FSFR2100U - Fairchild

June 2010

FSFR series Rev.1.0.9

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

FSFR-Series — Fairchild Power Switch (FPS™)

for Half-Bridge Resonant Converters

Features

 Variable Frequency Control with 50% Duty Cycle

for Half-bridge Resonant Converter Topology

 High Efficiency through Zero Voltage Switching (ZVS)

 Internal UniFET™s with Fast-Recovery Type Body

Diode (trr<160ns).

 Fixed Dead Time (350ns) Optimized for MOSFETs

 Up to 300kHz Operating Frequency

 Pulse Skipping for Frequency Limit (Programmable)

at Light-Load Condition

 Remote On/Off Control Using Control Pin

 Protection Functions: Over-Voltage Protection

(OVP), Over-Load Protection (OLP), Over-Current

Protection (OCP), Abnormal Over-Current Protection

(AOCP), Internal Thermal Shutdown (TSD)

Applications

 PDP and LCD TVs

 Desktop PCs and Servers

 Adapters

 Telecom Power Supplies

 Audio Power Supplies

Description

The FSFR-series include highly integrated power

switches designed for high-efficiency half-bridge

resonant converters. Offering everything necessary to

build a reliable and robust resonant converter, the FSFR-

series simplifies designs and improves productivity, while

improving performance. The FSFR-series combines

power MOSFETs with fast-recovery type body diodes, a

high-side gate-drive circuit, an accurate current

controlled oscillator, frequency limit circuit, soft-start, and

built-in protection functions. The high-side gate-drive

circuit has a common-mode noise cancellation capability,

which guarantees stable operation with excellent noise

immunity. The fast-recovery body diode of the MOSFETs

improves reliability against abnormal operation

conditions, while minimizing the effect of the reverse

recovery. Using the zero-voltage-switching (ZVS)

technique dramatically reduces the switching losses and

efficiency is significantly improved. The ZVS also

reduces the switching noise noticeably, which allows a

small-sized Electromagnetic Interference (EMI) filter.

The FSFR-series can be applied to various resonant

converter topologies, such as: series resonant, parallel

resonant, and LLC resonant converters.

Related Resources

AN-4151 — Half-Bridge LLC Resonant Converter Design

Using FSFR-Series Fairchild Power Switch (FPS™)

Ordering Information

Part

Number Package

Operating

Junction

Temperature

RDS(ON_MAX)

Maximum Output Power

without Heatsink

(VIN=350~400V) (1,2)

Maximum Output

Power with Heatsink

(VIN=350~400V)(1,2)

FSFR2100U

9-SIP

-40 to +130°C

0.51Ω 180W 400W

FSFR2000 0.67Ω 160W 350W

FSFR1900 0.85Ω 140W 300W

FSFR1800 0.95Ω 120W 260W

FSFR1700 1.25Ω 100W 200W

FSFR1600 1.55Ω 80W 160W

FSFR1800L

9-SIP(L-Forming)

0.95Ω 120W 260W

FSFR1700L 1.25Ω 100W 200W

FSFR1600L 1.55Ω 80W 160W

Notes:

1. The junction temperature can limit the maximum output power.

2. Maximum practical continuous power in an open-frame design at 50°C ambient.

FSFR series Rev.1.0.9 2

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Application Circuit Diagram

Rsense

Control

IC

CDL

VCC VDL

LVcc

RT

CON

CS

SG PG

VCTR

HVCC

Cr

Llk

Lm

Ns

Vo

D1

D2 RF

CF

Np Ns

KA431

VIN

Figure 1. Typical Application Circuit (LLC Resonant Half-Bridge Converter)

Block Diagram

1.5

s

μ

Figure 2. Internal Block Diagram

FSFR series Rev.1.0.9 3

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Pin Configuration

1 2 3 4 5 6 7 8 9 10

VDL CON

RT

CS

SG

PG

LVcc

HVcc

VCTR

Figure 3. Package Diagram

Pin Definitions

Pin # Name Description

1 VDL This is the drain of the high-side MOSFET, typically connected to the input DC link voltage.

2 CON

This pin is for enable/disable and protection. When the voltage of this pin is above 0.6V, the

IC operation is enabled. When the voltage of this pin drops below 0.4V, gate drive signals for

both MOSFETs are disabled. When the voltage of this pin increases above 5V, protection is

triggered.

