EC5116 E-CMOS | Alldatasheet
Document overview
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Technical content
Features
◆4.5V to 40V operating input range ◆3A output current ◆Up to 94% efficiency ◆High efficiency (>78%) at light load ◆Internal Soft-Start ◆Adjustable switch frequency ◆Input under-voltage lockout ◆Start-up current run-away protection ◆Output short protection ◆Feedback short protection ◆Thermal protection ◆Available in SOP8 and ESOP8 package
Applications
◆Distributed Power Systems ◆Networking Systems ◆FPGA, DSP , ASIC Power Supplies ◆Green Electronics/ Appliances Typical application
3A, 40V Asynchronous Step-Down Converter Ordering/Marking Information EC5116 XX X X R：Tape & Reel Package Type： F：Pb Free MH：ESOP8 G：Green M1 ：SOP8 Pin Configurations Absolute Maximum Ratings Recommended Operating Conditions Thermal Performance Device Marking Package Information EC5116MNXR EC5116 LLLLL YYWW ESOP8 YY: Year code WW: Week code LLLLL: Lot no. EC5116M1XR EC5116 LLLLL YYWW SOP8
3A, 40V Asynchronous Step-Down Converter Note 1) Exceeding these ratings may damage the device. 2) The EC5116 guarantees robust performance from -40°C to 150°C junction temperature. The junction temperature range specification is assured by design, characterization and correlation with statistical process controls. 3) The EC5116 includes thermal protection that is intended to protect the device in overload conditions. Thermal protection is active when junction temperature exceeds the maximum operating junction temperature. Continuous operation over the specified absolute maximum operating junction temperature may damage the device. 4) Measured on JESD51-7, 4-layer PCB.
Electrical Characteristics
VIN = 12V, TA = 25º C, unless otherwise stated. Item Symbol Condition Min. Typ. Max. Units VIN Under-voltage Lockout Threshold VIN_MIN VIN falling 3.6 3.8 4 V VIN Under-voltage Lockout Hysteresis VIN_MIN_HYST VIN rising 200 400 600 mV Shutdown Supply Current ISD VEN=0V 1.6 3 µA Supply Current IQ VEN=5V, VFB=1V 30 65 90 µA Feedback Voltage VFB 3.6V<VVIN<40V 0.784 0.8 0.816 V Top Switch Resistance5) RDS(ON)T 63 78 m Top Switch Leakage Current ILEAK_TOP VIN=40V, VEN=0V, VSW=0V 0.1 uA Top Switch Current Limit5) ILIM_TOP Minimum Duty Cycle 3.6 4.5 A Switch Frequency FSW RRT = 330k 100 160 220 kHz Minimum On Time5) TON_MIN 117 ns Minimum Off Time TOFF_MIN VFB=0V 100 150 200 ns EN Shutdown Threshold VEN_TH VEN falling, FB=1V 1 1.2 1.4 V EN shut down hysteresis VEN_HYST VEN rising, FB=1V 50 100 150 mV Thermal Shutdown5) TTSD 137 °C Thermal Shutdown Recovery Hysteresis5) TTSDR 13 °C Note： 5) Guaranteed by design.
3A, 40V Asynchronous Step-Down Converter Pin Description PIN SOP8 Name Description 1 SW SW is the switching node that supplies power to the output. Connect the output LC filter from SW to the output load. 2 EN Drive EN pin high to turn on the regulator and low to turn off the regulator.
3 COMP
Compensation pin. Comp is used to compensate the regulation control loop. Connect a series RC network from COMP to GND to compensate the regulation control loop. One ceramic cap such as several tens pF is usually connected from COMP to GND to decouple the voltage noise 4 FB Output feedback pin. FB senses the output voltage and is regulated by the control loop to FB reference voltage 0.8V. Connect a resistive divider at FB. 5 GND Ground. 6 RT Voltage at the RT pin is regulated at 1.2V. Switch frequency of the regulator can be adjusted by connecting a resistor at the RT pin to ground. 7 VIN Input voltage pin. VINsupplies power to the IC. Connect a 3.8V to 40V supply to VIN and bypass VIN to GND with a suitably large capacitor to eliminate noise on the input pin to the IC. 8 BST Bootstrap pin for top switch. A 0.1uF or larger capacitor should be connected between this pin and SW pin to supply current to the top switch and top switch driver. Block Diagram
3A, 40V Asynchronous Step-Down Converter Typical Performance Characteristics Vin=12V, Vo=5V, L=22uH, Cout=47uF, Cin=20uF, Ta=25°C unless otherwise noted.
