MC33163 查看數據表（PDF） - Motorola => Freescale
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MC33163 Datasheet PDF : 16 Pages
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Calculation
ton
toff
(Notes 1, 2, 3)
ton
CT
IL(avg)
Ipk (Switch)
RSC
L
Vripple(pp)
Vout
MC34163 MC33163
Figure 27. Design Equations
Step–Down
Step–Up
) Vout VF
* * Vin Vsat Vout
) Vout VF – Vin
Vin – Vsat
ǒ Ǔton
toff
) ƒ
ton
toff
1
32.143 · 10–6
ƒ
Iout
) IL(avg)
DIL
2
ǒ Ǔ0.25
Ipk (Switch)
* * Vin
Vsat
DIL
Vout ton
ǒ Ǔ DIL
)2
1
8ƒ CO
(ESR)2
ǒ Ǔ) Vref
R2
R1
1
ǒ Ǔton
toff
) ƒ
ton
toff
1
32.143 · 10–6
ǒ Ǔƒ
) Iout
ton
toff
1
) IL(avg)
DIL
2
0.25
ǒ ǓIpk (Switch)
* Vin Vsat
DIL
ton
[ ton Iout
ǒ ǓCO
) Vref
R2
R1
1
Voltage–Inverting
) |Vout| VF
* Vin Vsat
ǒ Ǔton
toff
) ƒ
ton
toff
1
32.143 · 10–6
ǒ Ǔƒ
) Iout
ton
toff
1
) IL(avg)
DIL
2
0.25
ǒ ǓIpk (Switch)
* Vin Vsat
DIL
ton
[ ton Iout
ǒ ǓCO
) Vref
R2
R1
1
The following Converter Characteristics must be chosen:
Vin – Nominal operating input voltage.
Vout – Desired output voltage.
Iout – Desired output current.
∆IL – Desired peak–to–peak inductor ripple current. For maximum output current it is suggested that ∆IL 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 ∆IL = 2(IL(avg)). This will proportionally reduce
converter output current capability.
p – 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.
NOTES: 1. Vsat – Saturation voltage of the output switch, refer to Figures 7 and 8.
NOTES: 2. VF – Output rectifier forward voltage drop. Typical value for 1N5822 Schottky barrier rectifier is 0.5 V.
NOTES: 3. The calculated ton/toff must not exceed the minimum guaranteed oscillator charge to discharge ratio of 8, at the minimum
NOTES: 3. operating input voltage.
14
MOTOROLA ANALOG IC DEVICE DATA
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