Datasheet FSQ211 Datasheet (Fairchild)

FSQ211 Green Mode Fairchild Power Switch (FPS

FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

April 2007

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Features

 Internal Avalanche-Rugged SenseFET  Precision Fixed Operating Frequency (67KHz)  Burst-Mode Operation  Internal Start-up Circuit  Pulse-by-Pulse Current Limiting  Overload Protection (OLP)  Internal Thermal Shutdown Function (TSD)  Auto-Restart Mode  Under-Voltage Lockout (UVLO) with Hysteresis  Built-in Soft-Start  Secondary-Side Regulation

Applications

 Charger & Adapter for Mobile Phone, PDA, & MP3  Auxiliary Power for White Goods, PC, C-TV, &

Monitor

Related Application Notes  AN-4137 Design Guidelines for Off-line Flyback

Converters using FPS™

 AN-4141 Troubleshooting and Design Tips for

Fairchild Power Switch (FPS™) Flyback Applications

 AN-4147 Design Guidelines for RCD Snubber of

Flyback

 AN-4134Design Guidelines for Off-line Forward

Converters using FPS™

 AN-4138Design Considerations for Battery Charger

Using Green Mode Fairchild Power Switch (FPS™)

Description

The FSQ211 consists of an integrated Pulse Width Modulator (PWM) and SenseFET, specifically designed for high-performance, off-line Switch Mode Power Supplies (SMPS) with minimal external components. This device is an integrated high-voltage power switching regulator that combines a VDMOS SenseFET with a voltage mode PWM control block. The integrated PWM controller features include a fixed oscillator, Under Voltage Lockout (UVLO) protection, Leading Edge Blanking (LEB), an optimized gate turn-on/turn-off driver, Thermal Shutdown (TSD) protection, and temperature compensated precision-current sources for loop compensation and fault protection circuitry.

When compared to a discrete MOSFET and controller or RCC switching converter solution, the FSQ211 device reduces total component count and design size and weight, while increasing efficiency, productivity, and system reliability. This device provides a basic platform well suited for cost-effective flyback converters.

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Ordering Information

Part Number Package Top Mark BV

FSQ211 8DIP

FSQ211L 8LSOP

FPSTM is a trademark of Fairchild Semiconductor Corporation

Q211

Q211L

f

DSS

650V 67KHz

R

OSC

DS(ON)

18Ω

Typical Application

AC

IN

Drain

Vstr

PWM

FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

DC

OUT

Internal Block Diagram

Vfb Vcc

Figure 1. Typical Flyback Application

GND

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Figure 2. Functional Block Diagram of FSQ211

Pin Assignments

FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

1

2

Vcc

Vfb

3

45

NC

Drain

8GND

Drain

7

6

Drain

Vstr

Figure 3. Pin Configuration (Top View)

Pin Definitions

Pin Name Description

1

2

3

4

5

6,7,8 Drain

GND

V

CC

V

FB

NC

Vstr

Ground. SenseFET source terminal on primary side and internal control ground. Positive supply voltage input. Although connected to an auxiliary transformer winding,

current is supplied from pin 5 (Vstr) via an internal switch during startup (see Block Diagram). It

is not until V

reaches the UVLO upper threshold (9V), that the internal start-up switch opens

CC

and device power is supplied via the auxiliary transformer winding.

Feedback. Inverts input to the PWM comparator with its normal input level between 0.5V and

2.5V. It has a 0.4mA current source connected internally, while a capacitor and opto-coupler are typically connected externally. A feedback voltage of 4.5V triggers overload protection (OLP). There is a time delay while charging external capacitor C internal 5µA current source. This time delay prevents false triggering under transient conditions, but allows the protection mechanism to operate under true overload conditions.

No Connection. Start-up. This pin connects directly to the rectified AC line voltage source. At start-up, the

internal switch supplies internal bias and charges an external storage capacitor placed between the VCC pin and ground. Once the VCC reaches 9V, the internal switch stops charging the capacitor.

