Vbus
tON
IN
/FLAG
/DIR
/EN
Transciever
NCP374
Battery output
Transciever
Downstream Vbu s connection
Figure 5. FLAG Status in Vbus Mode
Logic Inputs
To enable Charge operation (Charge Mode), the DIR pin
shall be forced to low and EN to high. A high level on the
DIR pin disconnects IN pin from Vbus pin. DIR does not
overdrive an OVLO or UVLO fault (FLAG status is still
available).
Table 1. TABLE SELECTION OF CHARGE MODES
OVP @ VBUS (+28 V,
DIR
EN
MODE
−28 V, OVLO 5.77 V)
0
0
NA
NA
0
1
Charge
Yes
1
0
VBUS
Yes
1
1
Disable
Yes (out off)
Protection
OCP (IN to VBUS)
NA
NA
Yes
NA
OCP (VBUS to IN)
NA
NA
NA
NA
Negative Voltage and Reverse Current
The device protects the system connected on IN pin from
negative voltage occurring on Vbus pin, down to −28 V.
When a negative voltage occurs, the IN pins are
disconnected from Vbus pins . This negative protection is
available in all modes
Thermal Shutdown Protection
In case of internal overheating, the integrated thermal
shutdown protection allows to open the internal MOSFET
in order to instantaneously decrease the device temperature.
The thermal threshold has been set at 150°C. FLAG is then
tied to low to inform the MCU.
As the thermal hysteresis is 30°C, the MOSFET will be
closed as soon the device temperature falls down to 120°C.
If the fault event is still present, the temperature increase
one more time and engages the thermal shutdown one more
time until fault event disappeared.
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