Datasheet 2A 380KHZ 20V PWM Buck DC/DC Converter General Description Features The TD1410 is a 380 KHz fixed frequency monolithic step down switch mode regulator with a built in internal Power MOSFET. It achieves 2A continuous output current over a wide input supply range with excellent load and line regulation. The device includes a voltage reference, oscillation circuit, error amplifier, internal PMOS and etc. The PWM control circuit is able to adjust the duty ratio linearly from 0 to 100%. An enable function, an over current protection function and a short circuit protection function are built inside. An internal compensation block is built in to minimize external component count. TD1410 2A Constant Output Current 140mΩ RDSON Internal Power PMOSFET Switch Up to 95% Efficiency Fixed 380KHz Frequency Wide 3.6V to 20V Input Voltage Range Output Adjustable from 1.235V to 18 V Built in Frequency Compensation Built in Thermal Shutdown Function Built in Current Limit Function SOIC-8 Package is Available The minimum dropout up to 0.3V Applications The TD1410 serves as ideal power supply units for portable devices. Portable DVD LCD Monitor / TV Battery Charger ADSL Modem Telecom / Networking Equipment Figure 1 Package Type of TD1410 September, 2006 1 Datasheet 2A 380KHZ 20V PWM Buck DC/DC Converter TD1410 Pin Configurations Figure 2 Pin Configuration of TD1410 (Top View) Pin Description Pin Number Pin Name Description 1,6, 8 NC Not Connect. 2 Vin 3 SW 4 GND 5 FB 7 EN Supply Voltage Input Pin. TD1410 operates from a 3.6V to 23V DC voltage. Bypass Vin to GND with a suitably large capacitor to eliminate noise on the input. Power Switch Output Pin. SW is the switch node that supplies power to the output. Ground Pin. Care must be taken in layout. This pin should be placed outside of the Schottky Diode to output capacitor ground path to prevent switching current spikes from inducing voltage noise into TD1410. Feedback Pin. Through an external resistor divider network, FB senses the output voltage and regulates it. The feedback threshold voltage is 1.235V. Enable Pin. EN is a digital input that turns the regulator on or off .Drive EN pin high to turn on the regulator, drive it low to turn it off. Ordering Information TD1410 X X Packing Blank: Tube R: Type and Reel Circuit Type Package S: SOP8 September, 2006 2 Datasheet 2A 380KHZ 20V PWM Buck DC/DC Converter TD1410 Function Block Figure 3 Function Block Diagram of TD1410 Absolute Maximum Ratings Parameter Symbol Input Voltage Feedback Pin Voltage Enable Pin Voltage Switch Pin Voltage Power Dissipation Operating Junction Temperature Storage Temperature Lead Temperature (Soldering, 10 sec) ESD (HBM) VIN VFB VEN VSW PD TJ TSTG TLEAD Value -0.3 to 22 -0.3 to Vin -0.3 to Vin -0.3 to Vin Internally limited 150 -65 to 150 260 2000 Unit V V V V mW ºC ºC ºC V 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. September, 2006 3 Datasheet 2A 380KHZ 20V PWM Buck DC/DC Converter TD1410 Recommended Operating Conditions Parameter Symbol Min. Max. Unit Input Voltage VIN 3.6 20 V Operating Junction Temperature TJ -40 125 ºC Operating Ambient Temperature TA -40 85 ºC Electrical Characteristics VCC = 12V, Ta = 25℃ unless otherwise specified. Parameters Input voltage Symbol Test Condition VIN Min. Typ. 3.6 Max. Unit 20 V Shutdown Supply Current ISTBY VEN=0V 30 90 uA Quiescent Supply Current ICC VEN=2V, VFB=1.3V 3.6 4 mA Feedback Voltage VFB VIN = 3.6V to 23V 1.235 1.26 V Feedback Bias Current IFB VFB=1.3V 0.1 0.5 uA Switch Current Limit ILIM 