SenseFET Drain. The drain pins are designed to connect directly to the primary lead of the

transformer and are capable of switching a maximum of 650V. Minimizing the length of the trace connecting these pins to the transformer decreases leakage inductance.

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from 3V to 4.5V using an

FB

FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

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. T

Symbol Parameter Value Unit

V

Drain Pin Voltage 650 V

DRAIN

V

Vstr Pin Voltage 650 V

STR

VDG Drain-Gate Voltage 650 V

VGS Gate-Source Voltage

VCC Supply Voltage 20 V

VFB Feedback Voltage Range -0.3 to V

PD Total Power Dissipation 1.40 W

TJ Operating Junction Temperature Internally limited °C

TA Operating Ambient Temperature -25 to +85 °C

T

Storage Temperature -55 to +150 °C

STG

Notes:

1. Repetitive rating: Pulse width is limited by maximum junction temperature.

2. L = 24mH, starting T

= 25°C.

J

=25°C unless otherwise specified.

A

±20

STOP

V

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Thermal Impedance

TA=25°C unless otherwise specified.

Symbol Parameter Value Unit

8DIP

θJA

θJC

Notes:

3. Free standing with no heatsink; without copper clad. Measurement condition – Just before junction temperature T

enters into OTP.

J

4. Measured on the DRAIN pin close to plastic interface.

5. All items are tested with the JEDEC standards: JESD 51-2 and 51-10 (DIP).

Junction-to-Ambient Thermal Impedance

Junction-to-Case Thermal Impedance

(3)

(4)

89 °C/W

14 °C/W

FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

Electrical Characteristics

TA=25°C unless otherwise specified,

Symbol Parameter Conditions Min. Typ. Max. Unit

SENSEFET SECTION

VDS=650V, VGS=0V 25

I

Zero-Gate-Voltage Drain Current

DSS

R

Drain-Source On-State Resistance

DS(ON)

VDS=520V, VGS=0V,

=125°C

T

C

(6)

VGS=10V, ID=0.2A 18 25 Ω

200

gfs Forward Trans-Conductance VDS=50V, ID=0.2A 1.0 1.3 S

C

Input Capacitance 162

ISS

C

Output Capacitance 18

OSS

C

Reverse Transfer Capacitance

RSS

VGS=0V, VDS=25V,

f=1MHz

3.8

CONTROL SECTION

f

Switching Frequency 61 67 73 KHz

OSC

Δf

Switching Frequency Variation

OSC

D

Maximum Duty Cycle 60 67 74 %

MAX

V

START

V

STOP

UVLO Threshold Voltage

(7)

-25°C ≤ TA ≤ 85°C ±5 ±10 %

=GND 8 9 10 V

FB

VFB=GND 6 7 8 V

IFB Feedback Source Current 0V ≤ VFB ≤ 3V 0.35 0.40 0.45 mA

t

Internal Soft-Start Time 10 15 20 ms

S/S

BURST-MODE SECTION

V

0.6 0.7 0.8 V

BURH

V

BURL

V

BUR(HYS)

Burst-Mode Voltage

=25°C

T

J

0.45 0.55 0.65 V

Hysteresis 150 mV

PROTECTION SECTION

I

Peak Current Limit di/dt= 65mA/µs 0.32 0.38 0.44 A

LIM

TSD Thermal Shutdown Temperature

(8)

125 145 °C

VSD Shutdown Feedback Voltage 4.0 4.5 5.0 V

I

Shutdown Delay Current 3V ≤ VFB ≤ VSD 4 5 6 µA

DELAY

TOTAL DEVICE SECTION

IOP Operating Supply Current

(control part only)

ICH Start-Up Charging Current VCC=0V , V

VCC ≤ 16V 1.5 3.0 mA

=50V 450 550 650 µA

STR

Notes:

6. Pulse test: Pulse width ≤ 300us, duty ≤ 2%.

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

8. These parameters, although guaranteed, are not 100% tested in production.

µA

pF

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Typical Performance Characteristics

These characteristic graphs are normalized at T

= 25°C.