3A, 40V Asynchronous Step-Down Converter Functional Description The EC5116 is an asynchronous, current -mode, step-down regulator. It re gulates input voltages from 3.8V to 40V down to an output voltage as low as 0.8V, and is capable of supplying up to 3A of load current. Current-Mode Control The EC5116 utilizes current-mode control to regulate the output voltage. The output voltage is measured at the FB pin through a resistive divider and the error is amplified by the internal transconductance error amplifier. The output of internal error amplifier is compared to the switch current measured internally to control the output current limit. PFM Mode The EC5116 operates in PFM mode at light load. In PFM mode, switch frequency is continuously controlled in proportion to the load current, i.e. switch frequency is decreased when load current drops to boost power efficiency at light load by reducing switch-loss, while switch frequency is increased when load current rises, minimizing both load current and output voltage ripples. Power Switch An N-Channel MOSFET switch is integrated on the EC5116 to down convert the input voltage to the regulated output voltage. Since the top MOSFET needs a gate voltage great than the input voltage, a boost capacitor connected between BST and SW pins is required to drive the gate of the top switch. The boost capacitor is charged by the internal 3.3V rail when S W is low. VIN Under-Voltage Protection EC5116 can regulate a wide range input voltage down to an output voltage. If the input voltage decreases to under voltage lockout threshold, the regulator enters into UVLO protection to shutdown internal logic and fu nction blocks. Enable Pin EN pin is a digital control pin that turns the regulator on and off. Drive EN pin high to turn on the regulator and drive it low to turn it off. A resistor such as 100K can be connected between EN pin and VIN pin for automatic startup. COMP Voltage The current limit is decided by the maximum comp voltage which is around 2.5V. Comp voltage is also adjusted with the output current. The comp voltage decreases as load current drop. When comp voltage keeps the maximum value for aroun d 12480 cycle, the over load protection is triggered. IC enters into the hiccup mode during the OLP. Output Current Run-Away Protection At start-up, due to the high voltage at input and low voltage at output, current inertia of output inductance can be easily built up, resulting in a large start-up output current. COMP value is limited and rise up slowly for a period of time when start up. By such control mechanism, the output current at start -up is well controlled. Output Short Protection When the output is shorted to ground, output current rapidly rises and if it hits the OCP (over current protection) limit, which is 1.3A above the normal peak current limit, switch frequency is halved to allow time for the inductor current to fall to a safe level. If the OCP limit is hit again in the next cycle, switch frequency is halved again. In the extreme case, switch frequency can be decreased to 1/12 8 of the original frequency set by the resistor at the RT pin. Feedback Short Protection If the FB pin is detected to be short to ground for more than 15 switch cycles, the EC5116 is latched off. The regulator can be Reactivated again through recycling Vin or EN voltage. Thermal Protection When EC5116 inner temperature rises above the Over Temperature Protection threshold, it is forced into thermal shut - down. Only when IC inner temperature drops below Over Temperature Recovery threshold can the regulator becomes active again.
3A, 40V Asynchronous Step-Down Converter
Application Information
Setting the Output Voltage The output voltage is set using a resistive divider from the output voltage to FB pin as Figure 1. The voltage divider divides the output voltage down to the feedback voltage by the ratio: Where VFB is the f eedback voltage and VOUT is the output voltage. The output voltage is: VFB is 0.8V reference. R2 can be as high as 100K, but a typical value is 10K~20K.For example,R2 is 22K,R5 is determined by: One ceramic cap (C5) such as 100nF/6.3V is suggested to parallel with R2 to decou ple noise voltage for feedback loop stability in some practical application. Operating Frequency EC5116 working frequency can be adjusted in different application. Set the resistor connected to RT pin to setup the working frequency as Figure 2 and follow ing expression. EN Function EN pin is a digital input that turns the regulator ON or OFF. Drive EN pin high to turn on the regulator and drive it low to turn off regulator. Usually, pull up with 100K (R1) resistor for automatic startup (R6=NC). Low input voltage protection can be setup through EN pin to adjust the R1and R6 as Figure 3. EN pin voltage below 1.2V to turn off EC5116 when low input voltage.
