© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
FSFM260N / FSFM300N Rev. 1.0.0
April 2009
FSFM260N / FSFM300N
Green-Mode Fairchild Power Switch (FPS™)
Features
!Internal Avalanche-Rugged SenseFET
!Advanced Burst-Mode Operation Consumes Under
1W at 240VAC and 0.5W Load
!Precision Fixed Operating Frequency: 67kHz
!Internal Startup Circuit
!Over-Voltage Protection (OVP)
!Overload Protection (OLP)
!Internal Thermal Shutdown Function (TSD)
!Abnormal Over-Current Protection (AOCP)
!Auto-Restart Mode
!Under-Voltage Lockout (UVLO) with Hysteresis
!Low Operating Current: 2.5mA
!Built-in Soft-Start: 15ms
Applications
!Power Supply for LCD TV and Monitor, VCR, SVR,
STB, DVD, and DVD Recorder
!Adapter
Related Resources
Visit: http://www.fairchildsemi.com/apnotes/ for:
!AN-4134: Design Guidelines for Offline Forward
Converters Using Fairchild Power Switch (FPS)
!AN-4137: Design Guidelines for Offline Flyback
Converters Using Fairchild Power Switch (FPS)
!AN-4140: Transformer Design Consideration for
Offline Flyback Converters Using Fairchild Power
Switch (FPS)
!AN-4141: Troubleshooting and Design Tips for
Fairchild Power Switch (FPS) Flyback Applications
!AN-4145: Electromagnetic Compatibility for Power
Converters
!AN-4147: Design Guidelines for RCD Snubber of
Flyback Converters
!AN-4148: Audible Noise Reduction Techniques for
Fairchild Power Switch (FPS™) Applications
Description
The FSFM260/300 is an integrated Pulse Width
Modulator (PWM) and SenseFET specifically designed
for high-performance offline Switch Mode Power
Supplies (SMPS) with minimal external components.
This device is an integrated high-voltage power-
switching regulator that combines an avalanche-rugged
SenseFET with a current-mode PWM control block. The
PWM controller includes an integrated fixed-frequency
oscillator, under-voltage lockout, leading-edge blanking
(LEB), optimized gate driver, internal soft-start,
temperature-compensated precise-current sources for a
loop compensation, and self-protection circuitry.
Compared with discrete MOSFET and PWM controller
solutions, it can reduce total cost, component count, size,
and weight while simultaneously increasing efficiency,
productivity, and system reliability. This device is a basic
platform for cost-effective designs of flyback converters.
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 2
Ordering Information
Notes:
1. The junction temperature can limit the maximum output power.
2. 230VAC or 100/115VAC with doubler.
3. Typical continuous power in a non-ventilated enclosed adapter measured at 50°C ambient temperature.
4. Maximum practical continuous power in an open-frame design at 50°C ambient.
5. Eco status for both the FSFM2600N and FSFM300NS is RoHS.
For Fairchild’s definition of “green” Eco Status, please visit:
http://www.fairchildsemi.com/company/green/rohs_green.html. Eco Status: RoHS.
Product
Number PKG.(5) Operating
Temp.
Current
Limit
RDS(ON)
Max.
Maximum Output Power(1)
Replaces
Devices
230VAC±15%(2) 85-265VAC
Adapter(3) Open
Frame(4) Adapter(3) Open
Frame(4)
FSFM260N 8-DIP -25 to +85°C 1.5A 2.6Ω23W 35W 17W 26W FSDM0465RS
FSQ0465RS
FSFM300N 8-DIP -25 to +85°C 1.6A 2.2Ω26W 40W 20W 30W
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 3
Application Diagram
Figure 1. Typical Flyback Application
Internal Block Diagram
Figure 2. Internal Block Diagram
VCC
GND
Drain
VO
PWM
FB
AC
IN
VSTR
FSFM260 Rev. 00
ILIM
8V/12V
Vref
S
QR
VCC
Idelay IFB
VSD
VOVP
VOCP
S
Q
Q
R
R
2.5R
VCC good
VCC Drain
FB
GND
Gate
driver
VCC good
VBURL/VBURH
4
ILIM
OSC
Vstr
3
2 85
FSFM260 Rev.00
1
Q
VCC
VCC
76
TSD
Burst
Normal PWM
LEB
250ns
VCC
Soft-
Start
LPF
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 4
Pin Configuration
Figure 3. Pin Configuration (Top View)
Pin Definitions
Pin # Name Description
1GNDGround. This pin is the control ground and the SenseFET source.
