ATA6663/ATA6664 [APPLICATION NOTE]
9201B–AUTO–06/15
4
1.3
System Control (EN, INH and WAKE)
1.3.1
Enable Pin (EN)
This pin controls the operating mode of the interface. If EN = 1, the interface is in normal mode with transmission paths from
TXD to LIN and from LIN to RXD both active. After a falling edge on EN while TXD is set to high, the device switches to sleep
mode, no transmission is possible anymore, and the LIN pin is pulled to VS by a weak current source.
During sleep mode the device is still supplied from the battery voltage with the supply current of typically 10µA. The pin EN
provides a pull-down resistor in order to force the transceiver into sleep mode for fail-safe reasons in the case of an
unconnected EN line.
1.3.2
Inhibit Pin (INH)
This pin is a high-side switch to VS and it is intended to be used to control an external voltage regulator or to switch the LIN
master pull-up resistor on/off in case the device is used in a master node (see
). The output transistor is protected
by internal temperature monitoring. If the device is in normal or in fail-safe mode, the inhibit high-side switch is turned on, in
sleep mode it is turned off.
Figure 1-1.
Switching the LIN Master Pull-up Resistor by the INH Output
With this measure the current consumption in the case of a short circuit between LIN and GND can be reduced to a
minimum, because the Atmel ATA6663/ATA6664 can be switched into sleep mode and therefore the INH output is off.
A wake-up event on the LIN bus (remote wake-up) or at the pin wake (local wake-up) switches the IC into fail-safe mode in
which the INH output is on. The same happens after a system power-up.
1.3.3
Wake Pin (WAKE)
This pin is a high voltage input used to wake up the device from sleep mode. It is usually connected to an external switch in
order to generate a local wake-up. A pull-up current source with typically –10µA is implemented as well as a debounce timer.
On the development board there is the push button S1 to generate a local wake-up by pulling the WAKE pin to GND. The
resistor R4 = 2.7k
is needed to limit the input current in the case of voltage transients.
Even if the WAKE pin is pulled to GND, it is possible to switch the IC into sleep mode. If no local wake-up is required for the
application, the WAKE pin can be connected directly to the VS pin.
RDson
VS
VS
VBAT
LIN sub bus
Atmel
ATA6663/ATA6664
(Part)
INH
LIN
GND
1kΩ
