FAN6300A/H — Highly Integrated Quasi-Resonant Current Mode PWM Controller

January 2014

FAN6300A / FAN6300H
Highly Integrated Quasi-Resonant Current Mode
PWM Controller
Features Description
 High-Voltage Startup The highly integrated FAN6300A/H of PWM controller
provides several features to enhance the performance
 Quasi-Resonant Operation
of flyback converters. FAN6300A is applied on quasi-
 Cycle-by-Cycle Current Limiting resonant flyback converters where maximum operating
frequency is below 100 kHz. FAN6300H is suitable for
 Peak-Current-Mode Control
high-frequency operation (up to 190 kHz). A built-in HV
 Leading-Edge Blanking (LEB) startup circuit can provide more startup current to
reduce the startup time of the controller. Once the VDD
 Internal Minimum tOFF
voltage exceeds the turn-on threshold voltage, the HV
 Internal 5 ms Soft-Start startup function is disabled immediately to reduce power
consumption. An internal valley voltage detector
 Over Power Compensation
ensures power system operates at quasi-resonant
 GATE Output Maximum Voltage operation over a wide-range of line voltage and any load
conditions, as well as reducing switching loss to
 Auto-Recovery Over-Current Protection(FB Pin) minimize switching voltage on drain of power MOSFET.
 Auto-Recovery Open-Loop Protection(FB Pin)
To minimize standby power consumption and light-load
 VDD Pin and Output Voltage (DET Pin) efficiency, a proprietary green-mode function provides
OVP Latched off-time modulation to decrease switching frequency
and perform extended valley voltage switching to keep
 Low Frequency Operation (below 100 kHz) for
to a minimum switching voltage. The operating
FAN6300A
frequency is limited by minimum toff time, which is 38 µs
 High Frequency Operation (up to 190 kHz) for to 8 µs in FAN6300A and 13 µs to 3 µs in FAN6300H,
FAN6300H so FAN6300H can operate at higher switching
frequency than FAN6300A.
Applications FAN6300A/H controller also provides many protection
functions. Pulse-by-pulse current limiting ensures the
 AC/DC NB Adapters fixed-peak current limit level, even when a short circuit
 Open-Frame SMPS occurs. Once an open-circuit failure occurs in the
feedback loop, the internal protection circuit disables
PWM output immediately. As long as VDD drops below the
turn-off threshold voltage, the controller also disables
PWM output. The gate output is clamped at 18 V to
protect the power MOS from high gate-source voltage
conditions. The minimum tOFF time limit prevents the
system frequency from being too high. If the DET pin
triggers OVP, internal OTP is triggered and the power
system enters latch-mode until AC power is removed.
The FAN6300A/H controller is available in the 8-pin
Small Outline Package (SOP).

Ordering Information
Part Number Operating Temperature Range Package Packing Method
FAN6300AMY
-40°C to +125°C 8-Lead, Small Outline Package (SOP) Tape & Reel
FAN6300HMY
For Fairchild’s definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN6300A/H • Rev. 1.0.2
 FAN6300A/H — Highly Integrated Quasi-Resonant Current Mode PWM Controller
Application Diagram

Figure 1. Typical Application

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com

FAN6300A / FAN6300H • Rev. 1.0.2 2
 FAN6300A/H — Highly Integrated Quasi-Resonant Current Mode PWM Controller
Internal Block Diagram
HV VDD
8 6
Internal
OVP Bias
IH V
4 .2V T w o Steps
U VLO
27 V 16 V/10 V/ 8V
2R Latched
FB 2 Soft -Start
5ms F B OLP
T im er
R 52 m s

2 .1m s
30 µs
Starter

Blanking D RV
C ircuit
CS 3 5 GA T E
SE T
S Q
PW M
Over-Pow er C ur rent Lim it 18 V
C om pensation R C LR Q
ID ET

Latched

0.3 V
tO F F - M IN Valley
D etector
V D ET tT IM E -O U T

V D ET
tO F F S/ H
Blanking Latched
2. 5V
D ET OVP

DET 1 0 .3 V Internal
Latched
5V I D ET OT P

4 7
GN D NC
Figure 2. Functional Block Diagram

Marking Information

: Fairchild Logo
Z: Plant Code
ZXYTT ZXYTT X: Year Code
Y: Week Code
6300A 6300H
TT: Die Run Code
TPM TPM T: Package Type (M = SOP)
P: Y = Green Package
M: Manufacturing Flow Code