2V
CC
Power Supply. This pin is the positive supply input, providing internal operating current for
both startup and steady-state operation.
3FB
Feedback. This pin is internally connected to the inverting input of the PWM comparator. The
collector of an opto-coupler is typically tied to this pin. For stable operation, a capacitor should
be placed between this pin and GND. If the voltage of this pin reaches 6V, the overload pro-
tection triggers, which shuts down the FPS.
4I
LIM
Peak Current Limit. Adjusts the peak current limit of the Sense FET. The feedback 0.9mA
current source is diverted to the parallel combination of an internal 2.8kΩ resistor and any ex-
ternal resistor to GND on this pin to determine the peak current limit.
5V
STR
Startup. This pin is connected directly, or through a resistor, to the high-voltage DC link. At
startup, the internal high-voltage current source supplies internal bias and charges the exter-
nal capacitor connected to the VCC pin. Once VCC reaches 12V, the internal current source is
disabled. It is not recommended to connect VSTR and drain together.
6,7,8 Drain SenseFET Drain. High-voltage power SenseFET drain connection.
GND
VCC
ILIM VSTR
8-DIP
FB
Drain
FSFM260 Rev.1.0.0
Drain
Drain
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 5
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be opera-
ble above the recommended operating conditions and stressing the parts to these levels is not recommended. In addi-
tion, extended exposure to stresses above the recommended operating conditions may affect device reliability. The
absolute maximum ratings are stress ratings only. TA = 25°C, unless otherwise specified.
Notes:
6. VFB is internally clamped and its maximum clamping current capability is 100μA.
7. Repetitive rating: pulse-width limited by maximum junction temperature.
8. L=14mH, starting TJ=25°C.
Thermal Impedance
TA = 25°C unless otherwise specified.
Notes:
9. Free standing with no heat-sink under natural convection.
10. Infinite cooling condition - refer to the SEMI G30-88.
11. Measured on the package top surface.
Symbol Parameter Min. Max. Unit
VSTR VSTR Pin Voltage 650 V
VDS Drain Pin Voltage 650 V
VCC Supply Voltage 21 V
VFB Feedback Voltage Range(6) -0.3 8.0 V
IDM Drain Current Pulsed 9.6 A
ID
Continuous Drain Current of
FSFM260(7)
TC = 25°C 2.2
A
TC = 100°C 1.4
Continuous Drain Current of
FSFM300(7)
TC = 25°C 2.8
TC = 100°C 1.7
EAS Single Pulsed Avalanche Energy(8) FSFM260 120 mJ
FSFM300 190
PDTotal Power Dissipation (TC=25°C) 1.5 W
TJOperating Junction Temperature Internally Limited °C
TAOperating Ambient Temperature -25 +85 °C
TSTG Storage Temperature -55 +150 °C
ESD
Electrostatic Discharge Capability Human Body Model,
JESD22-A114 2.0
kV
Electrostatic Discharge Capability, Charged Device Model,
JESD22-C110 2.0
Symbol Parameter Package Value Unit
θJA Junction-to-Ambient Thermal Resistance(9)
8-DIP
80 °C/W
θJC Junction-to-Case Thermal Resistance(10) 20 °C/W
ΨJT Junction-to-Top Thermal Resistance(11) 35 °C/W
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 6
Electrical Characteristics
TA = 25°C unless otherwise specified.
