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

mF 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

W up to 3.0 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.

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

Hints

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

+

TJ(max) *TA

R

qJA

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:

Ptot + Vin *Ignd (Iout) ) [Vin * Vout] *Iout

or

VinMAX +

Ptot ) Vout * Iout

Ignd ) Iout

If a 150 mA output current is needed then the ground

current from the data sheet is 40

mA. For an NCP511SN30T1

(3.0 V), the maximum input voltage will then be 5.6 V.

Figure 16. Typical Application Circuit

Battery or

Unregulated

Voltage

C1

C2

OFF

ON

1

2

3

5

4

+

+

1

10

0.1

0.01

100

Figure 17. Output Capacitor vs. Output Current

0150

25

50

75

100

125

UNSTABLE

STABLE