MC34063A, MC33063A
8
S Q
R
7
R
sc
0.33
V
in
25 V
100
6
+
V
CC
+
-
1
Q2
Q1
2
I
pk
Osc
C
T
1N5819
3
L
C
T
470
pF
1.0
µH
+
V
out
100
220
µH
Comp.
1.25 V
Ref
Reg
5
R2
R1
1.2 k
3.6 k
4
470
+
V
out
5.0 V/500 mA
C
O
Optional Filter
Test
Line Regulation
Load Regulation
Output Ripple
Short Circuit Current
Efficiency
Output Ripple With Optional Filter
Conditions
V
in
= 15 V to 25 V, I
O
= 500 mA
V
in
= 25 V, I
O
= 50 mA to 500 mA
V
in
= 25 V, I
O
= 500 mA
V
in
= 25 V, R
L
= 0.1
Ω
V
in
= 25 V, I
O
= 500 mA
V
in
= 25 V, I
O
= 500 mA
Results
12 mV =
±0.12%
3.0 mV =
±0.03%
120 mVpp
1.1 A
83.7%
40 mVpp
Figure 9. Step–Down Converter
8
1
1
8
V
7
R
sc
V
in
6
2
V
out
R
sc
V
in
7
2
6
Figure 10. External Current Boost Connections for I
C
Peak Greater than 1.5 A
10a. External NPN Switch
10b. External PNP Saturated Switch
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7
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