NOT RECOMMENDED FOR NEW DESIGNS
SG6848x1 — Low Cost, Green-Mode PWM Controller for Flyback Converters
July 2014
SG6848x1
Low-Cost, Green-Mode PWM Controller for Flyback
Converters
Features
Green-Mode PWM Controller
Low Startup Current: 5
μA
Low Operating Current: 3 mA
Programmable PWM Frequency
Peak-Current-Mode Operation
Leading-Edge Blanking
Built-in Synchronized Slope Compensation
Cycle-by-Cycle Current Limiting
Constant Output Power Limit
Gate Output Voltage Clamped at 15 V
Small SSOT-6 Package
Applications
General-purpose switched-mode power supplies
(SMPS) and flyback power converters, such as:
Description
This highly integrated PWM controller provides several
enhancements to meet the low standby-power needs of
low-power SMPS. To minimize standby power
consumption, the proprietary Green Mode provides off-
time modulation to continuously decrease PWM
frequency under light-load conditions. Green Mode
enables the power supply to meet even strict power
conservation requirements.
The BiCMOS fabrication process enables reducing the
startup current to 5
μA
and the operating current to
3 mA. As a result, a large startup 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 (90 V
AC
to
264 V
AC
). Cycle-by-cycle current limiting ensures safe
operation during short-circuits.
To protect the external power MOSFET from damage by
supply over voltage, the SG6848X1 output driver is
clamped at 15 V. The SG6848X1 controllers can be
used to improve the performance and reduce the
production cost of power supplies. The SG6848X1 can
replace linear and RCC power supplies. It is available in
DIP-8 and SSOT-6 packages.
Battery chargers for cellular phones, cordless phones,
PDAs, digital cameras, and power tools
consoles, and portable audio players
Power adapters for ink jet printers, video game
Open-frame SMPS for TV/DVD standby and auxiliary
supplies, home appliances, and consumer electronics
Replacements for linear transformers and RCC SMPS
PC 5 V Standby Power
Ordering Information
Part Number
SG6848TZ1
SG6848DZ1
SG6848DY1
Operating
Temperature Range
-40 to +105°C
-40 to +105°C
-40 to +105°C
Package
6-Lead, SUPERSOT™-6, JEDEC MO-193, 1.6 mm Wide
8-Lead, MDIP, JEDEC MS-001, .300" Wide, Two Dap
8-Lead, MDIP, JEDEC MS-001, .300" Wide, Two Dap
Packing
Method
Tape & Reel
Tube
Tube
© 2007 Fairchild Semiconductor Corporation
SG6848x1 • Rev. 1.4.2
www.fairchildsemi.com
NOT RECOMMENDED FOR NEW DESIGNS
SG6848x1 — Low-Cost, Green-Mode PWM Controller for Flyback Converters
Pin Configurations
Figure 4.
SSOT-6 Pin Configuration
Figure 5.
DIP-8 Pin Configuration
Pin Definitions
DIP
Pin #
1
2
3
4
4
SSOT
Pin #
6
5
Name
GATE
VDD
NC
Description
The totem-pole output driver for driving the power MOSFET
Power supply
No connection
Current sense. This pin senses the voltage across a resistor. When the voltage reaches
SENSE the internal threshold, PWM output is disabled. This activates over-current protection.
This pin also provides current amplitude information for current-mode control.
A resistor connected from the RI pin to ground generates a constant current source
used to charge an internal capacitor and determine the switching frequency. Increasing
the resistance reduces the amplitude of the current source and the switching frequency.
A 95 kΩ resistor, R
I
, results in a 50
μA
constant current, I
I
, and a 70 kHz switching
frequency.
No connection
Feedback. The FB pin provides the output voltage regulation signal. It provides
feedback to the internal PWM comparator, so that the PWM comparator can control the
duty cycle.
Ground
5
3
RI
6
7
8
2
1
NC
FB
GND
© 2007 Fairchild Semiconductor Corporation
SG6848x1 • Rev. 1.4.2
www.fairchildsemi.com
4
NOT RECOMMENDED FOR NEW DESIGNS
SG6848x1 — Low-Cost, Green-Mode PWM Controller for Flyback Converters
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be
operable above the recommended operating conditions and stressing the parts to these levels is not recommended.
In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability.
The absolute maximum ratings are stress ratings only.
Symbol
V
VDD
V
FB
V
SENSE
T
J
Θ
JA
T
STG
T
L
ESD
DC Supply Voltage
(1,2)
Input Voltage to FB Pin
Parameter
Min.
-0.3
-0.3
SSOT
DIP
-55
Max.
25
6.0
6.0
150
208.4
82.5
+150
+260
3.0
300
Unit
V
V
V
°C
°C/W
°C/W
°C
°C
kV
V
Input Voltage to Sense Pin
Operating Junction Temperature
Thermal Resistance; Junction-to-Air
Storage Temperature Range
Lead Temperature; Wave Soldering or IR, 10 Seconds
Human Body Model, JESD22-A114
Machine Model, JESD22-A115
Notes:
1. All voltage values, except differential voltages, are given with respect to GND pin.
2. Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device.
© 2007 Fairchild Semiconductor Corporation
SG6848x1 • Rev. 1.4.2
www.fairchildsemi.com
5
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