NCP502, NCV502
www.onsemi.com
6
DEFINITIONS
Load Regulation
The change in output voltage for a change in output
current at a constant temperature.
Dropout Voltage
The input/output differential at which the regulator output
no longer maintains regulation against further reductions in
input voltage. Measured when the output drops 3.0% below
its nominal. The junction temperature, load current, and
minimum input supply requirements affect the dropout level.
Maximum Power Dissipation
The maximum total dissipation for which the regulator
will operate within its specifications.
Quiescent Current
The quiescent current is the current which flows through
the ground when the LDO operates without a load on its
output: internal IC operation, bias, etc. When the LDO
becomes loaded, this term is called the Ground current. It is
actually the difference between the input current (measured
through the LDO input pin) and the output current.
Line Regulation
The change in output voltage for a change in input voltage.
The measurement is made under conditions of low
dissipation or by using pulse technique such that the average
chip temperature is not significantly affected.
Line Transient Response
Typical over and undershoot response when input voltage
is excited with a given slope.
Thermal Protection
Internal thermal shutdown circuitry is provided to protect
the integrated circuit in the event that the maximum junction
temperature is exceeded. When activated at typically 160
°C,
the regulator turns off. This feature is provided to prevent
failures from accidental overheating.
Maximum Package Power Dissipation
The maximum power package dissipation is the power
dissipation level at which the junction temperature reaches
its maximum operating value, i.e. 125
°C. Depending on the
ambient power dissipation and thus the maximum available
output current.
APPLICATIONS INFORMATION
A typical application circuit for the NCP502 series is
shown in Figure 1, front page.
Input Decoupling (C1)
A 1.0 F capacitor either ceramic or tantalum is
recommended and should be connected close to the NCP502
package. Higher values and lower ESR will improve the
overall line transient response. If large line or load transients
are not expected, then it is possible to operate the regulator
without the use of a capacitor.
TDK capacitor: C2012X5R1C105K, or C1608X5R1A105K
Output Decoupling (C2)
The NCP502 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 5.0 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.
TDK capacitor: C2012X5R1C105K, C1608X5R1A105K,
or C3216X7R1C105K
Enable Operation
The enable pin will turn on the regulator when pulled high
and turn off the regulator when pulled low. 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 Vin 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 as short as
possible.
Thermal
As power across the NCP502 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 NCP502 has good thermal
conductivity through the PCB, the junction temperature will
be relatively low with high power dissipation applications.
