L5973AD

8/14

Figure 8. Driving Circuitry

3.7 INHIBIT FUNCTION

The inhibit feature allows to put in stand-by mode the device. With INH pin higher than 2.2V the device is dis-

abled and the power consumption is reduced to less than 100

µA. With INH pin lower than 0.8V, the device is

enabled. If the INH pin is left floating, an internal pull up ensures that the voltage at the pin reaches the inhibit

threshold and the device is disabled. The pin is also Vcc compatible.

3.8 THERMAL SHUTDOWN

The shutdown block generates a signal that turns off the power stage if the temperature of the chip goes higher

than a fixed internal threshold (150°C). The sensing element of the chip is very close to the PDMOS area, so

ensuring an accurate and fast temperature detection. An hysteresis of approximately 20°C avoids that the de-

vices turns on and off continuously

4

ADDITIONAL FEATURES AND PROTECTIONS

4.1 FEEDBACK DISCONNECTION

In case of feedback disconnection, the duty cycle increases versus the maximum allowed value, bringing the

output voltage close to the input supply. This condition could destroy the load.

To avoid this dangerous condition, the device is turned off if the feedback pin remains floating.

4.2 OUTPUT OVERVOLTAGE PROTECTION

The overvoltage protection, OVP, is realized by using an internal comparator, which input is connected to the

feedback, that turns off the power stage when the OVP threshold is reached. This threshold is typically 30%

higher than the feedback voltage.

When a voltage divider is requested for adjusting the output voltage (see test application circuit), the OVP inter-

vention will be set at:

feedback pin and ground.

Vgsmax

GATE

STOP

DRIVE

DRAIN

OFF

ON

PDMOS

VOUT

DRAIN

VCC

C

ESR

D00IN1133

ON/OFF

CONTROL

CLAMP

L

V

OVP

1.3

R

1

R

2

+

R

2

-------------------- V

FB

⋅⋅

=