Figure 3. Marking Diagram

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com

FAN6300A / FAN6300H • Rev. 1.0.2 3
 FAN6300A/H — Highly Integrated Quasi-Resonant Current Mode PWM Controller
Pin Configuration

Figure 4. Pin Configuration

Pin Definitions
Pin # Name Description
This pin is connected to an auxiliary winding of the transformer via resistors of the divider for
the following purposes:
- Generates a ZCD signal once the secondary-side switching current falls to zero.
- Produces an offset voltage to compensate the threshold voltage of the peak current limit to
provide a constant power limit. The offset is generated in accordance with the input voltage
1 DET when PWM signal is enabled.
- Detects the valley voltage of the switching waveform to achieve the valley voltage switching
and minimize the switching losses.
A voltage comparator and a 2.5 V reference voltage develop a output OVP protection. The ratio
of the divider decides what output voltage to stop gate, as an optical coupler and secondary
shunt regulator are used.
The feedback pin should to be connected to the output of the error amplifier for achieving the
voltage control loop. The FB should be connected to the output of the optical coupler if the
error-amplifier is equipped at the secondary-side of the power converter.
For the primary-side control application, FB is applied to connect a RC network to the ground
2 FB for feedback-loop compensation.
The input impedance of this pin is a 5 kΩ equivalent resistance. A 1/3 attenuator connected
between the FB and the PWM circuit is used for the loop-gain attenuation. FAN6300A/H
performs an open-loop protection once the FB voltage is higher than a threshold voltage
(around 4.2 V) more than 55 ms.
Input to the comparator of the over-current protection. A resistor senses the switching current
3 CS
and the resulting voltage is applied to this pin for the cycle-by-cycle current limit.
The power ground and signal ground. A 0.1 µF decoupling capacitor placed between VDD and
4 GND
GND is recommended.
Totem-pole output generates the PWM signal to drive the external power MOSFET. The
5 GATE
clamped gate output voltage is 18 V.
Power supply. The threshold voltages for startup and turn-off are 16 V and 10 V, respectively.
6 VDD
The startup current is less than 20 µA and the operating current is lower than 4.5 mA.
7 NC No connect
8 HV High-voltage startup.

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com

FAN6300A / FAN6300H • Rev. 1.0.2 4
 FAN6300A/H — Highly Integrated Quasi-Resonant Current Mode PWM Controller
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

VDD DC Supply Voltage 30 V
VHV HV 500 V
VH GATE -0.3 25.0 V
VL VFB, VCS, VDET -0.3 7.0 V
PD Power Dissipation 400 mW
TJ Operating Junction Temperature +150 °C
TSTG Storage Temperature Range -55 +150 °C
TL Lead Temperature (Soldering 10 Seconds) +270 °C
Human Body Model, JEDEC:JESD22-A114 3.0
ESD KV
Charged Device Model, JEDEC:JESD22-C101 1.5
Notes:
1. Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device.
2. All voltage values, except differential voltages, are given with respect to GND pin.

Recommended Operating Conditions

The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended
operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not
recommend exceeding them or designing to Absolute Maximum Ratings.

Symbol Parameter Conditions Min. Typ. Max. Unit

TA Operating Ambient Temperature -40 +125 °C

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com

FAN6300A / FAN6300H • Rev. 1.0.2 5
 FAN6300A/H — Highly Integrated Quasi-Resonant Current Mode PWM Controller
Electrical Characteristics
Unless otherwise specified, VDD=10~25 V, TA=-40°C~125°C (TA=TJ).

