AU5783 Просмотр технического описания (PDF) - Philips Electronics

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AU5783

J1850/VPW transceiver with supply control function

Philips Electronics 

Philips Semiconductors

J1850/VPW transceiver with supply control function

Objective specification

AU5783

essentially disconnecting an electronic control unit from the J1850

bus line. The TX signal is internally looped back to the RX output.

The AU5783 features special robustness at its BAT and BUS pins

hence the device is well protected for applications in the automotive

environment. Specifically the BAT input is protected against 40V

load dump and jump start condition. The BUS output is protected

against wiring fault conditions e.g. short circuit to ground and battery

voltage as well as typical automotive transients and electrostatic

discharge. In addition, an over-temperature shutdown function with

hysteresis is incorporated which protects the device under network

fault conditions. In case of the die temperature reaching the trip

point, the AU5783 will latch-off the transceiver function. The device

is reset on the first rising edge on the TX input after a decrease in

the junction temperature.

Table 1. Control input summary

Z = Input connected to high impedance permitting it to float. Typically accomplished by turning off the output of a microcontroller.

X = Don’t care; The input may be at either logic level.

NSTB 4X/LOOP

TX

Mode

Bus

BUS

RX (out)

INH

transmitter

1

0

1

normal operation

active

high

low

high

1

0

0

normal operation

passive

float

bus state, high

Note 2

1

1

1

4X transmit

active

high

low

high

1

1

0

4X transmit

passive

float

bus state, high

Note 2

1

Z

1

loop-back

passive

float

low

high

1

Z

0

loop-back

passive

float

high

high

0 or Z

X

X

standby (default state after power on), off

Note 1

float

bus state, high

Note 5

1 –> 0

X

X

go to sleep command, Note 4

off

float

bus state, float, Note 3

Note 5

0 or Z

X

X

sleep, Note 4

off

float

bus state, float

Note 5

NOTES:

1. After power-on, the AU5783 enters standby mode since the input pins NSTB and 4X/LOOP are assumed to be floating. In standby mode the

voltage regulator is enabled via the INH output, and therefore power is supplied to the microcontroller. When the microcontroller begins

operation it will normally set the control inputs NSTB high and 4X/LOOP to low state in order to start normal operation of the AU5783.

2. RX outputs the bus state. If the bus level is below the receiver threshold (i.e., all transmitters passive), then RX will be high. Otherwise, if the

bus level is above the receiver threshold (i.e., at least one transmitter is active), then RX will be low.

3. INH is turned off after a time-out period.

4. For entering the sleep mode (e.g., to deactivate INH), the “Go To Sleep” command needs to be applied. The “Go To Sleep” command is a

high-to-low transition on the NSTB input. When the “Go To Sleep” command is present, the INH flag is deactivated. This signal can be used

to turn-off the voltage regulator of an electronic module. After the voltage regulator is turned off the microcontroller is no longer supplied and

the NSTB input will be floating. The INH output will be set again upon detection of bus activity or occurrence of a local wake-up event.

5. In standby and sleep mode, the detection of a wake-up condition (e.g., high level on BUS) will be signalled on the output RX.

1999 May 11

5

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