NCP500, NCV500

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DEFINITIONS

Load Regulation

The change in output voltage for a change in output load

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 2% below its

nominal. The junction temperature, load current, and

minimum input supply requirements affect the dropout level.

Output Noise Voltage

This is the integrated value of the output noise over a

specified frequency range. Input voltage and output load

current are kept constant during the measurement. Results

are expressed in

Quiescent Current

The current which flows through the ground pin when the

regulator 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 power dissipation level at which the junction

temperature reaches its maximum operating value, i.e.

125

°C.

APPLICATIONS INFORMATION

The NCP500 series regulators are protected with internal

thermal shutdown and internal current limit. A typical

application circuit is shown in Figure 27.

Input Decoupling (C1)

A 1.0

mF capacitor either ceramic or tantalum is

recommended and should be connected close to the NCP500

package. Higher values and lower ESR will improve the

overall line transient response.

Output Decoupling (C2)

The NCP500 is a stable component and does not require

a minimum Equivalent Series Resistance (ESR) or a

minimum output current. 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. Figure 29 shows the stability region for a range of

operating conditions and ESR values.

Noise Decoupling

The NCP500 is a low noise regulator without the need of

an external bypass capacitor. It typically reaches a noise level

of 50

mVRMS overall noise between 10 Hz and 100 kHz. The

classical bypass capacitor impacts the start up phase of

standard LDOs. However, thanks to its low noise

architecture, the NCP500 operates without a bypass element

and thus offers a typical 20

ms start up phase.

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. The turn−on/turn−off transient

voltage being supplied to the enable pin should exceed a

slew rate of 10 mV/

ms to ensure correct operation. If the

enable is not to be used then the pin should be connected

Thermal

As power across the NCP500 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

effect the rate of junction temperature rise for the part. This

is stating that when the NCP500 has good thermal

conductivity through the PCB, the junction temperature will

be relatively low with high power dissipation applications.