Rainbow Electronics ATA6823 - Manual (Page 7)

7
4856E–AUTO–07/07
ATA6823 [Preliminary]
Pulling the EN2 pin up to the V
BAT
level will drive the IC into Active mode. EN2 is debounced with
a time constant of 20 µs, based on a 100 kHz clock.
• Go to Active using the LIN interface
The second possibility for wake-up can be performed using the LIN transceiver. In Sleep mode,
the LIN receiver is partially active.
The wake-up by LIN requires 2 steps:
1. If the voltage on pin LIN is below a value of V
/DATwake
(about V
VBAT
– 2V) the receive part
of the LIN interface is active (not to be confused with Active mode of the whole IC). The
active receive part is able to detect a valid LOW on the LIN pin.
2. If LIN = LOW during a filter time t
wakeLIN
(typically 70 µs) the IC will change to Active
mode. A short change back to HIGH during the filter time will reset the filter. This infor-
mation is stored in a latch after entering Active mode
If the change to Active mode was caused by LIN, the EN1 or EN2 pins may remain LOW without
disturbing the Active mode.
• Stay in Active via EN1
The input EN1 is intended to keep the IC in Active Mode via a signal from the microcontroller.
The input is ESD-protected by diodes against GND and VCC. Therefore, the input voltage must
be positive and not higher than V
CC
. EN1 cannot be used to switch from Sleep to Active because
the VCC regulator is off in the Sleep mode and V
CC
will be zero.
• Go to Sleep
A HIGH to LOW transition at pin EN1 and a following permanent LOW for the time t
gotosleep
(typically 20 µs) switches the IC to Sleep mode.
Figure 5-1 illustrates the wake-up by LIN. The status PREWAKE is characterized by the acti-
vated receive block of the LIN interface. After going to Active mode, the V
CC
regulator starts
working.
Go to Sleep is possible with a valid HIGH to LOW transition at pin EN1 (permanent LOW for
longer than t
db
) if EN1 was in a valid HIGH state (HIGH for longer than t
db
) before.