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150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3122
FEATURES
Output voltage: 3.3V, 5.0V, 12V, and adjustable output version Adjustable version output voltage range:1.23V to 37V4% 150KHz15% fixed switching frequency Voltage mode non-synchronous PWM control Thermal-shutdown and current-limit protection ON/OFF shutdown control input Operating voltage can be up to 40V Output load current: 3A Low power standby mode Built-in switching transistor on chip TO220-5LTO252-5L and TO263-5L packages
GENERAL DESCRIPTION
The FSP3122 series are monolithic IC that design for a step-down DC/DC converter, and own the ability of driving a 3A load without additional transistor component. Due to reducing the number of external component, the board space can be saved easily. The external shutdown function can be controlled by logic level and then come into standby mode. The internal compensation makes feedback control have good line and load regulation without external design. Regarding protected function, thermal shutdown is to prevent over temperature operating from damage, and current limit is against over current operating of the output switch. The FSP3122 series operates at a switching frequency of 150 KHz thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. Other features include a guaranteed 4% tolerance on output voltage under specified input voltage and output load conditions, and 15% on the oscillator frequency. The output version included fixed 3.3V, 5V, 12V, and an adjustable type. The packages are available in a standard 5-lead TO-220 package 5-lead TO252 package and a 5-lead TO-263 package. (2) TO252-5L (Top View)
5 SD 4 FB 3 GND 2 OUTPUT 1 VIN
5 4 3 2 1 Metal Tab GND SD FB GND OUTPUT VIN
APPLICATIONS
Simple High-efficiency step-down regulator On-card switching regulators Positive to negative converter
PIN CONFIGURATION
(1) TO220-5L (Top View)
Metal Tab Gnd
(3) TO263-5L (Top View)
5 4 3 2 1 SD FB GND OUTPUT VIN
Symbol 1 2 3 4 5
Name Vin Output Gnd FB SD
Descriptions Operating Voltage Input Switching Output Ground Output Voltage Feedback Control ON/OFF Shutdown
Metal Tab Gnd
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150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3122
BLOCK DIAGRAM
SD 5 1 VIN 220mV Current Source bias 1.235V Reference 2.5V Regulator Start up Comp
+
220mV
+
FB 4
Amp
-
Frequency compensation
+
Comp
Pre-driver
150KHz OSC.
Thermal Limit
ABSOLUTE MAXIMUM RATINGS
Symbol VCC VSD VFB VOUT PD TST TOP VOP Paramrter Supply Voltage ON/OFF Pin input Voltage Feedback Pin Voltage Output Voltage to Ground Power Dissipation Storage Temperature Operating Temperature Operating Voltage Rating +45 -0.3 to +25 -0.3 to +25 -1 Internally Limited -65 to +150 -40 to +125 +4.5 to +40 Unit V V V V W V
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+
Comp
-
3A Sw itch 2 OUTPUT 3 GND
2007-6-12
150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3122
ELECTRICAL CHARACTERISTICS (ALL OUTPUT VOLTAGE VERSIONS)
Unless otherwise specified, VIN=12V for 3.3V,5V, adjustable version and VIN=24V for the 12V version. ILOAD=0.5A Symbol Paramrter Conditions Min. Typ. Max. Unit VFB=1.3V(Adjustable 50 40 nA IB Feedback bias current version only) 100 127 150 173 FOSC Oscillator frequency KHz 110 173 IOUT=3A 1.16 1.4 V VSAT Saturation voltage no outside circuit VFB=0V force driver on Max.Duty Cycle(ON) VFB=0V force driver on 100 % DC 0 Min.Duty Cycle(OFF) VFB=12V force driver off Peak current 3.6 6.9 A ICL Current limit no outside circuit VFB=0V force driver on no outside circuit Output 50 A Output=0 VFB=12V force driver off IL leakage current Output=-1 VIN=40V 5 30 mA IQ Quiescent Current VFB=12V force driver off 7.8 10 mA Standby Quiesient ON/OFF Pin=5V ISTBY 85 200 A Current VIN=40V VIL VIH IH IL JC ON/OFF pin logic input threshold voltage ON/OFF pin logic input current ON/OFF pin input current Thermal Resistence Thermal Resistence With copper area of approximately 3 in2 Low(regultaor ON) High(regultaor OFF) VLOGIC=2.5V(OFF) VLOGIC=0.5V(ON) TO252-5L TO220-5L TO263-5L TO252-5L TO220-5L TO263-5L Junction to case Junction to ambient 2.0 6 0.02 10 2.5 3.5 30 28 30 15 A 5 /W 1.4 0.6 V
JA
/W
ELECTRICAL CHARACTERISTICS (CONTINUED)
Symbol FSP3122-ADJ VFB FSP3122-3.3V VOUT FSP3122-5V VOUT FSP3122-12V VOUT Parameter Output Feedback Efficiency Output voltage Efficiency Output voltage Efficiency Output voltage Conditions 4.5VVIN40V 0.2AILOAD3A VOUT programmed for 3V VIN =12V, ILOAD =3A 5VVIN40V 0.2AILOAD3A VIN =12V, ILOAD =3A 7VVIN40V 0.2AILOAD3A VIN =12V, ILOAD =3A 15VVIN40V 0.2AILOAD3A Typ. 1.23 72 3.3 72 5 79 12 11.52/11.4 12.48/12.6 4.8/4.75 5.2/5.25 3.168/3.135 3.432/3.465 Limit 1.193/1.18 1.267/1.28 Unit V VMIN VMAX % V VMIN VMAX % V VMIN VMAX % V VMIN VMAX %
90 Efficiency VIN =15V, ILOAD =3A Specifications with boldface type are for full operating temperature range, the other type are for TJ=25C.
