NCP370
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5
Characteristics UnitMaxTypMinConditionsSymbols
TIMINGS
DIRECT MODE
Start Up Delay t
on
From V
in
> UVLO to V
out
w 0.3 V 20 30 40 ms
FLAG Going Up Delay t
start
From V
out
> 0.3 V to FLAG = 1.2 V 20 30 40 ms
Turn Off Delay t
off
From V
in
> OVLO to V
out
v 0.3 V
V
in
Increasing from 5 V to 8 V at 3 V/ms
1.5 5.0
ms
Alert Delay t
stop
From V
in
> OVLO to FLAG v 0.4 V See Figure
3 and 9 V
in
Increasing from 5 V to 8 V at 3 V/ms
1.5
ms
Disable Time t
dis
REV = 1.2 V, From DIR = 0.4 V to 1.2 V to V
out
v 0.3 V
2.5
ms
REVERSE MODE
Reverse Start Up Delay ton
REV
V
out
w 2.5 V, From REV = 1.2 to 0.55 to
V
in
w 0.3 V, Reverse Mode
0.6 1.2 1.8 ms
Reverse FLAG Going Up Delay tstart
REV
From V
in
w 0.3 V FLAG = 1.2 V, Reverse Mode 0.6 1.2 1.8 ms
Rearming Reverse Delay t
RRD
V
out
> 2.5 V, R
in
= 1 W, Reverse Mode
20 30 40 ms
Over Current Regulation Time t
REG
V
out
> 2.6, V
in
> 0.3 V, Reverse Mode 0.5 1.2 1.8 ms
OCP Delay Time t
OCP
From I
reverse
> I
lim
, 1 A/1 ms
5
ms
Reverse Disable Time t
REVDIS
From REV = 0.55 V to 1.2 V, to V
in
< 0.3 V.
V
out
= 5 V
200
ms
NOTE: Electrical parameters are guaranteed by correlation across the full range of temperature.
TYPICAL OPERATING CHARACTERISTICS
Operation
The NCP370 provides overvoltage protection for positive
and negative voltages, up to 28 V or down to −28 V on
IN pins. At powerup, with DIR pin = low, REV = high, the
output rises 30 ms after the input rises above the UVLO. The
NCP370 provides a FLAG output, which alerts the system
that a fault has occurred. The FLAG signal rises 30 ms after
the output signal rises.
A Reverse Mode is available when an accessory is
connected on IN pins and the internal battery is applied on
the OUT pin, allowing the accessory to be powered. In this
mode, no supply must be connected on IN pins and REV pin
must be tied to low level. The NCP370 provides overcurrent
protection for the battery from current faults in the
accessory.
Undervoltage Lockout (UVLO)
To ensure proper turn−on operation from AC/DC (or Wall
adapter charging) under any conditions, the device has a
built−in undervoltage lock out (UVLO) circuit. During
positive going slope on V
in
, the output remains disconnected
from input until V
in
voltage is above UVLO. The FLAG
output will be low as long as V
in
has not reached UVLO
threshold. This circuit has a 60 mV hysteresis to provide
noise immunity to transient conditions.
In Reverse Mode (REV pin v 0.55 V, DIR w 1.2 V),
UVLO and OVLO comparators are inactivated.
Overvoltage Lockout (OVLO)
To protect connected systems on Vout pin from
overvoltage, the device has a built−in overvoltage lock out
(OVLO) circuit. During overvoltage condition, the output is
disabled as long as the input voltage exceeds OVLO.
Additional OVLO thresholds can be manufactured
(Please contact your ON Semiconductor representative for
availability).
FLAG output will be low since V
in
is higher than OVLO.
This circuit has a 80 mV hysteresis to provide noise
immunity to transient conditions.
Oversystem Voltage Lockout (OVLO
00
)
A second overvoltage comparator is available for
supplying the sytem (output) by the Wall Adaptor (input) by
setting DIR = low and REV = low. The R
DS(on)
will be
higher during this mode allowing to handle few 10 mA
.
This additional comparator allows to put higher input
voltage (OVLO = 8.27 V typical) on the NCP370 during test
production sequence (I.E: One Time Programming of the
cell phone, PDA). This parameter is 25°C guaranteed only.
FLAG Output
The NCP370 provides a FLAG output which alerts that a
fault has occurred. As soon as a fault state is detected by the
NCP370 (see Figure 3), the FLAG pin output goes low,
alerting the micro−controller to take appropriate action.
