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AS1112

Datasheet - D e t a i l e d D e s c r i p t i o n

Overtemperature Error/Warning Flags

The AS1112 provides a overtemperature circuit to indicate that the device is in an overtemperature condition. If the device junction temperature

(TJ) exceeds the threshold temperature (150°C typ), the overtemperature circuit trips and pulls XERR to ground. The overtemperature flag sta-

tus can be read out from the AS1112 status register.

To prevent an overtemperature condition the AS1112 offers an temperature warning flag at 125°C typical. This flag can be used to take precau-

tions (e.g. start an external cooling) against a overtemperature condition.

Open LED Detection

The AS1112 integrated open LED detection circuit reports an error if any of the 16 LEDs is open or disconnected from the circuit. The open LED

detection circuit trips when the error detection is activated (see Table 8) and the voltage at OUTn is less than VLOD.

Note:

The voltage at each OUTn is sampled 1 s after being switched on. Please refer to Figure 10.

The open LED detection circuit also pulls XERR to GND when tripped. The open LED status of each channel can also be read out from the

AS1112 status information data (SID) during a greyscale data input cycle.

Shorted LED Detection

The AS1112 integrated shorted LED detection circuit detects if any of the 16 LEDs is short-circuited. The shorted LED detection circuit trips when

the error detection is activated and the voltage at OUTn is higher than VLSD.

Note:

The voltage at each OUTn is sampled 1 s after being switched on. Please refer to Figure 10.

The shorted LED status of each channel can only be read out from the AS1112 status information data (SID) during a greyscale data input cycle.

Table 8. XERR Truth Table

Error Condition

Error Information

Selected Mode

Status

Temp.

OUTn Voltage

Thermal

Error Flag

Thermal

Warning

Flag

Open LED

Detect

Short

LED

Detect

OEN Mode XERR

O

p

e

n

TJ < TTEF

OUTn > VLOD

0

Don't Care

0

Don't Care

0

0

1

normal

OUTn < VLOD

0

Don't Care

1

Don't Care

0

0

0

open error

TJ > TTEF

OUTn > VLOD

1

Don't Care

0

Don't Care

0

0

0

temp. error

OUTn < VLOD

1

Don't Care

1

Don't Care

0

0

0

open & temp.

error

T

e

m

p

TJ > TTEF

Don't Care

0

Don't Care

Don't Care

Don't Care

1

0

1

normal

TJ < TTEF

Don't Care

1

Don't Care

Don't Care

Don't Care

1

0

0

temp error

TJ > TTWF

Don't Care

Don't Care

0

Don't Care

Don't Care

1

1

1

normal

TJ < TTWF

Don't Care

Don't Care

1

Don't Care

Don't Care

1

1

0

temp. warn