FAIRCHILD FAN6754

FAN6754
Highly Integrated Green-Mode PWM Controller
Brownout and Constant Power Limited by HV Pin
Features
Description
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The highly integrated FAN6754 PWM controller
provides several features to enhance the performance
of flyback converters. To minimize standby power
consumption, a proprietary green-mode function
provides off-time modulation to continuously decrease
the switching frequency under light-load conditions.
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High-Voltage Startup
AC Input Brownout Protection with Hysteresis
Low Operating Current: 1.7mA
Linearly Decreasing PWM Frequency to 22KHz
Frequency Hopping to Reduce EMI Emission
Under zero-load and very light-load conditions,
FAN6754 saves PWM pulses by entering deep burst
mode. This burst mode function enables the power
supply to meet international power conservation
requirements.
Fixed PWM Frequency: 65KHz
Peak-Current-Mode Control
Cycle-by-Cycle Current Limiting
Leading-Edge Blanking (LEB)
Internal Open-Loop Protection
GATE Output Maximum Voltage Clamp: 13V
VDD Under-Voltage Lockout (UVLO)
VDD Over-Voltage Protection (OVP)
Programmable Over-Temperature Protection (OTP)
Internal Latch Circuit (OVP, OTP)
Open-Loop Protection (OLP); Restart for MR, Latch
for ML
Built-in 8ms Soft-Start Function
Constant Power Limit (Full AC Input Range)
Internal OTP Sensor with Hysteresis
FAN6754 integrates a frequency-hopping function
internally to reduce EMI emission of a power supply
with minimum line filters. Built-in synchronized slope
compensation is accomplished by, proprietary internal
compensation for constant output power limit over
universal AC input range. Also, the gate output is
clamped at 13V to protect the external MOSFET from
over-voltage damage.
FAN6754 — Highly Integrated Green-Mode PWM Controller
September 2009
Other protection functions include AC input brownout
protection with hysteresis and VDD over-voltage
protection. For over-temperature protection, an external
NTC thermistor can be applied to sense the external
switcher’s temperature. When VDD OVP or OTP are
activated, an internal latch circuit is used to latch-off the
controller. The latch mode is reset when the VDD supply
is removed.
FAN6754 is available in an 8-pin SOP package.
Applications
General-purpose switch-mode power supplies and
flyback power converters, including:
ƒ
Power Adapters
Ordering Information
Part Number
Operating
Temperature Range
Eco
Status
FAN6754MRMY
-40 to +105°C
RoHS
8-Pin, Small Outline Package (SOP)
Tape & Reel
FAN6754MLMY
-40 to +105°C
RoHS
8-Pin, Small Outline Package (SOP)
Tape & Reel
Package
Packing Method
For Fairchild’s definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
www.fairchildsemi.com
FAN6754 — Highly Integrated Green-Mode PWM Controller
Application Diagram
Figure 1. Typical Application
Internal Block Diagram
HV
NC
4
3
Line Voltage
Sample Circuit
OVP
OTP
OLP
Latch
Protection
Brownout Protection
I HV
HV
Startup
Soft
Driver
Current Limit Compensation
OSC
VDD
S
Internal
BIAS
7
8
GATE
6
SENSE
Q
R
UVLO
Soft-Start
Comparator
17.5V/10V
Soft-Start
Green
Mode
Circuit
Blanking
Current-Limit
Comparator
VLimit
Debounce
OVP
PWM
Comparator
VDD-OVP
5.2V
Slope
Compensation
3R
IRT
RT
5
2
tD-OTP1
Counter
OTP
OLP
1.05V
tD-OTP2
OLP
Comparator
Counter
0.7V
FB
R
OLP
Delay
4.6V
1
GND
Figure 2. Functional Block Diagram
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
www.fairchildsemi.com
2
F - Fairchild Logo
Z - Plant Code
X - 1-Digit Year Code
Y - 1-Digit Week Code
TT - 2-Digit Die Run Code
T - Package Type (M=SOP)
P - Y: Package (Green)
M - Manufacture Flow Code
ZXYTT
6754ML
TPM
ZXYTT
6754MR
TPM
Figure 3. Top Mark
Pin Configuration
SOP-8
GND
1
8
GATE
FB
2
7
VDD
NC
3
6
SENSE
HV
4
5
RT
Figure 4. Pin Configuration (Top View)
FAN6754 — Highly Integrated Green-Mode PWM Controller
Marking Information
Pin Definitions
Pin #
Name
1
GND
Description
Ground. This pin is used for the ground potential of all the pins. A 0.1µF decoupling capacitor
placed between VDD and GND is recommended.
