SLLS636D – DECEMBER 2004 – REVISED MARCH 2005

MC33063A, MC34063A

1.5A PEAK BOOST/BUCK/INVERTING SWITCHING REGULATORS

7

POST OFFICE BOX 655303

TYPICAL CHARACTERISTICS

Q

S

R

CT

Ipk

Q2

Q1

2

1

CT

Oscillator

_

+

1.25-V

Reference

Regulator

4

5

3

8

7

6

RSC

0.33

Ω

3.8 k

Ω

R2

L

220

µH

CO

1N5819

470

µF

470 pF

R1

1.2 k

Ω

100

µF

+

+

VCC

Vout

5 V/500 mA

1.0

µH

100

µF

+

Vout

Optional Filter

Vin

25 V

Comparator

TEST

CONDITIONS

RESULTS

Line Regulation

VIN = 15 V to 25 V, IO = 500 mA

12 mV

± 0.12%

Load Regulation

VIN = 25 V, IO = 50 mA to 500 mA

3 mV

± 0.03%

Output Ripple

VIN = 25 V, IO = 500 mA

120 mVPP

Short-Circuit Current

VIN = 25 V, RL = 0.1 Ω

1.1 A

Efficiency

VIN = 25 V, IO = 500 mA

83.7%

Output Ripple With Optional Filter

VIN = 25 V, IO = 500 mA

40 mVPP

Figure 8. Step-Down Converter