3A 150KHz PWM Buck DC/DC Converter EC9301A General Description Features The EC9301A is a series of easy to use fixed and 3.3V,5V and adjustable output Versions adjustable step-down (buck) switch-mode voltage Output adjustable from 1.23V to 43V regulators. These devices are available in fixed output Fixed 150KHz frequency internal oscillator voltage of 3.3V, 5V, and an adjustable output version. Guaranteed 3A output load current Both versions are capable of driving a 3A load with Input voltage range up to 45V excellent line and load regulation. Low power standby mode, IQ typically 80 μA TTL shutdown capability Requiring a minimum number of external components, Excellent line and load regulation these regulators are simple to use and include internal Requires only 4 external components frequency High efficiency Thermal shutdown and current limit protection Available in TO-220B/TO220 and TO-263 packages 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 Applications Simple High-efficiency step-down regulator a two stage frequency reducing current limit for the On-card switching regulators output switch and an over temperature shutdown for Positive to negative converter complete protection under fault conditions. LCD monitor and LCD TV DVD recorder and PDP TV Battery charger Step-down to 3.3V for microprocessors 80 μA standby current. Self protection features include The EC9301A is available in TO-220B-5L ,TO220-5L and TO-263-5L packages. Package Types Figure 1. Package Types of EC9301A E-CMOS Corp. (www.ecmos.com.tw) Page 1 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A Pin Assignment (Top-View) TO220B-5L/TO220-5L TO263-5L Figure 2. Pin Configuration of EC9301A Pin Descriptions 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 E-CMOS Corp. (www.ecmos.com.tw) Page 2 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A Ordering/ Marking Information Package type TO220B-5L Part Number Marking Marking Information EC9301AXXXA1R 1. VV is the Output Voltage (XXX：Output Voltage) (33=3.3V;50=5.0V;AJ=Adjustable) TO263-5L TO220-5L EC9301AXXXAAR (XXX：Output Voltage) 9301A VVLLL YYWWT 2. LLL：last three number of lot no. 3. YYWW：Date Code 4. T：Internal tracking Code EC9301AXXXABR (XXX：Output Voltage) Function Block Diagram Figure 3 Function Block Diagram of EC9301A E-CMOS Corp. (www.ecmos.com.tw) Page 3 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A Absolute Maximum Ratings Parameter Symbol Value Unit Input Voltage VIN -0.3 ~ 45 V Feedback VFB -0.3 ~ VIN +0.3 V ON/OFF Pin voltage VEN -0.3~ VIN +0.3 V Output pin voltage VSW -0.3 ~ VIN +0.3 V Power Dissipation PD Internally limited mW Operating Junction Temperature TJ 150 o -65~+150 o 260 o pin voltage Storage Temperature Lead Temperature (Soldering, 10 sec) Tstg TLead ESD(HBM) C C C 2000 MSL V Level 3 Thermal Resistance-Junction to Ambient RθJA 23 ℃/W Thermal Resistance-Junction to Case RθJA 3.5 ℃/W 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. Recommended Operating Conditions Parameter Symbol Min. Max. Unit Input Voltage VIN 3.6 45 V Operating Junction Temperature TJ -40 125 ℃ Operating Ambient Temperature TA -40 85 ℃ E-CMOS Corp. (www.ecmos.com.tw) Page 4 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A Electrical Characteristics Specifications with boldface type are for full operationg temperature range, the other type are for TJ=25℃. Note1: Thermal resistance with copper area of approximately 3 in Symbol Parameter 2. Conditions Min. Typ. Max. Unit Ib Feedback bias current Adjustable only, 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 - 80 200/250 uA FOSC Oscillator frequency 127 150 173 KHz VSAT Saturation voltage IOUT=3A 1.2 1.4/1.5 V ICL Current Limit Peak Current (VFB=0V) 4.5 5.5/6.5 A IL Output leakage current Output=0V (VFB=12V) 50 uA IL Output leakage current Output=-1V (VIN=36V) 2 30 mA VIL ON/OFF pin logic input Low (Regulator ON) 1.3 0.6 V VIH Threshold voltage High (Regulator OFF) IH ON/OFF pin input current VLOGIC=2.5V(Regulator OFF) 5 15 uA IL ON/OFF pin input current VLOGIC=0.5V(Regulator ON) 0.02 5 uA Thermal Resistance Junction TO220B-5L/TO220-5L 2.5 to Case TO263-5L 3.5 Thermal Resistance Junction TO220B-5L/TO220-5L 28 to Ambient (Note1) TO263-5L 23 θJC θJA 2.0 1.3 V ℃/W ℃ /W Electrical Characteristics (Continued) Specifications with boldface type are for full operationg temperature range, the other type are for TJ=25℃. Note1: Thermal resistance with copper area of approximately 3 in 2. 