MC34063A MC33063A
Figure 9. Step–Down Converter
8
S Q
R
7
Ipk
Osc
6
100
+
VCC
+
–
5
Comp.
1.25 V
Ref
Reg
Q2
Q1
1
2
CT
1N5819
3
L
CT
470
pF
4
1.0
µH
+
CO
Vout
100
220
µH
Rsc
0.33
Vin
25 V
R2
3.6 k
R1
1.2 k
470
+
Vout
5.0 V/500 mA
Optional Filter
Test
Line Regulation
Load Regulation
Output Ripple
Short Circuit Current
Efficiency
Output Ripple With Optional Filter
Conditions
Vin = 15 V to 25 V, IO = 500 mA
Vin = 25 V, IO = 50 mA to 500 mA
Vin = 25 V, IO = 500 mA
Vin = 25 V, RL = 0.1
Ω
Vin = 25 V, IO = 500 mA
Vin = 25 V, IO = 500 mA
Results
12 mV =
±0.12%
3.0 mV =
±0.03%
120 mVpp
1.1 A
83.7%
40 mVpp
Figure 10. External Current Boost Connections for IC Peak Greater than 1.5 A
10a. External NPN Switch
10b. External PNP Saturated Switch
8
1
8
1
Vout
7
Rsc
Vin
6
2
Vout
Rsc
Vin
7
2
6
6
MOTOROLA ANALOG IC DEVICE DATA
ONSEMI [ ON SEMICONDUCTOR ]
