Datasheet 2.5A 150KHZ PWM Buck DC/DC Converter General Description Features The TD1507 is a easy to use adjustable step-down (buck) switch-mode voltage regulators. The device is available in an adjustable output version. It is capable of driving a 2.5A load with excellent line and load regulation. • • • • • • • • • • • Requiring a minimum number of external components, the regulator is simple to use and include internal frequency compensation, and a fixed-frequency oscillator. The output voltage is guaranteed to ±3% tolerance under specified input voltage and output load conditions. The oscillator frequency is guaranteed to ±15%. External shutdown is included, featuring typically 80 µA standby current. Self protection features include a two stage frequency reducing current limit for the output switch and an over temperature shutdown for complete protection under fault conditions. TD1507 Adjustable output version Output adjustable from 1.23v to 34V Fixed 150KHz frequency internal oscillator Guaranteed 2.5A output load current Input voltage range up to 36V Low power standby mode, IQ typically 70 µA TTL shutdown capability Excellent line and load regulation High efficiency Thermal shutdown and current limit protection Available in TO252-5L package Applications • • • • • • • The TD1507 is available in TO252-5L package. Simple High-efficiency step-down regulator On-card switching regulators Positive to negative converter LCD monitor and LCD TV DVD recorder and PDP TV Battery charger Step-down to 3.3V for microprocessors Package Types TO252-5L Figure 1. Package Types of TD1507 October, 20, 2005. Techcode Semiconductor Limited 1 Datasheet 2.5A 150KHZ PWM Buck DC/DC Converter TD1507 Pin Descriptions Pin Assignments 5 ON/OFF 4 Feedback 3 Gnd 2 Output 1 Vin TO252-5L Name Description Vin Input supply voltage Output Switching output Gnd Ground Feedback Output voltage feedback ON/OFF ON/OFF shutdown Active is “Low” or floating Ordering Information TD1507 X X Packing Blank: Tube R: Tape and Reel Circuit Type Package T: TO252-5L October, 20, 2005. Techcode Semiconductor Limited 2 Datasheet 2.5A 150KHZ PWM Buck DC/DC Converter TD1507 Functional Block Diagram Figure 2. Functional Block Diagram of TD1507 Typical Application Figure 3. Typical Application of TD1507 October, 20, 2005. Techcode Semiconductor Limited 3 Datasheet 2.5A 150KHZ PWM Buck DC/DC Converter TD1507 Absolute Maximum Ratings Note1: Stresses greater than those listed under Maximum Ratings may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. Parameter Value Unit -0.3 to 40 V Feedback VFB pin voltage -0.3 to Vin+0.3 V ON/OFF Pin voltage -0.3 to Vin+0.3 V Output pin voltage -0.3 to Vin+0.3 V -1 V Internally limited W Operating Temperature Range -40 to +125 ºC Storage Temperature -65 to +150 ºC Lead Temperature (Soldering, 10 sec) 200 ºC ESD(HM) 2000 V Supply Voltage Vin Output Voltage to Ground (Steady State) Power Dissipation Electrical Characteristics Unless otherwise specified, Vin = 12V. Iload = 0.5A, Ta = 25℃. Symbol Parameter Conditions Min. Typ. Max. Unit Ib Feedback bias current VFB=1.3V 10 50/100 nA IQ Quiescent current VFB=12V force driver off 5 10 mA ISTBY Standby quiescent current ON/OFF=5V, VIN=36V 70 150 uA FOSC Oscillator frequency 150 173 KHz VSAT Saturation voltage IOUT=2A 1.10 1.4/1.5 V ICL Current Limit Peak Current (VFB=0V) 4.5 5.5/6.5 A IL IL Output leakage current Output=0V (VFB=12V) 50 uA Output leakage current Output=-1V (VIN=36V) 2 30 mA VIL VIH ON/OFF pin logic input Threshold voltage Low (Regulator ON) 1.3 0.6 V IH ON/OFF pin input current VLOGIC=2.5V(Regulator OFF) 127 High (Regulator OFF) October, 20, 2005. 2.0 1.3 5 V 15 uA Techcode Semiconductor Limited 4 Datasheet 2.5A 150KHZ PWM Buck DC/DC Converter IL θJC θJA TD1507 ADJ Thermal Resistance Junction to Case Thermal Resistance Junction to Ambient (Note1) Vfb: Output Voltage η: Efficiency TD1507 VLOGIC=0.5V(Regulator ON) 0.02 TO252-5L 10 O C/W TO252-5L 50 O C/W 11V≤VIN ≤36V, 0.2A≤ILOAD ≤ 3A, VOUT for 9V VIN=12V,VOUT=9V,ILOAD=3A 1.193/ 1.180 1.23 5 1.267/ 1.280 88 uA V % Specifications with boldface type are for full operationg temperature range, the other type are for TJ=25OC. Note1: Thermal resistance with copper area of approximately 3 in2. October, 20, 2005. Techcode Semiconductor Limited 5 Datasheet 2.5A 150KHZ PWM Buck DC/DC Converter TD1507 Typical Performance Characteristics Figure 4. Output Voltage vs. Temperature Figure 5. Switching Frequency vs. Temperature Figure 6. Output Saturation Characteristics Figure 7. Quiescent Current vs. Temperature October, 20, 2005. Techcode Semiconductor Limited 6 Datasheet 2.5A 150KHZ PWM Buck DC/DC Converter Figure 8. ON/OFF Pin Voltage TD1507 Figure 9. ON/OFF Pin Sink Current Figure 10. Output Saturation Characteristics October, 20, 2005. Techcode Semiconductor Limited 7 Datasheet 2.5A 150KHZ PWM Buck DC/DC Converter TD1507 Typical Application Circuit Figure 11. Typical Application of TD1507 Vout 3.3V 5V 9V 12V R2 2.7K 11K 43K 13K R1 1.6K 3.6K 6.8K 1.5K Cf (Operational) 33nf 10nf 1.5nf 1nf Table 1. Vout VS. R1, R2, Cf Select Table Output Voltage 3.3V 5V 9V 12V Input Voltage 6V ~ 18V 6V ~36V 8V ~ 18V 8V ~36V 12V ~18V 12V ~36V 15V ~ 18V 15V ~36V Inductor (L1) 47uh 68uh 33uh 47uh 47uh 47uh 47uh 47uh Output Capacitor (Cout) Through Hole Electrolytic 470uf/25V 560uf/25V 330uf/25V 470uf/25V 330uf/25V 470uf/25V 220uf/25V 330uf/25V Table 2. Typical Application Buck Regulator Design Procedure October, 20, 2005. Techcode Semiconductor Limited 8 Datasheet 2.5A 150KHZ PWM Buck DC/DC Converter TD1507 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. Function Description Pin Functions +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 The TO252 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 in2, 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. 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 The TD1507 (TO252 package) junction temperature rise above ambient temperature with a 2.5A 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 2.5A 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. 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 80uA. 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 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. The TD1507 is available in TO252-5L package. The TO252 package needs a heat sink under most conditions. The size of the heatsink depends on the input voltage, the output voltage, the load current and the ambient temperature. The TD1507 junction temperature rises above ambient temperature for a 2.5A load and different input and output voltages. The data for these curves was taken with the TD1507 (TO252 October, 20, 2005. Techcode Semiconductor Limited 9 Datasheet 2.5A 150KHZ PWM Buck DC/DC Converter TD1507 Package Information October, 20, 2005. Techcode Semiconductor Limited 10 Datasheet 2.5A 150KHZ PWM Buck DC/DC Converter TD1507 Design Notes October, 20, 2005. Techcode Semiconductor Limited 11