A

FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

1.15

1.10

1.05

1.00

REF

V

0.95

0.90

0.85

-50 0 50 100 150

Temperature [°C]

Figure 4. Reference Voltage (V

1.15

1.10

1.05

1.00

OP

I

0.95

0.90

0.85

-50 0 50 100 150

) vs. TA Figure 5. Operating Supply Current (IOP) vs. TA

REF

Temperature [°C]

1.15

1.10

1.05

1.00

STAART

V

0.95

0.90

0.85

-50 0 50 100 150

1.15

1.10

1.05

1.00

STOP

V

0.95

0.90

0.85

-50 0 50 100 150

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Temperature [°C]

Figure 6. Start Threshold Voltage (V

) vs. TA Figure 7. Stop Threshold Voltage (V

START

Temperature [°C]

STOP

) vs. TA

1.15

1.10

1.05

1.00

OSC

f

0.95

0.90

0.85

-50 0 50 100 150

Temperature [°C]

1.15

1.10

1.05

1.00

MAX

D

0.95

0.90

0.85

-50 0 50 100 150

Temperature [°C]

Figure 8. Operating Frequency (f

) vs. TA Figure 9. Maximum Duty Cycle (D

OSC

) vs. TA

MAX

Typical Performance Characteristics (Continued)

These characteristic graphs are normalized at T

= 25°C.

A

FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

1.15

1.10

1.05

1.00

LIM

I

0.95

0.90

0.85

-50 0 50 100 150

Temperature [°C]

Figure 10. Peak Current Limit (I

1.15

1.10

1.05

1.00

FB

I

0.95

0.90

0.85

-50 0 50 100 150

Temperature [°C]

) vs. TA Figure 11. Feedback Source Current (IFB) vs. TA

LIM

1.15

1.10

1.05

1.00

DELAY

I

0.95

0.90

0.85

-50 0 50 100 150

1.15

1.10

1.05

SD

1.00

V

0.95

0.90

0.85

-50 0 50 100 150

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Temperature [°C]

Figure 12. Shutdown Delay Current (I

) vs. TA Figure 13. Shutdown Feedback Voltage (VSD) vs. TA

DELAY

Temperature [°C]

FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

Functional Description

1. Start-up: At start-up, the internal high-voltage current

source supplies the internal bias and charges the external V case of the FSQ211, when V starts switching and the internal high-voltage current source stops charging the capacitor. The device is in normal operation provided V After start-up, the bias is supplied from the auxiliary transformer winding.

Calculating the V design with the FSQ211. At initial start-up, the maximum value of start operating current I which supplies current to UVLO and V charging current I – 100µA. After V the bias winding supplies V When the bias winding voltage is not sufficient, the V level decreases to the UVLO stop voltage and the internal current source is activated again to charge the V

capacitor. To prevent this VCC fluctuation

CC

(charging/discharging), the V chosen with a value between 10µF and 47µF.

V

CC

V

START

V

STOP

Figure 15. Charging V

capacitor, as shown in Figure 14. In the

CC

reaches 9V, the device

CC

does not drop below 7V.

CC

VIN,dc

I

STR

Vstr

V

cc

9V/7V

L

H

Figure 14. Internal Start-up Circuit

capacitor is an important step in a

CC

is about 100µA,

VCC

CC

VIN, dc

I

Vcc=ISTR-ISTART

I

Vcc=ISTR-ISTART

UVLO

STR

of the VCC capacitor is equal to I

reaches the UVLO start voltage, only

current to the device.

