FSFR1700HSL - Fairchild - Datasheet.Directory

August 2011

FSFR1800 / FSFR1700-HS • Rev.1.0.0

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

FSFR-HS Series — Advanced 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)

 Built-in High-Side Gate Driver IC

 Internal UniFET™s with Fast-Recovery Type Body

Diode (trr=160ns Typical)

 Fixed Dead Time (350ns) Optimized for MOSFETs

 Operating Frequency Up to 600kHz for Soft-Start

 Self Auto-Restart Operation for All Protections, Despite

External LVCC Bias

 Line UVLO with Programmable Hysteresis Level

 Simple On/Off with Line UVLO Pin

 Easy Configuration and Compatibility with FAN7930 for

Line UVLO without External Components

 Protection Functions: Over-Voltage Protection (OVP),

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

Description

The FSFR-HS is a highly integrated power switch

designed for high-efficiency half-bridge resonant

converters. Offering everything necessary to build a

reliable and robust resonant converter, the FSFR-HS

simplifies designs while improving productivity and

performance. The FSFR-HS combines power MOSFETs,

a high-side gate-drive circuit, an accurate current-

controlled oscillator, and built-in protection functions.

The high-side gate-drive circuit has a common-mode

noise cancellation capability, which provides stable

operation with excellent noise immunity. Using zero-

voltage-switching (ZVS) technique dramatically reduces

the switching losses and significantly improves efficiency.

The ZVS also reduces the switching noise noticeably,

even though the operating frequency increases. It allows

a small Electromagnetic Interference (EMI) filter, besides

the high operating frequency, to reduce the volume of the

resonant tank and to increase power density.

The FSFR-HS can be applied to resonant converter

topologies such as series resonant, parallel resonant,

and LLC resonant converters.

Related Resources

AN4151 — 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)

FSFR1800HS 9-SIP

-40 to +130°C 0.95Ω 120W 260W

FSFR1800HSL 9-SIP

L-Forming

FSFR1700HS 9-SIP

-40 to +130°C 1.25Ω 100W 200W

FSFR1700HSL 9-SIP

L-Forming

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.

FSFR1800 / FSFR1700-HS • Rev.1.0.0 2

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

Application Circuit Diagram

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

Block Diagram

Figure 2. Internal Block Diagram

FSFR1800 / FSFR1700-HS • Rev.1.0.0 3

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

Pin Configuration

Figure 3. Package Diagram

Pin Definitions

Pin # Name Description

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

2 LS This is the line-sensing pin for the input voltage Under-Voltage Lockout (UVLO).

3 RT

This pin is used for controlling the switching frequency in normal operation. When any

protections are triggered, the internal Auto/Restart (A/R) circuit starts to sense the voltage on

the pin, which is discharged naturally by external resistance. The IC can be operated with

A/R when the voltage decreases 0.1V. Typically, an opto-coupler is connected to control the

switching frequency for the output voltage regulation and resistors for setting minimum /

maximum operating frequency.

4 CS

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

voltage is applied to this pin.

5 SG This pin is the ground of the control part.

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.

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

FSFR1800 / FSFR1700-HS • Rev.1.0.0 4

FSFR-HS Series — Advanced 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.

Symbol Parameter Min. Max. Unit

VDS Maximum Drain-to-Source Voltage (DL-CTR and CTR-PG) 500 V

LVCC Low-Side Supply Voltage -0.3 25.0 V

HVCC to CTR 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

VRT Timing Resistor Connecting and Auto-Restart Pin Voltage -0.3 5.0 V

VLS Line Sensing Input Voltage -0.3 LVCC V

VCS Current Sense (CS) Pin Input Voltage -5 1 V

fsw Recommended Switching Frequency 10 600 kHz

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

PD Total Power Dissipation(4) FSFR1800HS/L 11.7

FSFR1700HS/L 11.6

TJ Maximum Junction Temperature(5) +150

C

Recommended Operating Junction Temperature(5) -40 +130

TSTG Storage Temperature Range -55 +150 C

MOSFET Section

VDGR Drain Gate Voltage (RGS=1M) 500 V

VGS Gate Source (GND) Voltage ±30 V

IDM Drain Current Pulsed(6) FSFR1800HS/L 23

FSFR1700HS/L 20

ID Continuous Drain Current

FSFR1800HS/L TC=25C 7.0

TC=100C 4.5

FSFR1700HS/L TC=25C 6.0

TC=100C 3.9

Package Section

Torque Recommended Screw Torque 5~7 kgf·cm

Notes:

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

4. Per MOSFET when both MOSFETs are conducting.

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

6. 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)

FSFR1800HS/L 10.7

ºC/W

FSFR1700HS/L 10.8

FSFR1800 / FSFR1700-HS • Rev.1.0.0 5

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

Electrical Characteristics

TA=25°C, LVCC, HVCC =17VDC and RT=26 k unless otherwise specified.

