TJA1053 Fault-tolerant CAN transceiver

Philips SemiconductorsProduct specificationFault-tolerant CAN transceiverTJA1053Wake-up requests are recognized by the transceiver whena dominant signal is detected on either bus line or if theWAKE pin is connected to ground. On a wake-up requestthe transceiver will set the INH output which can be usedto activate the external V CC voltage regulator. If V CC isprovided the wake-up request can be read on the NERR orRXD outputs, on which the external microcontroller canwake up the transceiver (switch to normal operating mode)via STB and EN.To prevent false wake-up due to transients or RF fields,wake-up voltage threshold levels have to be maintainedfor a certain period of time. In the low power modes thefailure detection circuit remains partly active to preventincreased power consumption should errors 3, 4 and 7occur.Power onAfter power-on V BAT is switched on, the INH pin willbecome HIGH and an internal power-on flag will be set.This flag can be read via the NERR pin (STB = 1, EN = 0)and will be reset by entering the normal operation mode.The EN and STB pins will internally be set to LOW level, ifthe V CC voltage is below a certain threshold level, toprovide fail safe functionality.ProtectionsA current limiting circuit protects the transmitter outputstages against short-circuit to positive and negativebattery voltage.If the junction temperature exceeds a maximum value, thetransmitter output stages are disabled. Because thetransmitter is responsible for the major part of the powerdissipation, this will result in a reduced power dissipationand hence a lower chip temperature. All other parts of theIC will remain operating.The CANH and CANL inputs are protected againstelectrical transients which may occur in an automotiveenvironment.Table 1Truth table of CAN transceiverSTB EN MODE INH NERR RXD RTL0 0 V BAT standby (1) HIGH active LOW wake-up interrupt signal if V CC is present switched to V BAT0 0 sleep (2) floating switched to V BAT0 1 go to sleep command floating switched to V BAT1 0 V CC standby (3) HIGH active LOW V BATpower-on flagactive LOW wake-upinterruptswitched to V CC1 1 normal operation mode HIGH active LOW error flag HIGH = receive;LOW = dominantreceived dataswitched to V CCNotes1. Wake-up interrupts are released when entering normal operating mode.2. If go to sleep command was used before (EN may turn LOW as V CC drops, without affecting internal functionsbecause of fail safe functionality).3. V BAT power-on flag will be reset when entering normal operation mode.2000 Dec 18 6