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FS7M0680
Features
* * * * * * * * * * *
Fairchild Power Switch(FPS)
Description
The Fairchild Power Switch (FPS) product family is specially designed for an off line SMPS with minimal external components. The Fairchild Power Switch (FPS) consists of high voltage power SenseFET and current mode PWM controller. The PWM controller includes integrated fixed oscillator, under voltage lock out, leading edge blanking block, optimized gate turnon/turn-off driver, thermal shut down protection, over voltage protection, temperature compensated precise current sources for loop compensation and fault protection circuit. Compared to discrete MOSFET and PWM controller or ring choke converter (RCC) solutions, the Fairchild Power Switch (FPS) can reduce total cost, component count, size and weight simultaneously increasing efficiency, productivity, and system reliability. It has simple applications well suited for cost down design for flyback converter or forward converter.
TO-3P-5L
Precise Fixed Operating Frequency FS7M0680(66kHz) Pulse By Pulse Current Limiting Over Current Protection Over Load Protection Over Voltage Protection (Min. 25V) Internal Thermal Shutdown Function Under Voltage Lockout with Hysteresis Internal High Voltage Sense FET Latch Up Mode Soft Start
1
1. DRAIN 2. GND 3. VCC 4. FB 5. S/S
Internal Block Diagram
#5 S o ft S ta rt #3 Vcc
UVLO Internal Vias O SC PW M Com parator
+ -
#1 D R AIN
Vref
S R
Q Ron R o ff
#4 Feedback
Ifb
Vref Vref
3R R
+
Vfb offset
S
V cc R eset
Idelay
Q
D elay 12 0ns
+ -
Vsd Vcc Vovp
R
Vo cp
R sense
Therm al S hutdo w n
#2 S o urce GND
Rev.1.0.0
(c)2003 Fairchild Semiconductor Corporation
FS7M0680
Absolute Maximum Ratings
Parameter Maximum Drain Voltage
(1)
Symbol VD,MAX VDGR VGS IDM EAS IAS ID ID VCC,MAX VFB PD Derating TA TSTG
Value 800 800 30 24.0 455 20 6.0 3.8 30 -0.3 to VSD 150 1.21 -25 to +85 -55 to +150
Unit V V V ADC mJ A ADC ADC V V W W/C C C
Drain-Gate Voltage (RGS=1M) Gate-Source (GND) Voltage Drain Current Pulsed (2) Single Pulsed Avalanche Energy (3) Avalanche Current
(4)
Continuous Drain Current (TC=25C) Continuous Drain Current (TC=100C) Maximum Supply Voltage Input Voltage Range Total Power Dissipation Operating Ambient Temperature Storage Temperature
Note: 1. Tj = 25C to 150C 2. Repetitive rating: Pulse width limited by maximum junction temperature 3. L = 24mH, VDD = 50V, RG = 25, starting Tj =25C 4. L = 13H, starting Tj = 25C
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FS7M0680
Electrical Characteristics (SenseFET part)
(Ta=25C unless otherwise specified) Parameter Drain-Source Breakdown Voltage Zero Gate Voltage Drain Current Symbol BVDSS IDSS Condition VGS=0V, ID=50A VDS=Max., Rating, VGS=0V VDS=0.8Max., Rating, VGS=0V, TC=125C VGS=10V, ID=5.0A VDS=15V, ID=5.0A VGS=0V, VDS=25V, f=1MHz VDD=0.5BVDSS, ID=8.0A (MOSFET switching time are essentially independent of operating temperature) VGS=10V, ID=8.0A, VDS=0.5BVDSS (MOSFET switching time are essentially independent of operating temperature) Min. 800 1.5 Typ. 1.6 2.5 1600 140 42 60 150 300 130 70 16 27 Max. 50 200 2.0 nC nS pF Unit V A A S
Static Drain-Source On Resistance (note1) RDS(ON) Forward Transconductance Input Capacitance Output Capacitance Reverse Transfer Capacitance Turn On Delay Time Rise Time Turn Off Delay Time Fall Time Total Gate Charge (Gate-Source+Gate-Drain) Gate-Source Charge Gate-Drain (Miller) Charge
Note: 1. Pulse test: Pulse width 300S, duty cycle 2% 1 2. S = --R