Symbol Parameter 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 FSFR1800HS/L VGS=10V, ID=3.0A 0.77 0.95



FSFR1700HS/L VGS=10V, ID=2.0A 1.00 1.25

trr Body Diode Reverse

Recovery Time(7)

FSFR1800HS/L VGS=0V, IDIODE=7.0A,

dIDIODE/dt=100A/μs 160

FSFR1700HS/L VGS=0V, IDIODE=6.0A,

dIDIODE/dt=100A/μs 160

Supply Section

ILK Offset Supply Leakage Current HVCC=VCTR=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=50KHz 6 9 mA

No Switching 100 200 μA

IOLVCC Operating LVCC Supply Current (RMS Value) fOSC=50KHz 7 11 mA

No Switching 2 4 mA

UVLO Section

LVCCUV+ LVCC Supply Under-Voltage Positive Going Threshold (LVCC,START) 11.2 12.5 13.8 V

LVCCUV- LVCC Supply Under-Voltage Negative Going Threshold (LVCC,STOP) 8.9 10.0 11.1 V

LVCCUVH LVCC Supply Under-Voltage Hysteresis 2.5 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

VRT Output Voltage on RT Pin

RT=26k

1.5 2.0 2.5 V

fOSC Output Oscillation Frequency 47 50 53 kHz

DC Output Duty Cycle 48 50 52 %

Protection Section

VRT,RESET Threshold Voltage to Begin Restart 0.07 0.12 0.17 V

tDELAY,RESET Delay to Disable OSC Circuit After Protection fosc=50kHz 20 ms

VLINE On Threshold of Input Voltage 2.38 2.50 2.62 V

ILINE Hysteresis Current for Line UVLO 7.5 9.5 11.5 μA

VOVP LVCC Over-Voltage Protection 21 23 25 V

VAOCP AOCP Threshold Voltage -1.0 -0.9 -0.8 V

tBAO AOCP Blanking Time(7) V

CS < VAOCP 50 ns

VOCP OCP Threshold Voltage -0.64 -0.58 -0.52 V

tBO OCP Blanking Time(7) V

CS < VOCP 1.0 1.5 2.0 μs

tDA Delay Time (Low-Side) Detecting from VAOCP to Switch Off(7) 250 400 ns

TSD Thermal Shutdown Temperature(7) 120 135 150

C

Dead-Time Control Section

DT Dead Time(8) 350 ns

Notes:

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

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

FSFR1800 / FSFR1700-HS • Rev.1.0.0 6

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

Typical Performance Characteristics

These characteristic graphs are normalized at TA=25ºC.

0.9

0.95

1.05

1.1

-50-250 255075100

0.9

0.95

1.05

1.1

-50 -25 0 25 50 75 100

Normalized at 25°C

Figure 4. Low-Side MOSFET Duty Cycle

vs. Temperature Figure 5. Switching Frequency vs. Temperature

0.9

0.95

1.05

1.1

-50 -25 0 25 50 75 100

Normalized at 25°C

0.9

0.95

1.05

1.1

-50-250 255075100

Figure 6. High-Side VCC (H

CC) Start vs. Temperature Figure 7. High-Side VCC (H

CC) Stop vs. Temperature

0.9

0.95

1.05

1.1

-50-250 255075100

0.9

0.95

1.05

1.1

-50-250 255075100

Figure 8. Low-Side VCC (L

CC) Start vs. Temperature Figure 9. Low-Side VCC (L

CC) Stop vs. Temperature

FSFR1800 / FSFR1700-HS • Rev.1.0.0 7

FSFR-HS Series — Advanced 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

1.05

1.1

-50 -25 0 25 50 75 100

Temp (

Normalized at 25

0.9

0.95

1.05

1.1

-50 -25 0 25 50 75 100

Temp (

Norm alized at 25

Figure 10. LVCC OVP Voltage vs. Temperature Figure 11. RT

oltage vs. Temperature

0.9

0.95

1.05

1.1

-50 -25 0 25 50 75 100

Temp (

Normalized at 25

Figure 12.

RT,RESET vs. Temperature Figure 13. OCP Voltage vs. Temperatu

Figure 14.

