ATA6613-EK Atmel, ATA6613-EK Datasheet - Page 7

• Manufacturer Part Number: ATA6613-EK
• Description: BOARD DEMO LIN-MCM FOR ATA6613
• Manufacturer: Atmel

Specifications of ATA6613-EK

• Main Purpose: Interface, LIN + MCU
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: ATA6613
• Primary Attributes: LIN-SBC (System-Basis-Chip) Transceiver, LIN 2.0, Voltage Regulator, Window Watchdog
• Secondary Attributes: 16 kB Flash, 4 Power Modes: Pre-Normal, Normal, Sleep, Silent, 48-QFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Figure 3-1.
9127A–AUTO–05/08
NTRIG
NRES
VCC
3.3V
5V
Watchdog Timing Sequence with R8 = 51 k
Undervoltage Reset
t
reset
= 4 ms
The microcontroller pin PD3 is used by default to trigger the watchdog. In order to lead the sig-
nals generated from pin PD3 to the watchdog trigger input NTRIG, the jumper TRIG has to be
set. If it is not possible to use the pin PD3 to trigger the watchdog as it is being used for
another function, remove the TRIG jumper completely and connect the NTRIG pin directly to
another microcontroller pin using a 1-wire cable.
If the watchdog is not used, the trigger input can be left open on the development board, as it
is equipped with an internal pull-up resistor. For normal use of ATA6612 and ATA6613 with
deactivated watchdog, it is recommended that the trigger input pin NTRIG is tied directly to
VCC for EMC reasons.
Replacing the resistor R8 results in a frequency change of the internal oscillator. This in turn
results in different watchdog timing. The following formula demonstrates how the frequency of
the internal oscillator depends on the value of the resistor R8. Refer also to the
ATA6612/ATA6613 datasheet for further information:
t
t
R
With the values given in the datasheet, you can calculate all relevant watchdog times (for
example the open window and the closed window) using t
In general, both ATA6612 and ATA6613 are shipped with an oscillator start-up time of 65 ms.
Due to the extra-long lead time of 155 ms it should be possible in almost all cases to meet the
first open window of the watchdog.If more time is needed, the default start-up time of the
microcontroller 65 ms can be reduced via the fuse bits to 4.1 ms or even 0 ms. The IC
mounted on the board is delivered with a start-up time of 65 ms.
OSC
OSC
WD_OSC
[R
in µs
WD_OSC
in k
] = –0.0004
t
d
= 155 ms
t
trig
> 200 ns
t
1
= 20.6 ms
(R
WD_OSC
t
wd
)
t
2
2
+ 0.405
= 21 ms
R
t
1
WD_OSC
OSC
ATA6612/ATA6613
.
t
2
Watchdog Reset
t
nres
= 4 ms
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