TS34063A Datasheet, PDF (7/8 Pages) Taiwan Semiconductor Company, Ltd – Dc to Dc Converter Controller

Design Formula Table
Test
ton
toff
( ton+ toff )
CT
Ipk(switch)
Rsc
L(min)
Co
Step Up
Vout + Vf − Vin(min)
Vcc(min) − Vsat
1
f min
4.0 x 10 ^–5 ton
2Iout(max)
⎜⎜⎝⎛
ton
toff
+ 1_{⎟⎟⎠⎞}
⎜⎜⎝⎛
0.3
Ipk ( switch)
⎟⎟⎠⎞
⎜⎜⎝⎛
Vin( min ) −Vsat
Ipk(switch)
⎟⎟⎠⎞
*
ton(
max
)
⎜⎜⎝⎛
9
Iout *ton
Vripple( pp)
⎟⎟⎠⎞
Step Down
Vout + Vf
Vcc − Vsat − Vout
1
f min
4.0 x 10 ^–5 ton
2Iout(max)
⎜⎜⎝⎛
Ipk
0.3
(switch)
⎟⎟⎠⎞
Voltage Inverting
| Vout | +Vf
Vcc − Vsat
1
f min
4.0 x 10 ^–5 ton
2Iout(max)
⎜⎜⎝⎛
ton
toff
+ 1_{⎟⎟⎠⎞}
⎜⎜⎝⎛
Ipk
0.3
(switch)
⎟⎟⎠⎞
⎜⎜⎝⎛
Vin(min) −Vsat −
Ipk (switch)
Vout
⎟⎟⎠⎞
*
ton(max)
⎜⎜⎝⎛
Vin(min) − Vsat
Ipk ( switch)
⎟⎟⎠⎞
*
ton(max)
⎜⎜⎝⎛
Ipk
(switch)(ton +
8Vripple( pp)
toff
)
⎟⎟⎠⎞
⎜⎜⎝⎛ ⁹
Iout *ton
Vripple( pp)
⎟⎟⎠⎞
Terms and Definitions
z Vsat = Saturation Voltage of the output switch.
z Vf = Forward Voltage drop of the rectifier.
The following power supply characteristics must be chosen:
z Vin= Normal input voltage
z Vout: Desied Output voltage, |Vout| =1.25 (1+R2 / R1)
z Iout : Desired output current.
z fmin : Minimum desired output switching frequency at the selected values for Vin and Io.
z Vripple(p-p): 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.
TS34063A
7-8
2005/02 rev. A