Toshiba TLP510E Руководство по техническому обучению - Страница 3

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1. MAIN POWER SUPPLY CIRCUIT

1-1. Description

This power supply boosts up at boost-up-converter just

after bridge-rectifying AC input voltage, supplies the

voltage smoothed to DC 350V to the lamp output. Then

current resonance DC-DC converter which uses the DC

350V as an input converts the voltage and supplies S6V,

+6V, +10V, +13V, +15.5V and –12V.

The boost-up-converter control IC, IC301, stabilizes AC

rectified voltage to DC 350V. The current resonance DC-

DC converter, IC303, turns FET Q102 and Q103 "ON/

OFF" alternately using the drive transformer T103 and

converts the voltage to secondary side through the

converter transformer T101. At this time, the voltage of

S6V at the secondary side is detected by IC402, the

negative feedback to IC303 is carried out at photo

coupler PH301 and then the voltage is stabilized. Other

outputs are determined by the turn ratio of secondary

side of T101, and the voltage rectified, smoothed, but not

stabilized are stabilized through the series regulator.

(+10V is stabilized at IC203, +13V at IC202, +15.5V at

IC201.)

The voltage rectified and smoothed by D105 and C113 at

primary winding of T101 is supplied as a V

IC301, IC302 and IC303 on primary side ICs, and also

the voltage rectified and smoothed by D106 and C114 is

supplied as a gate bias voltage of D306 TRIAC (triode

AC switch) which short-circuits the inrush current

limiting resistor R305. Therefore, when the electric

current resonance DC-DC converter stops to oscillate, the

voltage is not supplied so that the boost-up-

converter stops to operate.

1-2. Output Control

When the output control 1 and 2 of connector A develops

low, the voltage of approx. 14V is added to Q203 gate

and pins 4 of IC203, IC201, and IC202 through R205

and R206 respectively, since the transistors Q201 and

Q202 turn off. In this case, Q204, IC201, IC202 and

IC203 turn off, the voltages of +6V, +10V, +15.5V and

+13V are not developed.

When the output control 1 and 2 develop high, the

transistors Q201 and Q202 turn on, so no voltage is

added to the gate Q203, IC201, IC202 and IC203,

described above, and the voltage of +6V, +10V, –15.5V

and +13V are developed.

1-3. Voltage Switching

When the voltage switching terminal of connector C

opens, pin 1 develops low, since the pin 2 of IC401 is 6V,

higher than pin 2 (3V), the voltage adjusted to 16.3V is

directly developed from IC201, since the status of Q205

turns off. When the voltage switching terminal develops

ground potential, since pin 2 of IC401 develops 0V and

the voltage of pin 2 develops low, pin 1 develops high,

Q205 turns on, voltage-set-up resistor of R201 is short-

circuited and the voltage of IC201 rises from 16.3V to

18.0V.

1-4. Over-voltage Protection

When the negative feedback circuit of current resonance

DC-DC converter is shut down, the secondary side

voltage control is unable to operate, the voltage begins to

develop high without any restriction. At this time, when

the voltage of S6V and +6V exceeds 8.5V, the base of

transistor Q401 is biased through the zener diode D201,

and turns on, and then the voltage higher than 7V is

added to pin 6 (OVP) of IC303 through the photo coupler

PH302. When the voltage higher than 7V is added to pin

6, IC303 is latched, all outputs are shut down. ( Boost-

up-converter stops simultaneously, too.)

voltage of

When the voltage is added to +10V, +13V, +15.5V lines

from external side, (exceeding +15V for +10V line, 13V

for +13 line and 20V for +15.5V line), on each line

respectively through the zener diodes D202, D203 and

D204, the base voltage of Q401 is biased passing, IC303

is latched in the same way as the above-mentioned, all

outputs are shut down. When releasing the latch opera-

tion, stop to supply the commercial power supply and

then re-supply the commercial power after more than

approx. 120 seconds.

1-1