11V≤VIN≤45V, 0.2A≤ILOAD ≤3A 1.193/ Vout: Output Voltage 1.180 Vout for 9V ADJ η: Efficiency Vout: Output Voltage 3.3V 1.267/ VIN=12V,VOUT=9V,ILOAD=3A - 4.75V≤VIN≤45V, 0.2A≤ILOAD 3.168/ 1.280 88 ≤3A Vout: Output Voltage 7V≤VIN ≤45V, 0.2A≤ILOAD ≤ 3A - VIN=12V, ILOAD=3A Page 5 of 16 V 3.465 76 4.800/ - - % 5.200/ 5.0 4.750 5V % 3.432/ 3.135 VIN=12V, ILOAD=3A E-CMOS Corp. (www.ecmos.com.tw) - 3.3 η: Efficiency η: Efficiency V 1.23 V 5.250 83 - % 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A Typical Performance Characteristics Figure 4. Output Voltage vs. Temperature Figure 5. Switching Frequency vs. Temperature Figure 6. Output Saturation Characteristics E-CMOS Corp. (www.ecmos.com.tw) Figure 7. Quiescent Current vs. Temperature Page 6 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A Typical Performance Characteristics (Continued) Figure 8. ON/OFF Pin Voltage Figure 9. ON/OFF Pin Sink Current Figure 10. Output Saturation Characteristics E-CMOS Corp. (www.ecmos.com.tw) Page 7 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A Typical Application Circuit Figure 11. Typical Application of EC9301A For 3.3V Input Voltage Inductor (L1) 6V ~ 18V 6V ~ 45V 47uh 68uh Output Capacitor (Cout) Through Hole Electrolytic Surface Mount Tantalum 470uf/25V 330uf/6.3V 560uf/25V 330uf/6.3V Table 1. EC9301A Series Buck Regulator Design Procedure For 3.3V Figure 12. Typical Application of EC9301A For 5V Input Voltage Inductor (L1) 8V ~ 18V 8V ~ 45V 33uh 47uh Output Capacitor (Cout) Through Hole Electrolytic Surface Mount Tantalum 330uf/25V 220uf/10V 470uf/25V 330uf/10V Table 2. EC9301A Series Buck Regulator Design Procedure For 5V E-CMOS Corp. (www.ecmos.com.tw) Page 8 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A Figure 13. Typical Application of EC9301A For ADJ Note:In PCB layout. Reserved an area for CFF Vout 3.3V 5V 9V 12V R1 1.6K 3.6K 6.8K 1.5K R2 2.7K 11K 43K 13K Cf (Operational) 33nf 10nf 1.5nf 1nf Table 3. Vout VS. R1, R2, Cf Select Table Output Voltage 3.3V 5V 9V 12V Input Voltage 6V ~ 18V 6V ~45V 8V ~ 18V 8V ~45V 12V ~18V 12V ~45V 15V ~ 18V 15V ~45V 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 4. Typical Application Buck Regulator Design Procedure E-CMOS Corp. (www.ecmos.com.tw) Page 9 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A Function Description Pin Functions temperature rises above ambient temperature for a 3A load and different input and output voltages. +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 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. for these curves was (TO-220B/TO-220 taken with package) operating The data the EC9301A as a buck switching regulator in an ambient temperature of 25℃ (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 2, the package is soldered to should be at least 0.4 in and ideally should have 2 or more square inches of 2 oz. Additional copper characteristics, but area with improves copper areas the thermal greater than 2 approximately 6 in , 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 EC9301A (TO-263 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, Thermal Considerations but be aware that there are many factors that can affect the junction temperature. When load currents higher The EC9301A is available in two packages, a 5-pin than 3A are used, double sided or multilayer PC boards TO-220B/TO-220 and a 5-pin surface mount TO-263. with large copper areas and/or airflow might be needed, The TO-220B/TO-220 package needs a heat sink under especially for high ambient temperatures and high output most conditions. The size of the heatsink depends on voltages. the input voltage, the output voltage, the load current For the best thermal performance, wide copper traces and the ambient temperature. The EC9301A junction and generous amounts of printed circuit board copper should be used in the board layout. (Once exception to E-CMOS Corp. (www.ecmos.com.tw) Page 10 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A Function Description(Cont.) this is the output (switch) pin, which should not have L = (VOUT) * (VIN-VOUT) / VIN * f * ∆I large areas of copper.) Large areas of copper provide the Where VOUT is the output voltage, VIN is the input best transfer of heat (lower thermal resistance) to the voltage, f is the switching frequency, and ∆I is the