View FSP3124_4772901.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3124
FEATURES
Output voltage: 3.3V, 5.0V, 12V, and adjustable output version Adjustable version output voltage range:1.23V to 18V4% 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 22V Output load current: 3A Low power standby mode Built-in switching transistor on chip TO252-5L packages
GENERAL DESCRIPTION
The FSP3124 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. If current limit function occurred and VFB is down to 0.5V below, the switching frequency will be reduced. The FSP3124 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 package is available in a standard 5-lead TO-252 package.
APPLICATIONS
Simple High-efficiency step-down regulator On-card switching regulators Positive to negative converter
PIN CONFIGURATION
(Top View)
5 4 3 2 1 Metal Tab GND 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
1/9
2007-3-27
150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3124
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 +24 -0.3 to +18 -0.3 to +18 -1 Internally Limited -65 to +150 -40 to +125 +4.5 to +22 Unit V V V V W V
ELECTRICAL CHARACTERISTICS (ALL OUTPUT VOLTAGE VERSIONS)
Unless otherwise specified, VIN=12V for 3.3V,5V, adjustable version and VIN=18V for the 12V version. ILOAD=0.5A Symbol IB FOSC FCSP VSAT DC ICL IL IQ ISTBY VIL VIH IH IL JC Paramrter Feedback bias current Oscillator frequency Short Circuit Oscillator Frequency Saturation voltage Max.Duty Cycle(ON) Min.Duty Cycle(OFF) Current limit Output leakage current Output=-1 Quiescent Current Standby Quiesient Current Output=0 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 When Current Limit Occur and VFB 0.5V, TA=25C IOUT=3A no outside circuit VFB=0V force driver on VFB=0V force driver on VFB=12V force driver off Peak current no outside circuit VFB=0V force driver on no outside circuit VFB=12V force driver off VIN=22V VFB=12V force driver off ON/OFF Pin=5V VIN=22V Low(regultaor ON) High(regultaor OFF) VLOGIC=2.5V(OFF) VLOGIC=0.5V(ON) TO252-5L Junction to case Junction to ambient 10 2.0 -15 A -5 /W Conditions VFB=1.3V(Adjustable version only) Min. 127 110 10 Typ. -10 150 Max. -50 -100 173 173 50 1.4 1.5 100 0 3.6 3.4 6.9 7.5 -50 5 70 1.3 -30 10 200 250 0.6 Unit nA KHz kHz V % A A mA mA A V
30
JA
TO252-5L
50
/W
Specifications with boldface type are for full operating temperature range, the other type are for TJ=25C.
2/9
2007-3-27
150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3124
ELECTRICAL CHARACTERISTICS (CONTINUED)
Symbol FSP3124-ADJ VFB FSP3124-3.3V VOUT FSP3124-5.0V VOUT FSP3124-12V VOUT Parameter Output Feedback Efficiency Output voltage Efficiency Output voltage Efficiency Output voltage Conditions 5VVIN22V 0.2AILOAD3A VOUT programmed for 3V VIN =12V, ILOAD =3A 5.5VVIN22V 0.2AILOAD3A VIN =12V, ILOAD =3A 8VVIN22V 0.2AILOAD3A VIN =12V, ILOAD =3A 15VVIN22V 0.2AILOAD3A Typ. 1.23 75 3.3 75 5 80 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 %
Efficiency VIN =16V, ILOAD =3A 90 Specifications with boldface type are for full operating temperature range, the other type are for TJ=25C.
BLOCK DIAGRAM
3/9
2007-3-27
150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3124
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 18V) shuts the regulator down. If this shutdown feature is not needed, the ON/OFF pin can be wired to the ground pin. Thermal Considerations The TO-252 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 FSP3124 (TO-252 package) junction temperature rise above ambient temperature with a 3A 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.
4/9
2007-3-27
150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3124
TYPICAL APPLICATION CIRCUITS
(1) Fixed Output Circuit
(2) Adjustable Output Circuit
5/9
2007-3-27
150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3124
TYPICAL PERFORMANCE CHARACTERISTICS
6/9
2007-3-27
150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3124
TYPICAL PERFORMANCE CHARACTERISTICS (CONTINUED)
7/9
2007-3-27
150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3124
ORDERING INFORMATION
FSP3124XXXX Package: 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
Logo
3124-VV
YYWWXX
Part Number: 3124-ADJ: ADJ 3124-33: 3.3V 3124-50: 5.0V 3124-12: 12V Internal Code Date Code: YY: Year (01=2001) WW: Nth week (01~52)
8/9
2007-3-27
150KHZ 3A PWM BUCK DC/DC CONVERTER
FSP3124
PACKAGE INFORMATION
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 0.150 0.400 0.630 0.450 0.580 0.450 0.580 6.350 6.850 5.200 5.500 5.400 6.200 1.270TYP. 2.540TYP. 9.000 11.300 0.900 1.630 2.200 2.800 3.800REF
L3
Dimensions In Inches Min. Max. 0.087 0.094 0.000 0.006 0.016 0.025 0.018 0.023 0.018 0.023 0.250 0.270 0.205 0.217 0.213 0.244 0.050TYP. 1.000TYP. 0.360 0.452 0.035 0.064 0.087 0.110 0.150REF
9/9
2007-3-27
V
A1
E

▲Up To Search▲

Price & Availability of FSP3124

	To Download FSP3124 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .