AMIS-40616
LIN Transceiver with 5V Voltage Regulator
Table 4: Mode Selection
Mode
Vcc
Normal - Slope
On
Normal - Low Slope
Stand-by
Sleep
Notes:
1.
2.
3.
Data Sheet
On
On
Off
RxD
Low = dominant state
High = recessive state
Low = dominant state
High = recessive state
Low after LIN wake-up, high otherwise
Clamped to V
cc
INH
High if STB = High during state
transition; floating otherwise
High if STB = High during state
transition; floating otherwise
Floating
Floating
LIN
Normal slope
Low slope
Off
Off
30kΩ on LIN
On
On
Off
Off
Note
(1)
(2)
(3)
The normal slope mode is entered when pin EN goes high while TxD is in high state during EN transition.
The low slope mode is entered when pin EN goes high while TxD is in low state during EN transition. LIN transmitter gets on only after TxD returns to high after the
state transition.
The stand-by mode is entered automatically after power-up.
7.2.1. Normal Slope Mode
In normal slope mode the transceiver can transmit and receive data via LIN bus with speed up to 20kBaud. The transmit data stream of
the LIN protocol is present on the TxD pin and converted by the transmitter into a LIN bus signal with controlled slew rate to minimize
EMC emission. The receiver consists of the comparator that has a threshold with hysteresis in respect to the supply voltage and an
input filter to remove bus noise. The LIN output is pulled high via an internal 30kΩ pull-up resistor. For master applications it is needed
to put an external 1kΩ resistor with a serial diode between LIN and V
bb
(or INH). See Figure 2. The mode selection is done by
EN=HIGH when TxD pin is high. If STB pin is high during the standby-to-normal slope mode transition, INH pin is pulled high.
Otherwise, it stays floating.
7.2.2. Low Slope Mode
In low slope mode the slew rate of the signal on the LIN bus is reduced (rising and falling edges of the LIN bus signal are longer). This
further reduces the EMC emission. As a consequence the maximum speed on the LIN bus is reduced up to 10kBaud. This mode is
suited for applications where the communication speed is not critical. The mode selection is done by EN=HIGH when TxD pin is low. In
order not to transmit immediately a dominant state on the bus (because TxD=LOW), the LIN transmitter is enabled only after TxD
returns to high. If STB pin is high during the standby-to-low slope mode transition, INH pin is pulled high. Otherwise, it stays floating.
7.2.3. Stand-by Mode
The stand-by mode is always entered after power-up of the AMIS-40616. It can also be entered from normal mode when the EN pin is
low and the stand-by pin is high. From sleep mode it can be entered after a local wake-up or LIN wakeup. In stand-by mode the V
cc
voltage regulator for supplying external components (e.g. a microcontroller) stays active. Also the LIN receiver stays active to be able to
detect a remote wake-up via bus. The LIN transmitter is disabled and the slave internal termination resistor of 30kΩ between LIN and
V
bb
is disconnected in order to minimize current consumption. Only a pull-up current source between V
bb
and LIN is active.
7.2.4. Sleep Mode
The sleep mode provides extreme low current consumption. This mode is entered when both EN and STB pins are low coming from
normal mode. The internal termination resistor of 30kΩ between LIN and V
bb
is disconnected and also the V
cc
regulator is switched off
to minimize current consumption.
7.2.5. Wake-up
AMIS-40616 has two possibilities to wake-up from sleep or stand-by mode (see Figure 4):
•
Local wake-up: enables the transition from sleep mode to stand-by mode.
•
Remote wake-up via LIN: enables the transition from sleep- to stand-by mode and can be also detected when already in standby
mode.
A local wake-up is
only
detected in sleep mode if a transition from low to high or from high to low is seen on the wake pin.
AMI Semiconductor
– January 2007, M-20545-001
7
www.amis.com
AMI [ AMI SEMICONDUCTOR ]
