AUIPS7121R

Truth Table

Op. Conditions

Input

Output

Ifb pin voltage

Normal mode

H

L

0V

Normal mode

L

H

I load x Rfb / Ratio

Open load

H

L

0V

Open load

L

H

Ifb leakage x Rifb

Short circuit to GND

H

L

0V

Short circuit to GND

L

L

I fault x Rifb(latched)

Over temperature

H

L

0V

Over temperature

L

L

I fault x Rifb (latched)

Operating voltage

Maximum Vcc voltage : this is the maximum voltage before the breakdown of the IC process.

Operating voltage : This is the Vcc range in which the functionality of the part is guaranteed. The AEC-Q100 qualification

is run at the maximum operating voltage specified in the datasheet.

Reverse battery

During the reverse battery the Mosfet is turned on if the input pin is powered with a diode in parallel of the input transistor.

Power dissipation in the IPS : P = Rdson rev * I load² + Vcc² / 250 ( internal input resistor ).

If the power dissipation is too high in Rifb, a diode in serial can be added to block the current.

Active clamp

The purpose of the active clamp is to limit the voltage across the MOSFET to a value below the body diode break down

voltage to reduce the amount of stress on the device during switching.

The temperature increase during active clamp can be estimated as follows:

)

t

(

Z

P

CLAMP

TH

CL

Tj

⋅

=

∆

Where:

)

t

(

Z

CLAMP

TH

data sheets.

CLavg

CL

CL

I

V

P

⋅

=

: Power dissipation during active clamp

65V

V

2

I

I

CL

: Average current during active clamp

dt

di

I

t

CL

: Active clamp duration

L

V

V

dt

di

CL

=

: Demagnetization current

Figure 9 gives the maximum inductance versus the load current in the worst case : the part switches off after an over

temperature detection. If the load inductance exceeds the curve, a free wheeling diode is required.

Over-current protection

The threshold of the over-current protection is set in order to guarantee that the device is able to turn on a load with an

inrush current lower than the minimum of Isd. Nevertheless for high current and high temperature the device may switch

off for a lower current due to the over-temperature protection. This behavior is shown in Figure 11.

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