Philips Semiconductors

Product data

AU5780A

SAE/J1850/VPW transceiver

2001 Jun 19

853-2261 26558

FEATURES

Supports SAE/J1850 VPW standard for in-vehicle class B
multiplexing

Bus speed 10.4 kbps nominal

Drive capability 32 bus nodes

Low RFI due to output waveshaping with adjustable slew rate

Direct battery operation with protection against +50V load dump,
jump start and reverse battery

Bus terminals proof against automotive transients up to
200V/+200V

Thermal overload protection

Very low bus idle power consumption

Diagnostic loop-back mode

4X mode (41.6 kbps) reception capability

ESD protected to 9 KV on bus and battery pins

8-pin SOIC

DESCRIPTION

The AU5780A is a line transceiver being primarily intended for
in-vehicle multiplex applications. It provides interfacing between a
link controller and the physical bus wire. The device supports the
SAE/J1850 VPWM standard with a nominal bus speed of 10.4 kbps.

PIN CONFIGURATION

SL01207

SO8

R/F

GND

BATT

BUS_OUT

BUS_IN

/LB

AU5780A

QUICK REFERENCE DATA

SYMBOL

PARAMETER

CONDITIONS

MIN.

TYP.

MAX.

UNIT

BATT.op

Operating supply voltage

Operating ambient temperature

+125

BATT.ld

Battery voltage

load dump; 1s

+50

BATT.lp

Bus idle supply current

BATT

=12V

220

Bus voltage

0 < V

BATT

< 24V

+20

BOH

Bus output voltage

300

< R

< 1.6k

7.3

8.0

BO.LIM

Bus output source current

0V < V

< +6.0V

Bus input threshold

3.65

4.1

Delay TX to BUS_OUT, normal battery

Measured at 3.875V

, t

BUS_OUT transition times, rise and fall,
normal battery

Measured between

1.5 V and (V

BATT

2.75 V),

9 < V

BATT

< 16 V,

tested at an additional bus

load of R

LOAD

= 400

and

LOAD

= 22000 pF

ORDERING INFORMATION

DESCRIPTION

TEMPERATURE RANGE

ORDER CODE

DWG #

SO8:

8-pin plastic small outline package

40 to +125

AU5780AD

SOT96-1

Philips Semiconductors

Product data

AU5780A

SAE/J1850/VPW transceiver

2001 Jun 19

PIN DESCRIPTION

SYMBOL

PIN

DESCRIPTION

BATT

Battery supply input (12V nom.)

Transmit data input; low: transmitter passive; high: transmitter active

R/F

Rise/fall slew rate set input

Receive data output; low: active bus condition detected; float/high: passive bus condition detected

BUS_IN

Bus line receive input

/LB

Loop-back test mode control input; low: loop-back mode; high: normal communication mode

BUS_OUT

Bus line transmit output

GND

Ground

FUNCTIONAL DESCRIPTION

The AU5780A is an integrated line transceiver IC that interfaces an
SAE/J1850 protocol controller IC to the vehicle's multiplexed bus
line. It is primarily intended for automotive "Class B" multiplexing
applications in passenger cars using VPW (Variable Pulse Width)
modulated signals with a nominal bit rate of 10.4 kbps. The
AU5780A also receives messages in the so-called 4X mode where
data is transmitted with a typical bit rate of 41.6 kbps. The device
provides transmit and receive capability as well as protection to a
J1850 electronic module.

A J1850 link controller feeds the transmit data stream to the
transceiver's TX input. The AU5780A transceiver waveshapes the
TX data input signal with controlled rise & fall slew rates and
rounded shape. The bus output signal is transmitted with both
voltage and current control. The BUS_IN input is connected to the
physical bus line via an external resistor. The external resistor and
an internal capacitance provides filtering against RF bus noise. The
incoming signal is output at the RX pin being connected to the
J1850 link controller.

If the TX input is idle for a certain time, then the AU5780A enters a
low-power mode. This mode is dedicated to help meet ignition-off
current draw requirements. The BUS_IN input comparator is kept
alive in the low-power mode. Normal power mode will be entered
again upon detection of activity, i.e., rising edge at the TX input. The
device is able to receive and transmit a valid J1850 message when
initially in low-power mode.