LINE vs. Temperature Figure 15. ILINE vs. Temperature

FSFR1800 / FSFR1700-HS • Rev.1.0.0 8

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

Typical Performance Characteristics

(Continued)

These characteristic graphs are normalized at T

=25ºC.

Figure 16. t

DELAY,RESET

vs. Temperature Figure 17.

RT,RESET

vs. Temperature

FSFR1800 / FSFR1700-HS • Rev.1.0.0 9

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

Functional Description

1. Basic Operation: FSFR-HS 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 18.

Once LVCC is higher than LVCC,START = 12.5V, the IC

starts to operate, generates the low-side gate signal, and

drives the low-side MOSFET. The bootstrap diode and

capacitor is charged by the low-side MOSFET’s

operation. After the voltage on HVCC increases up to

HVCC,START, typically 9.2V, the high-side gate signal is

generated for the MOSFET.

Figure 18. MOSFET Gate Drive Signals

2. Internal Oscillator: FSFR-HS series employs a

current-controlled oscillator, as shown in Figure 19.

Internally, the voltage of the 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 the RT pin (ICTC) using a current mirror. Therefore,

the switching frequency increases as ICTC increases.

Figure 19. Current-Controlled Oscillator

3. Frequency Setting: Figure 20 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 21 shows

the typical circuit configuration for the RT pin, where the

opto-coupler transistor is connected to the RT pin to

modulate the switching frequency. The switching

frequency may be controlled from 20kHz to 500kHz.

The minimum switching frequency is determined as:

]Hz[

µ.Rp

fmin

min

540792



 (1)

Assuming the saturation voltage of opto-coupler

transistor is 0.2V, the maximum switching frequency is

determined as:

]Hz[

µ.R||Rp

fmaxmin

max

540792





(2)

Figure 20. Resonant Converter Typical Gain Curve

Figure 21. Frequency Control Circuit

To prevent excessive inrush current and overshoot of

output voltage during startup, the IC needs to increase

the voltage gain of the resonant converter progressively.

Since the voltage gain of the resonant converter is

inversely proportional to the switching frequency, 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 constructed by connecting R-C

series network to the RT pin, as shown in Figure 21.

Initially, the operating frequency is set by the parallel

impedance of RSS and Rmin.

FSFR1800 / FSFR1700-HS • Rev.1.0.0 10

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

The initial maximum frequency can be set up to 600kHz,

which is given by:

][

54.0||792 1

min

RRp







(3)

The soft-start time, tSS, can be calculated by:

]s[CRt SSSSSS 

(4)

4. Self Auto-Restart: The FSFR-HS series can restart

automatically even though any built-in protections are

triggered in case external supply voltage is applied. As

shown in Figure 22 and Figure 23; once a protection is

triggered, the power MOSFET immediately stops. The

counter starts to operate and 1008-clocks are counted,

then the V-I converter is disabled. CSS starts to be

naturally discharged with the series impedance of RSS

and Rmin until VRT drops to VRT,RESET, typically 0.1V. Then,

all protections are reset and the V-I converter resumes.

The FSFR-HS starts switching again with soft-start.

The counter operating time for 1008-clocks after

protection activation is set by the current out of the RT

pin until VRT drops to VRT,RESET. Finally, the stop time of

FSFR-HS can be estimated, without considering the

counter operation time, as:



]s[RRCt minSSSSSTOP 

(5)

Figure 22. Internal Block for Auto-Restart

Figure 23. Self Auto-Restart Operation

5. Protection Circuits: The FSFR-HS series has several

self-protective functions; such as Over-Current Protection

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

Voltage Protection (OVP), Thermal Shutdown (TSD), and

Line Under-Voltage Lockout (LUVLO or Brownout).

These protections are Auto-Restart Mode protections, as

shown in Figure 24.

Once a fault condition is detected, switching is instantly

terminated and the MOSFETs remain off. When LVCC falls

to the LVCC stop voltage of 10V and VRT is lower than

VRT,RESET of 0.1V, the protection is reset. The FSFR-HS

resumes normal operation when LVCC reaches the start

voltage of 12.5V.

Figure 24. Protection Blocks

5.1 Over-Current Protection (OCP): When the

sensing pin voltage drops below -0.58V and its duration

becomes more than OCP blanking time of 1.5µs, OCP

is triggered and the MOSFETs remain off.

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 is triggered. AOCP is triggered

without shutdown delay if the sensing pin voltage drops

below -0.9V.

