FS6407 datasheet(57/111 Pages) NXP

57 / 111 page

NXP Semiconductors

FS6407/FS6408

Figure 41. CAN timing diagram

6.8.1.2

Sleep mode

When the device is in LPOFF mode, the CAN transceiver is automatically set in Sleep mode with or without wake-up capability, depending

on the CAN mode bits configuration. In that case, the CANH and CANL pins are pulled down to GND via the internal RIN resistor, the TXD

and RXD pins are pulled down to GND, both driver and receiver are OFF.

The CAN mode is automatically changed to sleep with wake-up capability, if not configured to sleep without wake-up capability when the

device enters is LPOFF. After LPOFF, the initial CAN mode prior to enter LPOFF is restored (Figure 42).

Figure 42. CAN transition when device goes to LPOFF

6.8.2

Fault detection

6.8.2.1

TXD permanent dominant (timeout)

If TXD is set low for a time longer than tDOUT parameter, the CAN drivers are disabled, and the CAN bus returns to recessive state. The

CAN receiver continues to operate. This prevent the bus to be set in dominant state permanently in case a failure set the TXD input to

low level permanently.

The CAN_mode MSB bit is set to 0 and the flag TXD_dominant is reported in the Diag CAN1 register. The device recovers from this error

detection after setting the CAN_mode to Normal operation and when a high level is detected on TXD. The TXD failure detection is

operating when the CAN transceiver is in Normal mode and Listen Only mode.

0.3VDDIO

TXD

CANH

RXD

CANL

Vdiff

dominant

recessive

0.9V

0.5V

0.7VDDIO

high

low

high

low

Tloop (R-D)

Tloop (D-R)

(CANH - CANL)

CAN_mode

[1:0]

Sleep, no wake-up capability

Listen Only

Sleep, wake-up capability

Normal

Sleep, wake-up capability

CAN state before entering LPOFF

CAN state in LPOFF

CAN state after LPOFF

CAN state

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