(note1)
gfs Ciss Coss Crss td(on) tr td(off) tf Qg Qgs Qgd
3
FS7M0680
Electrical Characteristics (control part) (Continued)
(Ta=25C unless otherwise specified) Parameter UVLO SECTION Start Threshold Voltage Stop Threshold Voltage OSCILLATOR SECTION Initial Frequency Frequency Change With Temperature Maximum Duty Cycle Voltage Stability FEEDBACK SECTION Feedback Source Current Shutdown Delay Current Shutdown Feedback Voltage SOFT START SECTION Soft Start Voltage Soft Start Resistor REFERENCE SECTION Output Voltage (1) Temperature Stability Peak Current Limit PROTECTION SECTION Thermal Shutdown Temperature (Tj) (1) Over Voltage Protection Voltage Over Current Protection Voltage TOTAL DEVICE SECTION Start Up Current Operating Supply Current (Control Part Only) ISTART IOP Iop(lat) VCC=14V Ta=25C After latch, Vcc=Vstop-0.1V 150 40 8 250 80 12 350 uA mA uA TSD VOVP VOCP 140 25 1.05 28 1.10 31 1.15 C V V
(1)(2) (2)
Symbol VSTART VSTOP FOSC F/T Dmax Fstable IFB Idelay Vsd VSS Rsoft Vref Vref/T IOVER
Condition After turn on -25C Ta +85C 12V Vcc 23V Ta=25C, 0V Vfb 3V Ta=25C, 5V Vfb VSD
Min. 14 8 60 45 0 0.7 4.0 6.9
Typ. 15 9 66 5 50 1 0.9 5.0 7.5 5.0 18.5 5.00 0.3 4.00
Max. 16 10 72 10 55 3 1.1 6.0 8.1 5.3 22.0 5.20 0.6 4.48
Unit V V kHz % % % mA A V V k V mV/C A
VFB =2V Bias=Vref, SS=0V Ta=25C -25C Ta +85C Max. inductor current
4.7 16.0 4.80 3.52
CURRENT LIMIT (SELT-PROTECTION)SECTION
Note: 1. These parameters, although guaranteed, are not 100% tested in production 2. These parameters, although guaranteed, are tested in EDS (wafer test) process
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FS7M0680
General Application
In general, the FPS consists of several functional sections: under voltage lockout circuit (UVLO), reference voltage, oscillator (OSC), pulse width modulation (PWM) block, protection circuits and gate drive circuit.
Start-Up
The minimum current that FPS requires for the start-up is 80A. This current can be provided by the DC link bulk capacitor (DC start-up) or directly by the AC line (AC startup). DC start-up Assuming wide range input voltage (85-265V), the maximum value of Rstart is calculated with the minimum input voltage as follows:
R start = 85 2 - 15 = 1.3M -------------------------80A
power MOSFET. Then, the current required by the control IC is suddenly increased to 7mA, which makes it difficult for FPS to operate with the current provided through Rstart. Therefore, after FPS starts, the auxiliary winding of the transformer should supply most of the power required by the FPS. It is suitable to use an appropriately sized VCC capacitor, generally about 33F, because the starting time can be delayed if it is too large. This operation is described in figure 2. Although VCC needs to be set only above 9V during the normal operation, it should be set to such an extent that over voltage protection (OVP) is not activated during an overload condition. For full load, about 18~20V is appropriate for VCC and for no load, about 13~14V is suitable.
Protection
The FPS has not only pulse by pulse current limit circuit, but also several self-protection circuits. These protection circuits are fully integrated and do not require external components. After the protection circuits are activated, the FPS completely stops the SMPS (Latch Mode Protection) until the power on reset circuit is activated by removing and restoring input power, or restarts the SMPS automatically (Auto Restart Mode Protection).