3 RT This pin programs the switching frequency. Typically, an opto-coupler is connected to control

the switching frequency for the output voltage regulation.

4 CS

This pin senses the current flowing through the low-side MOSFET. Typically, negative

voltage is applied on this pin.

5 SG This pin is the control ground.

6 PG This pin is the power ground. This pin is connected to the source of the low-side MOSFET.

7 LVCC This pin is the supply voltage of the control IC.

8 NC No connection.

9 HVCC This is the supply voltage of the high-side gate-drive circuit IC.

10 VCTR This is the drain of the low-side MOSFET. Typically, a transformer is connected to this pin.

FSFR series Rev.1.0.9 4

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

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. TA=25°C unless otherwise specified.

Symbol Parameter Min. Max. Unit

VDS Maximum Drain-to-Source Voltage (VDL-VCTR and VCTR-PG) 500 V

LVCC Low-Side Supply Voltage -0.3 25.0 V

HVCC to VCTR High-Side VCC Pin to Low-Side Drain Voltage -0.3 25.0 V

HVCC High-Side Floating Supply Voltage -0.3 525.0 V

VCON Control Pin Input Voltage -0.3 LVCC V

VCS Current Sense (CS) Pin Input Voltage -5.0 1.0 V

VRT R

T Pin Input Voltage -0.3 5.0 V

dVCTR/dt Allowable Low-Side MOSFET Drain Voltage Slew Rate 50 V/ns

PD Total Power Dissipation(3)

FSFR2100U 12.0

W

FSFR2000 12.0

FSFR1900 11.8

FSFR1800 11.7

FSFR1700 11.6

FSFR1600 11.5

TJ Maximum Junction Temperature(4) +150

°C

Recommended Operating Junction Temperature(4) -40 +130

TSTG Storage Temperature Range -55 +150 °C

MOSFET Section

VDGR Drain Gate Voltage (RGS=1MΩ) 500 V

VGS Gate Source (GND) Voltage ±30 V

IDM Drain Current Pulsed(5)

FSFR2100U 32

A

FSFR2000 31

FSFR1900 26

FSFR1800 23

FSFR1700 20

FSFR1600 18

Continued on the following page…

FSFR series Rev.1.0.9 5

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Absolute Maximum Ratings (Continued)

Symbol Parameter Min. Max. Unit

MOSFET Section (Continued)

ID Continuous Drain Current

FSFR2100U TC=25°C 10.5

A

TC=100°C 6.5

FSFR2000 TC=25°C 9.5

TC=100°C 6.0

FSFR1900 TC=25°C 8.0

TC=100°C 5.0

FSFR1800 TC=25°C 7.0

TC=100°C 4.5

FSFR1700 TC=25°C 6.0

TC=100°C 3.9

FSFR1600 TC=25°C 4.5

TC=100°C 2.7

Package Section

Torque Recommended Screw Torque 5~7 kgf·cm

Notes:

3. Per MOSFET when both MOSFETs are conducting.

4. The maximum value of the recommended operating junction temperature is limited by thermal shutdown.

5. Pulse width is limited by maximum junction temperature.

Thermal Impedance

TA=25°C unless otherwise specified.

Symbol Parameter Value Unit

θJC Junction-to-Case Center Thermal Impedance

(Both MOSFETs Conducting)

FSFR2100U 10.44

ºC/W

FSFR2000 10.44

FSFR1900 10.56

FSFR1800 10.68

FSFR1700 10.79

FSFR1600 10.89

FSFR series Rev.1.0.9 6

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Electrical Characteristics

TA=25°C unless otherwise specified.