CC

capacitor should be

CC

I

STR

V

CC

I

START

UVLO

V

REF

VCCmust not dr op

below V

STOP

Bias winding

volt age

Capacitor Through Vstr

CC

blocks. The

REF

Vst r

J-F ET

t

STR

CC

2. Feedback Control: The FSQ211 is a voltage-mode

controlled device, as shown in Figure 16. Usually, an opto-coupler and shunt regulator, like KA431, are used to implement the feedback network. The feedback voltage is compared with an internally generated sawtooth waveform. This directly controls the duty cycle. When the shunt regulator reference pin voltage exceeds the internal reference voltage of 2.5V, the opto-coupler LED current increases, the feedback voltage V pulled down, and it reduces the duty cycle. This happens when the input voltage increases or the output load decreases.

VccV

5µA 0 .40mA

KA431

V

fb

4

+

C

fb

V

FB

-

V

SD

V

o

OSC

ref

Gate

driver

R

OLP

Figure 16. PWM and Feedback Circuit

3. Leading Edge Blanking (LEB): The instant the

internal SenseFET is turned on, the primary-side capacitance and secondary-side rectifier diode reverse recovery typically cause a high-current spike through the SenseFET. Excessive voltage across the R leads to incorrect pulse-by-pulse current limit protection. To avoid this, a leading edge blanking (LEB) circuit

SENSE

disables the pulse-by-pulse current limit protection block for a fixed time (t

) after the SenseFET turns on.

LEB

4. Protection Circuit: The FSQ211 has several

protective functions, such as overload protection (OLP), under-voltage lockout (UVLO), and thermal shutdown (TSD). Because these protection circuits are fully integrated inside the IC without external components, reliability is improved without increasing costs. Once a fault condition occurs, switching is terminated and the SenseFET remains off. This causes V V

reaches the UVLO stop voltage V

CC

to fall. When

CC

(7V), the

STOP

protection is reset and the internal high-voltage current source charges the V V

reaches the UVLO start voltage V

CC

capacitor via the Vstr pin. When

CC

START

(9V), the device 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.

OSC

5µA 400µA

V

fb

4

C

fb

RESET

+

-

R

OLP

4.5V

TSD

SRQ

A/R

GATE

DRIVE R

OLP, TSD

Protec tion Block

Figure 17. Protection Block

is

FB

resistor

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FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

4.1 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 operating normally, the overload protection (OLP) circuit can be activated during the load transition. To avoid this undesired operation, the OLP circuit is designed to be activated after a specified time to determine whether it is a transient situation or an overload situation. If the output consumes more than the maximum power determined by I (V

) decreases below its rating voltage. This reduces

O

, the output voltage

LIM

the current through the opto-coupler LED, which also reduces the opto-coupler transistor current, thus increasing the feedback voltage (V

). If VFB exceeds

FB

3V, the feedback input diode is blocked and the 5µA current source (I V

. In this condition, VFB increases until it reaches

CC

) starts to charge CFB slowly up to

DELAY

4.5V, when the switching operation is terminated, as shown in Figure 18. Shutdown delay is the time required to charge C

V

FB

from 3V to 4.5V with 5µA current source.

FB

Overload Protection

4.5V

3V

t12=CFB×(V(t2)-V(t1)) /I

t

1

tVtV

)()(

•

Ct

=m

FB

12

I

DELAY

DELA Y

t

2

VtVVtVAI

5.4)(,3)(,5;

===

21

Figure 18. Overload Protection (OLP)

4.2 Thermal Shutdown (TSD): The SenseFET and the

control IC are integrated, making it easier for the control IC to detect the temperature of the SenseFET. When the temperature exceeds approximately 145°C, thermal shutdown is activated.

5. Soft-Start: The FPS has an internal soft-start circuit

that slowly increases the feedback voltage, together with the SenseFET current, right after it starts up. The typical soft-start time is 15ms, as shown in Figure 19, where progressive increment of the SenseFET current is allowed during the start-up phase. Soft-start circuit progressively increases current limits to establish proper working conditions for transformers, inductors, capacitors, and switching device. It also helps prevent transformer saturation and reduces the stress on the secondary diode.

