SG6105 データシートの表示（PDF） - Unspecified

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SG6105

Power Supply Supervisor + Regulator + PWM

Unspecified 

Power Supply Supervisor + Regulator + PWM

Product Specification

SG6105

Example of Using SG6105 for the ATX

Power Supply

Protection against over-voltage, short-circuit and

fault conditions is mandatory in PC power supplies. These

protection circuits can be realized by using many discrete

components and comparators, which occupy a lot of PCB

space and also add to assembling costs. This single chip

controller IC provides complete protection circuits, shunt

regulators, and PWM control function and with less

number of components. SG6105 is an ideal controller IC

for PC switching mode power supplies.

The features and benefits of this device are listed

below:

Over-voltage and under-voltage protection for 3.3V,

5V and 12V without external divider

Over-power protection.

UV protection for –12V and/or –5V.

Power-down warning for power good signal.

Power good signal and power-fail lockup

Remote on/off control.

Delay time for PSON and PS-off signal.

Two shunt regulator for 3.3V and 5V-Standby

regulation.

Complete pulse width modulation (PWM) control

circuitry.

On-chip oscillator.

Programmable Soft-Start.

Maximum 93% duty cycle

Few external components

More reliable system

Little space on PCB

Easy trouble-shooting and implementation

FEATURE DESCRIPTIONS

Over voltage protection can be implemented without

any additional components. Over-voltage sense

Levels or 3.3V, 5V, 12V are 4.1V, 6.1V, 14.5V

respectively.

Over current and/or short circuit protection can also

be achieved by using over-power protection, in

which OPP pin is connected to the current

transformer (driver transformer).

The power good signal is asserted to indicate the

3.3V, 5V and 12V is above the under voltage

threshold level. PG pin goes high when the above

condition is reached. A 2K pull up resistor may connect to

5V.

The VCC can be supplied from the 5V-standby.

When the VCC voltage is higher than 7V, besides the

shunt regulator, the circuit of SG6105 will be

shutdown and reset. No extra power supply is

needed.

Two internal high precision 431 shunt regulators are

built-in. It provides stable reference voltages.

Complete PWM control circuitry including the error

amplifier for push-pull or half-bridge operation.

Supervisory Circuit Operation

The PC generates the remote ON/OFF logic (PSON),

which is “Low” for power supply “On” and “High” to

switch off the power supply. The remote ON/OFF is

connected to PSON input.

APPLICATION GUIDES

Introduction

The application guide shows the key-feature of

SG6105 and illustrates how to use in an ATX switching

mode power supply (SMPS). SG6105 is suitable for

half-bridge, push-pull topology. It incorporates with a

4-channel supervisor, including 5V-standby. The PWM

section of SG6105 comprises a built-in 65kHz oscillator

and high immunity circuits, which protect the system

from noise interference and provide more noise margins

for improper PCB layout. SG6105 has OVP and UVP for

12V, 5V and 3.3V. Besides, the NVP is used for negative

voltage protection, such as –12V and/or –5V. The UVAC

(AC fails detection) is applied to detect AC line condition.

Two built-in internal precision TL431 shunt regulators

can be used for 3.3V or 5V auxiliary standby power.

AC Fails Detection

Through a resistor divider, UVAC is connected to

the secondary power transformer for detecting the AC line

condition. Once the voltage of UVAC is lower than 0.7V

for a period of time, such as 200usec, the PG (power good)

signal will be pulled low to indicate an AC line

power-down condition. The voltage amplitude of the

©System General Corp.

Version 2.4(IRO33.0011.B1)

- 10 -

www.sg.com.tw

Apr.7, 2004

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