3 4 A Oscillator Frequency FOSC 380 440 KHz Frequency of Current Limit or Short Circuit Protection FOSC1 EN Pin Threshold VEN 1.21 320 VFB=0V 42 0.7 KHz 1.2 1.7 V IH VEN=2.5V -0.1 -1 uA IL VEN=0.5V -3 -10 uA Internal PMOS RDSON RDSON VIN =12V, VFB=0V VEN=12V, Iout=2A 140 mΩ Max. Duty Cycle DMAX VFB=0V, ISW=0.1A 100 % η VIN=12V ,Vout=5V Iout=2A EN Pin Input Leakage Current Efficiency Thermal Shutdown TOTSD - 92 165 September, 2006 4 - % ºC Datasheet 2A 380KHZ 20V PWM Buck DC/DC Converter TD1410 Typical Performance Characteristics Figure 4. Switching Frequency vs. Temperature Figure 6. Icc vs. Temperature Figure 5. Vfb vs. Temperature Figure 7. Efficiency vs. Load (Vin=10V) September, 2006 5 Datasheet 2A 380KHZ 20V PWM Buck DC/DC Converter Typical Application Circuit Fig8. TD1410 Typical Application Circuit @ 5V/2A Fig9. TD1410 Typical Application Circuit @ 3.3V/2A September, 2006 6 TD1410 Datasheet 2A 380KHZ 20V PWM Buck DC/DC Converter TD1410 Fig10. TD1410 Typical Application Circuit (with ceramic output capacitor) @ 5V/2A Fig11. TD1410 Typical Application Circuit (with ceramic output capacitor) @ 3.3V/2A September, 2006 7 Datasheet 2A 380KHZ 20V PWM Buck DC/DC Converter TD1410 Schottky Rectifier Selection Guide 2A Load Current Part Number Vendor B220 1 SK23 6 SR22 6 20BQ030 4 B230 1 SK23 6 SR23 3,6 SS23 2,3 Vin (Max) 20V 30V 3A Load Current Part Number Vendor B320 1 SK33 1,6 SS32 3 B330 1 B340L 1 MBRD330 4,5 SK33 1,6 SS33 2,3 Table 1 lists some rectifier manufacturers. No. 1 2 3 4 5 6 Vendor Diodes, Inc. Fairchild Semiconductor General Semiconductor International Rectifier On Semiconductor Pan Jit International Web Site www.diodes.com www.fairchildsemi.com www.gensemi.com www.irf.com www.onsemi.com www.panjit.com.tw Table 2 Schottky Diode manufacturers. Output Voltage VS R1, R2 Resistor Selection Guide Vout = (1+R1/R2)*1.235V Vout 1.8V 2.5V 3.3V 5V 9V 12V R2 11K 5K 1.6K 3.6K 6.8K 1.5K R1 5.1K 5.1K 2.7K 11K 43K 13K Table 3. Vout VS. R1, R2 Select Table September, 2006 8 Datasheet 2A 380KHZ 20V PWM Buck DC/DC Converter TD1410 curves was taken with the TD1410 (SOP8 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 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. GND Circuit ground. SW Internal switch. The voltage at this pin switches between (VIN – VGS) 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. 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, multi-layer board and the amount of solder on the board. FB Senses the regulated output voltage to complete the feedback loop. EN Allows the switching regulator circuit to be shutdown using logic level signals thus dropping the total input supply current to approximately 30uA. Pulling this pin below a threshold voltage of approximately 0.7 V turns the regulator down, and pulling this pin above 1.3V (up to a maximum of 12V) shuts the regulator on. For automatic starup condition , can be implemented by the addition of a resistive voltage divider from VIN to GND. 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. Thermal Considerations The TD1410 is available in SOP8 package. The SOP8 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 TD1410 junction temperature rises above ambient temperature for a 2A load and different input and output voltages. The data for these September, 2006 9 Datasheet 2A 380KHZ 20V PWM Buck DC/DC Converter Package Information SOP8 Package Outline Dimensions September, 2006 10 TD1410 Datasheet 2A 380KHZ 20V PWM Buck DC/DC Converter Design Notes September, 2006 11 TD1410