Rainbow Electronics ATA6834 - Manual (Page 6)

6
9122B–AUTO–10/08
ATA6833/ATA6834 [Preliminary]
3.2 Active Mode and Sleep Mode
The IC has two modes: Sleep Mode and Active Mode. Switching between the modes is
described below. By default the IC starts in Active Mode (which means normal operation) after
power-on. A Go to Sleep procedure switches the IC from Active Mode to Sleep Mode (standby).
A Go to Active procedure brings the IC back from Sleep Mode to Active Mode. When in Sleep
Mode the internal 5V supply (VINT regulator), the EN2 pin input structure, and a certain part of
the LIN receiver remain active to ensure a proper startup of the system. The VCC regulator is
turned off.
The Go to Sleep and Go to Active procedures are implemented as follows:
Go to Sleep:
Pin EN1 is a low-voltage input supplied by the VCC regulator. It is ESD protected by diodes
against VCC and GND. Thus the input voltage at pin EN1 must not go below GND or exceed the
output voltage of the VCC regulator. A transition from HIGH to LOW followed by a permanent
LOW signal for a minimum time period t
gotosleep
(typical 10 µs) at pin EN1 switches the IC to
Sleep Mode as the EN1 is edge triggered. V
CC
is switched off in Sleep Mode. It is recommended
to keep EN1 LOW during normal operation.
Go to Active Using Pin EN2:
Pin EN2 is a high-voltage input for external wake-up signals. Its input structure consists of a
comparator with a built-in hysteresis. It is ESD-protected by diodes against GND and V
BAT
, B,
and for this reason the applied input voltage must not go below GND or exceed V
BAT
. Pulling
EN2 up to V
BAT
switches the IC to Active Mode. EN2 is debounced and edge triggered.
Go to Active Using the LIN Interface:
Using the LIN interface provides a second possibility to wake-up the IC (see Figure 3-1 ). A fall-
ing edge at pin LIN followed by a dominant bus level maintained for a minimum time period
(T
bus
) and ending with a rising edge leads to a remote wake-up request. The device switches
from Sleep Mode to Active Mode. The VCC regulator is activated and the internal LIN slave ter-
mination resistor is switched on.
Figure 3-1. Wake-up Using the LIN Interface
Sleep Mode
LIN
VCC
EN1
Active Mode Active Mode
T
bus
= 90 µs Regulator Wake-up Time = 4 × T
OSC
T
gotosleep
= 10 µs
T
debounce