DC LINK
Rstart
The maximum power dissipation in Rstart is calculated with the maximum input voltage as follows:
( 265 2 - 15 ) Ploss = ------------------------------------- = 0.1 ( W ) 1.3M
2
Va
3 Vcc Good Logic Power on Reset
15V/9V
265V 85V
Latch Comparator
6V
Vz
5V Vref
UVLO
Good Logic
FPS
AC start-up When the start-up current is provided directly by the AC line through a single rectifier diode, the maximum value of Rstart is calculated with the minimum input voltage as follows:
2 * 85 2 - 15 R Start = --------------------------------------- / ( 80A ) 2 = 380k
Figure 1. Undervoltage lockout (UVLO) circuit
These two operations are user-selected operations, so the user can select proper device according to the shutdown mode. The operations principle and applications for each protection are described as follows.
Icc [mA]
The maximum power dissipation in Rstart is calculated with the maximum input voltage as follows:
Va ( rms ) = 2 1 ------ ( Vp sin t - 15 ) dt 2 o
20
= 177V ( Vp = 265 2 ) P loss Va ( rms ) 2 ( 177 ) 2 = -------------------------- = ----------------Rstart 380k = 82 ( mW )
7
Power On Reset Range
0.1 6V 9V 15V Vz
Vcc [V]
The current provided through the starting resistor charges the Vcc capacitor. When Vcc becomes higher than the threshold voltage, the FPS starts the switching operation of the built-in
Fig 2 < Start-up Waveform >
Figure 2. Variation of Icc according to Vcc
5
FS7M0680
5 uA Vo Vfb #4 Cfb D1
0.9mA OSC. D2 Vfb* R 2.5 R
Vck
FPS
PWM comp
S
Q
R Ioffset
KA431
Rsense
Sense
7.5V Thermal Shutdown
Reset
R S
Q
Shutdown
7 .5 V
3.2 V
0 t2
t
.
t2 =
C fb x 4. 3V 5 A
Shutdown
Figure 3. Pulse-width-modulation (PWM) block
Pulse by pulse current limit
Figure 3 shows the pulse-width-modulation (PWM) block of the FPS. Since the FPS employs the peak current mode control, the current through the power MOSFET is limited by the inverting input voltage of PWM comparator (Vfb*). Assuming that the 0.9mA current source flows only through the internal resistor (2.5R + R *= 2.8k) and the diode forward voltage drop is 0.7V, the anode voltage of diode D2 is about 3.2V. Since D1 is blocked when the feedback voltage (Vfb) exceeds 3.2V, the maximum voltage of the anode of D2 is 3.2V. Therefore, the maximum value of Vfb* is about 0.7V, which determines the maximum current through the power MOSFET.
Over Load Protection
Overload means that the load current exceeds a pre-set level due to the abnormal situation. In this situation, protection circuit should be activated in order to protect the SMPS. However, even when the SMPS is in the normal operation, the over load protection circuit can be activated during the load transition. In order to avoid this undesired operation, the over load situation should be distinguished from the normal load transition situation. As a measure against this problem, over load protection circuit in the FPS is designed to be activated after a specified period to determine whether it is a transient situation or an overload situation. The protection circuit is allowed to shut down the SMPS only when the over load condition continues longer than preset period. The detailed operation principle is explained in figure 3. Because of the pulse by pulse current limit circuit, the maximum current through the FPS is limited, and therefore the maximum 6
input power is restricted with a given input voltage. If the output consumes beyond this maximum power, the output voltage (Vo) decreases below the set voltage. This reduces the current through the opto-coupler diode, which also reduces opto-coupler transistor current increasing Vfb. If Vfb exceeds 3.2V, D1 is blocked and the 5A current source starts to charge Cfb slowly compared to when the 0.9mA current source charges Cfb. Vfb continues increasing until it reaches 7.5V, and the FPS shuts down at that time. The delay time for shutdown is the time required to charge Cfb from 3.2V to 7.5V with 5A. When Cfb is 10nF (103), t2 is approximately 8.6mS and when Cfb is 0.1F (104), t2 is approximately 86ms. These values are enough to prevent SMPS from being shut down for most transient situations. Just increasing Cfb to obtain a longer delay time may cause problems, because Cfb is an important parameter for determining the response speed of the SMPS. To solve this problem, auxiliary capacitor in series with zener diode can be used in parallel with Cfb. The breakdown voltage of the zener diode should be about 3.9 ~ 4.7V. When Vfb is below the zener voltage, the system dynamics is determined by Cfb. When Vfb exceeds the zener voltage, the delay time is determined by the auxiliary capacitor. By using large auxiliary capacitor, the delay time can be extended without sacrifice of the dynamic response.
