SYSTEM GENERAL SG6849 Product Specification

查询SG6849-100D供应商

Product Specification

Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback SG6849

FEATURES

 Linearly Decreasing PWM Frequency
 Green-Mode under Light-Load and Zero-Load

Conditions

 Constant Voltage (CV) and Constant Current (CC)
 No Secondary Feedback
 Low Startup Current (5uA)
 Low Operating Current (3.6mA)
 Leading-Edge Blanking
 Constant Power Limit
 Universal AC Input Range
 Synchronized Slope Compensation
 150°C OTP Sensor with Hysteresis
 V

Over Voltage Clamping

DD

 Cycle-by-Cycle Current Limiting
 Under Voltage Lockout (UVLO)
 Fixed PWM Frequency (65kHz/100kHz)
 Gate Output Maximum Voltage Clamped at 16.7V
 Small SOT-26 Package

APPLICATIONS

Low-power flyback power converters, such as

 Battery chargers for cellular phones, cordless phones,

PDAs, digital cameras, and power tools.

 Power adapters for ink jet printers, video game

consoles, and portable audio players.

 Open-frame SMPS for TV/DVD standby and other

auxiliary supplies, home appliances, consumer
electronics, and PC 5V standby-power.

 Replacements for linear transformers and RCC

SMPS.

DESCRIPTION

This highly integrated PWM controller provides several
features to enhance the performance of low power flyback
converters. To minimize standby power consumption, the
proprietary green-mode function provides off-time
modulation to linearly decrease the switching frequency
under light-load and zero-load conditions. This
green-mode function enables the power supply to easily
meet international power conservation requirements. The
supply voltage V
compensation, to regulate the output voltage without
requiring a conventional TL431 and a photo-coupler.
Another advantage of the SG6849 is that the typical
startup current is only 5uA, while the typical operating
current can be as low as 3.6mA. A large startup resistance
could be used to achieve even higher power conversion
efficiency. Built-in synchronized slope compensation
maintains the stability of peak current-mode control.
Proprietary internal compensation ensures constant output
power limiting over a universal range of AC input
voltages, from 90VAC to 264VAC.The SG6849 provides
many protection functions. Pulse-by-pulse current
limiting ensures a constant output current, even if a short
circuit occurs. Also, the internal protection circuit will
disable PWM output, if V
output is clamped at 16.7V to protect the power MOS
from over-voltage damage. The built-in over temperature
protection (OTP) function will shutdown the controller at
150°C with a 20°C hysteresis. The SG6849 is designed to
provide a low-cost total solution for flyback converters. It
is available in a small footprint, 6-pin, SOT-26 package.

is also used for feedback

DD

exceeds 22.7V. The gate

DD

TYPICAL IC APPLICATION

R

CIN

VIN

D

IN

D

1

VDD

GND

GATE

SENSE

Q1

RS

W

AUX

O

C

O

V

O

© System General Corp. - 1 - www.sg.com.tw
Version 1.0(IRO33.0002.B3) Dec.29, 2003

Product Specification

W

1

GN

WWV

N

Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback SG6849

MARKING INFORMATION PIN CONFIGURATION

MXYWW

1

1

8

SG6849-ZZZD

XXXXXXXYY

M: Mask Version

X: B= SG6849-65T

C= SG6849-100T

Y: Year

W

: Work Week

ZZZ: 65 or 100

XXXXXXX: Wafer Lot

YY: Year

WW: Week

V: Assembly Location

D

FB

NC

GATE

VDD

SENSE

SOT-26

GATE

6

2

3

5

VDD

4

SENSE

DIP-8

GND

1

2

C

8

FB

7

6

NC

NC

5

ORDERING INFORMATION

Part Number PWM Frequency Package

SG6849-65T 65kHz 6-Pin SOT-26

SG6849-100T 100kHz 6-Pin SOT-26

SG6849-65D 65kHz 8-pin DIP-8

SG6849-100D 100kHz 8-pin DIP-8

PIN DESCRIPTIONS

Name

GATE 1 6 Driver Output The totem-pole output driver to drive the power MOSFET.

VDD 2 5 Supply Power supply.

NC 3 NA NC pin.

SENSE 4 4 Analog Input

NC 5 3 NC pin.

NC 6 NA NC pin.

FB 7 2 Analog Input

GND 8 1 Supply Ground.

Pin No.

DIP-8 SOT-26

Type Function

Current s ense. It senses the voltage across a sensed r esistor. To provide over-c urrent

protection, PW M output is disabled if the voltage exceeds an internal thr eshold. This pin

also provides current information for current-mode control.

Feedback. The FB pin provides feedback information to the internal PWM compar ator.

This feedback is used to control the duty cycle. When no feedback is pr ovided, this pin is

left open.