2
FB
Feedback. The output voltage feedback information from the external compensation circuit is
fed into this pin. The PWM duty cycle is determined by this pin and the current-sense signal
from Pin 6. FAN6754 performs an open-loop protection (OLP); if the FB voltage is higher than a
threshold voltage (around 4.6V) for more than 55ms, the controller latches off the PWM.
3
NC
No Connection.
4
HV
High Voltage Startup. This pin is connected to the line input via a 1N4007 and 200kΩ resistors
to achieve brownout and high/low line compensation. Once the voltage on the HV pin is lower
than the brownout voltage, PWM output turns off. High/low line compensation dominates the
cycle-by-cycle current limiting to achieve constant output power limiting with universal input.
5
RT
Over-Temperature Protection. An external NTC thermistor is connected from this pin to GND.
The impedance of the NTC decreases at high temperatures. Once the voltage on the RT pin
drops below the threshold voltage, the controller latches off the PWM.
6
SENSE
Current Sense. This pin is used to sense the MOSFET current for the current-mode PWM and
current limiting.
7
VDD
Supply Voltage. IC operating current and MOSFET driving current are supplied using this pin.
This pin is connected to an external bulk capacitor of typically 47µF. The threshold voltage for
turn-on and turn-off is 16.5V and 9V, respectively. The operating current is lower than 2mA.
8
GATE
Gate Drive Output. The totem-pole output driver for the power MOSFET. It is internally clamped
below 13V.
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
www.fairchildsemi.com
3
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.
(1, 2)
Max.
Unit
30
V
VVDD
DC Supply Voltage
VFB
FB Pin Input Voltage
-0.3
7.0
V
SENSE Pin Input Voltage
-0.3
7.0
V
VRT
RT Pin Input Voltage
-0.3
7.0
V
VHV
HV Pin Input Voltage
500
V
PD
Power Dissipation (TA＜50°C)
400
mW
ΘJA
Thermal Resistance (Junction-to-Air)
141
°C/W
TJ
Operating Junction Temperature
-40
+125
°C
Storage Temperature Range
-55
+150
°C
+260
°C
4.5
kV
1500
V
VSENSE
TSTG
TL
ESD
Lead Temperature (Wave Soldering or IR, 10 Seconds)
Human Body Model, JEDEC:JESD22-A114
Charged Device Model, JEDEC:JESD22-C101
Notes:
1. All voltage values, except differential voltages, are given with respect to the network ground terminal.
2. Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device.
Recommended Operating Conditions
FAN6754 — Highly Integrated Green-Mode PWM Controller
Absolute Maximum Ratings
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
TA
RHV
Parameter
Conditions
Min.
Operating Ambient Temperature
-40
HV Startup Resistor
150
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
Typ.
Max.
+105
200
Unit
°C
kΩ
www.fairchildsemi.com
4
VDD=15V and TA=25°C unless otherwise noted.
