Datasheet

QS
R
C
T
I
pk
Q2
Q1
2
1
C
T
Oscillator
_
+
1.25-V
Reference
Regulator
4
5
3
8
7
6
R
SC
0.33 Ω
3.8 kΩ
R2
L
220 µH
C
O
1N5819
470 µF
470 pF
R1
1.2 kΩ
100 µF
+
+
V
CC
V
OUT
5 V/500 mA
1.0 µH
100 µF
+
Optional Filter
V
IN
25 V
Comparator
V
OUT
+ 1.25 (1 )
R2
R1
)
V
IN
8
7
6
1
2
8
7
6
1
2
R
SC
V
IN
R
SC
V
OUT
V
OUT
a) EXTERNAL npn SWITCH b) EXTERNAL pnp SATURATED SWITCH
MC33063A
MC34063A
SLLS636M –DECEMBER 2004– REVISED JANUARY 2011 www.ti.com
Figure 8. Step-Down Converter
TEST CONDITIONS RESULTS
Line regulation V
IN
= 15 V to 25 V, I
O
= 500 mA 12 mV ± 0.12%
Load regulation V
IN
= 25 V, I
O
= 50 mA to 500 mA 3 mV ± 0.03%
Output ripple V
IN
= 25 V, I
O
= 500 mA 120 mV
PP
Short-circuit current V
IN
= 25 V, R
L
= 0.1 Ω 1.1 A
Efficiency V
IN
= 25 V, I
O
= 500 mA 83.7%
Output ripple with optional filter V
IN
= 25 V, I
O
= 500 mA 40 mV
PP
Figure 9. External Current-Boost Connections for I
C
Peak Greater Than 1.5 A
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