STCC2540 Datasheet, PDF (16/32 Pages) STMicroelectronics – USB charging controller with integrated power switch

Application information
STCC2540
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
I_OS(typ)=
48000
-_R-----_I--_L---_I-_M----
(
m
A,
kΩ)
Equation 2
I_OS(min)=
48000
R^-----_I^--_L^---_I^-_M^{----1---.-0---3---7-}
(
m
A,
kΩ)
Equation 3
I_OS(max)=
48000
R^-----_I^--_L^---_I^-_M^{----0---.-9---6---2-}
(
m
A,
kΩ)
Equation 2 and Equation 3 allow the minimum and maximum variation to be estimated
around the typical value predefined by the external resistor, R_ILIM, 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).
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