NCP511, NCV511
www.onsemi.com
8
APPLICATIONS INFORMATION
A typical application circuit for the NCP511 series is
shown in Figure 16.
Input Decoupling (C1)
A 1.0 F capacitor either ceramic or tantalum is
recommended and should be connected close to the NCP511
package. Higher values and lower ESR will improve the
overall line transient response.
Output Decoupling (C2)
The NCP511 is a stable Regulator and does not require any
specific Equivalent Series Resistance (ESR) or a minimum
output current. Capacitors exhibiting ESRs ranging from a
few m up to 3.0 can thus safely be used. The minimum
decoupling value is 1.0 F and can be augmented to fulfill
stringent load transient requirements. The regulator accepts
ceramic chip capacitors as well as tantalum devices. Larger
values improve noise rejection and load regulation transient
response.
Enable Operation
The enable pin will turn on or off the regulator. These
limits of threshold are covered in the electrical specification
section of this data sheet. If the enable is not used then the
pin should be connected to V
in
.
Hints
Please be sure the V
in
and GND lines are sufficiently wide.
When the impedance of these lines is high, there is a chance
to pick up noise or cause the regulator to malfunction.
Set external components, especially the output capacitor,
as close as possible to the circuit, and make leads a short as
possible.
Thermal
As power across the NCP511 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 also the ambient
temperature effect the rate of temperature rise for the part.
This is stating that when the NCP511 has good thermal
conductivity through the PCB, the junction temperature will
be relatively low with high power dissipation applications.
The maximum dissipation the package can handle is
given by:
PD +
T
J(max)
*T
A
R
JA
If junction temperature is not allowed above the
maximum 125°C, then the NCP511 can dissipate up to
400 mW @ 25°C.
The power dissipated by the NCP511 can be calculated
from the following equation:
P
tot
+
ƪ
V
in
*I
gnd
(I
out
)
ƫ
)
[
V
in
* V
out
]
*I
out
or
V
inMAX
+
P
tot
)
V
out
*
I
out
I
gnd
) I
out
If a 150 mA output current is needed then the ground
current from the data sheet is 40 A. For an NCP511SN30T1
(3.0 V), the maximum input voltage will then be 5.6 V.
Figure 16. Typical Application Circuit
V
out
Battery or
Unregulated
Voltage
C1
C2
OFF
ON
1
2
3
5
4
+
+
1
10
0.1
0.01
I
O
, OUTPUT CURRENT (mA)
Figure 17. Output Capacitor vs. Output Current
ESR, OUTPUT CAPACITOR ()
015
25 50 75 100 125
C
out
= 1 F to 10 F
T
A
= 25°C to 125°C
V
in
= up to 6.0 V
UNSTABLE
STABLE
