VND10B

6/13

Figure 7. Switching Time Waveforms

FUNCTIONAL DESCRIPTION

The device has a common diagnostic output for

both channels which indicates open load in on-

state, open load in off-state, over temperature

From the falling edge of the input signal, the status

output, initially low to signal a fault condition

(overtemperature or open load on-state), will go

back to a high state with a different delay in case

discriminate the nature of the detected fault. To

protect the device against short circuit and over

current condition, the thermal protection turns the

integrated Power MOS off at a minimum junction

temperature of 140 °C. When this temperature

returns to 125 °C the switch is automatically turned

on again. In short circuit the protection reacts with

virtually no delay, the sensor (one for each

channel) being located inside each of the two

Power MOS areas. This positioning allows the

device to operate with one channel in automatic

thermal cycling and the other one on a normal

load. An internal function of the devices ensures

the fast demagnetization of inductive loads with a

allows to greatly reduces the power dissipation

according to the formula:

where f = switching frequency and

The maximum inductance which causes the chip

temperature to reach the shut-down temperature

in a specified thermal environment is a function of

according to the above formula. In this device if the

16V, both channel will switch off.

PROTECTING THE DEVICE AGAINST

REVERSE BATTERY

The simplest way to protect the device against a

continuous reverse battery voltage (-26V) is to

insert a Schottky diode between pin 1(GND) and

ground, as shown in the typical application circuit

(Figure 9).

The consequences of the voltage drop across this

diode are as follows:

– If the input is pulled to power GND, a negative

respect to power GND).

– The undervoltage shutdown level is increased

If there is no need for the control unit to handle

external analog signals referred to the power

GND, the best approach is to connect the

reference potential of the control unit to node [1]

(see application circuit in Figure 10), which

becomes the common signal GND for the whole

This solution allows the use of a standard diode.