NCP3065PG データシートの表示（PDF） - ON Semiconductor

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NCP3065PG

Up to 1.5 A Constant Current Switching Regulator for LEDs

ON Semiconductor 

NCP3065, NCV3065

APPLICATIONS

Figures 16 through 24 show the simplicity and flexibility

of the NCP3065. Two main converter topologies are

demonstrated with actual test data shown below each of the

circuit diagrams.

Figure 16 gives the relevant design equations for the key

parameters. Additionally, a complete application design aid

for the NCP3065 can be found at www.onsemi.com.

(See Notes 9, 10, 11)

Step-Down

Step-Up

ton

toff

ton

CT

IL(avg)

Ipk (Switch)

RSC

L

Vripple(pp)

Vout ) VF

Vin * VSWCE * Vout

Vout ) VF * Vin

Vin * VSWCE

ton

toff

ǒ Ǔ fĂ

ton

toff

)

1

ton

toff

ǒ Ǔ fĂ

ton

toff

)

1

CT

+

381.6 @ 10*6

fosc

*

343

@

10*12

Iout

ǒ Ǔ IoutĂ

ton

toff

)

1

IL(avg)

)

DIL

2

IL(avg)

)

DIL

2

0.20

IpkĂ(Switch)

0.20

IpkĂ(Switch)

ǒ Ǔ Vin * VSWCE * Vout

DIL

Ăton

Ǹǒ Ǔ2

DIL

1

8ĂfĂCO

) (ESR)2

ǒ Ǔ Vin * VSWCE

DIL

Ăton

[

tonĂIout

CO

)

DIL

@

ESR

Vout

ǒ Ǔ VTH

R2

R1

)

1

ǒ Ǔ VTH

R2

R1

)

1

Iout

VrefńRsense

VrefńRsense

9. VSWCE - Darlington Switch Collector to Emitter Voltage Drop, refer to Figures 7, 8, 9 and 10.

10. VF - Output rectifier forward voltage drop. Typical value for 1N5819 Schottky barrier rectifier is 0.4 V.

11. The calculated ton/toff must not exceed the minimum guaranteed oscillator charge to discharge ratio.

The Following Converter Characteristics Must Be Chosen:

Vin - Nominal operating input voltage.

Vout - Desired output voltage.

Iout - Desired output current.

DIL - Desired peak-to-peak inductor ripple current. For maximum output current it is suggested that DIL be chosen to be

less than 10% of the average inductor current IL(avg). This will help prevent Ipk (Switch) from reaching the current limit threshold

set by RSC. If the design goal is to use a minimum inductance value, let DIL = 2(IL(avg)). This will proportionally reduce

converter output current capability.

f - Maximum output switch frequency.

Vripple(pp) - Desired peak-to-peak output ripple voltage. For best performance the ripple voltage should be kept to a low

value since it will directly affect line and load regulation. Capacitor CO should be a low equivalent series resistance (ESR)

electrolytic designed for switching regulator applications.

Figure 16. Design Equations

http://onsemi.com

9

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