Over voltage Protection (OVP) Circuit
The FPS has a self-protection feature against malfunctions, such as feedback circuit open or short-circuit. When the feedback terminal is open due to a malfunction in the secondary side feedback circuit or a defect of solder, the current through the opto-coupler transistor becomes almost zero.
FS7M0680
Then, Vfb continues increasing and the preset maximum current flows through the primary side until the over load protection circuit is activated. Since maximum current is transferred to the secondary side, the secondary side voltage becomes much higher than the rated voltage. If there is no protection circuit against over voltage, the devices in the secondary side will be damaged. In order to prevent this situation, the FPS has an over voltage protection circuit (protection against feedback circuit abnormalities). In general, Vcc is proportional to the output voltage and FPS uses Vcc instead of directly monitoring the output voltage to detect over voltage situation. If VCC exceeds 24 V, the FPS activates the OVP circuit. Therefore, VCC should be properly designed to be below 24V during normal operation to avoid the undesired activation of OVP.
OCP (Over Current Protection)
to increase slowly, also increasing the duty ratio slowly. When the voltage of CS reaches about 3.2V, PNP transistor is turned off and Cs continues being charged up to 5V through Rss. Then, the voltage of the comparator inverting input follows the feedback voltage of pin 4 instead of following the voltage of CS. When the SMPS is shut down by the protection circuits, CS is discharged through the internal resistor allowing CS to be charged from 0V when the SMPS starts up again.
10V 5uA 0 .9 m A D2
Fa ir c hild P owe r S witc h(FP S )
PWM Comparator
D1
5V R ss 18.5K
OCP Operating
#4 Vfb
#5
SQ R
200ns 100ns delay
Latch signal
Cfb
Rsense
CS
OCP time R C OCP Level
Figure 5. Soft Start Circuit
Minimum Turn-on Time
Fiqure 4. OCP Function & Block
Even though the FPS has OLP (Over Load Protection) and pulse by pulse current limiting feature, these are not enough to protect FPS when a secondary side diode short or load short occurs. Therefore, FPS has internal OCP (Over Current Protection) circuit as shown in figure 4. When the gate turn-on signal is applied to the power MOSFET, the OCP block is enabled and monitors the current through the sensing resistor for 1us. The voltage across the resistor is compared with the preset OCP level. If the sensing resistor voltage is greater than the OCP level for longer than 200ns within the allowed comparison time of 1us, the reset signal is applied to the latch, resulting in the shutdown of SMPS. Here, the additional delay of 100ns after the 200ns delay is the time required for the operation of the protection circuit.
