FPF2701MPX datasheet(13/21 Pages) ONSEMI

13 / 21 page

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FPF2700 / FPF2701 / FPF2702

• Rev. 1.0.3

Table 1.

RSET Selection Guide

RSET

(k)

Current Limit [A]

Tol. (%)

Min.

Typ.

Max.

111

2.00

2.50

3.00

124

1.79

2.24

2.69

147

1.51

1.89

2.27

182

1.22

1.52

1.83

220

1.01

1.26

1.51

274

0.81

1.01

1.22

374

0.59

0.74

0.89

549

0.40

0.51

0.61

Figure 36. ILIM vs. RSET

Under-Voltage Lockout (UVLO)

The under-voltage lockout feature turns off the switch if

the input voltage drops below the under-voltage lockout

threshold. With the ON pin active (ON pin pulled LOW),

the input voltage rising above the under-voltage lockout

threshold causes a controlled turn-on of the switch

(Figure 37). The UVLO threshold voltage is set internally

at 2.5 V for VIN rising. The under-voltage lockout

threshold has a 0.1 V hysteresis.

VIN

FLAGB

Device Wake up

UVLO Threshold

VOUT

10%VOUT

90%VOUT

Rise time

Figure 37. Under-Voltage Lockout Performance

Power Good

FPF270X has a power good feature. The PGOOD pin is

an open-drain MOSFET that asserts HIGH when the

output voltage reaches 90% of the input voltage (Figure

26). A typical 3% PGOOD hysteresis is added to

PGOOD to prevent PGOOD from chattering as VOUT

falls near the PGOOD threshold voltage.

The PGOOD pin requires an external pull-up resistor

connected to an external voltage source compatible with

input levels of other chips connected to this pin.

PGOOD is kept LOW when the device is inactive. To

save current in the OFF state, the pull-up resistor of the

PGOOD pin can be connected to the output voltage

when there is no battery, provided that compatibility with

the input levels of other devices connected to PGOOD

is observed. A typical value of 100

kΩ is recommended

for the pull up resistor. When the power-good feature is

not used in the application, the PGOOD pin can be

connected to GND.

Thermal Shutdown

Thermal shutdown protects the die from internally or

externally generated excessive temperatures. During an

over-temperature

condition;

the

temperature

increases above 140°C, FLAGB is activated and the

switch is turned off.

When the die cools down sufficiently (die temperature

drops

below

the

threshold

level),

the

switch

automatically turns on again. To avoid unwanted

thermal oscillations, a 30°C (typical) thermal hysteresis

is implemented between thermal shutdown entry and

exit temperatures. Proper board layout is required to

prevent premature thermal shutdown (see Figure 38 for

thermal shutdown behavior on FPF2702)

VIN

FLAGB

Thermal Cycling

IOUT

Over

current

condition

ILIM

VOUT

Device cools off

Figure 38. FPF2702 Thermal Shutdown Behavior

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

100

200

300

400

500

600

RSET (k)

FPF2701MPX Datasheet(PDF) 13 Page - ON Semiconductor

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