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NCP370MUAITXG

P1-P3P4-P6P7-P9P10-P11
NCP370
http://onsemi.com
7
Figure 4. FLAG status in Reverse Mode
V
in
REV
DIR
FLAG
V
out
Battery
Output
micro−controllermicro−controller
External Accessory ID = 1
ton
rev
Table 1. FLAG TABLE
DIR REV IN OUT
FLAG
Status
Pass Element (Dual NMOS FET)
0 0 1.5 < V
in
< UVLO or
V
in
> OVLO
oo
Hiz Low Open
0 0 UVLO < V
in
< OVLO
oo
= V
in
−DROPOUT High Close
0 1 1.5 < V
in
< UVLO or
V
in
> OVLO
Hiz Low Open
0 1 UVLO < V
in
< OVLO = V
in
−DROPOUT High Close
1 0 = V
out
−DROPOUT V
out
> 2.5 V High Close
1 1 1.5 < V
in
< UVLO or
V
in
> OVLO
Hiz Low Open
1 1 UVLO < V
in
< OVLO Hiz High Open
DIR Input
To enable Direct Charge operation (Direct Mode), the
DIR pin shall be forced to low and REV to high. A high level
on the DIR pin disconnects OUT pin from IN pin. DIR does
not over−ride an OVLO or UVLO fault (FLAG status is still
available).
Table 2. TABLE SELECTION OF CHARGE MODES
DIR REV Mode
0 0 Enhance Mode
0 1 Direct Mode
1 0 Reverse Mode
1 1 Disable Mode
NCP370
http://onsemi.com
8
Negative Voltage and Reverse Current.
The device protects the downstream side from negative
voltage occurring on the IN pin, down to −28 V. When a
negative voltage occurs, the output is disconnected from the
IN pins.
Reverse Mode
In Reverse Mode, an external accessory plugged into the
bottom connector can be powered by the internal battery of
the system.
To access to the reverse mode, DIR pin must be tied high
(> 1.2) and REV must be tied high to low (< 0.55 V).
In this case, the core of the NCP370 will be supplied by
the battery, with a 2.5 V minimum voltage and 5.5 V
maximum voltage.
In this reverse state, both OCP and thermal modes are
available.
Overcurrent Protection (OCP)
This device integrates the reverse over current protection
function, from battery to external accessory.
That means the current across the internal NMOS is
limited when the value, set by the external R
limit
resistor,
exceeds I
OCP
.
An internal resistor is placed in series with the I
lim
pin
allowing a maximum OCP value when I
lim
pin is directly
connected to GND.
By adding external resistors in series from I
lim
to GND,
the OCP value is lowered. The typical overcurrent threshold
can be calculated with the following formula;
R
ilim
(kW) = (60 / I
OCP
) − 36
Figure 5. Reverse Mode Overcurrent Protection vs.
ILIM Resistance, R
LIMIT
During an overcurrent event, the N−MOSFETs turn off
and FLAG output goes low, allowing the micro−controller
to process the fault event and then disable reverse charge
path.
NCP370
http://onsemi.com
9
At power up (accessory is plugged on input pins), the
current is limited up to I
lim
for 1.2 ms (typical), to allow
capacitor charge and limit inrush current. If the I
lim
threshold is exceeded over 1.2 ms, the device enters
OCP burst mode until the overcurrent event disappears.
After 1 ms following the plug in of the accessory, the OCP
mode is engaged. See Figure 6.
tstart
REV
Figure 6. Overcurrent Protection Sequence
V
in
REV
DIR
FLAG
V
out
I
lim
Drive Current in Accessory
ID
I
REV
Accessory ID
Detection
t
REG
t
RRD
ton
REV
Thermal Shutdown Protection
In case of internal overheating, the integrated thermal
shutdown protection turns off the internal MOSFETs in
order to instantaneously decrease the device temperature.
The thermal threshold has been set at 150°C FLAG then
goes low to inform the MCU.
As the thermal hysteresis is 30°C, the MOSFETs will turn
on as soon the device temperature falls below 120°C.
If the fault event is still present, the temperature increase
engages the thermal shutdown again until the fault event
disappears.
PCB Recommendations
Since the NCP370 integrates the 1. 3A N−MOSFETs,
PCB rules must be respected to properly evacuate the heat
out of the silicon.
From an applications standpoint, PAD1 of the NCP370
package should be connected to an isolated PCB area to
increase the heat transfer if necessary.
In any case, PAD1 should be not connected to any other
potential or GND other than the isolated extra copper
surface.
To assist in the design of the transfer plane connected to
PAD1, Figure 7 shows the copper area required with respect
to R
q
JA
.
P1-P3P4-P6P7-P9P10-P11

NCP370MUAITXG

Mfr. #:
Buy NCP370MUAITXG
Manufacturer:
ON Semiconductor
Description:
Switching Controllers POS-NEG OVP W/OCP
Lifecycle:
New from this manufacturer.
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