sg6741tp Fairchild Semiconductor, sg6741tp Datasheet

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sg6741tp

Manufacturer Part Number
sg6741tp
Description
Sg6741-highly-integrated Green-mode Pwm Controller
Manufacturer
Fairchild Semiconductor
Datasheet
Highly-Integrated Green-Mode PWM Controller
FEATURES
APPLICATIONS
General-purpose switch-mode power supplies and
flyback power converters, including:
DESCRIPTION
The highly integrated SG6741 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
TYPICAL APPLICATION
© System General Corp.
Version 1.3.1 (IAO33.0047.B3)
Power adapters
Open-frame SMPS
High-voltage start-up
Low operating current (4mA)
Linearly decreasing PWM frequency to 22kHz
Frequency hopping to reduce EMI emission
Peak-current-mode control
Cycle-by-cycle current limiting
Leading-edge blanking
Synchronized slope compensation
Gate output maximum voltage clamp (18V)
V
V
Internal open-loop protection
Constant power limit (full AC input range)
DD
DD
over-voltage protection (auto restart)
under-voltage lockout (UVLO)
- 1 -
linearly decrease the switching frequency at light-load
conditions. To avoid acoustic-noise problems, the
minimum PWM frequency is set above 22KHz. This
green-mode function enables the power supply to meet
international power conservation requirements. With the
internal high-voltage start-up circuitry, the power loss due
to bleeding resistors is also eliminated. To further reduce
power consumption, SG6741 is manufactured using the
BiCMOS process, which allows operating current as low
as 4mA.
SG6741 integrates a frequency-hopping function that
helps reduce EMI emission of a power supply with
minimum line filters. Its built-in synchronized slope
compensation achieves stable peak-current-mode control.
The proprietary internal line compensation ensures
constant output power limit over a wide range of AC input
voltages, from 90VAC to 264VAC.
SG6741 provides many protection functions. In addition
to cycle-by-cycle current limiting, the internal open-loop
protection circuit ensures safety when an open-loop or
output short-circuit failure occurs. PWM output is
disabled until V
then the controller starts again. As long as V
about 26V, the internal OVP circuit is triggered.
SG6741 is available in an 8-pin DIP or SOP package.
www.sg.com.tw • www.fairchildsemi.com
DD
drops below the UVLO lower limit;
Product Specification
October 30, 2007
DD
SG6741
exceeds

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sg6741tp Summary of contents

Page 1

Highly-Integrated Green-Mode PWM Controller FEATURES High-voltage start-up Low operating current (4mA) Linearly decreasing PWM frequency to 22kHz Frequency hopping to reduce EMI emission Peak-current-mode control Cycle-by-cycle current limiting Leading-edge blanking Synchronized slope compensation Gate output maximum voltage clamp (18V) V ...

Page 2

... Highly-Integrated Green-Mode PWM Controller MARKING INFORMATION SOP P: Z =Lead Free Null=regular package SG6741TP XXXXXXXX: Y: Year; WW: Week XXXXXXXXYWWV V: Assembly Location ORDERING INFORMATION Part Number Pb-Free SG6741SZ PIN DESCRIPTIONS Pin No. Symbol Function 1 GND Ground 2 FB Feedback Start-up Input 5 RI Reference Setting ...

Page 3

Highly-Integrated Green-Mode PWM Controller BLOCK DIAGRAM © System General Corp. Version 1.3.1 (IAO33.0047.B3 www.sg.com.tw • www.fairchildsemi.com Product Specification SG6741 October 30, 2007 ...

Page 4

Highly-Integrated Green-Mode PWM Controller ABSOLUTE MAXIMUM RATINGS Symbol Parameter V Supply Voltage DD V Input Voltage to HV Pin HV V Input Voltage to FB, SENSE, Pin L P Power Dissipation, T < 50° Thermal Resistance, Junction-to-Air ...

Page 5

Highly-Integrated Green-Mode PWM Controller Oscillator Section Symbol Parameter F Frequency in Nominal Mode OSC t Hopping Period HOP F Green-Mode Frequency OSC-G F Frequency Variation vs Frequency Variation vs. Temp. Deviation DT Feedback Input Section Symbol ...

Page 6

Highly-Integrated Green-Mode PWM Controller Gate Section Symbol Parameter DCY Maximum Duty Cycle MAX V Gate Low Voltage GATE-L V Gate High Voltage GATE-H tr Gate Rising Time tf Gate Falling Time I Gate Source Current GATE-SOURCE V Gate Output Clamping ...

Page 7

Highly-Integrated Green-Mode PWM Controller TYPICAL CHARACTERISTIC Start-up Current ( Temperature DD- -40 -25 - Temperature (℃) Start Threshold Voltage ( Temperature DD-ON 20.0 19.0 18.0 17.0 ...

Page 8

Highly-Integrated Green-Mode PWM Controller Frequency in nominal mode ( Temperature OSC -40 -25 - Temperature (℃) . © System General Corp. Version 1.3.1 (IAO33.0047.B3) Maximum Duty Cycle (DCY ...

Page 9

Highly-Integrated Green-Mode PWM Controller Operation Description Start-up Current For start-up, the HV pin is connected to the line input or bulk capacitor through an external resistor, R recommended as 100KΩ. Typical start-up current drawn from pin HV is 2mA and ...

Page 10

Highly-Integrated Green-Mode PWM Controller Built-in Slope Compensation The sensed voltage across the current-sense resistor is used for peak-current-mode control and pulse-by-pulse current limiting. Built-in slope compensation improves stability and prevents sub-harmonic oscillation. SG6741 inserts a synchronized positive-going ramp at every ...

Page 11

Highly-Integrated Green-Mode PWM Controller REFERENCE CIRCUIT CIRCUIT (12V/5A) CN1 CN1 R3 SG6741 GND GATE VDD C12 SENSE BOM Reference Component ...

Page 12

Highly-Integrated Green-Mode PWM Controller PACKAGE INFORMATION 8PINS-SOP( Dimensions Millimeter Symbol Min. A 1.346 A1 0.101 4.648 E 3.810 e 1.016 F H 5.791 L 0.406 θ˚ 0° © System General Corp. Version 1.3.1 ...

Page 13

Highly-Integrated Green-Mode PWM Controller © System General Corp. Version 1.3.1 (IAO33.0047.B3 www.sg.com.tw • www.fairchildsemi.com Product specification SG6741 October 30, 2007 ...

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