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
24
V
VDD Section
VOP
Continuously Operating Voltage
VDD-ON
Start Threshold Voltage
VDD-OFF
Minimum Operating Voltage
15.5
16.5
17.5
V
8
9
10
V
VDD-OLP
IDD-OLP Off Voltage
5.5
6.5
7.5
V
VDD-LH
Threshold Voltage on VDD Pin for
Latch-Off Release Voltage
3.5
4.0
4.5
V
VDD-AC
Threshold Voltage on VDD Pin for
Disable AC recovery to avoid
Startup Failed
VDD-OFF
+2.5
VDD-OFF
+3.0
VDD-OFF
+3.5
V
30
µA
IDD-ST
Startup Current
VDD-ON – 0.16V
IDD-OP1
Operating Supply Current when
PWM operation
VDD=20V, FB=3V Gate
Open
1.7
2.0
mA
IDD-OP2
Operating Supply Current when
Gate Stop
VDD=20V, FB=3V
1.2
1.5
mA
ILH
Operating Current at PWM-Off
Phase Under Latch-Off
Conduction
VDD=5V
30
60
90
µA
IDD-OLP
Internal Sink Current under LatchVDD-OLP+0.1V
Off Conduction
180
210
240
µA
VDD-OVP
VDD Over-Voltage Protection
24
25
26
V
tD-VDDOVP
VDD Over-Voltage Protection
Debounce Time
75
165
255
µs
1.50
2.75
4.00
mA
FAN6754 — Highly Integrated Green-Mode PWM Controller
Electrical Characteristics
HV Section
Supply Current from HV Pin
VAC=90V(VDC=120V),
VDD=0V
VAC-OFF
Brownout Threshold
DC Source Series
R=200kΩ to HV Pin
See Equation 1
92
102
112
V
VAC-ON
Brownin Threshold
DC Source Series
R=200kΩ to HV Pin
See Equation 2
104
114
124
V
△VAC
VAC-ON - VAC-OFF
DC Source Series
R=200kΩ to HV Pin
6
12
18
V
tS-CYCLE
Line Voltage Sample Cycle
tH-TIME
Line Voltage Hold Period
IHV
tD-AC-OFF
(Eq.2)
PWM Turn-off Debounce Time
FB > VFB-N
220
FB < VFB-G
650
μs
20
μs
FB > VFB-N
65
75
85
ms
FB < VFB-G
180
235
290
ms
Continued on the following page…
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
www.fairchildsemi.com
5
Figure 5. Brownout Circuit
FAN6754 — Highly Integrated Green-Mode PWM Controller
Typical Performance Characteristics
Figure 6. Brownout Behavior
Figure 7. VDD-AC and AC Recovery
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
www.fairchildsemi.com
6
VDD=15V and TA=25°C unless otherwise noted.
Symbol
Parameter
Conditions
Min.
Typ.
Max. Units
61
65
69
±3.7
±4.2
±4.7
Oscillator Section
fOSC
Frequency in Normal Mode
tHOP
Hopping Period
fOSC-G
Center Frequency
Hopping Range
KHz
FB > VFB-N
3.9
4.4
4.9
ms
FB=VFB-G
10.2
11.5
12.8
ms
19
22
25
KHz
Green-Mode Frequency
fDV
Frequency Variation vs. VDD Deviation
VDD=11V to 22V
5
%
fDT
Frequency Variation vs. Temperature
Deviation
TA=-40 to +105°C
5
%
Feedback Input Section
AV
Input Voltage to Current-Sense Attenuation
1/4.5
1/4.0
1/3.5
V/V
ZFB
Input Impedance
13.5
15.5
17.5
kΩ
VFB-OPEN
Output High Voltage
VFB-OLP
FB Open-Loop Trigger Level
tD-OLP
VFB-N
VFB-G
FB Pin Open
Delay Time of FB Pin Open-Loop Protection
Green-Mode Entry FB Voltage
Green-Mode Ending FB Voltage
4.8
5.0
5.2
V
4.3
4.6
4.9
V
50
55
60
ms
Pin, FB Voltage
(FB =VFB-N)
2.6
2.8
3.0
V
Hopping Range
±3.7
±4.2
±4.7
kHz
Pin, FB Voltage
(FB =VFB-G)
2.1
2.3
2.5
V
Hopping Range
±1.27
±1.45
±1.62
kHz
VFB-ZDCR
FB Threshold Voltage for Zero-Duty Recovery
1.9
2.1
2.3
V
VFB-ZDC
FB Threshold Voltage for Zero-Duty
1.8
2.0
2.2
V
FAN6754 — Highly Integrated Green-Mode PWM Controller
Electrical Characteristics (Continued)
Continued on the following page…
PWM Frequency
fOSC
fOSC-G
VFB-ZDC VFB-ZDCR VFB-G
VFB-N
VFB
Figure 8. VFB vs. PWM Frequency
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
www.fairchildsemi.com
7
VDD=15V and TA=25°C unless otherwise noted.