© System General Corp. - 2 - www.sg.com.tw
Version 1.0(IRO33.0002.B3) Dec.29, 2003

Product Specification

p

r

Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback SG6849

BLOCK DIAGRAM

GND

VDD

2(5)

DIP-8(SOT-26)

8(1)

Internal
Supply

UVLO

17V/8V

OTP

SENSE

OSC

Green
Mode

Controller

S

R

Q

OCP

Comp

PWM
Comp

Com

Powe

Limiter

Slope

ensation

Σ

Driver

V

DD

VDD

VDDZ

Blanking

Circuit

4.5V

V

DD

GATE

1(6)

SENSE

4(4)

FB

7(2)

© System General Corp. - 3 -

www.sg.com.tw

Version 1.0(IRO33.0002.B3) Dec.29, 2003

Product Specification

Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback SG6849

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

DC Supply Voltage*

VDD

VFB FB Pin Input Voltage -0.3 to 7 V

V

SENSE

PD Power Dissipation 300 mW

RθJA Thermal Resistance (Junction to A ir)

RθJC Thermal R esistanc e (Junction to Case)

TJ Operating Junction Temperature 150 °C

T

STG

T

L

*All volt age values, except differential voltages, are given with respect to the network ground terminal.

Zener Clamp

Zener Current

Sense Pin Input Voltage -0.3 to 7 V

SOT-26

DIP-8

SOT-26

DIP-8

Storage Temperature Range -55 to +150 °C

Lead Temperature (Soldering)

ESD Capability, Human Body Model 3.0 kV

ESD Capability, Machine Model 300 V

20 sec SOT-26

10 sec DIP-8

25

30

10

243.3

113.0

115

67.1

220

260

V

V

mA

°C/W

°C/W

°C

OPERATING CONDITIONS

Symbol Parameter Value Unit

VDD DC Supply Voltage <22.7 V

TA Operating Ambient T emperature -30 to +85 °C

ELECTRICAL CHARACTERISTICS (V

=15V, TA=25°C)

DD

Feedback Input Section

Symbol Parameter Test Condition Min. Typ. Max. Unit

IOZ Zero Duty-Cycle FB Input C urrent 1.15 1.4 mA

VFB Open Loop Voltage 4.5 V

RFB Input Impedance FB Input Current = 0.1mA 2.4 kΩ

V

V

DDZ

*The feedback input is pulled by a transistor that is controlled by the VDD signal while VDD V

Feedback Threshold Voltage*

DD

FB Input Current = 0mA 20 22.7 25 V

FB Input Current = 0.8mA 18 20 22 V

≧

.

DDZ

© System General Corp. - 4 -

www.sg.com.tw

Version 1.0(IRO33.0002.B3) Dec.29, 2003

Product Specification

Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback SG6849

Current Sense Section

Symbol Parameter Test Condition Min. Typ. Max. Unit

TPD Propagation Delay 100 ns

VDD = 20V 0.84 0.89 0.94 V

VTH,VA

Current Limiting Valley Threshold Voltage for 65kHz

Current Limiting Valley Threshold Voltage for 100kHz

T

ON

VDD = 15V 0.72 0.77 0.82 V

VDD = 10V 0.58 0.63 0.68 V

VDD = 20V 0.76 0.81 0.86 V

VDD = 15V 0.65 0.70 0.75 V

VDD = 10V 0.52 0.57 0.62 V

V

V

Ramp

T

OFF

LIMIT

TH, FT

0.77V

High-Line

Sense Voltage

Low-Line Sense

Voltage

V

TH,V A

0V

T

1

T

2

Oscillator Section

Symbol Parameter Test Condition Min. Typ. Max. Unit

F

SG6849–65 Frequency 60 65 70 kHz

OSC

F

SG6849–100 Frequency 92 100 108 kHz

OSC

F

Green-Mode Burst Back Frequency* 20 25 30 kHz

OSC-G-BK

F

I

FB-G-OFF

FDV Frequenc y Variation versus VDD Deviation VDD = 10 to 20V 2 %

V

*Please see the “Green-Mode Burst B ack (F

Green-Mode OFF Frequency* 0 kHz

OSC-G-OFF

Green-Mode OFF FB Input Current 0.9 1.15 1.4 mA

DD-TH-G

V

OFF

) and Green-Mode OFF Frequency (F

OSC-G-BK

-Low Threshold Voltage for Exiting Green-Mode

DD

V

DD

+1.0

OFF

OSC-G-OFF

V

DD

+1.5

OFF

) vs. VDD” curves.

V

OFF

DD

+2.0

V

© System General Corp. - 5 -

www.sg.com.tw

Version 1.0(IRO33.0002.B3) Dec.29, 2003