Symbol Parameter Condition Min. Typ. Max. Unit
SenseFET Section
BVDSS
Drain Source Breakdown Voltage
VCC = 0V, ID = 250µA 650 V
IDSS1 Zero Gate Voltage Drain Current1 VDS = 650V, VGS = 0V,
TC = 25°C 250 µA
IDSS2 Zero Gate Voltage Drain Current2 VDS = 520V, VGS = 0V,
TC = 125°C 250 µA
RDS(ON)
Static Drain Source on Resistance of
FSFM260(12)
VGS = 10V, ID = 2.5A
2.20 2.60 Ω
Static Drain Source on Resistance of
FSFM300(12) 1.76 2.20 Ω
COSS Output Capacitance of FSFM260 VGS = 0V, VDS = 25V, f = 1MHz 60 pF
td(on) Turn-On Delay Time of FSFM260
VDD = 325V, ID = 5A
23
ns
trRise Time of FSFM260 20
td(off) Turn-Off Delay Time of FSFM260 65
tfFall Time of FSFM260 27
COSS Output Capacitance of FSFM300 VGS = 0V, VDS = 25V, f = 1MHz 75 pF
td(on) Turn-On Delay Time of FSFM300
VDD = 325V, ID = 5A
14
ns
trRise Time of FSFM300 26
td(off) Turn-Off Delay Time of FSFM300 32
tfFall Time of FSFM300 25
Control Section
fOSC Switching Frequency VFB = 3V 61 67 73 kHz
ΔfSTABLE Switching Frequency Stability 13V VCC 18V 0 1 3 %
ΔfOSC Switching Frequency Variation(13) -25°C TA 85°C 0 ±5 ±10 %
IFB Feedback Source Current VFB = GND 0.7 0.9 1.1 mA
DMAX Maximum Duty Cycle 71 77 83 %
DMIN Minimum Duty Cycle 0 %
VSTART UVLO Threshold Voltage VFB = GND 11 12 13 V
VSTOP 789V
tS/S Internal Soft-Start Time VFB = 3V 10 15 20 ms
Burst Mode Section
VBURH Burst Mode Voltages VCC = 14V 0.50 V
VBURL 0.35 V
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 7
Electrical Characteristics (Continued)
TA = 25°C unless otherwise specified.
Notes:
12. Pulse test: pulse width 300µs, duty 2%.
13. Guaranteed by design; not tested in production.
Symbol Parameter Condition Min. Typ. Max. Unit
Protection Section
VSD Shutdown Feedback Voltage VFB 5.5V 5.5 6.0 6.5 V
IDELAY Shutdown Delay Current VFB = 5V 3.5 5.0 6.5 µA
tLEB Leading Edge Blanking Time(13) 200 ns
ILIMIT Peak Current Limit FSFM260 TJ = 25°C, di/dt = 200mA/µs 1.32 1.50 1.68 A
FSFM300 1.41 1.60 1.79
VOVP Over-Voltage Protection 18.0 19.0 20.5 V
TSD Thermal Shutdown Temperature(13) 125 140 °C
Total Device Section
IOP Operating Supply Current VFB = GND, VCC = 14V 135mA
ISTART Start Current VCC = 10V (before VCC
reaches VSTART)150 200 250 µA
ICH Startup Charging Current VCC = 0V, VSTR=min. 50V 0.70 0.85 1.00 mA
VSTR Minimum VSTR Supply Voltage at ISTRIN=ISTART 24 V
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 8
Typical Performance Characteristics
Graphs are normalized at TA= 25°C.
Figure 4. Operating Supply Current (IOP) vs. TAFigure 5. UVLO Start Threshold Voltage
(VSTART) vs. TA
Figure 6. UVLO Stop Threshold Voltage
(VSTOP) vs. TA
Figure 7. Startup Charging Current (ICH) vs. TA
Figure 8. Switching Frequency (fOSC) vs. TAFigure 9. Maximum Duty Cycle (DMAX) vs. TA
-25 0 25 50 75 100 125
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
Temperature [°C]
-25 0 25 50 75 100 125
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
Temperature [°C]
-25 0 25 50 75 100 125
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
Temperature [°C]
-25 0 25 50 75 100 125
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
Temperature [°C]
-25 0 25 50 75 100 125
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
Temperature [°C]
-25 0 25 50 75 100 125
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
Temperature [°C]
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 9
Typical Performance Characteristics (Continued)
Graphs are normalized at TA= 25°C.
