DC-to-DC Converter Control Circuits

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7 Οκτ 2013 (πριν από 3 χρόνια και 10 μήνες)

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MC34063A
DC-to-DC Converter Control Circuits








































1
DESCRIPTION
The MC34063A Series is a monolithic control
circuit containing the primary functions required for
DC-to-DC converters. These devices consist of an
converters. Temperature compensated reference,
Comparator,controlled duty cycle oscillator with an
active current limit circuit,driver and high current
output switch. This series was specifically designed to
be incorporated in Step-Down and Step-Up and
Voltage applications with a minimum number of
external components.
The MC34063 is available in the plastic DIP-8,
SOP-8 and SOIC-8 package.
Features

Operation from 3.0V to 36 V Input

Low Standby Current

Current limiting

Output Switch current to 1.5A

Output Voltage Adjustable

Frequency Operature to 100kHz

Precision 2% Reference
ABSOLUTE MAXIMUM RATINGS
APPLICATION

Battery Chargers

NICs/Switches/Hubs

ADSL Modems

Negative Voltage Power Supplies
2008-7-14
www.szcyt.com
SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD

MC34063A










2
ELECTRICAL CHARACTERISTICS
(VCC=5.0 V, Ta=Tlow to Thigh,unless otherwise specified.)
NOTES:
1. Maximum package power dissipation limits must be observed.
2. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to
ambient temperature as possible.
2008-7-14
www.szcyt.com
SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD

MC34063A
3


7.
Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient
temperature as possible
.















2008-7-14
www.szcyt.com
SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD

MC34063A
4



8. If the output switch is driven into hard saturation (non−Darlington configuration) at low switch currents

(≤ 300 mA) and high driver currents (≥30 mA), it may take up to 2.0 s to come out of saturation. This
condition will shorten the off time at frequencies ≥ 30 kHz, and is magnified at high temperatures. This
condition does not occur with a Darlington configuration, since the output switch cannot saturate. If a
non−Darlington configuration is used, the following output drive condition is recommended.





2008-7-14
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SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD

MC34063A
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SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD

MC34063A
6

2008-7-14
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MC34063A
7


V
sat
= Saturation voltage of the output switch.
V
F
= Forward voltage drop of the output rectifier.
The following power supply characteristics must be chosen:
V
in
− Nominal input voltage.
V
out
− Desired output voltage, | V
out
|= 1.25(1+ R2/R1)
I
out
− Desired output current.
f
min
− Minimum desired output switching frequency at the selected values of Vin and I
O
.
V
ripple(pp)
− Desired peak−to−peak output ripple voltage. In practice, the calculated capacitor value will need
to be increased due to its equivalent series resistance and board layout. The ripple voltage should be kept to
a low value since it will directly affect the line and load regulation.

Figure 15. Design Formula Table





2008-7-14
www.szcyt.com
SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD

MC34063A
8



2008-7-14
www.szcyt.com
SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD

MC34063A
9








2008-7-14
www.szcyt.com
SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD

MC34063A
10





2008-7-14
www.szcyt.com
SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD






SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD.










IMPORTANT NOTICE
SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD. reserves the right to make changes without further notice
to any products or specifications herein. SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD. does not assume
any responsibility for use of any its products for any particular purpose, nor does SHENZHEN CYT OPTO-ELECTRONIC
TECHNOLOGY CO.,LTD. assume any liability arising out of the application or use of any its products or circuits. SHENZHEN
CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD. does not convey any license under its patent rights or other rights nor
the rights of others.
MAIN SITE(China):
SHENZHEN CYT OPTO-ELECTRONIC TECHNOLOGY CO.,LTD.
Address: Rm201-205, Building 4, Software park, Gaoxin center 2nd Rd, Nanshan District, Shenzhen
TEL:+86-755-86168222 FAX:+86-755-86168622 Technical support:+86-755-86169530
Business mail address: cyt@szcyt.com
Website: www.szcyt.com