Symbol
Parameter
Conditions
Min.
Typ.
Max. Units
Feedback Input Section
Current-Sense Section
tPD
Delay to Output
tLEB
Leading Edge Blanking Time
Vlimit-L
Current Limit at Low Line (VAC=86V)
VDC=122V, Series R=200kΩ
to HV
Vlimit-H
Current Limit tat High Line (VAC=259V)
VDC=366V, Series R=200kΩ
to HV
Period During Soft-Start Time
Startup Time
tSS
100
250
ns
230
280
330
ns
0.43
0.46
0.49
V
0.36
0.39
0.42
V
7
8
9
ms
86
89
92
%
1.5
V
GATE Section
DCYMAX
Maximum Duty Cycle
VGATE-L
Gate Low Voltage
VDD=15V, IO=50mA
VGATE-H
Gate High Voltage
VDD=12V, IO=50mA
tr
Gate Rising Time
VDD=15V, CL=1nF
100
ns
tf
Gate Falling Time
VDD=15V, CL=1nF
50
ns
Gate Output Clamping Voltage
VDD=22V
VGATECLAMP
8
V
9
13
17
V
9.50
10.55
11.60
KΩ
0.7V ＜ VRT ＜ 1.05V, after
12ms Latch Off
1.000
1.035
1.070
V
VRT ＜ 0.7V, After 100µs
Latch Off
0.65
0.70
0.75
V
VRTTH2 ＜ VRT ＜ VRTTH1
FB > VFB-N
14
16
18
VRTTH2 ＜ VRT ＜ VRTTH1
FB < VFB-G
40
51
62
VRT< VRTTH2
FB > VFB-N
110
185
260
VRT< VRTTH2
FB < VFB-G
320
RT Section
RRT
VRTTH1
VRTTH2
Internal Resistor from RT Pin
Over-Temperature Protection Threshold
Voltage
tD-OTP1
Over-Temperature Latch-Off Debounce
tD-OTP2
FAN6754 — Highly Integrated Green-Mode PWM Controller
Electrical Characteristics (Continued)
ms
µs
605
890
Over-Temperature Protection Section (OTP)
TOTP
TRestart
Protection Junction Temperature
Restart Junction Temperature
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
+135
°C
TOTP-25
°C
www.fairchildsemi.com
8
4
40
3.5
35
3
IDD-OP1 (mA)
IDD-ST (μA)
45
30
25
20
2.5
2
1.5
15
1
10
0.5
5
0
-40
-25
-10
5
20
35
50
65
80
95
110
125
-40
-25
-10
5
Temperature (℃ )
18
11
17.5
10.5
50
65
80
95
110
125
10
17
VDD-OFF (V)
V DD-ON (V)
35
Figure 10. Operation Supply Current (IDD-OP1)
vs. Temperature
Figure 9. Startup Current (IDD-ST) vs. Temperature
16.5
16
9.5
9
8.5
15.5
8
15
7.5
-40
-25
-10
5
20
35
50
65
80
95
110
-40
125
-25
-10
5
Temperature (℃ )
20
35
50
65
80
95
110
125
Temperature (℃ )
Figure 11. Start Threshold Voltage (VDD-ON)
vs. Temperature
Figure 12. Minimum Operating Voltage (VDD-OFF)
vs. Temperature
7
3.5
6
3
IHV-LC (uA)
5
IHV (mA)
20
Temperature (℃ )
4
3
2
FAN6754 — Highly Integrated Green-Mode PWM Controller
Typical Performance Characteristics (Continued)
2.5
2
1.5
1
1
0
0.5
-40
-25
-10
5
20
35
50
65
80
95
110
-40
125
-25
-10
5
Temperature (℃ )
20
35
50
65
80
95
110
125
Temperature (℃ )
Figure 13. Supply Current Drawn from HV Pin (IHV)
vs. Temperature
Figure 14. HV Pin Leakage Current After Startup
(IHV-LC) vs. Temperature
70
100
69
68
95
