NCP623

http://onsemi.com

5

APPLICATION HINTS

Input Decoupling − As with any regulator, it is necessary

to reduce the dynamic impedance of the supply rail that

feeds the component. A 1.0

mF capacitor either ceramic or

tantalum is recommended and should be connected close to

the NCP623 package. Higher values will correspondingly

improve the overall line transient response.

Output Decoupling − Due to a novel concept, the

NCP623 is a stable component and does not require any

Equivalent Series Resistance (ESR) neither 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.

Noise Performances − Unlike other LDOs, the NCP623

is a true low−noise regulator. With a 10 nF bypass capacitor,

it typically reaches the incredible level of 25

mVRMS overall

noise between 100 Hz and 100 kHz. To give maximum

insight on noise specifications, ON Semiconductor includes

spectral density graphics as well as noise dependency versus

bypass capacitor.

The bypass capacitor impacts the start−up phase of the

NCP623 as depicted by the data−sheet curves. A typical

1.0 ms settling time is achieved with a 10 nF bypass

capacitor. However, due to its low−noise architecture, the

NCP623 can operate without bypass and thus offers a typical

20

ms start−up phase. In that case, the typical output noise

stays lower than 65

mVRMS between 100 Hz − 100 kHz.

Protections − The NCP623 hosts several protections,

conferring natural ruggedness and reliability to the products

implementing the component. The output current is

internally limited to a minimum of 175 mA while

temperature shutdown occurs if the die heats up beyond

150

°C. These value lets you assess the maximum

differential voltage the device can sustain at a given output

current before its protections come into play.

The maximum dissipation the package can handle is given

by:

Pmax +

T

Jmax

–T

A

RqJA

dissipate up to 595 mW @ 25

°C.

The power dissipated by the NCP623 can be calculated

from the following formula:

Ptot

+ V

in @

I

gnd

(Iout) ) Vin * Vout @ Iout

or

Vinmax +

Ptot

) V

out @ Iout

I

gnd )

Iout

If a 150 mA output current is needed, the ground current

is extracted from the data−sheet curves: 6.5 mA @ 150 mA.

For a NCP623NW28R2 (2.8 V), the maximum input voltage

will then be 6.48 V, a rather comfortable margin.

Typical Application − The following figure portraits the

typical application for the NCP623 where both input/output

decoupling capacitors appear.

Figure 2. A Typical NCP623 Application with

Recommended Capacitor Values (QFN6)

64

12

3

Input

Output

C3

1.0

mF

C2

1.0

mF

C1

10 nF

On/Off

NCP623

5

Figure 3. A Typical NCP623 Application with

Recommended Capacitor Values (Micro8)

87

5

12

4

Output

Input

C2

1.0

mF

C3

1.0

mF

C1

10 nF

On/Off

NCP623

6

3

NC

NC