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UCC2807-3 PDF 데이터시트 : 부품 기능 및 핀배열

부품번호 UCC2807-3
기능 Programmable Maximum Duty Cycle PWM Controller
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UCC2807-3 데이터시트, 핀배열, 회로
application UCC1807-1/-2/-3
INFO UCC2807-1/-2/-3
available UCC3807-1/-2/-3
Programmable Maximum Duty Cycle PWM Controller
FEATURES
User Programmable Maximum PWM
Duty Cycle
100m A Startup Current
Operation to 1MHz
Internal Full Cycle Soft Start
Internal Leading Edge Blanking of
Current Sense Signal
1A Totem Pole Output
DESCRIPTION
The UCC3807 family of high speed, low power integrated circuits contains
all of the control and drive circuitry required for off-line and DC-to-DC fixed
frequency current mode switching power supplies with minimal external
parts count.
These devices are similar to the UCC3800 family, but with the added fea-
ture of a user programmable maximum duty cycle. Oscillator frequency and
maximum duty cycle are programmed with two resistors and a capacitor.
The UCC3807 family also features internal full cycle soft start and internal
leading edge blanking of the current sense input.
The UCC3807 family offers a variety of package options, temperature
range options, and choice of critical voltage levels. The family has UVLO
thresholds and hysteresis levels for off-line and battery powered systems.
Thresholds are shown in the table below.
Part Number
UCCx807-1
UCCx807-2
UCCx807-3
Turn-on Threshold
7.2V
12.5V
4.3V
Turn-off Threshold
6.9V
8.3V
4.1V
Packages
J
N, D
N, D, PW
BLOCK DIAGRAM
SLUS163 - JUNE 1997
1
UDG-95001-1




UCC2807-3 pdf, 반도체, 판매, 대치품
PIN DESCRIPTIONS (cont.)
TRIG/DISCH: Oscillator control pins. Trig is the oscillator
timing input, which has an RC-type charge/discharge sig-
nal controlling the chip’s internal oscillator. DISCH is the
pin which provides the low impedance discharge path for
the external RC network during normal operation. Oscil-
lator frequency and maximum duty cycle are computed
as follows:
fre que ncy
duty cycle
1.4
R A 2 R B CT
RA RB
RA 2RB
as shown in Figure 1.
UCC1807-1/-2/-3
UCC2807-1/-2/-3
UCC3807-1/-2/-3
For best performance, keep the lead from CT to GND as
short as possible. A separate ground connection for CT is
desirable. The minimum value of RA is 10kW , the mini-
mum value of RB is 2.2kW , and the minimum value of CT
is 47pF.
VDD: The power input connection for this device. Total
VDD current is the sum of quiescent current and the av-
erage OUT current. Knowing the operating frequency
and the MOSFET gate charge (Qg), average OUT cur-
rent can be calculated from
IOUT = Qg F, where F is frequency.
To prevent noise problems, bypass VDD to GND with a
ceramic capacitor as close to the chip as possible in par-
allel with an electrolytic capacitor.
UDG-95002-1
Figure 1. Oscillator Block Diagram
APPLICATIONS INFORMATION
The circuit shown in Fig. 2 illustrates the use of the
UCC3807 in a typical off-line application. The 100W,
200kHz, universal input forward converter produces a
regulated 12VDC at 8 Amps. The programmable maxi-
mum duty cycle of the UCC3807 allows operation down
to 80VRMS and up to 265VRMS with a simple RCD
clamp to limit the MOSFET voltage and provide core re-
set. In this application the maximum duty cycle is set to
about 65%. Another feature of the design is the use of a
flyback winding on the output filter choke for both boot-
strapping and voltage regulation. This method of loop clo-
sure eliminates the optocoupler and secondary side
regulator, common to most off-line designs, while provid-
ing good line and load regulation.
T1:
Core
Magnetics Inc. #P-42625-UG (ungapped)
Primary:
28 turns of 2x #26AWG
Secondary:
6 turns of 50x0.2mm Litz wire
L1:
Core:
Magnetics Inc. #P-42625-SG-37 (0.020”
gap)
Main Winding: 13 turns of 2x #18AWG
Second Winding: 11 turns of #26AWG
Magnetics Inc.
900 E. Butler Road
P.O. Box 391
Butler, PA 16003
Tel: (412) 282-8282
Fax: (412) 282-6955
4

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UCC2807-3 전자부품, 판매, 대치품
www.ti.com
PACKAGE OPTION ADDENDUM
22-Feb-2005
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI
to Customer on an annual basis.
Addendum-Page 2

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부품번호상세설명 및 기능제조사
UCC2807-1

Programmable Maximum Duty Cycle PWM Controller

Unitrode
Unitrode
UCC2807-1

Programmable Maximum Duty Cycle PWM Controller (Rev. B)

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