l6390 STMicroelectronics, l6390 Datasheet - Page 15

• Manufacturer Part Number: l6390
• Description: High-voltage High And Low Side Driver
• Manufacturer: STMicroelectronics

L6390
Smart shut down function
In common over-current protection architectures the comparator output is usually connected
to the SD input and an RC network is connected to this SD/OD line in order to provide a
mono-stable circuit, which implements a protection time that follows the fault condition.
Differently from the common fault detection systems, L6390 Smart Shut Down architecture
allows to immediately turn-off the output gate driver in case of fault, by minimizing the
propagation delay between the fault detection event and the actual outputs switch-off. In fact
the time delay between the fault and outputs disabling is not dependent on the RC value of
the external network connected to the pin but, thanks to the Smart Shut Down logic, it has a
preferential path in the IC immediately turning-OFF the driver outputs and latching the turn-
ON of the open drain switch until the SD signal has reached the input pin lower threshold.
After the SD signal goes below the lower threshold, the open drain is switched off. The
Smart SD system provides the possibility to increase the time constant of the external RC
network (that is the disable time after the fault event) up to very large values without
compromising the intervention time of the protection.
An external signal provided to the SD pin is not latched and can be used as control signal in
order to perform, for instance, PWM chopping through this pin. In fact when a PWM signal is
applied to the SD input and the logic inputs of the gate driver are stable, the outputs switch
from the low level to the state defined by the logic inputs and vice versa.
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