DCYMAX (%)
fOSC (KHz)
67
66
65
64
63
90
85
62
61
60
80
-40
-25
-10
5
20
35
50
65
80
95
110
125
-40
Temperature (℃ )
-10
5
20
35
50
65
80
95
110
125
Temperature (℃ )
Figure 15. Frequency in Normal Mode (fOSC)
vs. Temperature
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
-25
Figure 16. Maximum Duty Cycle (DCYMAX)
vs. Temperature
www.fairchildsemi.com
9
70
5.5
65
5
60
tD-OLP (ms)
VFB-OLP (V)
6
4.5
4
3.5
55
50
45
3
40
-40
-25
-10
5
20
35
50
65
80
95
110
125
-40
-25
-10
5
Temperature (℃ )
20
35
50
65
80
95
110
125
Temperature (℃ )
Figure 17. FB Open-Loop Trigger Level (VFB-OLP)
vs. Temperature
Figure 18. Delay Time of FB Pin Open-Loop Protection
(tD-OLP) vs. Temperature
28
120
27
110
25
IRT (uA)
VDD-OVP (V)
26
24
23
22
100
90
80
21
20
70
-40
-25
-10
5
20
35
50
65
80
95
110
125
-40
-25
-10
5
Temperature (℃ )
35
50
65
80
95
110
125
Figure 20. Output Current from RT Pin (IRT)
vs. Temperature
1.2
0.9
1.1
0.8
V RTTH2 (V)
VRTTH1 (V)
Figure 19. VDD Over-Voltage Protection (VDD-OVP)
vs. Temperature
1
0.9
0.8
-40
20
Temperature (℃ )
FAN6754 — Highly Integrated Green-Mode PWM Controller
Typical Performance Characteristics (Continued)
0.7
0.6
0.5
-30
-15
0
25
50
75
85
100
125
-40
-25
-10
5
20
35
50
65
80
95
110
125
Temperature (℃ )
Temperature (℃)
Figure 21. Over-Temperature Protection Threshold
Voltage (VRTTH1) vs. Temperature
Figure 22. Over-Temperature Protection Threshold
Voltage (VRTTH2) vs. Temperature
120
120
115
VAC-OFF (V)
V AC-ON (V)
115
110
110
105
100
105
95
100
90
-40
-25
-10
5
20
35
50
65
80
95
110
125
-40
Temperature (℃ )
-10
5
20
35
50
65
80
95
110
125
Temperature (℃ )
Figure 23. Brownin (VAC-ON) vs. Temperature
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
-25
Figure 24. Brownout (VAC-OFF) vs. Temperature
www.fairchildsemi.com
10
Startup Current
Gate Output / Soft Driving
For startup, the HV pin is connected to the line input
through an external diode and resistor; RHV, (1N4007 /
150KΩ recommended). Peak startup current drawn
from the HV pin is (VAC × 2 ) / RHV and charges the
hold-up capacitor through the diode and resistor. When
the VDD capacitor level reaches VDD-ON, the startup
current switches off. At this moment, the VDD capacitor
only supplies the FAN6754 to keep the VDD until the
auxiliary winding of the main transformer provides the
operating current.
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
13V Zener diode to protect power MOSFET transistors
against undesirable gate over voltage. A soft driving
waveform is implemented to minimize EMI.