Figure 10. Over-Voltage Protection (VOVP) vs. TAFigure 11. Feedback Source Current (IFB) vs. TA
Figure 12. Shutdown Delay Current (IDELAY) vs. TA Figure 13. Burst-Mode HIGH Threshold Voltage
(VBURH) vs. TA
Figure 14. Burst-Mode LOW Threshold Voltage
(VBURL) vs. TA
Figure 15. Peak Current Limit (ILIMIT) vs. TA
-25 0 25 50 75 100 125
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
Temperature [°C]
-25 0 25 50 75 100 125
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
Temperature [°C]
-25 0 25 50 75 100 125
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
Temperature [°C]
-25 0 25 50 75 100 125
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
Temperature [°C]
-25 0 25 50 75 100 125
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
Temperature [°C]
-25 0 25 50 75 100 125
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
Temperature [°C]
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 10
Functional Description
1. Startup: In previous generations of Fairchild Power
Switches (FPS™), the VCC pin had an external startup
resistor to the DC input voltage line. In this generation,
the startup resistor is replaced by an internal high-
voltage current source. At startup, an internal high-
voltage current source supplies the internal bias and
charges the external capacitor (Cvcc) connected to the
VCC pin, as illustrated in Figure 16. When VCC reaches
12V, the FSFM260/300 begins switching and the internal
high-voltage current source is disabled. Then, the
FSFM260/300 continues its normal switching operation
and the power is supplied from the auxiliary transformer
winding unless VCC goes below the stop voltage of 8V.
Figure 16. Internal Startup Circuit
2. Feedback Control: FSFM260/300 employs current-
mode control, as shown in Figure 17. An opto-coupler
(such as the FOD817A) and shunt regulator (such as the
KA431) are typically used to implement the feedback
network. Comparing the feedback voltage with the
voltage across the RSENSE resistor makes it possible to
control the switching duty cycle. When the reference pin
voltage of the shunt regulator exceeds the internal
reference voltage of 2.5V, the optocoupler LED current
increases, pulling down the feedback voltage and
reducing the duty cycle. This typically occurs when the
input voltage is increased or the output load is
decreased.
2.1 Pulse-by-Pulse Current Limit: Because current-
mode control is employed, the peak current through the
SenseFET is determined by the inverting input of the
PWM comparator (VFB*), as shown in Figure 17. When
the current through the opto-transistor is zero and the
current limit pin (#4) is left floating, the feedback current
source (IFB) of 0.9mA flows only through the internal
resistor (R+2.5R=2.8k). In this case, the cathode voltage
of diode D2 and the peak drain current have maximum
values of 2.5V and 1.5A, respectively. The pulse-by-
pulse current limit can be adjusted using a resistor to
GND on the current limit pin (#4). The current limit level
using an external resistor (RLIM) is given by:
where, ILIM is the desired drain current limit.
Figure 17. Pulse Width Modulation (PWM) Circuit
2.2 Leading-Edge Blanking (LEB): At the instant the
internal SenseFET is turned on, a high-current spike
occurs through the SenseFET, caused by primary-side
capacitance and secondary-side rectifier reverse
recovery. Excessive voltage across the RSENSE resistor
would lead to incorrect feedback operation in the current-
mode PWM control. To counter this effect, the FSFM260/
300 employs a leading edge blanking (LEB) circuit. This
circuit inhibits the PWM comparator for a short time
(tLEB) after the SenseFET is turned on.