surrounding air, and moving air lowers the thermal peak-to-peak inductor ripple current. resistance even further. Input Capacitor Setting the Output Voltage The input current to the step-down converter is The output voltage is set using a resistive voltage divider discontinuous, and so a capacitor is required to supply from the output voltage to FB(EC9301A-ADJ) The voltage the AC current to the step-down converter while divider divides the output voltage down by the ratio: maintaining the DC input voltage. A low ESR capacitor is VFB = VOUT * R1 / (R1 + R2) required to keep the noise at the IC to a minimum. Thus the output voltage is: Ceramic capacitors are preferred, but tantalum or VOUT = 1.235 * (R1 + R2) / R1 low-ESR electrolytic capacitors may also suffice. R1 can be as high as 100KΩ, but a typical value is 10KΩ. The input capacitor value should be greater than 10μF. Using that value, R2 is determined by: The capacitor can be electrolytic, tantalum or ceramic. R2 ~= 8.18 * (VOUT – 1.235) (KΩ) However since it absorbs the input switching current it For example, for a 3.3V output voltage, R1 is 10KΩ, and requires an adequate ripple current rating. Its RMS R2is 17KΩ. current rating should be greater than approximately 1/2 of the DC load current. Inductor For insuring stable operation should be placed as close to the IC as possible. Alternately a smaller high quality The inductor is required to supply constant current to the output load while being driven by the switched input voltage. A larger value inductor results in less ripple current that in turn results in lower output ripple voltage. However, the larger value inductor has a larger physical size, higher series resistance, and/or lower saturation current. Choose an inductor that does not saturate under ceramic 0.1μF capacitor may be placed closer to the IC and a larger capacitor placed further away. If using this technique, it is recommended that the larger capacitor be a tantalum or electrolytic type. All ceramic capacitors should be places close to the EC9301A. Output Capacitor the worst-case load conditions. A good rule for determining the inductance is to allow the peak-to-peak The output capacitor is required to maintain the DC ripple current in the inductor to be approximately 30% of output voltage. Low ESR capacitors are preferred to the maximum load current. Also, make sure that the peak keep the output voltage ripple low. The characteristics of inductor current (the load current plus half the peak to the output capacitor also affect the stability of the peak inductor ripple current) is below the TBDA minimum regulation control system. Ceramic, tantalum, or low current limit. The inductance value can be calculated by ESR electrolytic capacitors are recommended. In the the equation: case of ceramic capacitors, the impedance at the switching frequency is dominated by the capacitance, E-CMOS Corp. (www.ecmos.com.tw) Page 11 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A Function Description(Cont.) and so the output voltage ripple is mostly output capacitors, such as solid tantalum capacitors. independent of the ESR. The output voltage ripple is estimated to be: VRIPPLE ~= 1.4 * VIN * (fLC/fSW)^2 Where VRIPPLE is the output ripple voltage, VIN This capacitor type can be ceramic, plastic, silver mica, is the input voltage, fLC is the resonant etc.(Because of the unstable characteristics of ceramic frequency of the LC filter, fSW is the switching capacitors made with Z5U material, they are not frequency. In the case of tanatalum or low- recommended.) ESR electrolytic capacitors, the ESR Note:In PCB layout. Reserved an area for CFF. dominates the impedance at the switching frequency, and so the output ripple is Over Current Protection (OCP) calculated as: VRIPPLE ~= ∆I * RESR Where VRIPPLE is the output voltage ripple, ∆I is The cycle by cycle current limit threshold is set between the inductor ripple current, and RESR is the 4A and 5A. When the load current reaches the current equivalent series resistance of the output limit threshold, the cycle by cycle current limit circuit capacitors. turns off the high side switch immediately to terminate the current duty cycle. The inductor current stops rising. Output Rectifier Diode The cycle by cycle current limit protection directly limits inductor peak current. The average inductor current is also limited due to