The AU5780A features special robustness at its BATT and
BUS_OUT pins hence the device is well suited for applications in

the automotive environment. Specifically, the BATT input is
protected against 50V load dump, jump start and reverse battery
condition. The BUS_OUT output is protected against wiring fault
conditions, e.g., short circuit to battery voltage as well as typical
automotive transients (i.e., 200V / +200V). In addition, an
overtemperature shutdown function with hysteresis is incorporated
which protects the device under system fault conditions. The chip

temperature is sensed at the bus drive transistor in the output buffer.
In case of the chip temperature reaching the trip point, the AU5780A

will latch-off the transceiver function. The device is reset on the first
rising edge on the TX input after a small decrease of the chip
temperature.

The AU5780A also provides a loop-back mode for diagnostic
purpose. If the /LB pin is open circuit or pulled low, then TX signal is
internally looped back to the RX output independent of the signals
on the bus. In this mode the electronic module is disconnected from
the bus, i.e., the TX signal is not output to the physical bus line. In
this mode, it can be used, e.g., for self-test purpose.

The AU5780A is an enhanced successor of the AU5780. The
AU5780A provides improved wave shaping when exiting the low
power standby mode for reduced EMI. Several parameters that
were formerly only characterized to the maximum normal operating
supply of 16 volts, have now been characterized to 24 volt supplies.
These parameters which are tested and guaranteed to 24 volts are

identified with appropriate test conditions in the "conditions" columns

of the Characteristics tables, otherwise the conditions at the top of
the characteristic table applies to all parameters.

Philips Semiconductors

Product data

AU5780A

SAE/J1850/VPW transceiver

2001 Jun 19

CONTROL INPUT SUMMARY

/LB

MODE

BIT VALUE

BUS_OUT

(out)

Loop-back

TX passive (default state)

float

float (high)

Loop-back

TX active

float

low

Communication

Transmitter passive

float

bus state

Communication

Transmitter active

high

low

NOTE:
1. RX outputs the bus state. If the bus level is below the receiver threshold (i.e., all transmitters passive), then RX 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 RX will be low.

ABSOLUTE MAXIMUM RATINGS

According to the IEC 134 Absolute Maximum System; operation is not guaranteed under these conditions; all voltages are referenced to pin 8
(GND); positive currents flow into the IC; unless otherwise specified.

SYMBOL

PARAMETER

CONDITIONS

MIN.

MAX.

UNIT

BATT

supply voltage

+24

BATT.ld

short-term supply voltage

load dump; t < 1s

+50

BATT.tr1

transient supply voltage

SAE J1113 pulse 1

100

BATT.tr2

transient supply voltage

SAE J1113 pulses 2

+150

BATT.tr3

transient supply voltage

SAE J1113 pulses 3A, 3B

200

+200

Bus voltage

> 10 k

;

Rb >10

+20

B.tr1

transient bus voltage

SAE J1113 pulse 1

B.tr2

transient bus voltage

SAE J1113 pulses 2

+100

B.tr3

transient bus voltage

SAE J1113 pulses 3A, 3B

200

+200

DC voltage on pins TX, R/F, RX, /LB

0.3

ESD

BATT

ESD capability of BATT pin

Air gap discharge,
R=2k

, C=150pF

ESD

bus

ESD capability of BUS_OUT and BUS_IN pins

Air gap discharge,
R=2k

, C=150pF, R

> 10 k

ESD

logic

ESD capability of TX, RX, R/F, and /LB pins

Human Body,
R=1.5k

, C=100pF

tot

maximum power dissipation

at T

amb

= +125

164

thermal impedance

152

C/W

amb

operating ambient temperature

+125

stg

storage temperature

+150

junction temperature

+150

LEAD

Lead temperature

Soldering, 10 seconds maximum

265

CL(BUS)

Bus output clamp current

No latch-up, |V

BUS

| = 25 V

100

CL(BATT)

Battery clamp current

No latch-up or snap back,
|V

BATT

| = 25 V

100

NOTE:
1. For bus voltages 20V < V

bus

< 17V and +17V < V

bus

< +20V the current is limited by the external resistors R

and R

Part Number AU5780

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