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INTEGRATED CIRCUITS
AU5780A SAE/J1850/VPW transceiver
Product data Supersedes data of 1999 Jan 28 2001 Jun 19
Philips Semiconductors
Philips Semiconductors
Product data
SAE/J1850/VPW transceiver
AU5780A
FEATURES
multiplexing
• Supports SAE/J1850 VPW standard for in-vehicle class B • 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
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
• Bus terminals proof against automotive transients up to
–200V/+200V
BATT 1 8 GND
• 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
TX
2 AU5780A
7
BUS_OUT
R/F
3
6
/LB
RX
4 SO8
5
BUS_IN
SL01207
QUICK REFERENCE DATA
SYMBOL VBATT.op TA VBATT.ld IBATT.lp VB VBOH –IBO.LIM VBI tbo tr, tf PARAMETER Operating supply voltage Operating ambient temperature Battery voltage Bus idle supply current Bus voltage Bus output voltage Bus output source current Bus input threshold Delay TX to BUS_OUT, normal battery BUS_OUT transition times, rise and fall, normal battery Measured at 3.875V Measured between 1.5 V and (VBATT – 2.75 V), 9 < VBATT < 16 V, tr tested at an additional bus load of RLOAD = 400 W and CLOAD = 22000 pF load dump; 1s VBATT=12V 0 < VBATT < 24V 300Ω < RL < 1.6kΩ 0V < VBO < +6.0V –20 7.3 27 3.65 13 11 CONDITIONS MIN. 6 –40 TYP. 12 MAX. 24 +125 +50 220 +20 8.0 50 4.1 21 18 UNIT V °C V µA V V mA V µs µs
ORDERING INFORMATION
DESCRIPTION SO8: 8-pin plastic small outline package TEMPERATURE RANGE –40 to +125°C ORDER CODE AU5780AD DWG # SOT96-1
2001 Jun 19
2
853-2261 26558
Philips Semiconductors
Product data
SAE/J1850/VPW transceiver
AU5780A
BLOCK DIAGRAM
BATTERY (+12V) BATT 1
LOW–POWER TIMER
VOLTAGE REFERENCE
TEMP. PROTECTION
BUS_OUT TX 2 TX– BUFFER OUTPUT BUFFER 7 Rb Rs R/F 3
/LB
6
INPUT BUFFER
Rf
Vcc
Rd 4 RX VOLTAGE REFERENCE INPUT FILTER 5 BUS_IN
AU5780 8 GND
SL01208
2001 Jun 19
3
Philips Semiconductors
Product data
SAE/J1850/VPW transceiver
AU5780A
PIN DESCRIPTION
SYMBOL BATT TX R/F RX BUS_IN /LB BUS_OUT GND PIN 1 2 3 4 5 6 7 8 Battery supply input (12V nom.) Transmit data input; low: transmitter passive; high: transmitter active Rise/fall slew rate set input Receive data output; low: active bus condition detected; float/high: passive bus condition detected Bus line receive input Loop-back test mode control input; low: loop-back mode; high: normal communication mode Bus line transmit output Ground DESCRIPTION
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 .