Fairchild FPS Series Guida
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Building Block
Solutions for
Multi-Market
Applications
FPS™Design Guide
Fairchild Semiconductor
FPS™Fairchild’s Power Switch for
Switch Mode Power Supply
Design Guide
3
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FPS™Design Guide
What is Fairchild Power Switch FPS™ .......................................................................................................5
FPS™ Integrated Solution .........................................................................................................................6
Green FPS™ – New FPS™ Family.............................................................................................................7
Green FPS™ Features and Advantages......................................................................................................8
Burst Mode Operation .......................................................................................................................9
Frequency Modulation for EMI..........................................................................................................10
Over Load Protection .......................................................................................................................11
FPS™ Core Products..............................................................................................................................12
Complete FPS™ Product Offering Sorted by Output Power.........................................................................13
Typical Applications ..............................................................................................................................14
Examples of Typical Application Circuits .............................................................................................15-26
1W Power Supply with Less Than 100mW Standby Power..................................................................15
Dual Negative Output Non-Isolated Flyback .......................................................................................16
2.5W Single Output Isolated Flyback Using FSD200 with KA431 Reference .........................................17
10W Single Output Isolated Flyback Using FSDM0265R and Zener Diode ...........................................18
10W Multiple Output Isolated Flyback Using FSD210 with Primary Side Regulation...............................19
5W Buck Converter Using FSDL0165RN ...........................................................................................20
16W Multiple Output Isolated Flyback Converter Using FSDM0265RN.................................................21
180W–200W KA5Q1265RF Quasi-resonant Flyback with Input Power
Factor Correction Using FAN7527B/FQP13N50C.........................................................................22-23
40W Isolated Flyback Power Supply .................................................................................................24
24W Single Output 48V DC/DC Flyback Converter ...........................................................................25
Secondary Side Synchronous Rectification in a Power Over Ethernet Application ...................................26
Design Tools .........................................................................................................................................27
Ordering Guide ....................................................................................................................................28
Table Of Contents
5
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FPS™Design Guide
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.
What is Fairchild Power Switch (FPS™)
6
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FPS™Design Guide
Optimally Integrated Solution for Off-Line Switch Mode Power Supplies
• Integrated features in a single package
– SenseFET
– PWM controller
– Gate drive circuit
– Precise frequency oscillator
• Additional functions
– Startup circuit with soft start
– Frequency modulation
– Burst operation
• Protection function
– Over load protection
– Over voltage protection
– Over current protection
– Pulse by pulse current limit
– Over temperature protection
+
–
~~
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
7
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FPS™Design Guide
Green FPS™ – New FPS™ Family
Green FPS™ is a New Family of FPS™ Products:
• Used in low standby power applications that meet the less than
1 Watt standards (i.e. EnergyStar)
• Supports environmentally friendly systems
• Integrated solution of multiple protection and control features built with the power
switch MOSFET available in a very small package
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
8
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FPS™Design Guide
Simplified Application Circuit for FPS™Features
• 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 Frequency Options
(50/70/100/134kHz)
• External Frequency Synchronization
• Quasi Resonant
Snubber
Circuit Load
+
+++
Feedback
Circuit
Control
IC
FPS
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
• Broad Application Coverage with Extensive Expertise and Easy-to-Use Design Tools
Green FPS™ Features and Advantages
FPS™ Parallel Dice Solution
(Side-by-Side)
GNDVccIpk FB
Drain
Drain
Vstr Drain
SenseFET
PWM
IC
FPS™ Single Die Solution
(BCDMOS)
GND
GNDVFB GND
Vstr
Drain
Vcc
9
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FPS™Design Guide
Green FPS™ Feature – Burst Mode Operation
Current
Waveform
Feedback
Waveform
Burst
Operation
Normal Operation
Not
Switching
Not
Switching
V
BURSTH
V
BURSTL
(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.
standby normal standby normal
Burst Operation @ 85VAC Burst Operation @ 265VAC
10
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FPS™Design Guide
Green FPS™ Feature – Frequency Modulation for EMI
130kHz
131kHz
132kHz
133kHz
134kHz
135kHz
136kHz
137kHz
138kHz
2mS
A
B
C
130kHz134kHz
138kHz
Sawtooth
Waveform
Ton
Vfb
Vdrain
Idrain
ABC
• Fixed frequency oscillators generate Electromagnetic
Interference (EMI) in a narrow band of the frequency spectrum
• Fairchild’s latest FPS devices modulate its frequency over a
±4kHz frequency range
• EMI is thus spread over a wider range of frequencies
• Allows simple EMI filters to be employed for meeting world
wide EMI requirements
•Refer to Application Note AN-4145 Electromagnetic
Compatibility for Power Converters for additional information
Below shows the frequency spectrum waveforms of a fixed frequency device versus a device that employs
frequency modulation.
100kHz Fixed Frequency
FSDH0165
134kHz with Frequency Modulation
FSD210
Peak Level Limit
Peak Level Limit
Peak Waveform
Quasi Peak Waveform
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