Symbol Parameter Conditions Min. Typ. Max. Unit

VDD Section
VOP Continuously Operating Voltage 25 V
VDD-ON Turn-On Threshold Voltage 15 16 17 V
VDD-PWM-OFF PWM Off Threshold Voltage 9 10 11 V
VDD-OFF Turn-Off Threshold Voltage 7 8 9 V
VDD=VDD-ON -0.16 V
IDD-ST Startup Current 10 20 µA
GATE Open
VDD=15 V, fS=60 KHz,
IDD-OP Operating Current 4.5 5.5 mA
CL=2 nF
Green-Mode Operating Supply Current VDD=15 V, fS=2 KHz,
IDD-GREEN 3.5 mA
(Average) CL=2 nF
IDD-PWM-OFF Operating Current at PWM-Off Phase VDD=VDD-PWM-OFF-0.5 V 70 80 90 µA
VDD-OVP VDD Over-Voltage Protection (Latch-Off) 26 27 28 V
tVDD-OVP VDD OVP Debounce Time 100 150 200 µs
IDD-LATCH VDD OVP Latch-Up Holding Current VDD=5 V 42 µA
HV Startup Current Source Section
VHV-MIN Minimum Startup Voltage on Pin HV 50 V
VAC=90 V(VDC=120V)
IHV Supply Current Drawn from Pin HV 1.5 4.0 mA
VDD=0 V
HV=500 V,
IHV-LC Leakage Current After Startup 1 20 µA
VDD=VDD-OFF +1 V
Feedback Input Section
Input-Voltage to Current Sense AV =∆VCS/∆VFB
AV 1/2.75 1/3.00 1/3.25 V/V
Attenuation 0<VCS<0.9
ZFB Input Impedance 3 5 7 KΩ
IOZ Bias Current FB=VOZ 1.2 2 mA
VOZ Zero Duty-Cycle Input Voltage 0.8 1.0 1.2 V
VFB-OLP Open Loop Protection Threshold Voltage 3.9 4.2 4.5 V
Debounce Time for Open-Loop/Overload
tD-OLP 46 52 62 ms
Protection
tSS Internal Soft-Start Time 5 ms
Continued on the following page...

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com

FAN6300A / FAN6300H • Rev. 1.0.2 6
 FAN6300A/H — Highly Integrated Quasi-Resonant Current Mode PWM Controller
Electrical Characteristics (Continued)
Unless otherwise specified, VDD=10~25 V, TA=-40°C ~125°C (TA=TJ).

Symbol Parameter Conditions Min. Typ. Max. Unit

DET Pin OVP and Valley Detection Section
VDET-OVP Comparator Reference Voltage 2.45 2.50 2.55 V
(3)
Av Open-Loop Gain 60 dB
(3)
Bw Gain Bandwidth 1 MHz
VV-HIGH Output High Voltage 4.5 V
VV-LOW Output Low Voltage 0.5 V
tDET-OVP Output OVP (Latched) Debounce Time 100 150 200 µs
IDET-SOURCE Maximum Source Current VDET=0 V 1 mA
VDET-HIGH Upper Clamp Voltage IDET=-1 mA 5 V
VDET-LOW Lower Clamp Voltage IDET=1 mA 0.1 0.3 V
Delay Time from Valley-Signal Detected to
tVALLEY-DELAY (3) 200 ns
Output Turn-On
Leading-Edge-Blanking Time for DET when FAN6300A 4.0
tOFF-BNK (3) µs
PWM MOS Turns Off FAN6300H 1.5
FAN6300A 9
tTIME-OUT Time-Out after tOFF-MIN µs
FAN6300H 5
Oscillator Section
tON-MAX Maximum On-Time 38 45 54 µs
VFB≧VN,
8 µs
FAN6300A
VFB≧VN
3 µs
FAN6300H
tOFF-MIN Minimum Off-Time
VFB=VG
38 µs
FAN6300A
VFB=VG
13 µs
FAN6300H
Beginning of Green-On Mode at FB Voltage
VN 1.95 2.10 2.25 V
Level
Beginning of Green-Off Mode at FB Voltage
VG 1.0 1.2 1.4 V
Level
∆VFBG Green-Off Mode VFB Hysteresis Voltage 0.05 0.10 0.20 V
VFB<VG 1.8 2.1 2.4 ms
tSTARTER Start Timer (Time-Out Timer)
VFB>VFB-OLP 25 30 45 µs
Output Section
VDD=15 V,
VOL Output Voltage Low 1.5 V
IO=150 mA
VDD=12 V,
VOH Output Voltage High 7.5 V
IO=150 mA
tR Rising Time 145 200 ns
tF Falling Time 55 120 ns
VCLAMP Gate Output Clamping Voltage 16.7 18.0 19.3 V
Continued on following page…

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com

FAN6300A / FAN6300H • Rev. 1.0.2 7
 FAN6300A/H — Highly Integrated Quasi-Resonant Current Mode PWM Controller
Electrical Characteristics(Continued)
Unless otherwise specified, VDD=10~25 V, TA=-40°C ~125°C (TA=TJ).

