NCP140
www.onsemi.com
11
APPLICATIONS INFORMATION
General
The NCP140 is high performance low dropout regulator
capable of supplying 150 mA and providing very stable
output voltage with or without capacitors. The device is
designed to remain stable with any type of capacitor or even
without input and output capacitor. The NCP140 also offers
low quiescent current and very small packages suitable for
space constrains application. In connection with no
capacitor requirements the regulator is very useful in
wearable application, smartphones and everywhere where is
high power density required.
Input and Output Capacitor Selection
In spite of the NCP140 is designed as capless device
capacitors can be added to improve dynamic behavior such
as fast load transient or PSRR. Recommendation for
selection input and output capacitor is very similar as for
high performance LDO. Low ESR ceramic capacitor is the
most beneficial for improvement load transient and PSRR
but suitable is almost any type of capacitor. The NCP140
remains stable with electrolytic and tantalum capacitor too.
Enable Operation
The NCP140 uses the EN pin to enable/disable its device
and to deactivate/activate the active discharge function.
If the EN pin voltage is <0.4 V the device is guaranteed to
be disabled. The pass transistor is turned−off so that there is
virtually no current flow between the IN and OUT. The
active discharge transistor is active (only A option) so that
the output voltage V
OUT
is pulled to GND through a 100 W
resistor. In the disable state the device consumes as low as
typ. 10 nA from the V
IN
.
If the EN pin voltage >0.9 V the device is guaranteed to
be enabled. The NCP140 regulates the output voltage and
the active discharge transistor is turned−off.
The EN pin has internal pull−down current source with
typ. value of 100 nA which assures that the device is
turned−off when the EN pin is not connected. In the case
where the EN function isn’t required the EN should be tied
directly to IN.
Output Current Limit
Output Current is internally limited within the IC to a
typical 230 mA. The NCP140 will source this amount of
current measured with a voltage drops on the 90% of the
nominal V
OUT
. If the Output Voltage is directly shorted to
ground (V
OUT
= 0 V), the short circuit protection will limit
the output current to approximately 250 mA. The current
limit and short circuit protection will work properly over
whole temperature range and also input voltage range. There
is no limitation for the short circuit duration.
Thermal Shutdown
When the die temperature exceeds the Thermal Shutdown
threshold (T
SD
− 160°C typical), Thermal Shutdown event
is detected and the device is disabled. The IC will remain in
this state until the die temperature decreases below the
Thermal Shutdown Reset threshold (T
SDU
− 140°C typical).
Once the IC temperature falls below the 140°C the LDO is
enabled again. The thermal shutdown feature provides the
protection from a catastrophic device failure due to
accidental overheating. This protection is not intended to be
used as a substitute for proper heat sinking.
Power Dissipation
As power dissipated in the NCP140 increases, it might
become necessary to provide some thermal relief. The
maximum power dissipation supported by the device is
dependent upon board design and layout. Mounting pad
configuration on the PCB, the board material, and the
ambient temperature affect the rate of junction temperature
rise for the part.
The maximum power dissipation the NCP140 can handle
is given by:
P
D(MAX)
+
ƪ
85° C * T
A
ƫ
q
JA
(eq. 1)
The power dissipated by the NCP140 for given
application conditions can be calculated from the following
equation:
P
D
[ V
IN
ǒ
I
GND
@I
OUT
Ǔ
) I
OUT
ǒ
V
IN
* V
OUT
Ǔ
(eq. 2)
