ST1S14 datasheet(30/46 Pages) STMICROELECTRONICS

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Application information

ST1S14

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DocID17977 Rev 2

Figure 16. Minimum VFB for effective pulse-by-pulse protection over VIN

As a consequence of VIN > 12 V the pulse-by-pulse current protection (in the worst case

scenario which is the minimum VOSET) may not be effective to limit the inductor current to

the peak current limitation over the entire FB range 300 mV < VFB < 1.22 V.

In fact, at higher input voltage,

ΔI

L TON may be higher than

ΔI

L TOFF and so the inductor

current could escalate. The system typically meets Equation 31 at a current level higher

than the nominal value thanks to the voltage drop across stray components.

Figure 17. IL diverging triggers hiccup protection (VIN = 48 V)

In most of the application conditions the pulse-by-pulse current limitation is effective in

limiting the inductor current.

Whenever the current escalates, a second level current protection called “hiccup mode” is

enabled. In case the hiccup current level (6.2 A typ.) is triggered the switching activity is

ST1S14 数据表(PDF) 30 Page - STMicroelectronics