NCP502, NCV502

http://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

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

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

mF 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

W up to 5.0 W can thus safely be used. The minimum

decoupling value is 1.0

mF 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

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.