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FSP3122
TYPICAL PERFORMANCE CHARACTERISTICS
Normalized Output Voltage 1.5 OUTPUT VOLTAGE CHANGE(%) VIN=20V 1.0 0.5 0 -0.5 -1.0 -1.5 0 25 50 75 100 125 -50 -25 JUNCTION TEMPERATURE() ILOAD=3A
Switch Saturation Voltage SATURATION VOLTAGE(V) 1.60 1.40 1.20 1.00 1 0.80 0.60 2 3 0.5 1 2 SWITCH CURRENT(A) 3 1:-40 2:25 3:125 VIN=12V
Normalixed at TJ=25
Dropout Voltage INPUT-OUTPUT DIFFERENTIAL (V) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0 25 -50 -25 JUNCTION TEMPERATURE() 50 75 100 125 ILOAD=1A L=33H RIND=0.04O VOUT=VREG-50mV
FREQUENCY (KHz) 160 155 150 145 140 135 130
Switching Frequency
ILOAD=3A
-50 -25
0
25
50 75 100 125
JUNCTION TEMPERATURE()
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150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3122
ON/OFF Threshold Voltage THRESHOLD VOLTAGE(V)
SWITCH CURRENT LIMIT(A)
2.5 2.0 1.5 1.0 0.5 0.0 ON OFF
Switch Current Limit 5.50 5.00 4.50 4.00 3.50 VIN=12V Vout=5V
-50 -25 0 25
50 75 100 125
-50 -25 0 25 50 75 100 125 JUNCTION TEMPERATURE()
JUNCTION TEMPERATURE()
TYPICAL APPLICATION CIRCUITS
(1) Fixed Output Circuit
(2) Adjustable Output Circuit
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150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3122
FUNCTION DESCRIPTION
Pin Function
VIN This is the positive input supply for the IC switching regulator. A suitable input bypass capacitor must be present at this pin to minimize voltage transients and to supply the switching currents needed by the regulator. Ground Circuit ground. Output Internal switch. The voltage at this pin switches between (VIN - VSAT ) and approximately - 0.5V, with a duty cycle of approximately VOUT / VIN. To minimize coupling to sensitive circuitry, the PC board copper area connected to this pin should be kept a minimum. Feedback Senses the regulated output voltage to complete the feedback loop. ON/OFF Allows the switching regulator circuit to be shutdown using logic level signals thus dropping the total input supply current to approximately 150uA. Pulling this pin below a threshold voltage of approximately 1.3V turns the regulator on, and pulling this pin above 1.3V (up to a maximum of 25V) shuts the regulator down. If this shutdown feature is not needed, the ON/OFF pin can be wired to the ground pin or it can be left open, in either case the regulator will be in the ON condition. Thermal Considerations The FSP3122 is available in three packages, a 5-pin TO-220, 5-pin TO252 and a 5-pin surface mount TO-263. The TO-220 package needs a heat sink under most conditions. The size of the heat sink depends on the input voltage, the output voltage, the load current and the ambient temperature. The FSP3122 junction temperature rises above ambient temperature for a 3A load and different input and output voltages. The data for these curves was taken with the FSP3122 (TO-220 package) operating as a buck switching regulator in an ambient temperature of 25oC (still air). These temperature rise numbers are all approximate and there are many factors that can affect these temperatures. Higher ambient temperatures require more heat sinking. The TO-263 surface mount package tab is designed to be soldered to the copper on a printed circuit board. The copper and the board are the heat sink for this package and the other heat producing components, such as the catch diode and inductor. The PC board copper area that the package is soldered to should be at least 0.4 in 2, and ideally should have 2 or more square inches of 2 oz. Additional copper area improves the thermal characteristics, but with copper areas greater than approximately 6 in2, only small improvements in heat dissipation are realized. If further thermal improvements are needed, double sided, multilayer PC board with large copper areas and/or airflow are recommended. The FSP3122 (TO-263 package) junction temperature rise above ambient temperature with a 2A load for various input and output voltages. This data was taken with the circuit operating as a buck switching regulator with all components mounted on a PC board to simulate the junction temperature under actual operating conditions. This curve can be used for a quick check for the approximate junction temperature for various conditions, but be aware that there are many factors that can affect the junction temperature. When load currents higher than 2A are used, double sided or multilayer PC boards with large copper areas and/or airflow might be needed, especially for high ambient temperatures and high output voltages. For the best thermal performance, wide copper traces and generous amounts of printed circuit board copper should be used in the board layout. (Once exception to this is the output (switch) pin, which should not have large areas of copper.) Large areas of copper provide the best transfer of heat (lower thermal resistance) to the surrounding air, and moving air lowers the thermal resistance even further. Package thermal resistance and junction temperature rise numbers are all approximate, and there are many factors that will affect these numbers. Some of these factors include board size, shape, thickness, position, location, and even board temperature. Other factors are, trace width, total printed circuit copper area, copper thickness, single or double-sided, multilayer board and the amount of solder on the board. The effectiveness of the PC board to dissipate heat also depends on the size, quantity and spacing of other components on the board, as well as whether the surrounding air is still or moving. Furthermore, some of these components such as the catch diode will add heat to the PC board and the heat can vary as the input voltage changes. For the inductor, depending on the physical size, type of core material and the DC resistance, it could either act as a heat sink taking heat away from the board, or it could add heat to the board.