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

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

when auxiliary winding of the transformer supplies VCC

to the FPS™.

5.4 Thermal Shutdown (TSD): The MOSFETs and

the control IC in one package make it easier for the

control IC to detect the abnormal over-temperature of

the MOSFETs. If the temperature exceeds

approximately 130C, thermal shutdown triggers.

6. Line Under-Voltage Lockout (UVLO): FSFR-HS

includes precise line UVLO (or brownout) with

programmable hysteresis voltage. This function can start

or restart the IC when VLS for the scale-down voltage of

the DC-link by the sensing resistors, R1 and R2, is higher

than VLINE of 2.5V as the DC-link voltage increases and

vice versa. A hysteresis voltage between the start and

stop voltage of the IC is programmable by ILINE. In normal

operation, the comparator’s output is HIGH and ILINE is

deactivated so that a voltage on LS pin, VLS, can be

obtained as a divided voltage by R1 and R2. On the

contrary, ILINE is activated when the comparator’s output

is LOW. VLS is generated by the difference between the

current through R1 and ILINE.

FSFR1800 / FSFR1700-HS • Rev.1.0.0 11

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

CFilter can be used to reduce some noise induced from

transformer or switching transition. Generally, hundreds

of pico-farad to tens of nano-farad is adequate,

depending on the quantity of noise.

The start and stop input-voltage can be calculated as:

][

221

RRR

VV LINESTOPlinkdc







(6)

][1

,, VRIVV LINESTOPlinkdcSTARTlinkdc   (7)

Figure 25. Half-Wave Sensing

7. Simple Remote-On/Off: The power stage can be

shutdown with optional Auto-Restart Mode, as shown in

Figure 26.

To configure an external protection with Auto-Restart

Mode, an opto-coupler and the LS pin are used. When

the voltage on the LS pin is pulled below VLINE (2.5V), the

IC stops during the status holds. However, the opto-

coupler stops pulling down and the IC can perform the

auto-restart operation itself.

Figure 26. External Protection Circuits

8. Current-Sensing Methods: FSFR-HS series employs

negative voltage sensing to detect the drain current of

MOSFET, which allows a low-noise resistive sensing

using a filter with low time-constant and capacitive

sensing method.

8.1 Resistive Sensing Method: The IC can sense

drain current as a negative voltage, as shown in Figure

27 and Figure 28. Half-wave sensing allows low power

dissipation in the sensing resistor; while full-wave

sensing has less switching noise in the sensing signal.

For a time constant range for the filter, 3/100~1/10 of

the operating frequency is reasonable.

Figure 27. Half-Wave Sensing

Figure 28. Full-Wave Sensing

8.2 Capacitive Sensing Method: The drain current

can be sensed using an additional capacitor parallel

with the resonant capacitor, as shown in Figure 29.

During the low-side switch turn on, the current, iCB

through CB, makes VSENSE across RSENSE. The iCB is

scale-down of ip by the impedance ratio of Cr and CB.

Generally, 1/100~1/1000 is adequate for the ratio of CB

against Cr. RD is used as a damper for reducing noise

generated by switching transition. Several hundreds of

ohm to a few of kilo-ohms can be normally used.

VSENSE can be estimated as;

][VR

IV sense

Crsense 

(8)

Control

SG PG

sense

IDS

Np Ns

Control

SG PG

Np Ns

Rsense

IDS

VCS

FSFR1800 / FSFR1700-HS • Rev.1.0.0 12

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

Figure 29. Capacitive Sensing

9. PCB Layout Guidelines: Duty imbalance problems

may occur due to the radiated noise from the main

transformer, the inequality of the secondary side

leakage inductances of main transformer, and so on.

This is one of the reasons that the control components

in the vicinity of the 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 turn on by turns. The magnetic fields

with opposite directions induce a current through, into,

or out of the RT pin, which makes the turn-on duration

of each MOSFET different. It is strongly recommended

to separate the control components in the vicinity of the

RT pin from the primary current flow pattern in the PCB

layout. Figure 30 shows an example for a duty-

balanced case.

Figure 30. Example of Duty Balancin g

FSFR1800 / FSFR1700-HS • Rev.1.0.0 13

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

Physical Dimensions

Figure 31. 9-Lead, Single Inline Package (SIP)

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/.

FSFR1800 / FSFR1700-HS • Rev.1.0.0 14

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

Physical Dimensions

Figure 32. 9-Lead, Single Inline Package (SIP), L-Forming

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/.

FSFR1800 / FSFR1700-HS • Rev.1.0.0 15

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