UC33063A
LINEAR INTEGRATED CIRCUIT
DESIGN FORMULA TABLE
CALCULATION
STEP-DOWN
STEP-UP
VOLTAGE-INVERTING
tON
tOFF
VOUT + VF
VIN - VCE(SAT)
(tON+tOFF MAX
)
CT
ISW
RS
4x10-5 tON
2IOUT(MAX)
0.3/ISW
4x10-5 tON
4x10-5 tON
0.3/ISW
0.3/ISW
L(MIN)
CO
IOUT tON
VRIPPLE(P-P)
VCE(SAT)
VF
- Saturation voltage of the output switch.
- Forward voltage drop of the ringback rectifier.
The following power supply characteristics must be chosen:
VIN
- Nominal input voltage.
Desired output voltage, VOUT =1.25(1+R2/R1)
VOUT
IOUT
FMIN
-
- Desired output current.
- Minimum desired output switching frequency at the selected values for VIN and IOUT
.
VRIPPLE(P-P) - Desired peak-to-peak output ripple voltage. In practice, the calculated value will need to be increased
due to the capacitor equivalent series resistance and board layout. The ripple voltage should be kept
to a low value since it will directly effect the line and load regulation.
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
UNISONIC TECHNOLOGIES CO., LTD
10 of 10
www.unisonic.com.tw
QW-R103-044.B
UTC [ Unisonic Technologies ]
