In OS comparator mode, the OS output behaves like a thermostat. It becomes active

when the Temp exceeds the Tth(ots), and is reset when the Temp drops below the Thys.

Reading the device registers or putting the device into shutdown does not change the

state of the OS output. The OS output in this case can be used to control cooling fans or

thermal switches.

 

In OS interrupt mode, the OS output is used for thermal interruption. When the device is

powered-up, the OS output is first activated only when the Temp exceeds the Tth(ots); then

it remains active indefinitely until being reset by a read of any register. Once the OS output

has been activated by crossing Tth(ots) and then reset, it can be activated again only when

the Temp drops below the Thys; then again, it remains active indefinitely until being reset

by a read of any register. The OS interrupt operation would be continued in this sequence:

Tth(ots) trip, Reset, Thys trip, Reset, Tth(ots) trip, Reset, Thys trip, Reset, etc. Putting the

device into the shutdown mode by setting the bit 0 of the configuration register also resets

the OS output.

 

In both cases, comparator mode and interrupt mode, the OS output is activated only if a

number of consecutive faults, defined by the device fault queue, has been met. The fault

queue is programmable and stored in the two bits, B3 and B4, of the Configuration

register. Also, the OS output active state is selectable as HIGH or LOW by setting

accordingly the configuration register bit B2.

 

At power-up, the device is put into normal operation mode, the Tth(ots) is set to 80 C, the

Thys is set to 75 C, the OS active state is selected LOW and the fault queue is equal to 1.

The temp reading data is not available until the first conversion is completed in about

100 ms.

 

The OS response to the temperature is illustrated in Figure 6.

 

 

 

 

Tth(ots)

 

 

 

Thys

 

 

 

 

OS reset

 

OS active

 

 

 

 

OS reset

reading temperature limits

 

 

 

 

OS output in comparator mode

 

 

 

(1)

(1)

(1)

 

OS active

 

 

OS output in interrupt mode

 

 

 

002aae334

 

(1) OS is reset by either reading register or putting the device in shutdown mode. It is assumed that

the fault queue is met at each Tth(ots) and Thys crossing point.

Fig 6.

OS response to temperature

 

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