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System General
System General

SG5842JA Datasheet Preview

SG5842JA Datasheet

Highly Integrated Green-Mode PWM Controller

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SG5842JA pdf
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.DataSheet„4U.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



System General
System General

SG5842JA Datasheet Preview

SG5842JA Datasheet

Highly Integrated Green-Mode PWM Controller

No Preview Available !

SG5842JA pdf
Highly Integrated Green-Mode PWM Controller
MARKING DIAGRAMS
SG5842HATP
XXXXXXXXYWWV
H: J = with Frequency Hopping
Null = without Frequency
Hopping
T: D = DIP, S = SOP
P: Z = Lead Free
Null = regular package
XXXXXXXX: Wafer Lot
Y: Year; WW: Week
V: Assembly Location
Product Specification
SG5842A/JA
PIN CONFIGURATION
GND
FB
VIN
RI
GATE
VDD
SENSE
RT
ORDERING INFORMATION
www.DataSheetP4aUr.tcNoummber
OTP Latch OVP Latch Frequency Hopping Pb-Free
SG5842JASZ
Yes Yes Yes
SG5842JADZ
Yes Yes Yes
SG5842ASZ (Preliminary) Yes Yes No
SG5842ADZ (Preliminary Yes Yes No
Package
8-Pin SOP
8-Pin DIP
8-Pin SOP
8-Pin DIP
PIN DESCRIPTIONS
Pin No. Symbol Function Description
1
GND
Ground
Ground.
The signal from the external compensation circuit is fed into this pin. The PWM duty cycle is
2
FB
Feedback
determined in response to the signal from this pin and the current-sense signal from Pin 6. If FB
voltage exceeds the threshold, the internal protection circuit disables PWM output after a
predetermined delay time.
For start-up, this pin is pulled high to the rectified line input via a resistor. Since the start-up
3 VIN Start-up Input current requirement of the SG5842A/JA is very small, a large start-up resistance can be used
to minimize power loss.
4
RI
Reference
Setting
A resistor connected from the RI pin to GND pin provides a constant current source. This
determines the center PWM frequency. Increasing the resistance reduces PWM frequency.
Using a 26Kresistor results in a 65KHz center PWM frequency.
5
RT
Temperature
Detection
For over-temperature protection. An external NTC thermistor is connected from this pin to the
GND pin. The impedance of the NTC decreases at high temperatures. Once the voltage of the
RT pin drops below a fixed limit, PWM output is latched off.
6
SENSE
Current Sense
Current sense. The sensed voltage is used for peak-current-mode control and cycle-by-cycle
current limiting.
7
VDD
Power Supply Power supply. The internal protection circuit disables PWM output if VDD is over-voltage.
8
GATE
Driver Output The totem-pole output driver for the power MOSFET, which is internally clamped below 18V.
© System General Corp.
Version 1.4.2 (IAO33.0026.B6)
- 2 - www.sg.com.tw • www.fairchildsemi.com
October 30, 2007


Part Number SG5842JA
Description Highly Integrated Green-Mode PWM Controller
Maker System General
Total Page 14 Pages
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