MC34063SMDBKGEVB 查看數據表（PDF） - ON Semiconductor

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MC34063SMDBKGEVB

1.5 A, Step-Up/Down/Inverting Switching Regulators

ON Semiconductor 

MC34063A, MC33063A, SC34063A, SC33063A, NCV33063A

Calculation

ton/toff

(ton + toff)

toff

ton

CT

Ipk(switch)

Rsc

L(min)

CO

Step−Up

Step−Down

Vout ) VF * Vin(min)

Vin(min) * Vsat

Vout ) VF

Vin(min) * Vsat * Vout

1

1

f

f

ton ) toff

ton

toff

)

1

(ton + toff) − toff

4.0 x 10−5 ton

ǒ Ǔ 2Iout(max)

ton

toff

)

1

ton ) toff

ton

toff

)

1

(ton + toff) − toff

4.0 x 10−5 ton

2Iout(max)

0.3/Ipk(switch)

ǒ Ǔ (Vin(min) * Vsat)

Ipk(switch)

ton(max)

0.3/Ipk(switch)

ǒ Ǔ (Vin(min) * Vsat * Vout)

Ipk(switch)

ton(max)

9

Ioutton

Vripple(pp)

Ipk(switch)(ton ) toff)

8Vripple(pp)

Voltage−Inverting

|Vout| ) VF

Vin * Vsat

1

f

ton ) toff

ton

toff

)

1

(ton + toff) − toff

4.0 x 10−5 ton

ǒ Ǔ 2Iout(max)

ton

toff

)

1

0.3/Ipk(switch)

ǒ Ǔ (Vin(min) * Vsat)

Ipk(switch)

ton(max)

9

Ioutton

Vripple(pp)

Vsat = Saturation voltage of the output switch.

VF = Forward voltage drop of the output rectifier.

The following power supply characteristics must be chosen:

ǒ Ǔ Vin − Nominal input voltage.

Vout − Desired output voltage, |Vout| + 1.25

Iout − Desired output current.

1

)

R2

R1

fmin − Minimum desired output switching frequency at the selected values of Vin and IO.

Vripple(pp) − Desired peak−to−peak output ripple voltage. In practice, the calculated capacitor value will need to be increased due to its

equivalent series resistance and board layout. The ripple voltage should be kept to a low value since it will directly affect the

line and load regulation.

NOTE: For further information refer to Application Note AN920A/D and AN954/D.

Figure 17. Design Formula Table

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