6

4887D–AUTO–12/06

ATA6621

3.13

Modes of Operation

Figure 3-1.

Modes of Operation

3.13.1

Normal Mode

This is the normal transmitting and receiving mode. The voltage regulator is in normal mode and

can source 50 mA. The undervoltage detection is activated. The watchdog needs a trigger signal

from PTRIG or NTRIG to avoid resets at NRES.

3.13.2

Silent Mode

A falling edge at EN while TXD is high switches the IC into Silent Mode. The TXD signal has to

be logic high during the Mode Select window (Figure 3-2 on page 7). For EN and TXD either two

independent outputs can be used, or two outputs from the same microcontroller port; in the sec-

ond case, the mode change is only one command. In Silent Mode, the transmission path is

disabled. Supply current from V

The overall supply current from V

I

Pre-normal Mode

VCC: 5V/50 mA with undervoltage

monitoring

Communication: OFF

a

b

Silent Mode

VCC: 5V

±7%/50 mA

with undervoltage monitoring

Communication: OFF

EN = 1

Go to silent command

EN = 0

TXD = 1

Local wake-up event

c: Bus wake-up event

d: NRES switches to low

e: Wake-up from wake-up switch

b

EN = 1

b

c + d + e

Normal Mode

VCC: 5V

±2%/50 mA

with undervoltage

monitoring

Communication: ON

Unpowered Mode

Sleep Mode

VCC: switched off

Communication: OFF

Go to sleep command

Local wake-up event

EN = 0

TXD = 0

EN = 1

b

c + e

d