Datasheet

TJA1085 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
Product data sheet Rev. 1 — 23 October 2012 24 of 61
NXP Semiconductors
TJA1085
FlexRay active star coupler
Autonomous Error Confinement (AEC):
Setting the AEC bit enables the autonomous error confinement feature of the TJA1085.
When AEC is enabled, a bus error (TxE_BRx = 1) triggers a transition from
Branch_Normal to Branch_FailSilent. AEC is disabled by default.
Bus Failure Timer (BFT):
Setting the BFT bit enables the bus failure timer.
When the BFT is enabled, pulses shorter than t
to(BFT)
are ignored, resulting in more robust
bus error detection. The BFT is enabled by default.
Wake-up detection on branch x (WUD_BRx):
Setting the WUD_BRx bit enables wake-up detection on the specified branch.
Each branch in a TJA1085 star network contains a low-power receiver for detecting
remote wake-up events. These events can be enabled and disabled individually. This
feature makes it possible to minimize quiescent current consumption, especially in
AS_Sleep mode. Wake-up detection is enabled by default on all branches.
Communication Controller interface Enable (CC_EN):
Setting bit CC_EN enables the communication controller interface.
A communication controller can be connected to the TJA1085 when CC_EN = 1. If
CC_EN = 0, the RXD output driver is switched off to minimize current consumption in
AS_Normal mode. The CC interface is disabled by default.
TRXD0/1 interface Enable (TRXD_EN):
Setting bit TRXD_EN enables the TRXD0 and TRXD1 interfaces.
When the TRXD0/1 interfaces are enabled, several TJA1085 devices can be connected
together to form a single active star. If only one TJA1085 is needed at any time, the
TRXD0/1 interfaces can be disabled to minimize current consumption in AS_Normal
mode. The TRXD0 and TRXD1 interfaces are enabled by default.
Clamp detection (CLAMP_DET):
Setting bit CLAMP_DET enables clamp detection on TXEN, TRXD and on the four
branches.
When clamp detection is enabled, a CLAMP_ERROR interrupt is generated if clamping is
detected on TXEN (CLAMP_TXEN = 1), TRXD (CLAMP_TRXD = 1) or on a branch
(CLAMP_BRx). Clamp detection is enabled by default.
Bit latching (BIT_LATCHING):
When bit latching is enabled (BIT_LATCHING = 1), the status bits in the General and
Branch X status registers reflect the latched state until the register is read. Once the
register has been read, latching is released and the bits then reflect the current ‘live’
status. When bit latching is disabled, the status bits reflect the ‘live’ status at all times. Bit
latching is disabled by default.