Symbol Parameter Test Conditions Min. Typ. Max. Unit

MOSFET Section

BVDSS Drain-to-Source Breakdown Voltage ID=200μA, TA=25°C 500

V

ID=200μA, TA=125°C 540

RDS(ON) On-State Resistance

FSFR2100U VGS=10V, ID=6.0A 0.41 0.51

Ω

FSFR2000 VGS=10V, ID=5.0A 0.53 0.67

FSFR1900 VGS=10V, ID=4.0A 0.74 0.85

FSFR1800 VGS=10V, ID=3.0A 0.77 0.95

FSFR1700 VGS=10V, ID=2.0A 1.00 1.25

FSFR1600 VGS=10V, ID=2.25A 1.25 1.55

trr Body Diode Reverse

Recovery Time(6)

dIDiode/dt=100A/μs

ns

FSFR2100U VGS=0V, IDiode=12.0A 120

FSFR2000 VGS=0V, IDiode=9.5A 125

FSFR1900 VGS=0V, IDiode=8.0A 140

FSFR1800 VGS=0V, IDiode=7.0A 160

FSFR1700 VGS=0V, IDiode=6.0A 160

FSFR1600 VGS=0V, IDiode=5.0A 65

Supply Section

ILK Offset Supply Leakage Current H-VCC=VCTR=600V/500V 50 μA

IQHVCC Quiescent HVCC Supply Current (HVCCUV+) - 0.1V 50 120 μA

IQLVCC Quiescent LVCC Supply Current (LVCCUV+) - 0.1V 100 200 μA

IOHVCC Operating HVCC Supply Current

(RMS Value)

fOSC=100KHz, VCON > 0.6V 6 9 mA

No Switching, VCON < 0.4V 100 200 μA

IOLVCC Operating LVCC Supply Current

(RMS Value)

fOSC=100KHz, VCON > 0.6V 7 11 mA

No Switching, VCON < 0.4V 2 4 mA

Continued on the following page…

FSFR series Rev.1.0.9 7

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Electrical Characteristics (Continued)

TA=25°C unless otherwise specified.

Symbol Parameter Test Conditions Min. Typ. Max. Unit

UVLO Section

LVCCUV+ LVCC Supply Under-Voltage Positive Going Threshold (LVCC Start) 13.0 14.5 16.0 V

LVCCUV- LVCC Supply Under-Voltage Negative Going Threshold (LVCC Stop) 10.2 11.3 12.4 V

LVCCUVH LVCC Supply Under-Voltage Hysteresis 3.2 V

HVCCUV+ HVCC Supply Under-Voltage Positive Going Threshold (HVCC Start) 8.2 9.2 10.2 V

HVCCUV- HVCC Supply Under-Voltage Negative Going Threshold (HVCC Stop) 7.8 8.7 9.6 V