Symbol Parameter Conditions Min. Typ. Max. Unit

Current Sense Section
tPD Delay to Output 20 150 200 ns
Limit Voltage on CS Pin for Over-Power IDET < 74.41 µA 0.82 0.85 0.88 V
VLIMIT
Compensation IDET=550 µA 0.380 0.415 0.450 V
(3) tON=45 µs 0.3 V
VSLOPE Slope Compensation
tON=0 µs 0.1 V
Leading-Edge-Blanking Time
tBNK 525 625 725 ns
(MOS Turns ON)
VCS Clamped High Voltage once CS Pin
VCS-H CS Pin Floating 4.5 5.0 V
Floating
tCS-H Delay Time once CS Pin Floating CS Pin Floating 150 µs
Internal Over-Temperature Protection Section
(3)
TOTP Internal Threshold Temperature for OTP +140 °C
(3)
TOTP-HYST Hysteresis Temperature for Internal OTP +15 °C
Note:
3. Guaranteed by design.

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com

FAN6300A / FAN6300H • Rev. 1.0.2 8
 FAN6300A/H — Highly Integrated Quasi-Resonant Current Mode PWM Controller
Typical Performance Characteristics
Graphs are normalized at TA=25°C.

17.0 10.00

9.80
16.5

VDD-PWM-OFF(V)
9.60
VDD-ON (V)

16.0

9.40

15.5
9.20

15.0 9.00
-40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃ -40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
o
Temperature( C) Temperature(°C)

Figure 5. Turn-On Threshold Voltage Figure 6. PWM-Off Threshold Voltage

8.1 18

8.0 16

7.9 14
VDD-OFF (V)

IDD-ST(µA)
7.8 12

7.7 10

7.6 8

7.5 6
-40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃ -40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
Temperature(oC) Temperature(°C)

Figure 7. Turn-Off Threshold Voltage Figure 8. Startup Current

4.50 4.0

3.5
4.20

3.0
3.90
I HV(mA)
IDD-OP(mA)

2.5

3.60
2.0

3.30 1.5

1.0
3.00 -40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
-40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
Temperature(°C)
Temperature(°C)

Figure 9. Operating Current Figure 10. Supply Current Drawn From HV Pin

0.32 0.40

0.31
0.35
0.30
0.30
0.29
IHV-LC(µA)

VDET-LOW (V)

0.25
0.28

0.27 0.20

0.26 0.15

0.25
0.10
-40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
-40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
Temperature(°C) Temperature(oC)

Figure 11. Leakage Current After Startup Figure 12. Lower Clamp Voltage

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com

FAN6300A / FAN6300H • Rev. 1.0.2 9
 FAN6300A/H — Highly Integrated Quasi-Resonant Current Mode PWM Controller
Typical Performance Characteristics (Continued)
These characteristic graphs are normalized at TA = 25°C.
8.70
2.52

2.51 8.40
VDET-OVP(V)

toff-min(µs)
2.50 8.10

2.49
7.80

2.48
-40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃ 7.50
-40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃
Temperature(oC)
Temperature(°C)

Figure 13. Comparator Reference Voltage Figure 14. Minimum Off Time (VFB>VN)

42.0 2.50

40.0 2.40

2.30

tSTARTER(ms)
38.0
t OFF-MIN(μs)

2.20
36.0
2.10

34.0 2.00

32.0 1.90
-40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃ -40℃ -25℃ -10℃ 5℃ 20℃ 35℃ 50℃ 65℃ 80℃ 95℃ 110℃ 125℃

Temperature(oC)
Temperature(°C)

Figure 15. Minimum Off Time (VFB=VG) Figure 16. Start Timer (VFB<VG)

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com

FAN6300A / FAN6300H • Rev. 1.0.2 10
 FAN6300A/H — Highly Integrated Quasi-Resonant Current Mode PWM Controller
Operation Description
The FAN6300A/H PWM controller integrates designs to Green-Mode Operation
enhance the performance of flyback converters. An
The proprietary green-mode function provides off-time
internal valley voltage detector ensures power system
modulation to linearly decrease the switching frequency
operates at Quasi-Resonant (QR) operation across a
under light-load conditions. VFB, which is derived from
wide range of line voltage. The following descriptions
the voltage feedback loop, is taken as the reference. In
highlight some of the features of the FAN6300A/H.
Figure 19, once VFB is lower than VN, tOFF-MIN increases
Startup Current linearly with lower VFB. The valley voltage detection
signal does not start until tOFF-MIN finishes. Therefore, the
For startup, the HV pin is connected to the line input or valley detect circuit is activated until tOFF-MIN finishes,
bulk capacitor through an external diode and resistor, which decreases the switching frequency and provides
RHV, which are recommended as 1N4007 and 100 kΩ. extended valley voltage switching. However, in very light
Typical startup current drawn from the HV pin is 1.2 mA load condition, it might fail to detect the valley voltage
and it charges the hold-up capacitor through the diode after the tOFF-MIN expires. Under this condition, an internal
and resistor. When the VDD voltage level reaches VDD-ON, tTIME-OUT signal initiates a new cycle start after a 9 μs
the startup current switches off. At this moment, the VDD delay (with 5 µs delay for H version). Figure 20 and
capacitor only supplies the FAN6300A/H to maintain VDD Figure 21 show the two different conditions.
until the auxiliary winding of the main transformer
provides the operating current. tO F F -M I N

