MC34166 ON Semiconductor, MC34166 Datasheet - Page 10

• Manufacturer Part Number: MC34166
• Description: (MC33166 / MC34166) Step-Up/Down/Inverting Switching Regulators
• Manufacturer: ON Semiconductor

Figure 21 shows that the MC34166 can be configured as a step−up/down converter with the addition of an external power MOSFET. Energy
is stored in the inductor during the on−time of transistors Q
the output filter capacitor and load. This circuit configuration has two significant advantages over the basic step−up converter circuit. The first
advantage is that output short−circuit protection is provided by the MC34166, since Q
output voltage can be programmed to be less than V
its energy with respect to ground rather than with respect to V
for the MOSFET. The network consists of components R
*Gate resistor R
+
G
, zener diode D
Figure 22. Step−Up/Down Converter Printed Circuit Board and Component Layout
L = Coilcraft M1496−A or General Magnetics Technology GMT−0223, 42 turns of #16 AWG
on Magnetics Inc. 58350−A2 core.
Heatsink = AAVID Engineering Inc.
Line Regulation
Load Regulation
Output Ripple
Short Circuit Current
Efficiency
(Bottom View)
PWM
3.45″
Oscillator
3
Test
3
, and diode D
Thermal
Figure 21. Step−Up/Down Converter
4
are required only when V
in
. Notice that during the off−time, the inductor forward biases diodes D
V
V
V
V
V
in
in
in
in
in
MC34166, MC33166
= 8.0 V to 24 V, I
= 12 V, I
= 12 V, I
= 12 V, R
= 12 V, I
G
1
, D
http://onsemi.com
in
and Q
S
R
. When operating with V
3
, and D
MC34166: 5903B, or 5930B MTP3055EL: 5925B
5
Conditions
Q
O
O
O
+
L
2
= 0.1 A to 0.6 A
= 0.6 A
= 0.6 A
. During the off−time, the energy is transferred, with respect to ground, to
= 0.1 W
10
4
.
ILIMIT
in
UVLO
Reference
0.47
is greater than 20 V.
C
O
F
= 0.6 A
EA
+
V in
+
4.7 k
in
−
R
1
greater than 20 V, a gate protection network is required
F
is directly in series with V
Q
Î Î Î Î Î
Î Î Î Î Î
Î Î Î Î Î
Î Î Î Î Î
Î Î Î Î Î
+
1
23 mV = ± 0.41%
3.0 mV = ± 0.005%
100 mV
4.0 A
82.8%
Î Î Î
4
2
1
RF
−
+
1N4148
12 V
V
V O
1N5822
Results
in
D
1N967A
1.5 k
pp
4
D
R
R1
330
C
6.8 k
+
1
D
1
R
in
(Top View)
3
2
C F
*R
620
G
in
+
1000
C
and the load. Second, the
O
190 mH
1N5822
1
MTP3055EL
+
and D
L
D
D2
2
Q
28 V/0.6 A
2
2
Î
Î Î
Î Î
V
, transferring
R G
O
D3
Î Î
Î