2.3 Constant Power Limit Circuit: Due to the circuit
delay of FPS, the pulse-by-pulse limit current increases
a little bit when the input voltage increases. This means
unwanted excessive power is delivered to the secondary
side. To compensate, the auxiliary power compensation
network in Figure 18 can be used. RLIM can adjust pulse-
by-pulse current by absorbing internal current source
(IFB: typical value is 0.9mA) depending on the ratio
between resistors. With the suggested compensation
circuit, additional current from IFB is absorbed more
proportionally to the input voltage (VDC) and achieves
constant power in wide input range. Choose RLIM for
proper current to the application, then check the pulse-
by-pulse current difference between minimum and
maximum input voltage. To eliminate the difference (to
gain constant power), Ry can be calculated by:
8V/12V
2
Vref
Internal
Bias
VCC
5
Vstr
Istart
VCC good
VDC
CVcc
FSFM260 Rev: 00
(1)
LIM
SPE
C
LIMLIM
LIM Rk
IR
I+Ω
=8.2
_
(2)
LIMSPEC_LIM
LIM
LIM II
k8.2I
R
==>
Ω
3OSC
VCC VCC
Idelay IFB
VSD
R
2.5R
Gate
driver
OLP
D1 D2
+
Vfb*
-
Vfb
KA431
CB
VO
FOD817A
Rsense
SenseFET
FSFM260 Rev: 00
a
lim_spec dc
p
y
fb lim_comp
N
IV
N
RIΔI
××
×(3)
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 11
where, Ilim_spec is the limit current stated on the
specification; Na and Np are the number of turns for VCC
and primary side, respectively; Ifb is the internal current
source at feedback pin with a typical value of 0.9mA; and
ΔIlim_comp is the current difference that must be
eliminated. In case of capacitor in the circuit 1µF, 100V is
good choice for all applications.
Figure 18. Constant Power Limit Circuit
Figure 19. Auto Restart Operation
3. Protection Circuit: The FSFM260/300 has several
self protective functions, such as overload protection
(OLP), over-voltage protection (OVP), and thermal
shutdown (TSD). Because these protection circuits are
fully integrated into the IC without external components,
the reliability is improved without increasing cost. Once
the fault condition occurs, switching is terminated and
the SenseFET remains off. This causes VCC to fall.
When VCC reaches the UVLO stop voltage, 8V, the
protection is reset and the internal high-voltage current
source charges the VCC capacitor via the Vstr pin. When
VCC reaches the UVLO start voltage, 12V, the FSFM260/
300 resumes normal operation. In this manner, the auto-
restart can alternately enable and disable the switching
of the power SenseFET until the fault condition is
eliminated (see Figure 19).
3.1 Overload Protection (OLP): Overload is defined as
the load current exceeding a pre-set level due to an
unexpected event. In this situation, the protection circuit
should be activated to protect the SMPS. However, even
when the SMPS is in the normal operation, the overload
protection circuit can be activated during the load
transition. To avoid this undesired operation, the
overload protection circuit is designed to be activated
after a specified time to determine whether it is a
transient situation or an overload situation. Because of
the pulse-by-pulse current limit capability, the maximum
peak current through the SenseFET is limited and,
therefore the maximum input power is restricted with a
given input voltage. If the output consumes beyond this
maximum power, the output voltage (VO) decreases
below the set voltage. This reduces the current through
the opto-coupler LED, which also reduces the opto-
coupler transistor current, increasing the feedback
voltage (VFB). If VFB exceeds 2.5V, D1 is blocked and
the 5µA current source starts to charge CB slowly up to
VCC. In this condition, VFB continues increasing until it
reaches 6V, when the switching operation is terminated,
as shown in Figure 20. The delay time for shutdown is
the time required to charge CB from 2.5V to 6.0V with
5µA. In general, a 10 ~ 50ms delay time is typical for
most applications.
