
The achievable bit rate is primarily a function of the network time
constant and the bit timing parameters. For example, the maximum
bus speed is 33 kpbs with bus loading as specified in J2411 for a full
32 node bus, while 41.6 kbps at is possible with modified bus
loading. The AU5790 also supports low-power sleep mode to help
meet ignition-off current draw requirements.
The protocol controller feeds the transmit data stream to the
transceiver’s TxD input. The AU5790 transceiver converts the TxD
data input to a bus signal with controlled slew rate and waveshaping
to minimize emissions. The bus output signal is transmitted via the
CANH in/output, connected to the physical bus line. If TxD is low,
then a typical voltage of 4 V is output at the CANH pin. If TxD is high
then the CANH output is pulled passive low via the local bus load
resistance R
T
. To provide protection against a disconnection of the
module ground, the resistor R
T
is connected to the RTH pin of the
AU5790. By providing this switched ground pin, no current can flow
from the floating module ground to the bus. The bus receiver detects
the data stream on the bus line. The data signal is output at the RxD
pin being connected to a CAN controller. The AU5790 provides
appropriate filtering to ensure low susceptibility against
electromagnetic interference. Further enhancement is possible with
applying an external capacitor between CANH and ground potential.
The device features low bus output leakage current at power supply
failure situations.
If the NSTB and EN control inputs are pulled low or floating, the
AU5790 enters a low-power or “sleep” mode. This mode is
dedicated to minimizing ignition-off current drain, to enhance system
efficiency. In sleep mode, the bus transmit function is disabled, e.g.
the CANH output is inactive even when TxD is pulled low. An
internal network active detector monitors the bus for any occurrence
of signal edges on the bus line. If such edges are detected, this will
be signalled to the CAN controller via the RxD output. Normal
transmission mode will be entered again upon a high level being
applied to the NSTB and EN control inputs. These signals are
typically being provided by a controller device.
Sleeping bus nodes will generally ignore normal communication on
the bus. They should be activated using the dedicated wake-up
mode. When NSTB is low and EN is high the AU5790 enters
wake-up mode i.e. it sends data with an increased signal level. This
will result in an activation of other bus nodes being attached to the
network.
The AU5790 also provides a high-speed transmission mode
supporting bit rates up to 100 kbps. If the NSTB input is pulled high
and the EN input is low, then the internal waveshaping function is
disabled, i.e. the bus driver is turned on and off as fast as possible
to support high-speed transmission of data. Consequently, the EMC
performance is degraded in this mode compared to the normal
transmission mode. In high-speed transmission mode the AU5790
supports the same bus signal level as specified for the CANH output
in normal mode.
The AU5790 features special robustness at its BAT and CANH pins.
Hence the device is well suited for applications in the automotive
environment. The BAT input is protected against 40 V load dump
and jump start condition. The CANH output is protected against
wiring fault conditions, e.g., short circuit to ground or battery voltage,
as well as typical automotive transients. In addition, an
over-temperature shutdown function with hysteresis is incorporated
protecting the device under system fault conditions. In case of the
chip temperature reaching the trip point, the AU5790 will latch-off
the transmit function. The transmit function is available again after a
small decrease of the chip temperature. The AU5790 contains a
power-on reset circuit. For V
bat
< 2.5 V, the CANH output drive will
be turned off, the output will be passive, and RxD will be high. For
2.5 V < V
bat
< 5.3 V, the CANH output drive may operate normally or
be turned off.
Table 1. Control Input Summary
NSTB
0
0
1
1
EN
0
1
0
1
TxD
Don’t Care
Tx-data
Tx-data
Tx-data
Sleep mode
Wake-up transmission mode
High-speed transmission mode
Normal transmission mode
Description
0V
0 V, 12 V
0 V, 4 V
0 V, 4 V
CANH
RxD
float (high)
bus state
1
bus state
1
bus state
1
NOTE:
1. RxD outputs the bus state. If the bus level is below the receiver threshold (i.e., all transmitters passive), then RxD will be floating (i.e., high,
considering external pull-up resistance). Otherwise, if the bus level is above the receiver threshold (i.e., at least one transmitter is active),
then RxD will be low.
2001 May 18
5
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