Rainbow Electronics ATA6664 User Manual
Features
• Operating Range from 5V to 27V
• Baud Rate up to 20Kbaud
• Improved Slew Rate Control According to LIN Specification 2.0, 2.1 and SAEJ2602-2
• Fully Compatible with 3.3V and 5V Devices
• Atmel ATA6663: TXD Time-out Timer, Atmel ATA6664: No TXD Time-out Timer
• Normal and Sleep Mode
• Wake-up Capability via LIN Bus (90µs Dominant)
• External Wake-up via WAKE Pin (35µs Low Level)
• INH Output to Control an External Voltage Regulator or to Switch the Master Pull-up
• Very Low Standby Current During Sleep Mode (10µA)
• Wake-up Source Recognition
• Bus Pin Short-circuit Protected versus GND and Battery
• LIN Input Current < 2µA if V
• Overtemperature Protection
• High EMC Level
• Interference and Damage Protection According to ISO/CD 7637
• Fulfills the OEM “Hardware Requirements for LIN in Automotive Applications Rev.1.1”
• Packages: SO8, DFN8
Is Disconnected
BAT
1. Description
The Atmel ATA6663 is a fully integrated LIN transceiver complying with the LIN
specification 2.0, 2.1 and SAEJ2602-2. The Atmel ATA6664 is an identical version,
the only difference is that the TXD-dominant Time-out function is disabled so the
device is able to send a static low signal to the LIN bus. It interfaces the LIN protocol
handler and the physical layer. The device is designed to handle the low-speed data
communication in vehicles, for example, in convenience electronics. Improved slope
control at the LIN bus ensures secure data communication at up to 20Kbaud with an
RC oscillator for protocol handling. Sleep Mode guarantees minimal current consumption even in the case of a floating bus line or a short circuit on the LIN bus to GND.
The ATA6663/ATA6664 feature advanced EMI and ESD performance.
LIN Transceiver
Atmel ATA6663
Atmel ATA6664
9146E–AUTO–03/11
Figure 1-1. Block Diagram
1
RXD
Receiver
Filter
7
VS
6
LIN
TXD
4
VS
WAKE
3
2. Pin Configuration
Figure 2-1. Pinning SO8, DFN8
WAKE
RXD
EN
TXD
TXD
time-out
timer
(only ATA6663)
Wake-up
timer
1
2
SO8
3
4
8
7
6
5
Wake-up bus timer
Slew rate control
Control unit
Sleep mode
2 8
EN
INH
VS
LIN
GND
RXD
EN
WAKE
TXD
Short-circuit and overtemperature protection
VS
INH
DFN8
3 x 3
INH
VS
LIN
GND
5
GND
Table 2-1. Pin Description
Pin Symbol Function
1 RXD Receive data output (open drain)
2 EN Enables normal mode; when the input is open or low, the device is in sleep mode
3 WAKE High voltage input for local wake-up request. If not needed, connect directly to VS
4 TXD Transmit data input; active low output (strong pull-down) after a local wake-up request
5 GND Ground, heat sink
6 LIN LIN bus line input/output
7 VS Battery supply
8INH
2
Atmel ATA6663/ATA6664
Battery-related inhibit output for controlling an external voltage regulator or to switch-off the LIN master
pull-up resistor; active high after a wake-up request
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3. Functional Description
3.1 Physical Layer Compatibility
Since the LIN physical layer is independent from higher LIN layers (e.g., the LIN protocol
layer), all nodes with a LIN physical layer according to LIN2.x can be used along with LIN
physical layer nodes, which are according to older versions (i.e., LIN1.0, LIN1.1, LIN1.2,
LIN1.3), without any restrictions.
3.2 Supply Pin (VS)
Undervoltage detection is implemented to disable transmission if VS falls to a value below 5V
in order to avoid false bus messages. After switching on V
and INHIBIT is switched on. The supply current in sleep mode is typically 10µA.