Valley Detection 2 .1 m s

The DET pin is connected to an auxiliary winding of the

transformer via resistors of the divider to generate a
valley signal once the secondary-side switching current
discharges to zero. It detects the valley voltage of the
switching waveform to achieve the valley voltage
switching. This ensures QR operation, minimizes
38/13 μ s
switching losses, and reduces EMI. Figure 17 shows
divider resistors RDET and RA. RDET is recommended as
150 kΩ to 220 kΩ to achieve valley voltage switching. 8 /3μ s
When VAUX (in Figure 17) is negative, the DET pin
voltage is clamped to 0.3 V.
1 .2 V 2 .1 V VFB
Figure 19. VFB vs. tOFF-MIN Curve

Figure 17. Valley Detect Section

The internal timer (minimum tOFF time) prevents gate
retriggering within 8 µs (3 µs for H version) after the gate Figure 20. QR Operation in Extended Valley Voltage
signal going-low transition. The minimum tOFF limit Detection Mode
prevents system frequency being too high. Figure 18
shows a typical drain voltage waveform with first valley
switching.

Figure 21. Internal tTIME-OUT Initiates New Cycle After

Failure to Detect Valley Voltage
Figure 18. First Valley Switching
(with 5 µs Delay for FAN6300H version)

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com

FAN6300A / FAN6300H • Rev. 1.0.2 11
 FAN6300A/H — Highly Integrated Quasi-Resonant Current Mode PWM Controller
Current Sensing and PWM Current Limiting VDD Over-Voltage Protection
Peak-current-mode control is utilized to regulate output VDD over-voltage protection prevents damage due to
voltage and provide pulse-by-pulse current limiting. The abnormal conditions. Once the VDD voltage is over the
switch current is detected by a sense resistor into the CS VDD over-voltage protection voltage (VDD-OVP) and lasts
pin. The PWM duty cycle is determined by this current- for tVDDOVP, the PWM pulse is disabled until the VDD
sense signal and VFB. When the voltage on CS reaches voltage drops below the UVLO, then starts again.
around VLIMIT = (VFB-1.2)/3, the switch cycle is terminated
immediately. VLIMIT is internally clamped to a variable Output Over-Voltage Protection
voltage around 0.85 V for output power limit. The output over-voltage protection works by the
Leading-Edge Blanking (LEB) sampling voltage, as shown in Figure 23, after switch-off
sequence. A 4 μs (1.5 μs for H version) blanking time
Each time the power MOFFET switches on, a turn-on ignores the leakage inductance ringing. A voltage
spike occurs on the sense resistor. To avoid premature comparator and a 2.5 V reference voltage develop an
termination of the switching pulse, lead-edge blanking time output OVP protection. The ratio of the divider
is built in. During the blanking period, the current limit determines the sampling voltage of the stop gate, as an
comparator is disabled; it cannot switch off the gate driver. optical coupler and secondary shunt regulator are used.
If the DET pin OVP is triggered, the power system enters
Under-Voltage Lockout (UVLO) latch-mode until AC power is removed.
The turn-on, PWM-off, and turn-off thresholds are fixed
internally at 16/10/8 V. During startup, the startup
capacitor must be charged to 16 V through the startup
resistor to enable the IC. The hold-up capacitor
continues to supply VDD until energy can be delivered
from the auxiliary winding of the main transformer. VDD
must not drop below 10 V during this startup process.
This UVLO hysteresis window ensures that hold-up
capacitor is adequate to supply VDD during startup.
Gate Output
The BiCMOS output stage is a fast totem-pole gate
driver. Cross conduction has been avoided to minimize
heat dissipation, increase efficiency, and enhance
reliability. The output driver is clamped by an internal
18 V Zener diode to protect power MOSFET transistors Figure 23. Voltage Sampled After 4μs
against undesired over-voltage gate signals. (1.5 μs for FAN6300H version) Blanking Time
After Switch-Off Sequence
Over-Power Compensation
To compensate this variation for wide AC input range, Short-Circuit and Open-Loop Protection
the DET pin produces an offset voltage to compensate The FB voltage increases every time the output of the
the threshold voltage of the peak current limit to provide power supply is shorted or overloaded. If the FB voltage
a constant-power limit. The offset is generated in remains higher than a built-in threshold for longer than tD-
accordance with the input voltage when PWM signal is OLP, PWM output is turned off. As PWM output is turned-
enabled. This results in a lower current limit at high-line off, the supply voltage VDD begins decreasing.
inputs than low-line inputs. At fixed-load condition, the
CS limit is higher when the value of RDET is higher. RDET When VDD goes below the PWM-off threshold of 10 V,
also affects the H/L line constant power limit. VDD decreases to 8 V, then the controller is totally shut
down. VDD is charged up to the turn-on threshold voltage
of 16 V through the startup resistor until PWM output is
restarted. This protection feature continues as long as
the overloading condition persists. This prevents the
power supply from overheating due to overloading.

