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L6376

0.5 A high-side driver quad intelligent power switch

STMicroelectronics 

Overtemperature protection (OVT)

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Overtemperature protection (OVT)

L6376

If the chip temperature exceeds Θlim (measured in a central position in the chip) the chip

deactivates itself.

The following actions are taken:

● all the output stages are switched off;

● the signal DIAG is activated (active low).

Normal operation is resumed as soon as (typically after some seconds) the chip

temperature monitored goes back below Θlim-ΘH.

The different thresholds with hysteretic behavior assure that no intermittent conditions can

be generated.

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Undervoltage protection (UV)

The supply voltage is expected to range from 9.5 V to 35 V, even if its reference value is

considered to be 24 V. In this range the device operates correctly. Below 9.5 V the overall

system has to be considered not reliable. Consequently the supply voltage is monitored

continuously and a signal, called UV, is internally generated and used.

The signal is “on” as long as the supply voltage does not reach the upper internal threshold

of the Vs comparator Vsth. The UV signal disappears above Vsth.

Once the UV signal has been removed, the supply voltage must decrease below the lower

threshold (i.e. Vsth-Vshys) before it is turned on again.

The hysteresis Vshys is provided to prevent intermittent operation of the device at low supply

voltages that may have a superimposed ripple around the average value.

The UV signal switches off the outputs, but has no effect on the creation of the reference

voltages for the internal comparators, nor on the continuous operation of the charge-pump

circuits.

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Diagnostic logic

The situations that are monitored and signalled with the DIAG output pin are:

● current limit (OVC) in action; there are 4 individual current limiting circuits, one per each

output; they limit the current that can be sunk from each output, to a typical value of

800 mA, equal for all of them;

● under voltage (UV);

● over temperature protection (OVT).

The diagnostic signal is transmitted via an open drain output (for ease of wired-or

connection of several such signals) and a low level represents the presence of at least one

of the monitored conditions, mentioned above.

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