Figure 20. Overload Protection
Vfb Drain
Vcc
GND
I_lim
VDC Np
Na
-
+
CY
RY
RLIM
L
p
a
DCyN
N
VV ×=
compensation
network
FSFM260 Rev. 00
Fault
situation
8V
12V
Vcc
Vds
t
Fault
occurs Fault
removed
Normal
operation
Normal
operation
Power
on
FSFM260 Rev: 00
VFB
t
2.5V
6.0V
Overload protection
T12= Cfb*(6.0-2.5)/Idelay
T1T2
FSFM260 Rev: 00
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 12
3.2 Over-Voltage Protection (OVP): If the secondary
side feedback circuit malfunctions or a solder defect
causes an open in the feedback path, the current
through the opto-coupler transistor becomes almost
zero. Then, VFB climbs up in a similar manner to the
overload situation, forcing the preset maximum current
to be supplied to the SMPS until the overload protection
is activated. Because more energy than required is
provided to the output, the output voltage may exceed
the rated voltage before the overload protection is
activated, resulting in the breakdown of the devices in
the secondary side. To prevent this situation, an over-
voltage protection (OVP) circuit is employed. In general,
VCC is proportional to the output voltage and the
FSFM260/300 uses VCC instead of directly monitoring
the output voltage. If VCC exceeds 19V, an OVP circuit is
activated, terminating the switching operation. To avoid
undesired activation of OVP during normal operation,
VCC should be designed below 19V.
3.3 Thermal Shutdown (TSD): The SenseFET and the
control IC are built in one package. This allows for the
control IC to detect the heat generation from the
SenseFET. When the temperature exceeds
approximately 140°C, the thermal shutdown is activated.
3.4 Abnormal Over-Current Protection (AOCP): When
the secondary rectifier diodes or the transformer pins are
shorted, a steep current with extremely high di/dt can
flow through the SenseFET during the LEB time. Even
though the FPS has overload protection, it is not enough
to protect the FPS in those abnormal cases, since
severe current stress is imposed on the SenseFET until
OLP triggers. This IC has an internal AOCP circuit
shown in Figure 21. When the gate turn-on signal is
applied to the power SenseFET, the AOCP block is
enabled and monitors the current through the sensing
resistor. The voltage across the resistor is compared with
a preset AOCP level. If the sensing resistor voltage is
greater than the AOCP level, the set signal is applied to
the latch, resulting in the shutdown of the SMPS.
Figure 21. Abnormal Over-Current Protection
4. Soft-Start: The FSFM260/300 has an internal soft-
start circuit that increases PWM comparator inverting
input voltage, together with the SenseFET current,
slowly after it starts up. The typical soft-start time is
15ms. The pulse width to the power switching device is
progressively increased to establish the correct working
conditions for transformers, inductors, and capacitors.
The voltage on the output capacitors is progressively
increased to smoothly establish the required output
voltage. It also helps prevent transformer saturation and
reduce the stress on the secondary diode during startup.
5. Burst Operation: To minimize power dissipation in
standby mode, the FSFM260/300 enters burst mode
operation. As the load decreases, the feedback voltage
decreases. As shown in Figure 22, the device
automatically enters burst mode when the feedback
voltage drops below VBURL (350mV). At this point,
switching stops and the output voltages start to drop at a
rate dependent on standby current load. This causes the
feedback voltage to rise. Once it passes VBURH (500mV)
switching resumes. The feedback voltage then falls and
the process repeats. Burst mode operation alternately
enables and disables switching of the power SenseFET,
thereby reducing switching loss in standby mode.
Figure 22. Waveforms of Burst Operation
S
Q
Q
R
OSC
VOCP
GND
Gate
driver
LEB
FSFM260 Rev: 00
R
2.5R
1
AOCP protection
VFB
Vds
0.35V
0.5V
Ids
Vo
Voset
time
Switching
disabled
T1 T2 T3
Switching
disabled T4
FSFM260 Rev: 00
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 13
PCB Layout Guide
Due to the combined scheme, FPS shows better noise
immunity than conventional PWM controller and
MOSFET discrete solutions. Furthermore, internal drain
current sense eliminates noise generation caused by a
sensing resistor. There are some recommendations for
PCB layout to enhance noise immunity and suppress the
noise inevitable in power-handling components.