3.3 Ground Pin (GND)
The Atmel ATA6663/ATA6664 does not affect the LIN Bus in the case of a GND disconnection. It is able to handle a ground shift up to 11.5% of V
3.4 Bus Pin (LIN)
A low-side driver with internal current limitation and thermal shutdown, and an internal pull-up
resistor are implemented as specified by LIN2.x. The voltage range is from –27V to +40V. This
pin exhibits no reverse current from the LIN bus to V
disconnection. The LIN receiver thresholds are compatible to the LIN protocol specification.The fall time (from recessive to dominant) and the rise time (from dominant to recessive)
are slope controlled. The output has a self-adapting short-circuit limitation: During current limitation, as the chip temperature increases, the current is reduced.
Atmel ATA6663/ATA6664
, the IC switches to fail-safe mode
S
.
S
, even in the case of a GND shift or V
S
Batt
Note: The internal pull-up resistor is only active in normal and fail-safe mode.
3.5 Input/Output Pin (TXD)
In Normal Mode the TXD pin is the microcontroller interface to control the state of the LIN output. TXD must be at Low- level in order to have a low LIN Bus. If TXD is high, the LIN output
transistor is turned off and the Bus is in recessive state. The TXD pin is compatible to both a
3.3V or 5V supply. During fail-safe Mode, this pin is used as output and is signalling the wakeup source (see Section 3.14 “Wake-up Source Recognition” on page 8). It is current limited to
<8mA.
3.6 TXD Dominant Time-out Function (only Atmel ATA6663)
The TXD input has an internal pull-down resistor. An internal timer prevents the bus line from
being driven permanently in dominant state. If TXD is forced to low longer than t
the pin LIN will be switched off (recessive mode). To reset this mode, TXD needs to be
switched to high (> 10µs) before switching LIN to dominant again.
Note: The ATA6664 does not provide this functionality.
DOM
> 40ms,
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3
3.7 Output Pin (RXD)
This pin forwards information on the state of the LIN bus to the microcontroller. LIN high
(recessive) is indicated by a high level at RXD, LIN low (dominant) is reported by a low voltage
at RXD. The output is an open drain, therefore, it is compatible to a 3.3V or 5V power supply.
The AC characteristics are defined by a pull-up resistor of 5kΩ to 5V and a load capacitor of
20pF. The output is short-current protected. In unpowered mode (V
off. For ESD protection a Zener diode with V
3.8 Enable Input Pin (EN)
This pin controls the operation mode of the device. If EN = 1, the device is in normal mode,
with the transmission path from TXD to LIN and from LIN to RXD both active. At a falling edge
on EN, while TXD is already set to high, the device switches to sleep mode and transmission
is not possible. In sleep mode, the LIN bus pin is connected to V
source. The device can transmit only after being woken up (see Section 3.9, “Inhibit Output
Pin (INH)” ).
During sleep mode the device is still supplied from the battery voltage. The supply current is
typically 10µA. The pin EN provides a pull-down resistor in order to force the transceiver into
sleep mode in case the pin is disconnected.
3.9 Inhibit Output Pin (INH)
This pin is used to control an external voltage regulator or to switch on/off the LIN Master
pull-up resistor in case the device is used in a Master node. The inhibit pin provides an internal
switch towards pin V
or fail-safe mode, the inhibit high-side switch is turned on. When the device is in sleep mode,
the inhibit switch is turned off, thus disabling the voltage regulator or other connected external
devices.
= 0V), RXD is switched
S
= 6.1V is integrated.
Z
with a weak pull-up current
S
which is protected by temperature monitoring. If the device is in normal
S
A wake-up event on the LIN bus or at pin WAKE will switch the INH pin to the V
system power-up (V
3.10 Wake-up Input 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 the application to generate a local wake-up. A pull-up current source with typically –10µA is implemented. The voltage threshold for a wake-up signal is
3V below the VS voltage with an output current of typically –3µA.
If a local wake-up is not needed in the application, pin WAKE can directly be connected to pin
VS.
3.11 Operation Modes
1. Normal Mode
This is the normal transmitting and receiving mode. All features are available.
2. Sleep Mode
In this mode the transmission path is disabled and the device is in low-power mode.
Supply current from V
pin WAKE will be detected and will switch the device to fail-safe mode. If EN then
switches to high, normal mode is activated. Input debounce timers at pin WAKE
(t
), LIN (t
WAKE
motive transients or EMI. In sleep mode the INH pin remains floating.
level. After a
S
rises from zero), the pin INH switches automatically to the VS level.