HVCCUVH HVCC Supply Under-Voltage Hysteresis 0.5 V

Oscillator & Feedback Section

VCONDIS Control Pin Disable Threshold Voltage 0.36 0.40 0.44 V

VCONEN Control Pin Enable Threshold Voltage 0.54 0.60 0.66 V

VRT V-I Converter Threshold Voltage

RT=5.2KΩ

1.5 2.0 2.5 V

fOSC Output Oscillation Frequency 94 100 106 KHz

DC Output Duty Cycle 48 50 52 %

fSS Internal Soft-Start Initial Frequency fSS=fOSC+40kHz, RT=5.2KΩ 140 KHz

tSS Internal Soft-Start Time 2 3 4 ms

Protection Section

IOLP OLP Delay Current VCON=4V 3.6 4.8 6.0 μA

VOLP OLP Protection Voltage VCON > 3.5V 4.5 5.0 5.5 V

VOVP LVCC Over-Voltage Protection L-VCC > 21V 21 23 25 V

VAOCP AOCP Threshold Voltage ΔV/Δt=-0.1V/µs -1.0 -0.9 -0.8 V

tBAO AOCP Blanking Time(6) VCS < VAOCP; ΔV/Δt=-0.1V/µs 50 ns

VOCP OCP Threshold Voltage V/Δt=-1V/µs -0.64 -0.58 -0.52 V

tBO OCP Blanking Time(6) VCS < VOCP; ΔV/Δt=-1V/µs 1.0 1.5 2.0 μs

tDA Delay Time (Low Side) Detecting from

VAOCP to Switch Off(6) ΔV/Δt=-1V/µs 250 400 ns

TSD Thermal Shutdown Temperature(6) 110 130 150

°C

ISU Protection Latch Sustain LVCC Supply

Current LVCC=7.5V 100 150 μA

VPRSET Protection Latch Reset LVCC Supply

Voltage 5 V

Dead-Time Control Section

DT Dead Time(7) 350 ns

Notes:

6. This parameter, although guaranteed, is not tested in production.

7. These parameters, although guaranteed, are tested only in EDS (wafer test) process.

FSFR series Rev.1.0.9 8

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Typical Performance Characteristics

These characteristic graphs are normalized at TA=25ºC.

0.9

0.95

1

1.05

1.1

-50 -25 0 25 50 75 100

Temp (OC)

Normalized at 25OC

Temp (

O

C)

0.9

0.95

1

1.05

1.1

-50-250 255075100

Normalized at 25

O

C

Figure 4. Low-Side MOSFET Duty Cycle

vs. Temperature

Figure 5. Switching Frequency vs. Temperature

0.9

0.95

1

1.05

1.1

-50-250 255075100

Temp (

O

C)

Normalized at 25

O

C

0.9

0.95

1

1.05

1.1

-50 -25 0 25 50 75 100

Temp (

O

C)

Normalized at 25

O

C

Figure 6. High-Side VCC (H

V

CC) Start

vs. Temperature

Figure 7. High-Side VCC (H

V

CC) Stop

vs. Temperature

0.9

0.95

1

1.05

1.1

-50 -25 0 25 50 75 100

Temp (OC)

Normalized at 25OC

0.9

0.95

1

1.05

1.1

-50 -25 0 25 50 75 100

Temp (

O

C)

Normalized at 25

O

C

Figure 8. Low-Side VCC (L

V

CC) Start

vs. Temperature

Figure 9. Low-Side VCC (L

V

CC) Stop

vs. Temperature

FSFR series Rev.1.0.9 9

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Typical Performance Characteristics (Continued)

These characteristic graphs are normalized at TA=25ºC.

0.9

0.95

1

1.05

1.1

-50 -25 0 25 50 75 100

Temp (OC)

Normalized at 25OC

0.9

0.95

1

1.05

1.1

-50 -25 0 25 50 75 100

Temp (

O

C)

Normalized at 25

O

C

Figure 10. OLP Delay Current vs. Temperature Figure 11. OLP Protection Voltage

vs. Temperature

0.9

0.95

1

1.05

1.1

-50 -25 0 25 50 75 100

Temp (OC)

Normalized at 25OC

0.9

0.95

1

1.05

1.1

-50 -25 0 25 50 75 100

Temp (

O

C)

Normalized at 25

O

C

Figure 12. LVCC OVP Voltage vs. Temperature Figure 13. RT

V

oltage vs. Temperature

0.9

0.95

1

1.05

1.1

-50 -25 0 25 50 75 100

Temp (OC)

Normalized at 25OC

0.9

0.95

1

1.05

1.1

-50 -25 0 25 50 75 100

Temp (

O

C)

Normalized at 25

O

C

Figure 14. CON Pin Enable Voltage

vs. Temperature

Figure 15. OCP Voltage vs. Temperature

FSFR series Rev.1.0.9 10

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Functional Description

1. Basic Operation: FSFR-series is designed to drive

high-side and low-side MOSFETs complementarily with

50% duty cycle. A fixed dead time of 350ns is introduced

between consecutive transitions, as shown in Figure 16.

