150KHZ 3A PWM BUCK DC/DC CONVERTER FSP3124 FEATURES z z z z z z z z z z Output voltage: 3.3V, 5.0V, 12V, and adjustable output version Adjustable version output voltage range:1.23V to 18V±4% 150KHz±15% 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 APPLICATIONS z z z Simple High-efficiency step-down regulator On-card switching regulators Positive to negative converter 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. PIN CONFIGURATION z GENERAL DESCRIPTION (Top View) 5 SD 4 FB 3 GND 2 OUTPUT 1 VIN Symbol Name Descriptions 1 2 3 4 5 Vin Output Gnd FB SD Operating Voltage Input Switching Output Ground Output Voltage Feedback Control ON/OFF Shutdown Metal Tab GND 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 Paramrter Feedback bias current Oscillator frequency Short Circuit Oscillator Frequency VSAT Saturation voltage DC Max.Duty Cycle(ON) Min.Duty Cycle(OFF) ICL IL IQ ISTBY VIL VIH IH IL θJC θJA Conditions VFB=1.3V(Adjustable version only) 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=25°C 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 Min. -10 127 110 150 10 30 Max. -50 -100 173 173 Unit 50 kHz 1.4 1.5 100 0 3.6 6.9 3.4 7.5 5 70 Low(regultaor ON) High(regultaor OFF) Typ. 1.3 KHz V % A -50 µA -30 10 200 250 mA mA 0.6 µA V 2.0 VLOGIC=2.5V(OFF) -15 µA VLOGIC=0.5V(ON) -5 TO252-5L Junction to case 10 ℃/W TO252-5L Junction to ambient 50 ℃/W Specifications with boldface type are for full operating temperature range, the other type are for TJ=25ºC. 2/9 nA 2007-3-27 150KHZ 3A PWM BUCK DC/DC CONVERTER FSP3124 ELECTRICAL CHARACTERISTICS (CONTINUED) FSP3124-ADJ FSP3124-3.3V FSP3124-5.0V FSP3124-12V Symbol Parameter VFB Output Feedback η Efficiency VOUT Output voltage η Efficiency VOUT Output voltage η Efficiency VOUT Output voltage Conditions 5V≤VIN≤22V 0.2A≤ILOAD≤3A VOUT programmed for 3V VIN =12V, ILOAD =3A 5.5V≤VIN≤22V 0.2A≤ILOAD≤3A VIN =12V, ILOAD =3A 8V≤VIN≤22V 0.2A≤ILOAD≤3A VIN =12V, ILOAD =3A 15V≤VIN≤22V 0.2A≤ILOAD≤3A Typ. Limit Unit 1.23 1.193/1.18 1.267/1.28 V VMIN VMAX 75 3.3 3.168/3.135 3.432/3.465 75 5 4.8/4.75 5.2/5.25 80 12 11.52/11.4 12.48/12.6 η Efficiency VIN =16V, ILOAD =3A 90 Specifications with boldface type are for full operating temperature range, the other type are for TJ=25ºC. 3/9 BLOCK DIAGRAM 2007-3-27 % V VMIN VMAX % V VMIN VMAX % V VMIN VMAX % 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 6/9 TYPICAL PERFORMANCE CHARACTERISTICS 2007-3-27 150KHZ 3A PWM BUCK DC/DC CONVERTER FSP3124 7/9 TYPICAL PERFORMANCE CHARACTERISTICS (CONTINUED) 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 PACKAGE INFORMATION D A D1 c1 L2 V L3 L1 A1 E FSP3124 e b c e1 Symbol A A1 b c c1 D D1 E e e1 L1 L2 L3 V 9/9 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 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 2007-3-27