0.0

0.2

0.4

0.6

0.8

1.0

1.2

5

10

15

20

25

30

35

40

45

SHORT CIRCUIT VOLTAGE (v)

SAFE OPERATING AREA

LM22679, LM22679-Q1

www.ti.com

SNVS581L – FEBRUARY 2013 – REVISED NOVEMBER 2014

Device Functional Modes (continued)

(5)

Where:

given application can drive the output voltage to

checked. Equation 6 gives the maximum input voltage, when in this mode, before damage occurs.

(6)

Where:

NOTE

If the input voltage should exceed this value, while in foldback mode, the regulator and/or

the diode may be damaged.

It is important to note that the voltages in these equations are measured at the inductor. Normal trace and wiring

resistance will cause the voltage at the inductor to be higher than that at a remote load. Therefore, even if the

load is shorted with zero volts across its terminals, the inductor will still see a finite voltage. It is this value that

reduced to a value much lower than that required to initiate foldback. This load "hysteresis" is a normal aspect of

any type of current limit foldback associated with voltage regulators.

The safe operating area, when in short circuit mode, is shown in Figure 11. Operating points below and to the

right of the curve represent safe operation.

Figure 11. SOA

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