21

4964B–AUTO–07/07

ATA6842

7.10

Warning Lamp

The ATA6842 features a watchdog-controlled output, WLN, which can be used to switch a warn-

ing lamp. Depending on the warning lamp polarity pin (WLP), the warning lamp output is

switched either to low level or to open drain, when a Warning lamp request (that is, On in Table

7-9 on page 25, column WLN) occurs or the corresponding SPI command is transmitted. For the

behavior of WLN output refer to Table 7-4. The driver is short-circuit proof and will switch off

after a debounce time. An activation of the warning lamp due to Warning lamp request is sup-

pressed for 768

× t

phase (exception: lower thermal threshold level reached). The driver also has a current sensor

and a voltage monitoring which sets SPI flags if the corresponding thresholds are reached.

Warnlamp is open drain during suppression time after wake-up. If the oscillator does not work

4 ms after start up, the internal oscillator watchdog timeout is reached and the warning lamp is

switched on.

7.11

Reset

When V12, VI, V5 or V5A are beyond their corresponding normal operating range or the temper-

ature has reached the upper temperature level, a reset is indicated at the outputs RESN

(640

× t

mand. Via input RSTN, the SPI Interface and the watchdog can be reset by an external signal

(see Table 7-9 on page 25).

Table 7-4.

Warning Lamp Status Table

Warnlamp

Request

TWLN (SPI)

Overcurrent

in WLN

Occurred

Thermal

Threshold #1

Reached

Suppression Time

After

Wake-up/VI Reset

V12

WLP

WLN

Yes

x

x

No

t < 768

× t

WD

> 4.8V

Low

Open drain

Yes

x

x

No

t > 768

× t

WD

> 4.8V

Low

Low

Yes

x

No

Yes

t < 768

× t

WD

> 4.8V

Low

Open drain

Yes

x

No

Yes

t > 768

× t

WD

> 4.8V

Low

Low

No

High

x

No

t > 768

× t

WD

> 4.8V

Low

Low

No

Low

x

No

x

> 4.8V

Low

Open drain

Yes

x

Yes

Yes

x

> 4.8V

Low

Open drain

Yes

x

x

No

x

> 4.8V

High

Open drain

Yes

x

No

Yes

x

> 4.8V

High

Open drain

No

High

x

No

t > 768

× t

WD

> 4.8V

High

Low

No

Low

x

No

x

> 4.8V

High

Open drain

No

High

Yes

Yes

x

> 4.8V

High

Open drain

No

High

No

Yes

x

> 4.8V

x

Open drain

x

x

x

x

x

< 4.8V

x

Open drain