Soft start operation
At startup, the voltage of the PWM comparator inverting input is saturated to its maximum value. In that case, the power MOSFET current is at its maximum value and maximum allowable power is delivered to the secondary side until the output voltage is established. It should be noted that when the SMPS delivers maximum power to the secondary side during the startup, the entire circuit is seriously stressed. By using a soft start function, such stresses can be alleviated. Figure 5 shows how the soft-start circuit is implemented. When it starts up, the soft start capacitor Cs on pin 5 begins to be charged through the internal resistor (Rss), which forces the comparator inverting input voltage 7
FS7M0680
3. Application Note using the FPS
-Flyback Application (70W)
HOT
5D-9 /NTC 47 k BD1 1 50uF /4 00V 700K /1W UF4007 3.3 nF/630V
D10LC20U 1 0uH
10 00uF/ 3 5V
10 00uF /2 5V
12V / 4A DC OUTPUT
2.2 nF
2.2nF UF4004 13mH 10
D10SC4M 10 uH
1 .5K 3 S/S 5 Vc c GND 2 1 Drain F B 47uF /5 0V 10 00uF/ 1 6V 50 0 2 .2K OPTO 10 00uF /1 0V
5V / 4A DC OUTPUT
0.1uF/275V AC
FS7M0680R
4 2.2nF KA431 0.1 uF/ mono lithic 2 .2K 22nF /Film Opto
FUSE
1uF /5 0V
PRIMARY GND
Transformer Specification
2. Winding Specification
No. NP/2 NB N5V N12V NP/2 PIN(S F) 24 13 89 12 10 45 WIRE 0.35 x 1 0.3 x 1 0.45 x 4 0.3 x 4 0.4 x 1 TURNS 23 10 3 7 23 SOLENOID WINDING WINDING METHOD SOLENOID WINDING COPPER WINDING SOLENOID WINDING
INSULATION : POLYESTER TAPE t = 0.050mm, 1Layer INSULATION : POLYESTER TAPE t = 0.050mm, 3Layer INSULATION : POLYESTER TAPE t = 0.050mm, 1Layer INSULATION : POLYESTER TAPE t = 0.050mm, 1Layer OUTER INSULATION : POLYESTER TAPE t = 0.050mm, 3Layer
3. Electical Characteristic
CLOSURE INDUCTANCE LEAKAGE L PIN 2-5 2-5 SPEC. 700uH 10% 15uH MAX. REMARKS 1kHz, 1V 2nd ALL SHORT
4. Core & Bobbin
CORE : EER 2834 BOBBIN : EER2834
8
FS7M0680
-Forward Application (180W)
223 56K 56K /2W T1 T13,14 102 472 /275V 0.47uF /275V 220k 470uF /200V /1W UF4007 UF4007 Line Inductor
/630V /2W NTC FUSE Line Inductor
12V/8A + 12V / 10A
T3 10
2200uF
2200uF
472 /275V 33k /0.5W 33k /0.5W UF4007
220k /1W
470uF /200V
S30SC4M T8,9
5V/15A
L4
+ 5V / 26A
2.2k UF4004 T6 10 3300uF 1000uF 2.2k
Vcc
Drain
T10,11,12 T7 5.6k 1k
SPS
GN D
33uF /35V 1uF /50V 333
S.S.
F.B.
123 Q817 820
104 Q817 103 103 KA431
Transformer Specification
2. Winding Specification
No. NP/2 N+5V N+12V NP/2 NVCC PIN(S F) 13 8, 9 10, 11, 12 13, 14 9 13 76 WIRE 0.65 x 1 14mm x 1 0.65 x 4 0.65 x 1 0.65 x 1 TURNS 50T 4T 5T 50T 6T WINDING METHOD SOLENOID WINDING COPPER WINDING SOLENOID WINDING SOLENOID WINDING SOLENOID WINDING
3. Electical Characteristic
CLOSURE INDUCTANCE LEAKAGE L PIN 1-3 1-3
4. Secondary Inductor(L2) Specipication
Core : Power Core 27 16 Grade 5V : 12T (1 x 2) 10V : 27T (1.2 x 1)
9
FS7M0680
Typical Performance Characteristics
1.20 1.15
1.20 1.15
Normalized to 25C
Normalized to 25C
-20 0 20 40 60 80 Temperature [C] 100 120 140 160
1.10 1.05 1.00 0.95 0.90 0.85 0.80 -40
1.10 1.05 1.00 0.95 0.90 0.85 0.80 -40 -20 0 20 40 60 80 100 120 140 160
Temperature [C]
Figure 1. Operating Supply Current vs. Temp.
