TK75003 Ver la hoja de datos (PDF) - Toko America Inc

Número de pieza

componentes Descripción

Fabricante

TK75003

PWM CONTROLLER

Toko America Inc  

TK75003

APPLICATION INFORMATION (CONT.)

tOFF = CT x 14 kΩ.

TK75003 IN NON-ISOLATED APPLICATIONS

VIN

VAUX

Although the IC was intended for off-line power-supply

+

applications with the voltage-error amplifier at the isolated

VOUT

output, it is easy and economical to use the device in non-

isolated applications, too. Figure 7 shows a low-cost boost

VCC

CT

power factor corrector controlled by the TK75003. Power

Q1

DRV

VAUX

CT

OC

FB

GND

RS

R1

factor correction is achieved by controlling the boost

converter with constant-frequency peak-current control

and exploiting the variation of the allowed peak-current

level caused by the variable duty ratio and the stabilizing

ramp. Figure 8 shows a buck-boost converter with negative

TL431

input voltage and positive output voltage, controlled by the

TK75003. In both cases, the voltage-error amplifier is a

TL431 shunt regulator, and a PNP transistor provides

interface between the TL431 and the control IC.

FIGURE 5: TK75003 IN A FORWARD CONVERTER

WITH CONSTANT OFF-TIME CURRENT-MODE

CONTROL

CT

0

FB

0.98 V

3.2 V

1.1 V

FEEDBACK VOLTAGE LEVEL

CT

FB

AC

IN

VCC

CT

DRV

FB

GND

VOUT

+

TL431

FIGURE 7: TK75003 IN A LOW COST BOOST

POWER FACTOR CORRECTOR

FIGURE 6: TIMING PIN AND FEEDBACK PIN

VOLTAGES WITH CONSTANT OFF-TIME CURRENT-

MODE CONTROL

VIN (-)

VCC

CT

DRV

FB

GND

VOUT (+)

TL431

January 1999 TOKO, Inc.

FIGURE 8: NON-ISOLATED NEGATIVE-TO-POSITIVE

CONVERTER

Page 11

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