When you plug into a power receptacle anywhere in the world, more than likely the plug you are holding links
you to an off-line AC to DC power converter. The heart of today’s off-line converter is an integrated circuit (IC)
that not only contains the Pulse Width Modulation (PWM) circuitry and a power MOSFET converter that is
required for efficient conversion from AC to DC but also integrates a myriad of control and protection circuitry
that makes yesterday’s off-line converters bulky by comparison. Fairchild Power Switch (FPS™) is a family of
products that combines the avalanche rugged power SenseFET with state-of-the-art PWM circuitry to address a
variety of Switch Mode Power Supplies (SMPS).
An FPS™ IC contains protection against excessive heating within the converter, overloading of any DC output,
excessive currents that could damage the power MOSFET and excessive voltage of controlled DC output. These
necessary protection features are combined with advanced control features such as burst mode operation for
low standby power, a precision oscillator with frequency modulation to minimize EMI, and soft start.
Fairchild offers two design approaches:
1) Parallel dice, with SenseFET and PWM die side-by-side in one package,
2) Single die, monolithic design
The choice of these approaches allow cost-effective designs for a broad range of applications that include
chargers, adapters, set top boxes, VCR, DVD players, LCD and CRT TVs, LCD and CRT monitors, white goods,
PCs, notebooks and assorted household appliances.
The integration level is optimal and minimizes component count and saves board space. The FPS™ concept
provides cost-effective solutions for Flyback and Forward Converter topologies with outstanding reliability.
Combined with years of manufacturing expertise, these state-of-the-art off-line power switching solutions provide
the designers with the ability to do rapid production ramp-ups of their advanced SMPS design.
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.fair
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5
FPS™Design Guide
+
–
~~
AC
Input
Vo
Softstart
Frequency
Setting
Current
Sensing
MOSFET
Drive
PWM
Controller
Startup
Resistor
MOSFET
UC3842
Comp
Vref
RtCt
Isense
Vfb
Vcc
Out
GND
FPS™ Integrated Solution
Optimally Integrated Solution for Off-Line Switch Mode Power Supplies
• Integrated features in a single package
– SenseFET
– PWM controller
– Gate drive circuit
equency oscillator
ecise fr
– Pr
• Additional functions
– Startup circuit with soft start
– Frequency modulation
– Burst operation
• Protection function
– Over load protection
– Over voltage protection
– Over current protection
ent limit
– Pulse by pulse cur
– Over temperature protection
r
6
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Green FPS™ – New FPS™ Family
Output Power GreenFPS™
Additional Features Application Example
Level Part Number
Low Power FSD200 Self biasing (FSD200) Charger
FSD210 Frequency modulation Auxiliary supply (for small display or controller
FS
DM311 Burst mode
boards in white goods for example)
FS
DL312 Built-in startup
Soft start
Medium Power
FSD1000 Auxiliary supplies PC main supply and PC auxiliary supply
(FPS with main power PWM integrated)
Burst mode
Programmable soft start
Internal startup
FS
DL0165RN Frequency modulation DVD player and auxiliary supply
FS
DH0265RN Built-in startup DVD player
FS
DM0265RN Soft start Digital Still Camera (DSC)
FSDL0365RN Burst mode DVD R/W
FSDM0365RN Programmable current limit LCD monitor
Digital Still Camera (DSC)
Set top box
FSDM0565R Bulit-in startup LCD monitor
FSDM07652R Soft start Notebook adapter
Burst mode Set top box
High Power FSCQ0765RT* Burst mode Color TV
FSCQ15658RT* Reducing IC current DVD receiver
Maximum frequency limit Plasma display panel
Soft start with fast settling
* Product in development
FPS™Design Guide
Green FPS™ is a New Family of FPS™ Products:
• Used in low standby power applications that meet the less than
att standar
1 W
• Suppor
• Integrated solution of multiple protection and control features built with the power
www
ts envir
switch MOSFET available in a very small package
.fair
childsemi.com/fps
ds (i.e. EnergyStar)
onmentally friendly systems
7
FPS™Design Guide
Snubber
Circuit
Load
+
+
++
Feedback
Circuit
Control
IC
FPS™
FPS™ Parallel Dice Solution
(Side-by- Side)
GNDVccIpkFB
Drain
Drain
VstrDrain
SenseFET
PWM
IC
FPS™ Single Die Solution
(BCDMOS)
GND
GNDVFBGND
Vstr
Drain
Vcc
Green FPS™ Features and Advantages
Simplified Application Cir
cuit for FPS
™
Featur
es
• Optimal Solution for Off-Line SMPS
• Integrated Avalanche Rugged SenseFET
• Pulse-by-Pulse Current Limiting
• Various Protection Functions
(Over Voltage, Over Load, Over
Current, Thermal Shutdown)
• Burst Mode Operation for Low
Standby Power
• Frequency Modulation for Reduced EMI
• Soft Start Function
• Operation Fr
equency Options
(50/70/100/134kHz)
• External Frequency Synchronization
• Quasi Resonant
Advantages
• Low Standby Consumption with Burst Mode Operation
• Fully Avalanche Rugged, 650V and 800V SenseFETs Improves Reliability
Reduced EMI with Fully Integrated Frequency Modulation
•
• Reduces the Total Bill-of-Materials Cost with Integrated Protection and Control Functions
oad Application Coverage with Extensive Exper
• Br
tise and Easy-to-Use Design T
8
ools
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FPS™Design Guide
Current
Waveform
Feedback
Waveform
Burst
Operation
Normal Operation
Not
Switching
Not
Switching
V
BURSTH
V
BURSTL
standbynormal
standbynormal
Burst Operation @ 85VAC Burst Operation @ 265VAC
Green FPS™ Feature – Burst Mode Operation
(Refer to schematic in Typical Application Circuit 40W Isolated Flyback Power Supply on page 24)
• In standby mode, outputs draw very little to no load current
• Output voltages increase causing the feedback voltage to decrease
• When the feedback voltage goes below VBURSTL threshold, switching stops in the FPS device
saving considerable power
• Depending on load current, the output voltages will eventually fall causing the feedback voltage to increase
• Once the feedback voltage crosses VBURSTH threshold, switching starts again
• A 5V output FSD210 board at 265V in no load standby consumes a mere 92mW
Below shows the waveforms of both normal and standby modes at the voltage extremes for the universal
voltage range.
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