Drain current

I

LIM

2.14ms 7steps

Figure 19. Internal Soft-Start

6. Burst Operation: To minimize the power dissipation

in standby mode, the FSQ211 enters burst mode operation. As the load decreases, the feedback voltage decreases. The device automatically enters burst mode when the feedback voltage drops below V

BURL

(0.55V). At this point, switching stops and the output voltages start to drop. This causes the feedback voltage to rise. Once is passes V

(0.70V), switching starts again.

BURH

The feedback voltage falls and the process repeats. Burst mode operation alternately enables and disables switching of the power MOSFET to reduce the switching loss in the standby mode.

OSC

GATE

DR IVE R

on/off

Burs t Oper ation Bloc k

V

fb

4

5µA 4 00µA

SRQ

0.70V /0.55V

Figure 20. Burst Operation Block

V

o

set

Vo

V

FB

0.7V

0.55V

I

ds

V

ds

t

Figure 21. Burst Operation Function

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FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

Application Tips

Methods of Reducing Audible Noise

Switching mode power converters have electronic and magnetic components that generate audible noises when the operating frequency is in the range of 20~20,000Hz. Even though they operate above 20kHz, they can make noise depending on the load condition. Designers can employ several methods to reduce noise.

Glue or Varnish

The most common method involves using glue or varnish to tighten magnetic components. The motion of core, bobbin and coil, and the chattering or magnetostriction of core, can cause the transformer to produce audible noise. The use of rigid glue and varnish helps reduce the transformer noise, but can crack the core. This is because sudden changes in the ambient temperature cause the core and the glue to expand or shrink at a different rate.

Ceramic Capacitor

Using a film capacitor instead of a ceramic capacitor as a snubber capacitor is another noise-reduction option. Some dielectric materials show a piezoelectric effect, depending on the electric field intensity. Therefore, a snubber capacitor becomes one of the most significant sources of audible noise. It is possible to use a Zener clamp circuit instead of an RCD snubber for higher efficiency as well as lower audible noise.

Figure 22. Equal Loudness Curves

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Adjusting Sound Frequency

Moving the fundamental frequency of noise out of 2~4kHz range is the third method. Generally, humans are more sensitive to noise in the range of 2~4kHz. When the fundamental frequency of noise is located in this range, the noise is perceived as louder, although

the noise intensity level is identical (refer to Figure 22 Equal Loudness Curves).

When FPS acts in burst mode and the burst operation is suspected to be a source of noise, this method may be helpful. If the frequency of burst-mode operation lies in the range of 2~4kHz, adjusting the feedback loop can shift the burst operation frequency. To reduce the burst operation frequency, increase a feedback gain capacitor (C

), opto-coupler supply resistor (RD), and feedback

F

capacitor (C (R

), as shown in Figure 23.

F

), and decrease a feedback gain resistor

B

Figure 23. Typical Feedback Network of FPS™

Other Reference Materials

AN-4134: Design Guidelines for Off-line Forward

Converters Using Fairchild Power Switch (FPS™)

AN-4137: Design Guidelines for Off-line Flyback

Converters Using Fairchild Power Switch (FPS™)

AN-4138: Design Considerations for Battery Charger

Using Green Mode Fairchild Power Switch (FPS™)

AN-4140: Transformer Design Consideration for Off-line

Flyback Converters Using Fairchild Power Switch (FPS™)

AN-4141: Troubleshooting and Design Tips for Fairchild

Power Switch (FPS™) Flyback Applications

AN-4147: Design Guidelines for RCD Snubber of

Flyback

AN-4148: Audible Noise Reduction Techniques for

FPS™ Application

Physical Dimensions

Dimensions are in millimeters unless otherwise noted.

FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

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Figure 24. 8-Lead Dual In-line Package (DIP)

Physical Dimensions (Continued)

Dimensions are in millimeters unless otherwise noted.

FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

TM

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Figure 25. 8-Lead LSOP

FSQ211 ⎯ Green Mode Fairchild Power Switch (FPS

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