High side

MOSFET

gate drive

Low side

MOSFET

gate drive

Dead time

time

Figure 16. MOSFETs Gate Drive Signal

2. Internal Oscillator: FSFR-series employs a current-

controlled oscillator, as shown in Figure 17. Internally,

the voltage of RT pin is regulated at 2V and the

charging/discharging current for the oscillator capacitor,

CT, is obtained by copying the current flowing out of RT

pin (ICTC) using a current mirror. Therefore, the switching

frequency increases as ICTC increases.

Figure 17. Current Controlled Oscillator

3. Frequency Setting: Figure 18 shows the typical

voltage gain curve of a resonant converter, where the

gain is inversely proportional to the switching frequency

in the ZVS region. The output voltage can be regulated

by modulating the switching frequency. Figure 19 shows

the typical circuit configuration for RT pin, where the opto-

coupler transistor is connected to the RT pin to modulate

the switching frequency.

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Gain

140 150

60 70 80 90 100 110 120 130

freq (kHz)

f min f normal f max f ISS

Soft-start

Figure 18. Resonant Converter Typical Gain Curve

Control

IC

VDL

LVcc

RT

CON

SG PG

R

min

R

max

C

ss

R

ss

Figure 19. Frequency Control Circuit

The minimum switching frequency is determined as:

min

5.2 100( )

k

fkHz

R

Ω

=× (1)

Assuming the saturation voltage of opto-coupler

transistor is 0.2V, the maximum switching frequency is

determined as:

max

min max

5.2 4.68

( ) 100( )

kk

fkHz

RR

Ω

=+ × (2)

To prevent excessive inrush current and overshoot of

output voltage during startup, increase the voltage gain

of the resonant converter progressively. Since the

voltage gain of the resonant converter is inversely

proportional to the switching frequency, the soft-start is

implemented by sweeping down the switching frequency

from an initial high frequency (fISS) until the output

voltage is established. The soft-start circuit is made by

connecting R-C series network on the RT pin, as shown

FSFR series Rev.1.0.9 11

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

in Figure 19. FSFR-series also has an internal soft-start

for 3ms to reduce the current overshoot during the initial

cycles, which adds 40kHz to the initial frequency of the

external soft-start circuit, as shown in Figure 20. The

initial frequency of the soft-start is given as:

min

5.2 5.2

( ) 100 40 ( )

ISS

SS

kk

f

kHz

RR

ΩΩ

=+×+ (3)

It is typical to set the initial frequency of soft-start two ~

three times the resonant frequency (fO) of the resonant

network.

The soft-start time is three to four times of the RC time

constant. The RC time constant is as follows:

SS SS SS

TRC=⋅ (4)

f

s

time

Control loop

take over

40kHz

f

ISS

Figure 20. Frequency Sweeping of Soft-start

4. Control Pin: The FSFR-series has a control pin for

protection, cycle skipping, and remote on/off. Figure 21

shows the internal block diagram for control pin.

Figure 21. Internal Block of Control Pin

Protection: When the control pin voltage exceeds 5V,

protection is triggered. Detailed applications are

described in the protection section.

Pulse Skipping: FSFR-series stops switching when the

control pin voltage drops below 0.4V and resumes

switching when the control pin voltage rises above 0.6V.

To use pulse-skipping, the control pin should be

connected to the opto-coupler collector pin. The

frequency that causes pulse skipping is given as:

()

kHz100x

Rk16.4

Rk2.5

maxmin

SKIP

+=

(5)

Figure 22. Control Pin Configuration for

Pulse Skipping

Remote On / Off: When an auxiliary power supply is

used for standby, the main power stage using FSFR-

series can be shut down by pulling down the control pin

voltage, as shown in Figure 23. R1 and C1 are used to

ensure soft-start when switching resumes.

OP1

Rmin

FPS

Main

Output

Main Off

Aux

Output

R1

C1

OP1

RT

CON

Figure 23. Remote On / Off Circuit

4. Current Sensing Method

Current Sensing Using Resistor: FSFR-series senses

drain current as a negative voltage, as shown in Figure

24 and Figure 25. Half-wave sensing allows low power

dissipation in the sensing resistor, while full-wave

sensing has less switching noise in the sensing signal.