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150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3122
ORDERING INFORMATION
FSP3122XXXX Package: T: TO220-5L K: TO263-5L D: TO252-5L Temperature Grade: Output Voltage: Packing: Blank: Tube or Bulk E: -40~125 Blank: ADJ A: Tape & Reel 33: 3.3V 50: 5.0V 12: 12V
MARKING INFORMATION
1) TO220-5L 2) TO263-5L
Logo
Logo
3122-VV
YYWWXX
Part Number: 3122-ADJ: ADJ 3122-33: 3.3V 3122-50: 5.0V 3122-12: 12V Internal Code Date Code: YY: Year (01=2001) WW: Nth week (01~52)
3122-VV
YYWWXX
Part Number: 3122-ADJ: ADJ 3122-33: 3.3V 3122-50: 5.0V 3122-12: 12V Internal Code Date Code: YY: Year (01=2001) WW: Nth week (01~52)
(3) TO252-5L
Logo
3122-VV
YYWWXX
Part Number: 3122-ADJ: ADJ 3122-33: 3.3V 3122-50: 5.0V 3122-12: 12V Internal Code Date Code: YY: Year (01=2001) WW: Nth week (01~52)
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150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3122
PACKAGE INFORMATION
1) TO220-5L
E
P
A F
Q
L
D
H1
e e1
b
C
J1
Symbol A b C D E e e1 F H1 J1 L P Q
Min. 4.07 0.76 0.36 14.22 9.78 1.57 6.68 1.14 5.46 2.29 13.21 3.68 2.54
Dimensions In Millimeters Nom. Max. 4.45 4.82 0.89 1.02 0.50 0.64 14.86 15.50 10.16 10.54 1.71 1.85 6.81 6.93 1.27 1.40 6.16 6.86 2.74 3.18 13.97 14.73 3.81 3.94 2.73 2.92
Min. 0.160 0.030 0.014 0.560 0.385 0.062 0.263 0.045 0.215 0.090 0.520 0.145 0.100
Dimensions In Inches Nom. 0.175 0.035 0.020 0.585 0.400 0.067 0.268 0.050 0.243 0.108 0.550 0.150 0.107
Max. 0.190 0.040 0.025 0.610 0.415 0.073 0.273 0.055 0.270 0.125 0.580 0.155 0.115
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150KHZ 3A PWM BUCK DC/DC CONVERTER
2) TO263-5L
FSP3122
E
L2
10.90
D L
9.10
15.70
2.50
e
1.00
B
1.70
Land Pattern Recommendation (Unit: mm)
A C2 C L1
Symbol A B C C2 D E e L L1 L2
Min. 4.07 0.51 0.36 1.14 8.20 9.65 1.57 14.45 1.78
Dimensions In Millimeters Nom. Max. 4.46 4.85 0.84 1.02 0.50 0.74 1.27 1.65 9.15 9.65 10.16 10.67 1.71 1.85 15.24 15.88 2.54 2.79 2.92
Min. 0.163 0.020 0.014 0.046 0.328 0.386 0.063 0.578 0.071
Dimensions In Inches Nom. 0.176 0.033 0.020 0.050 0.360 0.400 0.068 0.600 0.100
Max. 0.194 0.041 0.030 0.066 0.380 0.427 0.074 0.635 0.110 0.115
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150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3122
(3) TO252-5L
D D1
A c1
L1
L2
e e1
b
c
Symbol A A1 b c c1 D D1 E e e1 L1 L2 L3 V
Dimensions In Millimeters Min. Max. 2.200 2.400 0.000 0.127 0.400 0.600 0.430 0.580 0.430 0.580 6.350 6.650 5.200 5.400 5.400 5.700 1.270TYP. 2.540TYP. 9.500 9.900 1.400 1.780 2.550 2.900 3.800REF
L3
Dimensions In Inches Min. Max. 0.087 0.094 0.000 0.005 0.016 0.024 0.017 0.023 0.017 0.023 0.250 0.262 0.205 0.213 0.213 0.224 0.050TYP. 1.000TYP. 0.374 0.390 0.055 0.070 0.100 0.114 0.150REF
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V
A1
E

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