the limitation on peak inductor current. The output rectifier diode supplies the current to the When the cycle by cycle current limit circuit is triggered, inductor when the high-side switch is off. To reduce the output voltage drops as the duty cycle is decreasing. losses due to the diode forward voltage and recovery times, use a Schottky rectifier. Thermal Management and Layout Table 1 provides the Schottky rectifier part numbers based on the maximum input voltage and current rating. Consideration Choose a rectifier who’s maximum reverse voltage rating is greater than the maximum input voltage, and who’s current rating is greater than the maximum load current. In the EC9301A buck regulator circuit, high pulsing current flows through two circuit loops. The first loop starts from Feedforward Capacitor (CFF) the input capacitors, to the VIN pin, to the VOUT pins, to the filter inductor, to the output capacitor and load, and then returns to the input capacitor through ground. For output voltages greater than approximately 8V, an Current flows in the first loop when the high side switch is additional capacitor is required. The compensation on. The second loop starts from the inductor, to the capacitor is typically between 100 pF and 33 nF, and is output capacitors and load, to the GND pin of the wired in parallel with the output voltage setting resistor, EC9301A, and to the VOUT pins of the EC9301A. Current R2. It provides additional stability for high output flows in the second loop when the low side diode is on. voltages, low input-output voltages, and/or very low ESR In PCB layout, minimizing the two loops area reduces the E-CMOS Corp. (www.ecmos.com.tw) Page 12 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A Function Description(Cont.) noise of this circuit and improves efficiency. A ground Several layout tips are listed below for the best electric plane is recommended to connect input capacitor, output and thermal performance. capacitor, and GND pin of the EC9301A. 1. Do not use thermal relief connection to the VIN and In the EC9301A buck regulator circuit, the two major the GND pin. Pour a maximized copper area to the GND power dissipating components are the EC9301A and pin and the VIN pin to help thermal dissipation. output inductor. The total power dissipation of converter 2. Input capacitor should be connected to the VIN pin circuit can be measured by input power minus output and the GND pin as close as possible. power. 3. Make the current trace from VOUT pins to L to the Ptotal _loss = V IN × IIN – V O × IO GND as short as possible. The power dissipation of inductor can be approximately 4. Pour copper plane on all unused board area and calculated by output current and DCR of inductor. Pinductor _loss= IO 2 × Rinductor × 1.1 connect it to stable DC nodes, like VIN, GND, or VOUT. The junction to ambient temperature can be got from FB pin away from the VOUT pins. 5. Keep sensitive signal traces such as trace connecting power dissipation in the EC9301A and thermal impedance from junction to ambient. T (jun-amb) =(Ptotalloss–Pinductorloss)× ΘJA The maximum junction temperature of EC9301A is 145°C, which limits the maximum load current capability. Please see the thermal de-rating curves for the maximum load current of the EC9301A under different ambient temperatures. The thermal performance of the EC9301A is trongly affected by the PCB layout. Extra care should be taken by users during the design process to nsure that the IC will operate under the recommended environmental conditions. E-CMOS Corp. (www.ecmos.com.tw) Page 13 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A OUTLINE DRAWING FOR TO-220B-5L Dimensions In Millimeters Dimensions In Inches Symbol Min. Max. Min. Max. A 4.40 4.70 0.175 0.185 b 0.69 0.94 0.027 0.037 D 8.38 8.90 0.330 0.350 d1 1.0 0.039 d2 6.3 0.248 E 9.91 10.41 0.390 0.410 e 1.58 1.83 0.062 0.072 F 1.22 1.32 0.048 0.052 H1 6.40 0.250 H2 20.83 22.35 0.820 0.880 H3 23.93 25.45 0942 1.002 J1 J2 2.66 3.73 J3 Q 0.105 5.26 0.147 8.40 2.55 E-CMOS Corp. (www.ecmos.com.tw) 0.207 0.331 3.05 0.100 Page 14 of 16 0.120 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A OUTLINE DRAWING FOR TO-220-5L E-CMOS Corp. (www.ecmos.com.tw) Page 15 of 16 5J22N Rev. F001 3A 150KHz PWM Buck DC/DC Converter EC9301A OUTLINE DRAWING FOR TO-263-5L E-CMOS Corp. (www.ecmos.com.tw) Page 16 of 16 5J22N Rev. F001