FSFR series Rev.1.0.9 12

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Control

IC

CS

SG PG

Ns

Np Ns

Rsense

Ids

Cr

Ids

VCS

Figure 24. Half-Wave Sensing

Control

IC

CS

SG PG

Rsense

Ids

VCS

Ids

VCS

Ns

Np Ns

Cr

Figure 25. Full-Wave Sensing

Current Sensing Using Resonant Capacitor Voltage:

For high-power applications, current sensing using a

resistor may not be available due to the severe power

dissipation in the resistor. In that case, indirect current

sensing using the resonant capacitor voltage can be a

good alternative because the amplitude of the resonant

capacitor voltage (Vcrp-p) is proportional to the resonant

current in the primary side (Ipp-p) as:

2

pp

p

pp

Cr

s

r

I

VfC

π

−

−= (6)

To minimize power dissipation, a capacitive voltage

divider is generally used for capacitor voltage sensing, as

shown in Figure 26.

300~500kΩ

Ip

VCr

Vsense

VCrp-p

Vsensepk

delay d d

TRC

=

pk

sense B

pp

Cr sense B

VC

VCC

−=+2

pk

sense CON

VV=

VCON

Vsensepk

Figure 26. Current Sensing Using Resonant

Capacitor Voltage

5. Protection Circuits: The FSFR-series has several

self-protective functions, such as Overload Protection

(OLP), Over-Current Protection (OCP), Abnormal Over-

Current Protection (AOCP), Over-Voltage Protection

(OVP), and Thermal Shutdown (TSD). OLP, OCP, and

OVP are auto-restart mode protections; while AOCP and

TSD are latch-mode protections, as shown in Figure 27.

Auto-restart Mode Protection: Once a fault condition is

detected, switching is terminated and the MOSFETs

remain off. When LVCC falls to the LVCC stop voltage of

11.3V, the protection is reset. The FPS resumes normal

operation when LVCC reaches the start voltage of 14.5V.

FSFR series Rev.1.0.9 13

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Latch-Mode Protection: Once this protection is

triggered, switching is terminated and the MOSFETs

remain off. The latch is reset only when LVCC is

discharged below 5V.

LVCC good

7

11 / 14 V VREF Internal

Bias

LVCC good

LVCC

OLP

OVP

+

-

-Q

Q

R

S

F/F

LVCC < 5V

Latch

protection

-Q

Q

R

S

F/F

Auto-restart

protection

Shutdown

CON 20k

OCP

AOCP

TSD

Figure 27. Protection Blocks

5.1 Over-Current Protection (OCP): When the sensing

pin voltage drops below -0.58V, OCP is triggered and the

MOSFETs remain off. This protection has a shutdown

time delay of 1.5µs to prevent premature shutdown

during startup.

5.2 Abnormal Over-Current Protection (AOCP): If the

secondary rectifier diodes are shorted, large current with

extremely high di/dt can flow through the MOSFET

before OCP or OLP is triggered. AOCP is triggered

without shutdown delay when the sensing pin voltage

drops below -0.9V. This protection is latch mode and

reset when LVCC is pulled down below 5V.

5.3 Overload Protection (OLP): Overload is defined as

the load current exceeding its normal level due to an

unexpected abnormal event. In this situation, the

protection circuit should trigger to protect the power

supply. However, even when the power supply is in the

normal condition, the overload situation can occur during

the load transition. To avoid premature triggering of

protection, the overload protection circuit should be

designed to trigger only after a specified time to

determine whether it is a transient situation or a true

overload situation. Figure 26 shows a typical overload

protection circuit. By sensing the resonant capacitor

voltage on the control pin, the overload protection can be

implemented. Using RC time constant, shutdown delay

can be also introduced. The voltage obtained on the

control pin is given as:

2( ) pp

B

CON Cr

Bsense

C

VV

CC −

=+

(7)

where VCrp-p is the amplitude of the resonant capacitor

voltage.