There are typically two grounds in the conventional
SMPS: power ground and signal ground. The power
ground is the ground for primary input voltage and
power, while the signal ground is ground for PWM
controller. In FPS, those two grounds share the same
pin, GND. Normally the separate grounds do not share
the same trace and meet only at one point, the GND pin.
More, wider patterns for both grounds are good for large
currents by decreasing resistance.
Capacitors at the VCC and FB pins should be as close as
possible to the corresponding pins to avoid noise from
the switching device. Sometimes Mylar® or ceramic
capacitors with electrolytic for VCC is better for smooth
operation. The ground of these capacitors needs to
connect to the signal ground not the power ground.
The cathode of the snubber diode should be close to the
drain pin to minimize stray inductance. The Y-capacitor
between primary and secondary should be directly
connected to the power ground of DC link to maximize
surge immunity.
Because the voltage range of feedback line is small, it is
affected by the noise of the drain pin. Those traces
should not draw across or close to the drain line.
In FSFM260/300, drain pins are the heat radiation pins,
so wider PCB pattern is recommended to decrease the
package temperature. Drain pins are also high voltage
switching pins; however, too wide PCB pattern may
deteriorate EMI immunity.
Figure 23. Recommended PCB Layout
Mylar® is a registered trademark of DuPont Teijin Films.
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 14
Typical Application Circuit
Features
!Average efficiency of 25%, 50%, 75%, and 100% load conditions is higher than 80% at universal input
!Low standby mode power consumption (<1W at 230VAC input and 0.5W load)
!Enhanced system reliability through various protection functions
!Internal soft-start (15ms)
Key Design Notes
!The delay time for overload protection is designed to be about 23ms with C105 of 33nF. If faster/slower triggering of
OLP is required, C105 can be changed to a smaller/larger value (e.g. 100nF for 70ms).
!The SMD-type 100nF capacitor must be placed as close as possible to VCC pin to avoid malfunction by abrupt pul-
sating noises and to improve surge immunity.
1. Schematic
Figure 24. Demonstation Circuit of FSFM300N
Application FPS™ Device Input Voltage
Range Rated Output Power Output Voltage
(Maximum Current)
LCD Monitor
Power Supply FSFM300N 85-265VAC 30W 5.0V (2.0A)
14V (1.4A)
3
4
C102
150nF
275VAC
LF101
30mH
C101
150nF
275VAC
RT1
NTC
5D-9
F1
FUSE
250V
2A
C103
100 F
400V
R103
51k
1W
C104
3.3nF
630V
D101
1N4007
C105
33nF
100V
1
2
3
4
5
T1
EER3016
BD101
2KBP06M
1
2
R101
1M
1W
FSFM300N
VSTR
FB VCC
Drain
GND
6,7,8
1
2
3
5
6
10
C201
1000 F
25V
C202
1000 F
25V
L201
5H
14V, 1.4A
6
7
D202
MBRF1060
C203
2200 F
10V
C204
1000 F
10V
L202
5H
5V, 2A
R201
1k
R202
1.2k
R204
8k
R203
18k
C205
47nF
R205
8k
C301
4.7nF
Y2
IC301
FOD817C IC201
KA431
R102
75k
C107
47 F
50V
D102
UF 4004
C106
100nF
R108
N.C
ILIM
4R105
100
0.5W
ZD101
1N4745A
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 15
2. Transformer
Figure 25. Transformer Schematic Diagram
3. Winding Specification
4. Electrical Characteristics