3A, 40V Asynchronous Step-Down Converter For example, Vin=12V, setup the Vin=10V to trigger the low input voltage protection. So, R1 and R6 can be configured as R1=1M and R6=136.3K. BST Capacitor BST cap supplies the drive for the high -side N-MOSFE switch, connected from the BST pin to SW pin as Figure 4. The BST cap is charged by the in ternal 3.3V rail when SW is low. Usually, one ceramic cap 0.1uF or greater capacitor is ok for high side MOS driver. Compensation Loop COMP is used to compensate the regulation control loop for system stability and transient response. Connect a series RC Network (Pole-zero combination) from COMP to GND to optimize the control loop as Figure 5. In some cases, an additional ceramic capacitor (C6 such as 47pF) from COMP to GND is required to eliminate the high frequency noise influence. Normally application with 5V/3.3V output, 12V/24V input, the below table parameter is recommended. Power Inductor The inductor is required to supply constant current to the output load. A larger value inductor results in less current ripple and Also lower output ripple. However, the larger value inductor has a larger physical size, bigger series resistance, high cost or lower saturation current. A good rule to determining the inductance is to allow the peak -to-peak ripple current in the inductor. It’s recommended to allow inductor ripple current IPP of 30% maximum peak current. So we can get the proper inductor value as follow. Where VOUT is output voltage, VIN is input voltage, fS is switching frequency and IPP is the peak-to-peak inductor ripple current. Choose an inductor that will not be saturate under the maximum inductor peak current. The peak inductor current can be calculated by following expression: Where IOUT is the load current.
3A, 40V Asynchronous Step-Down Converter Freewheel Diode Freewheel diode supply the cur rent route when high side MOS turns off. The system efficiency is worse if the forward voltage drop is high. So, this diode is recommended to use the schottky diode with lower forward voltage drop to improve overall efficiency. For example, the B540 (5A/40V) schottky diode performs well in application. Input Capacitor Use low ESR capacitors for the best performance. Ceramic capacitors are preferred, but tantalum or low-ESR electrolytic Capacitors may also suffice. It’s recommended to choose X5R or X7R dielectrics when using ceramic capacitors. The RMS current in the input capacitor can be estimated by following expression: Choose the input capacitor whose RMS current rating greater than I Cinput. Input voltage ripple for low ESR capacitors can be estimated as follow: It should increase the input capacitor if the input voltage ripple is big. Besides, one ceramic cap such as 0.1uF is suggested to be placed as close to the IC as possible. Output Capacitor The output capacit or is required to maintain the DC output voltage. The output voltage ripple can be estimated by following. Where COUT is the output capacitance value and RESR is the equivalent series resistance (ESR) value of the output capacitor. Ceramic, tantalum, or low ESR electrolytic capacitors are recommended. Low ESR capacitors are preferred to keep the output Pcb Layout PCB layout is very important to achieve stable operation. It is highly recommended to duplicate EVB layout as follow these guidelines. 1. Keep the path of switching current short and minimize the loop area formed by input cap, high-side MOSFET and freewheel diode. 2. Bypass ceramic capacitors are suggested to be put close to the Vin Pin. 3. Ensure all feedback connec tions are short and direct. Place the feedback resistors and compensation components as close to the chip as possible. 4. Route SW away from sensitive analog areas such as FB. 5. Connect IN, SW, and especially GND respectively to a large copper area to cool the chip to improve thermal performance and long-term reliability. The 2os copper thickness is suggested for better thermal performance in real application. Figure 6 is the PCB layout reference.
3A, 40V Asynchronous Step-Down Converter Reference Design Reference 1: Vin: 8V~36V Vout: 5V Iout: 0~3A Reference 2: Vin: 5V~36V Vout: 3.3V Iout: 0~3A
3A, 40V Asynchronous Step-Down Converter Package Outline
3A, 40V Asynchronous Step-Down Converter