NCP623, NCV8623

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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 − Output capacitors exhibiting ESRs

ranging from a few m

W up to 3.0 W can safely be used. The

minimum decoupling value is 1.0

mF and can be augmented

to fulfill stringent load transient requirements. The regulator

works with 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 25

mVRMS overall noise between 100

Hz and 100 kHz. Spectral density graphics as well as noise

dependency versus bypass capacitor information is included

in this datasheet.

The bypass capacitor impacts the startup 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 startup phase. In that case, the typical output noise

stays lower than 65

mVRMS between 100 Hz − 100 kHz.

Protections − The NCP623 includes several protections

functions. 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

°C, then the NCP623 can

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

64

12

3

Input

Output

C3

1.0

mF

C2

1.0

mF

C1

10 nF

On/Off

NCP623

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