L6375

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Figure 1. Switching Waveforms

INPUT SECTION

An Single ended Input TTL/CMOS compatible with wide voltage range and high noise immunity (thanks to a

built in hysteresis) is available.

OVER TEMPERATURE PROTECTION (OVT)

An on-chip Over Temperature Protection provides an excellent protection of the device in extreme conditions.

Whenever the temperature - measured on a central portion of the chip- exceeds Tmax=150 C (typical value)

the device is shut off, and the DIAG2 output goes LOW. Normal operation is resumed as the chip temperature

(normally after few seconds) falls below Tmax-Thys= 130 C (typical value). The hysteresis avoid thats an inter-

mittent behaviour take place.

UNDER VOLTAGE PROTECTION (UV)

The supply voltage is expected to range from 8 to 35 V. In this range the device operates correctly. To avoid

any misfunctioning the supply voltage is continuously monitored to provide an under voltage protection. As Vs

falls below Vsth-Vshys (typically 7.5 V, see fig.1) the output power MOS is switched off and DIAG1 and DIAG2

(see Diagnostic truth table). Normal operation is resumed as soon as Vs exceeds Vsth. The hysteretic behaviour

prevents intermittent operation at low supply voltage.

OVER CURRENT OPERATION

In order to implement a short circuit protection the output power MOS is driven in linear mode to limit the output

current to the Isc (1.1A typical value). This condition (current limited to the Isc value) lasts for a Ton time interval,

that can be set by means of a capacitor (Cdon) connected to the ON DELAY pin according to the following for-

mula:

Ton = 1.28 msec/pF

for

50pF<Cdon< 2nF

After the Ton interval has expired the output power MOS is switched off for the Toff time interval with:

Toff = 64 ·Ton.

When also the Toff interval has expired, the out-put power MOS is switched ON. At this point in time two con-

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Vout

D94IN127A

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