5. Core & Bobbin
!Core: EER3016 (Ae=109.7mm2)
!Bobbin: EER3016
Position No Pin (sf) Wire Turns Winding Method
Bottom
Top
Np/2 3 20.25φ × 1 30 Two-Layer Solenoid Winding
Insulation: Polyester Tape t = 0.025mm, Three Layers
N14V 10 8 0.4φ × 2(TIW) 5 Solenoid Winding
Insulation: Polyester Tape t = 0.025mm, Three Layers
N5V 8 60.4φ × 3(TIW) 3 Solenoid Winding
Insulation: Polyester Tape t = 0.025mm, Three Layers
N5V 7 60.4φ × 3(TIW) 3 Solenoid Winding
Insulation: Polyester Tape t = 0.025mm, Three Layers
Na7 6 0.15φ × 1 7 Center Solenoid Winding
Insulation: Polyester Tape t = 0.025mm, Three Layers
Np/2 2 1 0.25φ × 1 19 Center Solenoid Winding
Insulation: Polyester Tape t = 0.025mm, Two Layers
Pin Specification Remarks
Inductance 1 - 3 1.2mH ± 10% 67kHz, 1V
Leakage 1 - 3 15µH Maximum Short all other pins
2
Bottom
Top
3
10
8
Np/2 2
N14V
N5V
Np/2 1
6
Na4 5
8
7
N5V 6
EER3016
N14V
Na
1
2
3
4
56
7
8
9
10
Np/2
N5V
Np/2
N5V
GND
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 16
6. Evaluation Board Part List
Part Value Note Part Value Note
Resistor Inductor
R101 1MΩ1W L201 5µH 5A Rating
R102 75kΩ1/2W L202 5µH 5A Rating
R103 51kΩ1W Diode
R105 100Ω1/4W D101 IN4007 1A, 1000V General-Purpose
Rectifier
R108 10kΩ1/4W D102 UF4004 1A, 400V Ultrafast Rectifier
R201 1kΩ1/4W ZD101 1N4745A 1W 16V Zener Diode
(optional)
R202 1.2kΩ1/4W D201 MBRF10H100 10A,100V Schottky Rectifier
R203 18kΩ1/4W D202 MBRF1060 10A,60V Schottky Rectifier
R204 8kΩ1/4W IC
R205 8kΩ1/4W IC101 FSFM300N FPS™
Capacitor IC201 KA431 (TL431) Voltage Reference
C101 150nF/275VAC Box Capacitor IC202 FOD817A Opto-Coupler
C102 150nF/275VAC Box Capacitor Fuse
C103 100µF/400V Electrolytic Capacitor Fuse 2A/250V
C104 3.3nF/630V Film Capacitor NTC
C105 33nF/50V Ceramic Capacitor RT101 5D-9
C106 100nF/50V SMD (1206) Bridge Diode
C107 47µF/50V Electrolytic Capacitor BD101 2KBP06M2N257 Bridge Diode
C201 1000µF/25V Low-ESR Electrolytic
Capacitor Line Filter
C202 1000µF/25V Low-ESR Electrolytic
Capacitor LF101 34mH
C203 2200µF/10V Low-ESR Electrolytic
Capacitor Transformer
C204 1000µF/10V Low-ESR Electrolytic
Capacitor T1 EER3016 Ae=109.7mm2
C205 47nF/50V Ceramic Capacitor
C301 4.7nF/1kV Ceramic Capacitor
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 17
Package Dimensions
Figure 26. 8-Lead Dual Inline Package (DIP)
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please
note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package
specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products.
Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings:
http://www.fairchildsemi.com/packaging/.
5.08 MAX
0.33 MIN
2.54
7.62
0.56
0.355
1.65
1.27
3.683
3.20
3.60
3.00
6.67
6.096
9.83
9.00
7.62
9.957
7.87
0.356
0.20
NOTES: UNLESS OTHERWISE SPECIFIED
A) THIS PACKAGE CONFORMS TO
JEDEC MS-001 VARIATION BA
B) ALL DIMENSIONS ARE IN MILLIMETERS.
C) DIMENSIONS ARE EXCLUSIVE OF BURRS,
MOLD FLASH, AND TIE BAR EXTRUSIONS.
D) DIMENSIONS AND TOLERANCES PER
ASME Y14.5M-1994
8.255
7.61
E) DRAWING FILENAME AND REVSION: MKT-N08FREV2.
(0.56)
FSFM260N / FSFM300N — Green-Mode Farichild Power Switch (FPS™)
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSFM260N / FSFM300N Rev. 1.0.0 18