PCA82C252 データシートの表示（PDF） - Philips Electronics

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PCA82C252

Fault-tolerant CAN transceiver

Philips Electronics 

Philips Semiconductors

Fault-tolerant CAN transceiver

Product specification

PCA82C252

To prevent false wake-up due to transients or RF fields,

wake-up voltage threshold levels have to be maintained

for a certain period of time. In the low power modes the

failure detection circuit remains partly active to prevent

increased power consumption should errors 3, 4 and 7

occur.

Power on

After power-on VBAT is switched on, the INH pin will

become 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, if

the VCC voltage is below a certain threshold level, to

provide fail safe functionality.

Protections

A current limiting circuit protects the transmitter output

stages against short-circuit to positive and negative

battery voltage.

If the junction temperature exceeds a maximum value, the

transmitter output stages are disabled. Because the

transmitter is responsible for the major part of the power

dissipation, this will result in a reduced power dissipation

and hence a lower chip temperature. All other parts of the

IC will remain operating.

The CANH and CANL inputs are protected against

electrical transients which may occur in an automotive

environment.

Table 1 Truth table of CAN transceiver

STB EN

MODE

INH

NERR

RXD

RTL

0 0 VBAT standby(1)

0 0 sleep(2)

HIGH LOW active wake-up interrupt signal if VCC is present switched to VBAT

floating

switched to VBAT

0 1 go to sleep command floating

1 0 VCC standby(3)

HIGH LOW active VBAT

power-on flag

LOW active wake-up

interrupt

switched to VBAT

switched to VCC

1 1 normal operation mode HIGH LOW active error flag

HIGH = receive;

LOW = dominant

received data

switched to VCC

Notes

1. Wake-up interrupts are released when entering normal operating mode.

2. If go to sleep command was used before (EN may turn LOW as VCC drops, without affecting internal functions

because of fail safe functionality).

3. VBAT power-on flag will be reset when entering normal operation mode.

1997 Oct 28

6

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