APL5912-KAC-TR Ver la hoja de datos (PDF) - Anpec Electronics

Número de pieza

componentes Descripción

Fabricante

APL5912-KAC-TR

0.8V Reference Ultra Low Dropout Linear Regulator

Anpec Electronics 

APL5912

Application Information (Cont.)

Feedback Network (Cont.)

PCB Layout Considerations (See Figure 2)

the calculated C1.

- The C1 calculated from equation (4) must meet

1. Please solder the Exposed Pad and VIN together

on the PCB. The main current flow is through the

the following equation :

C1(pF)

≥

5.1⋅

1+

50

ESR(mΩ)





⋅

1+

37.5 ⋅ VOUT(V)

R1(kΩ) 

..

(5)

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

If the C1(calculated) can not meet the equation (5),

please use the Condition 3.

- Use equation (2) to calculate the R2.

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

- Calculate the R1 as the following:

R1(kΩ) = (5.9⋅ESR(mΩ) + 294)⋅COUT(uF)− 37.5⋅ VOUT(V)..(6)

exposed pad. The role of VIN is a voltage sense.

Refer Figure 3 to make a proximate topology.

2. Please place the input capacitors for VIN and VCNTL

pins near pins as close as possible.

3. Ceramic decoupling capacitors for load must be

placed near the load as close as possible.

4. To place APL5912 and output capacitors near the

load is good for performance.

5. The negative pins of the input and output capacitors

and the GND pin of the APL5912 are connected to

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

the calculated R1. The minimum selected R1

is equal to 1kΩ when the calculated R1 is

smaller than 1k or negative.

the ground plane of the load.

6. Please connect PIN 3 and 4 together by a wide

track or plane on the Top layer.

7. Large current paths must have wide tracks.

- Calculate the C1 as the following :

8. See the Typical Application

C1(pF) =

(0.17

⋅

ESR(mΩ)

+

8.5)

⋅

COUT(uF)

⋅

1

+

37.5⋅ VOUT(V)

R1(kΩ) 

..

(7)

Where R1=R1(selected)

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

APL5912.

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

than the calculated C1.

- The C1 calculated from equation (7) must meet

the following equation :

C1(pF)

≥

0.033

+

1.25 ⋅ VOUT(V)

R1 (kΩ )





⋅ ESR (mΩ)

⋅ COUT(uF)

..

(8)

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

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

please use the Condition 2.

- Use equation (2) to calculate the R2.

CCNTL

VC N T L

VCNTL

VIN

A PL5912

VOUT

VOUT

C1

FB

GND

R2

CIN

COUT

R1

VIN

VO U T

Load

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.

Figure 2

- Connect the one pin of R1 to the Pin 3 of APL5912

- Connect the one pin of C1 to the Pin 3 of APL5912

Copyright © ANPEC Electronics Corp.

14

Rev. A.6 - Jun., 2005

www.anpec.com.tw

Share Link: