Diodes AP2202 Manuel d'utilisateur télécharger pdf (Page 24)

150mA RF ULDO REGULATOR AP2202

Data Sheet

Jul. 2011 Rev. 2. 2 BCD Semiconductor Manufacturing Limited

Input Capacitor

A 1

µF minimum capacitor is recommended to be

placed between V

and GND.

Output Capacitor

It is required to prevent oscillation. 1.0

µF minimum

is recommended when C

BYP

is unused. 2.2µF mini-

mum is recommended when C

BYP

is 100pF. The out-

put capacitor may be increased to improve transient

response.

Noise Bypass Capacitor

Bypass capacitor is connected to the internal voltage

reference. A 100pF capacitor connected from BYP to

GND make this reference quiet, resulting in a

significant reduction in output noise, but the ESR

stable area will be narrowed.

The start-up speed of the AP2202 is inversely

proportional to the value of reference bypass

capacitor. In some cases, if output noise is not a

major concern and rapid turn-on is necessary, omit

BYP

and leave BYP open.

Power Dissipation

Thermal shutdown may take place if exceeding the

maximum power dissipation in application. Under all

possible operating conditions, the junction tempera-

ture must be within the range specified under abso-

lute maximum ratings to avoid thermal shutdown.

To determine if the power dissipated in the regulator

reaches the maximum power dissipation (see figure

16,17), using:

= P

*θ

+ T

=(V

-V

OUT

)*I

OUT

GND

Where: T

≤T

J(max)

, T

J(max)

is absolute maximum rat-

ings for the junction temperature; V

GND

can be

ignored due to its small value.

J(max)

is 150

C, θ

is 200

C/W for SOT-23-5 pack-

age and 165

C/W for SOT-89 package, no heatsink is

required since the package alone will dissipate

enough heat to satisfy these requirements unless the

calculated value for power dissipation exceeds the

limit.

Example: For 2.8V version packaged in SOT-23-5,

OUT

=150mA, T

=50

C, V

IN(Max)

is:

(150

C-50

C)/(0.15A*200

C/W)+2.8V=6.133V

Therefore, for good performance, please make sure

that input voltage is less than 6.133V without heat-

sink when T

=50

Application Information

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Diodes AP2202 Manuel d'utilisateur Page 24

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