Soft-Start
For many applications, it is necessary to minimize the
inrush current at startup. The built-in 8ms soft-start
circuit significantly reduces the startup current spike
and output voltage overshoot.
Operating Current
Operating current is around 1.7mA. The low operating
current enables better efficiency and reduces the
requirement of VDD hold-up capacitance.
Slope Compensation
The sensed voltage across the current-sense resistor is
used for peak-current-mode control and cycle-by-cycle
current limiting. Built-in slope compensation improves
stability and prevents sub-harmonic oscillation.
FAN6754 inserts a synchronized, positive-going, ramp
at every switching cycle.
Green-Mode Operation
The proprietary green-mode function provides off-time
modulation to reduce the switching frequency in lightload and no-load conditions. VFB, which is derived from
the voltage feedback loop, is taken as the reference.
Once VFB is lower than the threshold voltage (VFB-N),
switching frequency is continuously decreased to the
minimum green-mode frequency of around 22KHz.
Constant Output Power Limit
When the SENSE voltage across sense resistor RSENSE
reaches the threshold voltage, around 0.46V for low-line
condition, the output GATE drive is turned off after a
small delay, tPD. This delay introduces an additional
current proportional to tPD • VIN / LP. Since the delay is
nearly constant regardless of the input voltage VIN,
higher input voltage results in a larger additional current
and the output power limit is higher than under low input
line voltage. To compensate this variation for a wide AC
input range, a power-limiter is controlled by the HV pin
to solve the unequal power-limit problem. The power
limiter is fed to the inverting input of the current limiting
comparator. This results in a lower current limit at highline inputs than at low-line inputs.
Current Sensing / PWM Current Limiting
Peak-current-mode control is utilized to regulate output
voltage and provide pulse-by-pulse current limiting. The
switch current is detected by a sense resistor into the
SENSE pin. The PWM duty cycle is determined by this
current-sense signal and VFB, the feedback voltage.
When the voltage on the SENSE pin reaches around
VCOMP = (VFB–0.6)/4, the switch cycle is terminated
immediately. VCOMP is internally clamped to a variable
voltage around 0.46V for low-line output power limit.
Leading-Edge Blanking (LEB)
Each time the power MOSFET is switched on, a turn-on
spike occurs on the sense-resistor. To avoid premature
termination of the switching pulse, a leading-edge
blanking time is built in. During this blanking period, the
current-limit comparator is disabled and cannot switch
off the gate driver.
Brownout and Constant Power Limited by
HV Pin
Unlike previous PWM controllers, FAN6754’s HV pin
can also detect the AC line voltage brownout function
and set the current limit level. Using a fast diode and
startup resistor to sample the AC line voltage, the peak
value refreshes and is stored in a register at each
sampling cycle. When internal update time is met, this
peak value is used for brownout and current-limit level
judgment. Equation 1 and 2 calculate the level of
brownin or brownout converted to RMS value. For
power saving, FAN6754 enlarges the sampling cycle to
lower the power loss from HV sampling at light load
condition.
Under-Voltage Lockout (UVLO)
The turn-on and turn-off thresholds are fixed internally
at 16.5V and 9V, respectively. During startup, the holdup capacitor must be charged to 16.5V through the
startup resistor to enable the IC. The hold-up capacitor
continues to supply VDD until the energy can be
delivered from auxiliary winding of the main transformer.
VDD must not drop below 9V during startup. This UVLO
hysteresis window ensures that hold-up capacitor is
adequate to supply VDD during startup.
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
FAN6754 — Highly Integrated Green-Mode PWM Controller
Functional Description
(RHV + 1.6)
(1)
)/ 2
1.6
(R + 1.6)
VAC - OFF (RMS) = ( 0.81V × HV
) / 2 ; the unit of RHV is kΩ (2)
1.6
VAC - ON (RMS) = ( 0.9V ×
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11
Thermal Protection
An NTC thermistor, RNTC, in series with resistor RA, can
be connected from the RT pin to ground. A constant
current IRT is output from the RT pin. The voltage on the
RT pin can be expressed as VRT= IRT • (RNTC + RPTC),
where IRT is 100µA. At high ambient temperature, RNTC
is smaller, such that VRT decreases. When VRT is less
than 1.035V (VRTTH1), the PWM turns off after 16ms
(tD-OTP1). If VRT is less than 0.7V (VRTTH2), PWM turns off
after 185µs (tD-OTP2).
