ATA6628_14 Datasheet, PDF (15/36 Pages) ATMEL Corporation – LIN Bus Transceiver with 3.3V (5V) Regulator and Watchdog

4.6 Unpowered Mode
If you connect battery voltage to the application circuit, the voltage at the VS pin increases according to the block capacitor
(see Figure 5-1 on page 18). After VS is higher than the VS undervoltage threshold VS_th, the IC mode changes from
Unpowered Mode to Fail-safe Mode. The VCC output voltage reaches its nominal value after t_VCC. This time, t_VCC, depends
on the VCC capacitor and the load.
The NRES is low for the reset time delay t_reset. During this time, t_reset, no mode change is possible.
IF VS drops below VS_th, then the IC switches to Unpowered Mode. The behavior of VCC, NRES and LIN is shown in Figure
4-8. The watchdog needs to be triggered.
Figure 4-8. VCC versus VS for the VCC = 3.3V Regulator
6
5.5
5
4.5
Regulator drop voltage V_D
4
LIN
3.5
3
2.5
VS
2
NRES
1.5
1
VCC
0.5
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
V_S (V)
4.7 High-speed Mode
If SP_MODE pin is high and the IC is in Normal Mode, the slew rate control is switched off. The slope time of the LIN falling
edge is t_{S_Fall} < 2µs. The slope time of the LIN rising edge strongly depends on the LIN capacitive and resistive load. To
achieve a high baud rate it is recommended to use a small resistor (500Ω) and a low capacitor. This allows very fast data
transmission up to 200kBaud, e.g., for electronic control (ECU) tests and microcontroller program or data download. In this
mode superior EMC performance is not guaranteed.
ATA6628/ATA6630 [DATASHEET]
15
9117I–AUTO–10/14