SG6846 데이터 시트보기 (PDF) - Fairchild Semiconductor

부품명

상세내역

제조사

SG6846

Highly Integrated Green-Mode PWM Controller

Fairchild Semiconductor 

November 2008

SG6846

Highly Integrated Green-Mode PWM Controller

Features

ƒ Low Startup Current: 8µA

ƒ Low Operating Current: 3.7mA

ƒ Peak-Current Mode of Operation with Cycle-by-

Cycle Current Limiting

ƒ PWM Frequency Continuously Decreasing with

Burst Mode at Light Loads

ƒ VDD Over-Voltage Protection (OVP)

ƒ AC Input Brownout Protection with Hysteresis

ƒ Constant Output-Power Limit (Full AC Input Range)

ƒ Internal Latch Circuit for OVP, OTP, and OCP

ƒ Two-level Over-Current Protection (OCP) with

96ms Delay Time

ƒ Very Few External Components

ƒ Programmable Over-Temperature Protection (OTP)

Applications

General-purpose switch-mode power supplies and

flyback power converters, including:

ƒ Power Adapters

ƒ Open-Frame SMPS

ƒ SMPS with Surge-Current Output, such as for

Printers, Scanners, Motor Drivers

Description

The highly integrated SG6846 series of PWM

controllers provides several features to enhance the

performance of flyback converters. To minimize

standby-power consumption, a proprietary green-mode

function provides off-time modulation to continuously

decrease the switching frequency under light-load

conditions. Under zero-load conditions, the power

supply enters burst-mode. This completely shuts off

PWM output. The output restarts just before the supply

voltage drops below the under-voltage lockout (UVLO)

lower limit. This green-mode function enables power

supplies to meet international power conservation

requirements easily.

The SG6846 is designed especially for switch-mode

power supply (SMPS) with surge-current output. It is

incorporated with a two-level OCP function. Besides the

cycle-by-cycle current limiting, if the switching current is

higher than 2/3 of the peak-current threshold for a delay

time, OCP is activated such that the SG6846 is totally

shut down. Other protection functions include: AC-input

brownout protection with hysteresis and VDD OVP. For

OTP, an external NTC thermistor can be applied to

sense the ambient temperature. When OCP, VDD OVP,

or OTP are activated, an internal latch circuit is used to

latch off the controller. The latch resets when the VDD

supply is removed.

Other features of this controller include built-in

synchronized slope compensation and proprietary

internal compensation for constant output-power limit

over universal-AC-input range. Also, the gate output is

clamped at 18V to protect the external MOSFET from

over-voltage damage.

The SG6846 series controllers are available in both 8-

pin dual in-line (DIP) and small outline (SOP) packages.

Ordering Information

Part

Number

SG6846LSZ

SG6846LSY

SG6846LDZ

SG6846LDY

Operating Temperature

Range

-20 to +85°C

-20 to +85°C

-20 to +85°C

-20 to +85°C

OTP Latch

Yes

Yes

Yes

Yes

Eco Status

RoHS

Green

RoHS

Green

Package

8-Pin SOP

8-Pin SOP

8-Pin DIP

8-Pin DIP

Packing

Method

Tape & Reel

Tape & Reel

Tube

Tube

For Fairchild’s definition of “green” Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.

© 2008 Fairchild Semiconductor Corporation

SG6846 • Rev. 1.3.1

www.fairchildsemi.com

Share Link: