Programmable diagnostic delay

L6376

12/18

Typical waveforms for short circuit operation are shown in Figure 5.

If both the ON DELAY and the OFF DELAY pins are grounded the non dissipative over

current protection is inhibited and the outputs in short circuit remain on until the thermal

shutdown switch OFF the whole device. In this case the short circuit condition is not

signalled by the DIAG pin (that continues to signal the under voltage and over temperature

conditions).

9

Programmable diagnostic delay

The current limiting circuits can be requested to perform even in absence of a real fault

condition, for a short period, if the load is of capacitive nature or if it is a filament lamp (that

exhibits a very low resistance during the initial heating phase).

To avoid the forwarding of misleading — i.e. short diagnostic pulses in coincidence with the

intervention of the current limiting circuits when operating on capacitive loads — the

activation of the diagnostic can be delayed with respect to the intervention of one of the

current limiting circuits.

DELAY pin and ground.

10

Reset input

An external reset input R (pin 18) is provided to simultaneously switch OFF all the outputs:

this signal (active low) is in effect an asynchronous reset that keeps the outputs low

independently from the input signals. For example, this reset input can be used by the CPU

to keep the outputs low after a fault condition (signaled by the DIAG pin).