sg5851 Fairchild Semiconductor, sg5851 Datasheet

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sg5851

Manufacturer Part Number
sg5851
Description
Sg5851 ? Low-cost Green-mode Pwm Controller For Flyback Converters
Manufacturer
Fairchild Semiconductor
Datasheet

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Part Number:
sg5851SZ
Manufacturer:
SYSTENG
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© 2007 Fairchild Semiconductor Corporation
SG5851 • Rev. 1.0.0
SG5851
Low-Cost Green-Mode PWM Controller for Flyback
Converters
Features
Applications
Ordering Information
SG5851SZ
SG5851DZ
Part Number
All packages are lead free per JEDEC: J-STD-020B standard.
Green-Mode PWM
Supports the “Blue Angel” Standard
Low Start-up Current: 9µA
Low Operating Current: 3mA
Leading-Edge Blanking
Constant Output Power Limit
Universal Input
Built-in Synchronized Slope Compensation
Current Mode Operation
Cycle-by-cycle Current Limiting
Under-Voltage Lockout (UVLO)
Programmable PWM Frequency with Frequency
Hopping
V
Gate Output Voltage Clamped at 17V
Low Cost
Few External Components Required
Power Adaptors
Open-Frame SMPS
DD
Over-Voltage Protection (Auto Restart)
Operating Temperature Range
-40°C to +85°C
-40°C to +85°C
8-pin Small Outline Package (SOP)
8-pin Dual in-line Package (DIP)
Description
This highly integrated PWM controller provides several
special enhancements designed to meet the low
standby-power needs of low-power SMPS. To minimize
standby power consumption, the proprietary green-
mode function provides off-time modulation to linearly
decrease the switching frequency under light-load
conditions. This green-mode function enables the
power supply to meet even the strictest power
conservation requirements.
The BiCMOS fabrication process enables reducing the
start-up current to 9µA and the operating current to
3mA. To further improve power conservation, a large
start-up resistance can be used. Built-in synchronized
slope compensation ensures the stability of peak
current mode control. Proprietary internal compensation
provides a constant output power limit over a universal
AC input range (90V
current limiting ensures safe operation even during
short-circuit conditions.
To protect the external power MOSFET from being
damaged by supply over voltage, the output driver is
clamped at 17V. SG5851 controllers, available in an
SOP package, can be used to improve the performance
and reduce the production cost of power supplies.
Package
AC
to 264V
AC
Packing Method
). Pulse-by-pulse
Tape & Reel
February 2008
www.fairchildsemi.com
Rail

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sg5851 Summary of contents

Page 1

... To protect the external power MOSFET from being damaged by supply over voltage, the output driver is clamped at 17V. SG5851 controllers, available in an SOP package, can be used to improve the performance and reduce the production cost of power supplies. -40°C to +85°C 8-pin Small Outline Package (SOP) -40° ...

Page 2

... Application Diagram Block Diagram © 2007 Fairchild Semiconductor Corporation SG5851 • Rev. 1.0.0 Figure 1. Typical Application Figure 2. Function Block Diagram 2 www.fairchildsemi.com ...

Page 3

... PWM output is disabled. This activates over-current protection. This pin also provides current amplitude information for current-mode control. 7 VDD Power Supply. 8 GATE Driver Output. The totem-pole output driver for driving the power MOSFET. © 2007 Fairchild Semiconductor Corporation SG5851 • Rev. 1.0 VDD SENSE ...

Page 4

... The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to Absolute Maximum Ratings. Symbol T Operating Ambient Temperature A © 2007 Fairchild Semiconductor Corporation SG5851 • Rev. 1.0.0 Parameter Parameter 4 Min. Max. Unit ...

Page 5

... Output Voltage Low GATE-L V Output Voltage High GATE-H t Rising Time r t Falling Time f V GATE- Output Clamp Voltage CLAMP © 2007 Fairchild Semiconductor Corporation SG5851 • Rev. 1.0.0 Conditions V =V – 0.1V DD DD-ON V =15V, GATE with DD 1nF to GND Auto Restart Auto Restart R =95KΩ =13 ...

Page 6

... This UVLO hysteresis window ensures that the hold-up capacitor is adequate to supply V Gate Output The SG5851 BiCMOS output stage is a fast totem-pole gate driver. Cross conduction has been avoided to minimize heat dissipation, increase efficiency, and enhance reliability. The output driver is clamped by an internal 17V Zener diode to protect power MOSFET transistors against undesired over-voltage gate signals ...

Page 7

... Temperature ( ℃ ) Figure 6. I DD-ST 70.0 69.8 69.6 69.4 69.2 69.0 -40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ Temperature (℃) Figure 8. f OSC © 2007 Fairchild Semiconductor Corporation SG5851 • Rev. 1.0.0 14.000 13.000 12.000 11.000 10.000 9.000 8.000 vs 2.000 1.800 1.600 1.400 1.200 -40℃ -25℃ -10℃ 5℃ vs ...

Page 8

... Temperature (℃) Figure 12. t LEB © 2007 Fairchild Semiconductor Corporation SG5851 • Rev. 1.0.0 2.30 2.28 2.26 2.24 2.22 2.20 65℃ 80℃ 95℃ 110℃ 125℃ vs 65℃ 80℃ 95℃ 110℃ 125℃ ...

Page 9

... Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/ © 2007 Fairchild Semiconductor Corporation SG5851 • Rev. 1.0 ...

Page 10

... Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/ © 2007 Fairchild Semiconductor Corporation SG5851 • Rev. 1.0.0 (Continued ...

Page 11

... Fairchild Semiconductor Corporation SG5851 • Rev. 1.0.0 11 www.fairchildsemi.com ...

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