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 9 of 61
NXP Semiconductors
TJA1085
FlexRay active star coupler
6.4.2 Local wake-up via pin LWU
Local wake-up is detected when the voltage on pin LWU is lower than V
th(wake)(LWU)
for
longer than t
det(wake)(LWU)
(falling edge on pin LWU). When local wake-up is detected, the
WU_LOCAL status bit is set and a WU interrupt is generated. At the same time, the
internal biasing of this pin is switched to pull-down.
If the voltage on pin LWU rises and remains above V
th(wake)(LWU)
for longer than
t
det(wake)(LWU)
(rising edge on pin LWU), local wake-up is not detected and the biasing on
pin LWU is switched to pull-up.
6.4.3 Wake-up via the TRXD0/1 interface
If the voltage on pin TRXD0 or pin TRXD1 is LOW for longer than t
det(wake)(TRXD)
, a WU
interrupt is generated and the WU_TRXD status bit is set.
The duration of each interruption is 130 ns.
The transition time from DATA_0 to DATA_1 and vice versa is about 20 ns.
The TJA1085 wake-up flag is set on receipt of the following frame payload:
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
Fig 4. Minimum bus pattern for bus wake-up via dedicated FlexRay data frame
015aaa343
V
dif
0 V
-2000
wake-up
+2000
870
ns
870
ns
870 ns 870 ns
770
ns
130 ns
130
ns
130
ns
5 µs
5 µs 5 µs 5 µs
Fig 5. Local wake-up timing on pin LWU
015aaa178
V
BAT
V
BAT
INH
0 V
0 V
LWU
t
det(wake)(LWU)
pull-up pull-up
t
det(wake)(LWU)
pull-down
t
d(LWUwake-INHH)