Highly Integrated Green-Mode PWM Controller
FEATURES
Green-Mode PWM Controller
Low Start-up Current (14µA)
Low Operating Current (4mA)
Programmable PWM Frequency with Hopping
(5842JA)
Peak-Current-Mode Control
Cycle-by-Cycle Current Limiting
Synchronized Slope Compensation
Leading-Edge Blanking
Constant Output Power Limit
Totem Pole Output with Soft Driving
VDD Over-Voltage Protection (OVP)
Programmable Over-Temperature Protection (OTP)
www.DataSheet4U.cInotemrnal Latch Circuit (OTP, OVP)
Internal Open-Loop Protection
VDD Under-Voltage Lockout (UVLO)
GATE Output Maximum Voltage Clamp (18V)
APPLICATIONS
General-purpose switch mode power supplies and flyback
power converters, including:
Notebook Power Adapters
Open-Frame SMPS
DESCRIPTION
The highly integrated SG5842A/JA series of PWM
controllers provides several features to enhance the
performance of flyback converters.
Product Specification
SG5842A/JA
To minimize standby power consumption, a proprietary
green-mode function provides off-time modulation to
continuously decrease the switching frequency at
light-load conditions. To avoid acoustic-noise problem,
the minimum PWM frequency set above 22KHz. This
green-mode function enables the power supply to meet
international power conservation requirements. To further
reduce power consumption, SG5842A/JA is
manufactured using the BiCMOS process. This allows a
low start-up current, around 14µA, and an operating
current of only 4mA. As a result, a large start-up
resistance can be used.
The SG5842A/JA built-in synchronized slope
compensation achieves stable peak-current-mode control.
SG5842JA integrates a frequency hopping function that
helps reduce EMI emission of a power supply with
minimum line filters.
SG5842A/JA provides many protection functions. In
addition to cycle-by-cycle current limiting, the internal
open-loop protection circuit ensures safety should an open
loop or output short-circuit failure occur. PWM output is
disabled until VDD drops below the UVLO lower limit,
then the controller starts again. As long as VDD exceeds
about 24V, the internal OVP circuit is triggered. An
external NTC thermistor can be applied for
over-temperature protection.
SG5842A/JA is available in an 8-pin DIP or SOP package.
TYPICAL APPLICATION
SG5842A/JA
© System General Corp.
Version 1.4.2 (IAO33.0026.B6)
-1-
www.sg.com.tw • www.fairchildsemi.com
October 30, 2007
