Rainbow Electronics ATA6662 - Manual (Page 6)

6
4916E–AUTO–02/07
ATA6662 [Preliminary]
3.13 Wake-up Source Recognition
The device can distinguish between a local wake-up request (pin WAKE) and a remote wake-up
request (dominant LIN bus). The wake-up source can be read on pin TXD in pre-normal mode. If
an external pull-up resistor (typically 5 k
Ω
) has been added on pin TXD to the power supply of
the microcontroller, a high level indicates a remote wake-up request (weak pull-down at pin
TXD) and a low level indicates a local wake-up request (strong pull-down at pin TXD).
The wake-up request flag (signalled on pin RXD) as well as the wake-up source flag (signalled
on pin TXD) are reset immediately if the microcontroller sets pin EN to high (see
Figure 3-2 on
page 7 and Figure 3-3 on page 7 ).
Figure 3-1. Mode of Operation
3.14 Fail-safe Features
• There are now reverse currents < 15 µA at pin LIN during loss of V
BAT
or GND; this is optimal
behavior for bus systems where some slave nodes are supplied from battery or ignition.
• Pin EN provides a pull-down resistor to force the transceiver into sleep mode if EN is
disconnected.
• Pin RXD is set floating if V
BAT
is disconnected.
• Pin TXD provides a pull-down resistor to provide a static low if TXD is disconnected.
• The LIN output driver has a current limitation, and if the junction temperature T
j
exceeds the
thermal shut-down temperature T
off
, the output driver switches off.
• The implemented hysteresis, T
hys
, enables the LIN output again after the temperature has
been decreased.
Pre-normal Mode
INH: high (INH internal high-side switch ON)
Communication: OFF
a b
Sleep Mode
INH: high impedance (INH HS switch OFF)
Communication: OFF
EN = 0; after 1 → 0 while TXD = 1
Go to sleep command
EN = 1
Local wake-up event
a: V
S
> 5V
b: V
S
< 5V
c: Bus wake-up event
d: Wake-up from wake switch
b
EN = 1
b
c
d
Normal Mode
INH: high (INH HS switch ON)
Communication: ON
Unpowered Mode
V
Batt
= 0V