STCC2540 datasheet(16/32 Pages) STMICROELECTRONICS

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Application information

STCC2540

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DocID024711 Rev 6

FAULT functionality

The FAULT open drain active low output is asserted during overcurrent or overtemperature

conditions. Signal is asserted until the fault is removed.

For overcurrent conditions, the STCC2540 device is designed to eliminate false FAULT

reporting, by using an internal deglitch delay (9 ms typ.).

In the case of overtemperature, there is no deglitch delay and the FAULT signal is asserted

immediately. It is deasserted with a delay after the device has cooled down and begins to

turn on. This unidirectional glitch immunity prevents FAULT oscillation during an

overtemperature event.

In the case of a fault condition, the host may disable the power switch by toggling EN input

to logic low.

Current limit programming

The current limit can be adjusted by an external resistor in the range 500 mA to 2.8 A

(max.). The programming resistor may be calculated using these equations:

Equation 1

Equation 2

Equation 3

Equation 2 and Equation 3 allow the minimum and maximum variation to be estimated

around the typical value predefined by the external resistor, RILIM, given in Equation 1.

Equation 2 and Equation 3 do not take into consideration external resistor variations.

5.7

Enable input

The enable input (EN, active high) serves to turn off the STCC2540 device and achieve the

lowest current consumption.

The behavior of the STCC2540 in disabled state (EN = 0) is following:

•

Power switch, USB data switch and emulation profiles are turned off

•

Output discharge circuit is turned on

•

The FAULT and CHARGING flags are cleared (the FAULT and CHARGING outputs are

set to Hi-Z mode).

IOS typ

()

48000

RILIM

----------------

mA k

()

IOS min

()

48000

RILIM

1.037

--------------------------

mA k

()

IOS max

()

48000

RILIM

0.962

--------------------------

mA k

()

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