APL5913 Ver la hoja de datos (PDF) - Anpec Electronics

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componentes Descripción

Fabricante

APL5913

0.8V Reference Ultra Low Dropout (0.25V@3A) Linear Regulator

Anpec Electronics 

APL5913

Application Information (Cont.)

Feedback Network (Cont.)

Select a proper R1(selected) to be a little larger

than the calculated R1.

- Calculate the C1 as the following :

[ ] C1(pF) = 0.71⋅ ESR(mΩ) + 101 ⋅ COUT(uF) ........ (4)

R1(kΩ )

Where R1=R1(selected)

Select a proper C1(selected) to be a little smaller

than the calculated C1.

- The C1 calculated from equation (4) must meet

the following equation:

C1 (pF)

≥

7.2

⋅ 1+

143

ESR (m

Ω

)





⋅

1

+

37.5 ⋅ VOUT(V)

R1 (kΩ)





..

(5)

Where R1=R1(calculated) from equation (3)

If the C1(calculated) can not meet the equation (8),

please use the Condition 2.

- Use equation (2) to calculate the R2.

The reason to have three conditions described above

is to optimize the load transient responses for all kinds

of the output capacitor. For stability only, the Condition

2, regardless of equation (5), is enough for all kinds of

output capacitor.

PCB Layout Considerations (See Figure 2)

1. Please solder the Exposed Pad and VIN together

on the PCB. The main current flow is through the

exposed pad. Refer Figure 3 to make a proximate

topology.

If the C1(calculated) can not meet the equation

(5), please use the Condition 3.

2. Please place the input capacitors for VIN and

VCNTL pins near pins as close as possible.

- Use equation (2) to calculate the R2.

•Condition 3 : Low ESR (eg. Ceramic Capacitors)

3. Ceramic decoupling capacitors for load must be

placed near the load as close as possible.

4. To place APL5913 and output capacitors near the

- Calculate the R1 as the following:

load is good for performance.

R1(kΩ) = (2.1⋅ESR(mΩ) + 300)⋅ COUT(uF) − 37.5⋅ VOUT(V).. (6)

5. The negative pins of the input and output capaci-

tors and the GND pin of the APL5913 are connected

Select a proper R1(selected) to be a little larger to the ground plane of the load.

than the calculated R1. The minimum selected 6. Please connect PIN 3 and 4 together by a wide

R1 is equal to 1kΩ when the calculated R1 is track.

smaller than 1k or negative.

- Calculate the C1 as the following :

C1(pF) =

(0.24⋅ESR(mΩ)

+

34.2)⋅

COUT(uF) ⋅

1+

37.5⋅ VOUT(V)

R1(kΩ) 

..

(7)

Where R1=R1(selected)

7. Large current paths must have wide tracks.

8. See the Typical Application

(see next page Figure 2)

- Connect the one pin of the R2 to the GND of

Select a proper C1(selected) to be a little smaller

than the calculated C1.

APL5913

- Connect the one pin of R1 to the Pin 3 of APL5913

- The C1 calculated from equation (7) must meet

- Connect the one pin of C1 to the Pin 3 of APL5913

the following equation :

C1 (pF)

≥

0.033

+

1.25 ⋅ VOUT(V)

R1 (kΩ )





⋅

ESR

(m

Ω

)

⋅

C OUT(uF)

.. (8)

Where R1=R1(calculated) from equation (6)

Copyright © ANPEC Electronics Corp.

14

Rev. A.4 - May., 2005

www.anpec.com.tw

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