5

ATA6670-EK [APPLICATION NOTE]

9243B–AUTO–06/15

2.

Typical Application Circuit

microcontroller is not switched off completely.

For this reason the INH output is not used to switch the power supply of the microcontroller on or off via an external voltage

regulator.

In addition, in nearly all applications both LIN transceivers inside the Atmel ATA6670 are supplied together.

If the microcontroller wants to switch the LIN transceivers inside the Atmel ATA6670 into Sleep mode during a Vs

undervoltage situation, the “Go to sleep” command is not successful and a potential deadlock of the module could result.

This scenario and how to avoid it is described in the Application Note “Sleep mode handling of the Atmel ATA6670 Dual LIN

transceiver.”

In this Application Note, Atmel recommends measuring the supply voltage of the LIN transceivers via a voltage divider

connected to the INH2 output and the ADC of the microcontroller. This allows an undervoltage threshold at the ADC to be

defined which covers all Vs undervoltage situations for both transceivers. As a result, at supply voltages below 5V switching

into Sleep mode must be avoided in order to be sure that after the “Go to sleep” Command none of the LIN transceivers is in

Fail- Safe mode instead of Sleep mode. The module's current consumption is not increased in Sleep mode, because the

INH2 output is switched off in Sleep mode, keeping the voltage divider inactive in this mode.

Figure 2-1.

Typical Application Circuit

100nF

560pF

22μF/50V

1

RXD1

EN1

TXD1

RXD2

EN2

WAKE2

TXD2

RXD1

EN1

+5V

TXD1

RXD2

EN2

ADC

VCC

GND

TXD2

VS1

S1

C2

C1

C4

C3

560pF

LIN1

GND1

INH2

VS2

LIN1

GND

VBAT

LIN2

LIN2

GND2

2

3

4

5

Wake

Switch

6

7

14

13

12

11

10

9

8

R1

4.7kΩ

R6

R7

2.7kΩ

R2

4.7kΩ

+

R5

10kΩ

R3

1kΩ

D3

LL4148

R4

1kΩ

D2

LL4148

D1

LL4148

R8

Atmel

ATA6670

(DFN14)

Micro-

controller