0.47
0.46
0.45
Vlimit (V)
0.44
Limited Power Control
0.43
0.42
The FB voltage increases every time the output of the
power supply is shorted or overloaded. If the FB voltage
remains higher than a built-in threshold for longer than
tD-OLP, PWM output is turned off. As PWM output is
turned off, VDD begins decreasing.
0.41
0.4
0.39
0.38
100 120 140 160 180 200 220 240 260 280 300 320 340 360 380
When VDD goes below the turn-off threshold (9V) the
controller is totally shut down and, VDD is continuously
discharged to VDD-OLP (6.5V) by IDD-OLP to lower the
average input power. This is called two-level UVLO. VDD
is cycled again. This protection feature continues as
long as the overloading condition persists. This
prevents the power supply from overheating due to
overloading conditions.
DC Voltage on HV Pin (V)
Figure 25. Linearly Current Limit Curve
VDD Over-Voltage Protection (OVP)
VDD over-voltage protection prevents damage due to
abnormal conditions. If the VDD voltage is over the overvoltage protection voltage (VDD-OVP) and lasts for tDVDDOVP, the PWM pulses are disabled until the VDD
voltage drops below the UVLO, then starts again. Overvoltage conditions are usually caused by open feedback
loops.
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
Noise Immunity
Noise on the current sense or control signal may cause
significant pulse-width jitter, particularly in continuousconduction mode. Slope compensation helps alleviate
this problem. Good placement and layout practices
should be followed. Avoiding long PCB traces and
component leads, locating compensation and filter
components near the FAN6754, and increasing the
power MOS gate resistance improve performance.
FAN6754 — Highly Integrated Green-Mode PWM Controller
The HV pin can perform current limit to shrink the
tolerance of OCP (Over-Current Protection) under full
range of AC voltage, to linearly current limit curve as
shown in Figure 25. FAN6754 also shrinks the Vlimit
2
level by half to lower the I RSENSE loss to increase the
heavy-load efficiency.
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12
5.00
4.80
A
0.65
3.81
5
8
B
6.20
5.80
PIN ONE
INDICATOR
1.75
4.00
3.80
1
5.60
4
1.27
(0.33)
0.25
M
1.27
C B A
LAND PATTERN RECOMMENDATION
0.25
0.10
SEE DETAIL A
1.75 MAX
0.25
0.19
C
0.10
0.51
0.33
0.50 x 45°
0.25
R0.10
FAN6754 — Highly Integrated Green-Mode PWM Controller
Physical Dimensions
C
OPTION A - BEVEL EDGE
GAGE PLANE
R0.10
OPTION B - NO BEVEL EDGE
0.36
NOTES: UNLESS OTHERWISE SPECIFIED
8°
0°
0.90
0.406
A) THIS PACKAGE CONFORMS TO JEDEC
MS-012, VARIATION AA, ISSUE C,
B) ALL DIMENSIONS ARE IN MILLIMETERS.
C) DIMENSIONS DO NOT INCLUDE MOLD
FLASH OR BURRS.
D) LANDPATTERN STANDARD: SOIC127P600X175-8M.
E) DRAWING FILENAME: M08AREV13
SEATING PLANE
(1.04)
DETAIL A
SCALE: 2:1
Figure 26. 8-Pin SOP-8 Package
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/.
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
www.fairchildsemi.com
13
FAN6754 — Highly Integrated Green-Mode PWM Controller
© 2009 Fairchild Semiconductor Corporation
FAN6754 • Rev. 1.0.0
www.fairchildsemi.com
14