S
is typically 10µA. A wake-up signal from the LIN bus or via
Batt
) and EN (t
BUS
sleep,tnom
) prevent unwanted wake-up events due to auto-
4
Atmel ATA6663/ATA6664
9146E–AUTO–03/11
3. Fail-safe Mode
Figure 3-1. Modes of Operation
Atmel ATA6663/ATA6664
The internal termination between pin LIN and pin VS is disabled. Only a weak pull-up
current (typical 10 µA) between pin LIN and pin V
activated independently from the actual level on pin LIN or WAKE.
At system power-up or after a wake-up event, the device automatically switches to
fail-safe mode. It switches the INH pin to a high state, to the V
exceeds 5V. LIN communication is switched off. The microcontroller of the application
will then confirm normal mode by setting the EN pin to high.
is present. Sleep mode can be
S
level when VS
S
b
EN = 1
& NOT b
Normal Mode
INH: high (INH HS switch ON)
Communication: ON
Table 3-1. Table of Operation Modes
Mode of Operation Transceiver INH RXD LIN
Power-up
a
Fail-safe Mode
Communication: OFF
RXD: see table of Modes
INH: high (INH HS switch ON) if VS > 5V
EN = 0
EN = 1
Go to sleep command
Local wake-up event
Fail-safe Off
On, except
VS < 5V
a: Power-up (VS > 3V)
< 5V
b: V
S
c: Bus wake-up event
d: Wake-up from wake switch
b
c or d
INH: high impedance (INH HS switch OFF)
Sleep Mode
Communication: OFF
High, except after
wake-up
Recessive
Normal On On LIN depending TXD depending
Sleep Off Off High ohmic Recessive
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Wake-up events from sleep mode:
•LIN bus
•EN pin
• WAKE pin
• VS undervoltage
Figure 3-1 on page 5, Figure 3-2 on page 6 and Figure 3-5 on page 8 show the details of
wake-up operations.
5
3.12 Remote Wake-up via Dominant Bus State
A voltage lower than the LIN pre-wake detection V
receiver and starts the wake-up detection timer.
at pin LIN activates the internal LIN
LINL
A falling edge at pin LIN, followed by a dominant bus level V
time period (> t
) and a rising edge at pin LIN results in a remote wake-up request. The
BUS
device switches to fail-safe mode. Pin INH is activated (switches to V
maintained for a certain
BUSdom
) and the internal termi-
S
nation resistor is switched on. The remote wake-up request is indicated by a low level at pin
RXD to interrupt the microcontroller (see Figure 3-2).
Figure 3-2. LIN Wake-up Waveform Diagram
Bus wake-up filtering time
LIN bus
INH
RXD
External
voltage
regulator
EN
(t
)
BUS
Low or floating
High or floating
Off state
Node in sleep state
High
Low
Regulator wake-up time delay
Normal
Mode
EN High
Microcontroller start-up
delay time
In sleep mode the device has a very low current consumption, even during short-circuits or
floating conditions on the bus. A floating bus can arise if the Master pull-up resistor is missing,
e.g., in case it is switched off when the LIN Master is in sleep mode or if the power supply of
the Master node is switched off.
To minimize the current consumption I
pre-wake threshold, the receiver is activated only for a specific time t
the voltage at the bus is lower than pre-wake detection low (V
during voltage levels at the LIN-pin below the LIN
VS
. If t
mon
) and higher than the LIN
LINL
elapses while
mon
dominant level, the receiver is switched off again and the circuit reverts to sleep mode. The
current consumption is then the result of I
VSsleep
plus I
. If a dominant state is reached on
LINwake
the bus no wake-up will occur. Even if the voltage exceeds the pre-wake detection high
(V
), the IC will remain in sleep mode (see Figure 3-3 on page 7).
LINH
This means the LIN bus must be above the Pre-wake detection threshold V
for a few
LINH
microseconds before a new LIN wake-up is possible.
6
Atmel ATA6663/ATA6664
9146E–AUTO–03/11
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