ATA6629/ATA6631
LIN Bus Transceiver with Integrated Voltage Regulator
DATASHEET
Features
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Supply voltage up to 40V
Operating voltage V
S
= 5V to 27V
Typically 10µA supply current during sleep mode
Typically 35µA supply current in silent mode
Linear low
-drop voltage regulator, 85mA current capability:
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Normal, fail-safe, and silent mode
Atmel ATA6629: V
CC
= 3.3V ±2%
Atmel ATA6631: V
CC
= 5.0V ±2%
Sleep mode: V
CC
is switched off
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V
CC
undervoltage detection with reset open drain output NRES (4ms reset time)
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Voltage regulator is short-circuit and over-temperature protected
LIN physical layer according to LIN 2.0, 2.1 and SAEJ2602-2
Wake-up capability via LIN bus (90µs dominant)
TXD time-out timer
Bus pin is overtemperature and short-circuit protected versus GND and battery
Advanced EMC and ESD performance
Fulfills the OEM “hardware requirements for LIN in automotive applications rev.1.1”
Interference and damage protection according to ISO7637
Package: S
O8
9165F-AUTO-10/14
1.
Description
Atmel
®
ATA6629/ATA6631 is a fully integrated LIN transceiver, designed according to the LIN specification 2.0, 2.1 and
SAEJ2602-2, with a low-drop voltage regulator (3.3V/5V/85mA). The combination of voltage regulator and bus transceiver
makes it possible to develop simple, but powerful, slave nodes in LIN bus systems. ATA6629/ATA6631 is designed to
handle the low-speed data communication in vehicles (for example, in convenience electronics). Improved slope control at
the LIN driver ensures secure data communication up to 20kBaud. The bus output is designed to withstand high voltage.
Sleep mode and silent mode guarantee minimized current consumption even in the case of a floating or a short circuited
LIN-bus.
Figure 1-1. Block Diagram
Atmel ATA6629/ATA6631
V
CC
5kΩ
RXD
5
Receiver
Normal and
Fail-safe
Mode
1
VS
-
+
4
RF-filter
LIN
V
CC
Wake-up bus timer
Short-circuit and
overtemperature
protection
TXD
6
TXD
Time-out
timer
Slew rate control
8
EN
2
Sleep
mode
Control
VCC
unit
switched
off
Normal/Silent/
Fail-safe Mode
3.3V/5V
Undervoltage reset
7
VCC
NRES
GND
3
2
ATA6629/ATA6631 [DATASHEET]
9165F–AUTO–10/14
3.
3.1
Functional Description
Physical Layer Compatibility
Since the LIN physical layer is independent from higher LIN layers (e.g., LIN protocol layer), all nodes with a LIN physical
layer according to revision 2.x can be mixed with LIN physical layer nodes, which are according to older versions (i.e., LIN
1.0, LIN 1.1, LIN 1.2, LIN 1.3) without any restrictions.
3.2
Supply Pin (VS)
LIN operating voltage is V
S
= 5V to 27V. An undervoltage detection is implemented to disable transmission if V
S
falls below
5V, in order to avoid false bus messages. After switching on V
S
, the IC starts with the fail-safe mode and the voltage
regulator is switched on.
The supply current in sleep mode is typically 10µA and 35µA in silent mode.
3.3
Ground Pin (GND)
The IC does not affect the LIN bus in the event of GND disconnection. It is able to handle a ground shift up to 11.5% of V
S
.
3.4
Voltage Regulator Output Pin (VCC)
The internal 3.3V/5V voltage regulator is capable of driving loads up to 85mA, supplying the microcontroller and other ICs on
the PCB and is protected against overload by means of current limitation and overtemperature shut-down. Furthermore, the
output voltage is monitored and will cause a reset signal at the NRES output pin if it drops below a defined threshold V
thun
.
3.5
Undervoltage Reset Output (NRES)
If the V
CC
voltage falls below the undervoltage detection threshold V
thun
, NRES switches to low after tres_f
(Figure
6-1 on page 15).
Even if V
CC
= 0V the NRES stays low, because it is internally driven from the V
S
voltage. If V
S
voltage ramps down, NRES stays low until V
S
< 1.5V and then becomes highly resistant.
The implemented undervoltage delay keeps NRES low for t
Reset
= 4ms after V
CC
reaches its nominal value.
3.6
Bus Pin (LIN)
A low-side driver with internal current limitation and thermal shutdown as well as an internal pull-up resistor according to LIN
specification 2.x is implemented. The voltage range is from –27V to +40V. This pin exhibits no reverse current from the LIN
bus to V
S
, even in the event of a GND shift or V
Batt
disconnection. The LIN receiver thresholds are compatible with the LIN
protocol specification.
The fall time (from recessive to dominant) and the rise time (from dominant to recessive) are slope controlled.
3.7
Input/Output (TXD)
In normal mode the TXD pin is the microcontroller interface to control the state of the LIN output. TXD must be pulled to
ground in order to drive the LIN bus low. If TXD is high or unconnected (internal pull-up resistor), the LIN output transistor is
turned off and the bus is in the recessive state. During fail-safe mode, this pin is used as output and is signalling the fail-safe
source.
3.8
Dominant Time-out Function (TXD)
The TXD input has an internal pull-up resistor. An internal timer prevents the bus line from being driven permanently in the
dominant state. If TXD is forced to low longer than t
DOM
> 27ms, the LIN bus driver is switched to the recessive state.
Nevertheless, when switching to sleep mode, the actual level at the TXD pin is relevant.
To reactivate the LIN bus driver, switch TXD to high (> 10µs).
4
ATA6629/ATA6631 [DATASHEET]
9165F–AUTO–10/14
3.9
Output Pin (RXD)
This pin reports the state of the LIN bus to the microcontroller. LIN high (recessive state) is reported by a high level at RXD;
LIN low (dominant state) is reported by a low level at RXD. The output has an internal pull-up resistor with typically 5kΩ to
V
CC
. The AC characteristics are measured with an external load capacitor of 20pF.
The output is short-circuit protected. In unpowered mode (that is, V
S
= 0V), RXD is switched off.
3.10
Enable Input Pin (EN)
The enable input pin controls the operation mode of the device. If EN is high, the circuit is in normal mode, with transmission
paths from TXD to LIN and from LIN to RXD both active. The VCC voltage regulator operates with 3.3V/5V/85mA output
capability.
If EN is switched to low while TXD is still high, the device is forced to silent mode. No data transmission is then possible, and
the current consumption is reduced to I
VS
typ. 35µA. The VCC regulator has its full functionality.
If EN is switched to low while TXD is low, the device is forced to sleep mode. No data transmission is possible, and the
voltage regulator is switched off.
ATA6629/ATA6631 [DATASHEET]
9165F–AUTO–10/14
5
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