5.4 Over-Voltage Protection (OVP): When the LVCC

reaches 23V, OVP is triggered. This protection is used

when auxiliary winding of the transformer to supply VCC

to FPS™ is utilized.

5.5 Thermal Shutdown (TSD): The MOSFETs and the

control IC in one package makes it easy for the control IC

to detect the abnormal over-temperature of the

MOSFETs. If the temperature exceeds approximately

130°C, the thermal shutdown triggers.

6. PCB Layout Guideline: Duty unbalance problems

may occur due to the radiated noise from main

transformer, the inequality of the secondary side leakage

inductances of main transformer, and so on. Among

them, it is one of the dominant reasons that the control

components in the vicinity of RT pin are enclosed by the

primary current flow pattern on PCB layout. The direction

of the magnetic field on the components caused by the

primary current flow is changed when the high and low

side MOSFET turns on by turns. The magnetic fields with

opposite direction from each other induce a current

through, into, or out of the RT pin, which makes the turn-

on duration of each MOSFET different. It is highly

recommended to separate the control components in the

vicinity of RT pin from the primary current flow pattern on

PCB layout. Figure 28 shows an example for the duty

balanced case.

Figure 28. Example for Duty Balancing

FSFR series Rev.1.0.9 14

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Typical Application Circuit (Half-Bridge LLC Resonant Converter)

Application FPS™ Device Input Voltage Range Rated Output Power Output Voltage

(Rated Current)

LCD TV FSFR2100U 400V (20ms Hold-up Time) 192W 24V-8A

Features

 High efficiency ( >94% at 400VDC input)

 Reduced EMI noise through zero-voltage-switching (ZVS)

 Enhanced system reliability with various protection functions

Figure 29. Typical Application Circuit

FSFR series Rev.1.0.9 15

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Typical Application Circuit (Continued)

Usually, LLC resonant converters require large leakage inductance value. To obtain a large leakage inductance,

sectional winding method is used.

 Core: EER3542 (Ae=107 mm2)

 Bobbin: EER3542 (Horizontal)

EC35

Np

2

69

12

10

Ns2

13

Ns1

Figure 30. Transformer Construction

Pins (S → F) Wire Turns Note

Np 8 → 1 0.12φ×30 (Litz Wire) 36

Ns1 12 → 9 0.1φ×100 (Litz Wire) 4 Bifilar Winding

Ns2 16 → 13 0.1φ×100 (Litz Wire) 4 Bifilar Winding

Pins Specifications Remark

Primary-Side Inductance (Lp) 1－8 630μH ± 5% 100kHz, 1V

Primary-Side Effective Leakage (Lr) 1－8 135μH ± 5% Short One of the secondary Windings

FSFR series Rev.1.0.9 16

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Physical Dimensions

Figure 31. 9-SIP Package

Package drawings are provided as a service to customers consideri ng Fairchild components. Drawings may change in any manner

without notic e. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representativ e to verify or

obtain the most recent revisi on. Package specific ati ons do not ex pand the terms of Fairchild’s worl dwide terms and condi tions,

specifically the warranty therein, which covers Fairchild products.

Always visit Fairchi l d Semiconductor ’s online packaging area for the most recent package drawings:

http://www.fairchildsemi.com/packaging/.

FSFR series Rev.1.0.9 17

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter

Physical Dimensions

Figure 32. 9-Lead, SIP Module, L-Forming, 3.2x10.5x26mm Body

Package drawings are provided as a service to customers consideri ng Fairchild components. Drawings may change in any manner

without notic e. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representativ e to verify or

obtain the most recent revisi on. Package specific ati ons do not ex pand the terms of Fairchild’s worl dwide terms and condi tions,

specifically the warranty therein, which covers Fairchild products.

Always visit Fairchi l d Semiconductor ’s online packaging area for the most recent package drawings:

http://www.fairchildsemi.com/packaging/.

FSFR series Rev.1.0.9 18

FSFR-Series — Fairchild Power Switch (FPS™) for Half-Bridge Resonant Converter