Figure 2. Start up Current vs. Temp.
1.20 1.15
1.20 1.15
Normalized to 25C
Normalized to 25C
1.10 1.05 1.00 0.95 0.90 0.85 0.80 -40 -20 0 20 40 60 80 100 120 140 160
1.10 1.05 1.00 0.95 0.90 0.85 0.80 -40 -20 0 20 40 60 80 100 120 140 160
Temperature [C]
Temperature [C]
Figure 3. Start Threshold Voltage vs. Temp.
Figure 4. Stop Threshold Voltage vs. Temp.
1.20 1.15
1.20 1.15 1.10
Normalized to 25C
1.10 1.05 1.00 0.95 0.90 0.85 0.80 -40 -20 0 20 40 60 80 100 120 140 160
Dmax [%]
1.05 1.00 0.95 0.90 0.85 0.80 -40 -20 0 20 40 60 80 100 120 140 160 Temperature [C]
Temperature [C]
Figure 5. Operating Frequency vs. Temp.
Figure 6. Maximum Duty Cycle vs. Temp.
10
FS7M0680
Typical Performance Characteristics (Continued)
1.20 1.15
Normalized to 25C
1.10 1.05 1.00 0.95 0.90 0.85 0.80 -40 -20 0 20 40 60 80 100 120 140 160
1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 -40
Normalized to 25C
-20
0
20
40
60
80
100 120 140 160
Temperature [C]
Temperature [C]
Figure 7. Minimum Duty Cycle vs. Temp.
Figure 8. Feedback Offset Voltage vs. Temp.
1.20 1.15
1.20 1.15
Normalized to 25C
Normalized to 25C
1.10 1.05 1.00 0.95 0.90 0.85 0.80 -40 -20 0 20 40 60 80 100 120 140 160
1.10 1.05 1.00 0.95 0.90 0.85 0.80 -40 -20 0 20 40 60 80 100 120 140 160
Temperature [C]
Temperature [C]
Figure 9. Shutdown Feedback Voltage vs. Temp.
Figure 10. Shutdown Delay Current vs. Temp.
1.20 1.15
1.20 1.15
Normalized to 25C
Normalized to 25C
-20 0 20 40 60 80 100 120 140 160
1.10 1.05 1.00 0.95 0.90 0.85 0.80 -40
1.10 1.05 1.00 0.95 0.90 0.85 0.80 -40 -20 0 20 40 60 80 100 120 140 160
Temperature [C]
Temperature [C]
Figure 11. SoftStart Voltage vs. Temp.
Figure 12. Over Voltage Protection vs. Temp.
11
FS7M0680
Typical Performance Characteristics (Continued)
1.4 1.3
1.20 1.15
Normalized to 25C
1.2 1.1 1.0 0.9 0.8 -40
Normalized to 25C
-20 0 20 40 60 80 100 120 140 160
1.10 1.05 1.00 0.95 0.90 0.85 0.80 -40 -20 0 20 40 60 80 100 120 140 160
Temperature [C]
Temperature [C]
Figure 13. Feedback Sink Current vs. Temp.
Figure 14. Peak Current vs. Temp.
18 16
Soft_start Time [ms]
14 12 10 8 6 4 2
0.2
0.4
0.6
0.8
1.0
Soft_start capacitor[F]
Figure 15. Soft_start Capacitor vs. Soft_start Temp.
12
FS7M0680
Package Dimensions
TO-3P-5L
13
FS7M0680
Package Dimensions (Continued)
TO-3P-5L (Forming)
14
FS7M0680
Ordering Information
Product Number FS7M0680TU FS7M0680YDTU
TU : Non Forming Type YDTU : Forming type
Package TO-3P-5L TO-3P-5L(Forming)
Rating 800V, 6A
Fosc 67kHz
15
FS7M0680
DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user.
www.fairchildsemi.com 11/17/03 0.0m 001 Stock#DSxxxxxxxx 2003 Fairchild Semiconductor Corporation
2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.

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