DocID025259 Rev 2

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STEF4S

Typical characteristics

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5.1

Operating modes

5.1.1

Turn-on

When the input voltage is applied and the EN pin is high, the output voltage is supplied with

pin, the total time from the enable signal going high and the output voltage reaching the

nominal value is around 0.6 ms.

5.1.2

Normal operating condition

The STEF4S E-fuse behaves like a mechanical fuse, buffering the circuitry on its output with

the same voltage shown at its input, apart from a small voltage fall due to the MOSFET

5.1.3

Output voltage clamp

Table 5 if the input voltage exceeds the typical thresholds of 3.8 V in the 3.3 V mode and 5.7

V in the 5 V mode.

5.1.4

Current limiting

When an overload event occurs, the current limiting circuit reduces the conductivity of the

power MOSFET, in order to clamp the input current at the pre-programmed value. The

current limit circuit has a foldback characteristic to reduce the power dissipation over the

power MOSFET in short-circuit condition.

5.1.5

Thermal shutdown and auto-retry function

If the device temperature exceeds the thermal shutdown threshold, typically 140 °C, the

thermal shutdown circuitry turns the power MOSFET off and disconnects the load. Once the

die temperature has decreased about 20 °C the device automatically attempts to apply

again the power to the load (auto-retry). This cycle persists until the fault condition is

removed.

5.2

nominal value as shown in Figure 4.

The below Table 6 shows the typical startup time obtained with the industry-standard values

Parameter

Value

None

10

47

100

0.6

2.3

10.8

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