Figure 22. H/L Line Constant Power Limit

Compensated by DET Pin

© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com

FAN6300A / FAN6300H • Rev. 1.0.2 12
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FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE
RELIABILITY, FUNCTION, OR DESIGN. TO OBTAIN THE LATEST, MOST UP-TO-DATE DATASHEET AND PRODUCT INFORMATION, VISIT OUR
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ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF
OTHERS. THESE SPECIFICATIONS DO NOT EXPAND THE TERMS OF FAIRCHILD’S WORLDWIDE TERMS AND CONDITIONS, SPECIFICALLY THE
WARRANTY THEREIN, WHICH COVERS THESE PRODUCTS.

AUTHORIZED USE
Unless otherwise specified in this data sheet, this product is a standard commercial product and is not intended for use in applications that require extraordinary
levels of quality and reliability. This product may not be used in the following applications, unless specifically approved in writing by a Fairchild officer: (1) automotive
or other transportation, (2) military/aerospace, (3) any safety critical application – including life critical medical equipment – where the failure of the Fairchild product
reasonably would be expected to result in personal injury, death or property damage. Customer’s use of this product is subject to agreement of this Authorized Use
policy. In the event of an unauthorized use of Fairchild’s product, Fairchild accepts no liability in the event of product failure. In other respects, this product shall be
subject to Fairchild’s Worldwide Terms and Conditions of Sale, unless a separate agreement has been signed by both Parties.
ANTI-COUNTERFEITING POLICY
Fairchild Semiconductor Corporation's Anti-Counterfeiting Policy. Fairchild's Anti-Counterfeiting Policy is also stated on our external website, www.fairchildsemi.com,
under Terms of Use
Counterfeiting of semiconductor parts is a growing problem in the industry. All manufacturers of semiconductor products are experiencing counterfeiting of their
parts. Customers who inadvertently purchase counterfeit parts experience many problems such as loss of brand reputation, substandard performance, failed
applications, and increased cost of production and manufacturing delays. Fairchild is taking strong measures to protect ourselves and our customers from the
proliferation of counterfeit parts. Fairchild strongly encourages customers to purchase Fairchild parts either directly from Fairchild or from Authorized Fairchild
Distributors who are listed by country on our web page cited above. Products customers buy either from Fairchild directly or from Authorized Fairchild Distributors
are genuine parts, have full traceability, meet Fairchild's quality standards for handling and storage and provide access to Fairchild's full range of up-to-date technical
and product information. Fairchild and our Authorized Distributors will stand behind all warranties and will appropriately address any warranty issues that may arise.
Fairchild will not provide any warranty coverage or other assistance for parts bought from Unauthorized Sources. Fairchild is committed to combat this global
problem and encourage our customers to do their part in stopping this practice by buying direct or from authorized distributors.
PRODUCT STATUS DEFINITIONS
Definition of Terms
Datasheet Identification Product Status Definition
Datasheet contains the design specifications for product development. Specifications may change
Advance Information Formative / In Design
in any manner without notice.
Datasheet contains preliminary data; supplementary data will be published at a later date. Fairchild
Preliminary First Production
Semiconductor reserves the right to make changes at any time without notice to improve design.
Datasheet contains final specifications. Fairchild Semiconductor reserves the right to make
No Identification Needed Full Production
changes at any time without notice to improve the design.
Datasheet contains specifications on a product that is discontinued by Fairchild Semiconductor.
Obsolete Not In Production
The datasheet is for reference information only.
Rev. I77

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