Article : [DIV475]

Titre : J. PALCZYNSKI, DN-48 Versatile Low Power SEPIC Converter Accepts Wide Input Voltage Range, UNITRODE, SLUA158, September 1999, 4 pages.

Cité dans : [DIV095]  Librairie TEXAS INSTRUMENTS - UNITRODE et Notes d'applications diverses, octobre 2013.
Cité dans : [DIV126]  T. LEQUEU, Librairie des fichiers PDF de composants, octobre 2022.
Cité dans :[LIVRE384]

Source : Unitrode http://www.ti.com Texas Instruments
Adresse : Unitrode Integrated Circuits Corporation - Southeast Design Center - 1005 Slater Road, Suite 206 - Morrisville, NC 27560 - (919) 94l-6355
Lien : SLUA158.pdf - 4 pages, 61 Ko, "DN-48 Versatile Low Power SEPIC Converter Accepts Wide Input Voltage Range", UNITRODE.
Pages : 1 - 4
Date : September 1999

Lien : UC1864.pdf - 12 pages, 532 Ko, UC1861-1868, UC2861-2868, UC3861-3868, Resonant-Mode Power Supply Controllers, Controls Zero Current Switched (ZCS), SLUS289 - OCTOBER 1998.

ABSTRACT :
This design note describes an output converter for battery-powered and automotive applications.
It uses a UCC3803 BiCMOS current-mode controller to provide a 5V output at full load of 100mA from an input of 2.5-13.5V after an initial startup at 5V.
The UC3803 is part of the UCC1800/1/2/3/4/5 family of high-speed, low-power integrated circuits, which contains all necessary control and drive components for off-line and DC-to-DC fixed-frequency current-mode switching power supplies with minimal parts count.

Intorduction :
Much attention has been given to the Single Ended
Primary Inductor Converter (SEPIC) topology re-cently
because output voltage may be either higher
or lower than input voltage. The output is also not
inverted as is the case in a flyback or Cuk topology.
Voltage conversion is accomplished without trans-formers,
instead using low cost inductors to transfer
energy. The input and output voltages are DC iso-lated
by a coupling capacitor. This design note illus-trates
an application for a 5V, 100mA output con-verter
for battery powered and Automotive
applications. It makes use of a UCC3803 BiCMOS
current mode controller to provide a 5V output at full
load of 100mA from an input of 2.5V to 13.5V after
an initial start-up at 5 volts.
This SEPIC converter uses current mode control to
simplify stabilization of the control loop. Peak cur-
rent in the FET is limited by the pulse by pulse cur-rent
limiting of the UCC3803. Switching frequency is
500kHz, allowing low output current handling and
low output ripple with small inductors and capaci-tors
while remaining in the continuous inductor cur-rent
mode (CCM). Once started, the low voltage
operation of the UCC3803 is extended by boot-strapping
from the output through a UC3612 Schot-tky
diode. By including slope compensation (Q2,
R3), the duty cycle may exceed 50% without experi-encing
subharmonic oscillations.
This topology places higher stresses on both the
switch and the diode than with other PWM topolo-gies.
Peak switch and diode stresses are both
VIN+VOUT and IIN + IOUT. Peak to peak ripple cur-rent
in the coupling capacitor is IIN + IOUT.

Bibliographie

  [1] :  [PAP158]  -------
  [2] : [99ART154] L.H. DIXON, High power factor preregulators for off-line power supplies, Unitrode Power Supply Design Seminar, SLUP087, 1988, vol. 6, pp. 1-16.
  [3] :  [PAP158]  -------
  [4] :  [DIV469]  UNITRODE, U-97 Modeling, Analysis and Compensation of the Current-Mode Converter, SLUA101, September 1999, 7 pages.
  [5] :  [PAP158]  -------

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