800KHz Synchronous Step-up Converter with 5.5A Switches EC3689 General Description Features The EC3689 devices provide a power supply solution for ◆ Synchronous Step-up Converter with 2.1A Output Current From 2.9V Input products powered by either a one-cell Li-Ion or Li-polymer battery. The converter generates a stable output voltage ◆ Wide VIN Range From 2.9V to 5.5V that is either adjusted by an external resistor divider or ◆ Input Under-voltage Lockout Protection fixed internally on the chip. It provides high efficient power ◆ Fixed and Adjustable Output Voltage conversion and is capable of delivering output currents up ◆ Built-in Output Over-voltage Protection to 2.1A at 5.3V at a supply voltage down to 2.9V. The ◆ Light-Load Pulse Skip Mode maximum peak current in the step-up switch is limited to a ◆ Load Disconnect During Shutdown value of 5.5A. The EC3689 operates at 800KHz switching ◆ Output Short Circuit Protection frequency and enters pulse-skip-mode (PSM) operation at ◆ Thermal Shutdown Protection light load currents to maintain high efficiency over the ◆ Available in a SOP8(Exposed PAD) Packages entire load current range. During shutdown, the load is completely disconnected from the battery. APPLICATIONS ◆ Power Bank ◆ USB Charging Port (5V) ◆ DC/DC Micro Modules Figure 1. EC3689 Typical Application Circuit E-CMOS Corp. (www.ecmos.com.tw) Page 1 of 8 4E02N-Rev.P001 800KHz Synchronous Step-up Converter with 5.5A Switches EC3689 Ordering Information Part Number Package Marking EC3689NNMHR SOP-8 (Exposed PAD) 3689 LLLLL YYWWT Marking Information 1. LLLLL ：Lot No 2. YYWW：Date Code 3. T：Internal Track Code Pin Configuration EC3689 Top View Pin Description NAME PIN NO. DESCRIPTION VIN 1 Input Supply voltage EN GND 2 3 Enable input.(1/VIN enabled,0/GND disabled) Analog Ground pin. Connect GND to PGND under EP. FB 4 Voltage feedback of adjustable versions. Connect FB to GND and set fixed 5.05V output voltage. VOUT 5 Step-up convert output SW 6, 7 Step-up and rectifying switch input PGND 8 Power Ground pin. EP E-CMOS Corp. (www.ecmos.com.tw) Exposed pad must be soldered to achieve appropriate power dissipation. Connect EP to GND. Page 2 of 8 4E02N-Rev.P001 800KHz Synchronous Step-up Converter with 5.5A Switches EC3689 Absolute Maximum Ratings(1) Symbol Parameter Rating Unit VIN Supply Voltage -0.3 to +6 V VOUT Output Voltage -0.3 to +6 V VFB/VSW /VEN Input Voltage -0.3 to +6 V IPK Peak Output Current Internally Limited A TLED Lead Temperature 260 ℃ TJ Junction Temperature -40 ~ +135 ℃ TSTG Storage Temperature -55 ~ +155 ℃ Thermal Characteristics Symbol Typical Value Parameter Unit ΘJA Junction-to-Ambient Resistance in free air 38.2 ℃/W PD Maximum Power Dissipation(TA=25℃) 2.6 W Recommended Operating Conditions(2) Symbol Parameter Rating Unit VIN Supply Voltage +2.9 to +5.5 V VOUT Output Voltage +2.9 to +5.5 V TOP Operating Temperature -40 ~ +85 ℃ Note (1): Stress beyond those listed under “Absolute Maximum Ratings” may damage the device. Note (2): The device is not guaranteed to function outside the recommended operating conditions. E-CMOS Corp. (www.ecmos.com.tw) Page 3 of 8 4E02N-Rev.P001 800KHz Synchronous Step-up Converter with 5.5A Switches EC3689 Electrical Characteristics TA = +25°C, 2.9V ≤ VIN ≤ 5.5V, unless otherwise noted. Typical values are at V IN= VEN =3.6V and VOUT=5V. PARAMETER TEST CONDITIONS MIN TYP 2.5 Input voltage range VIN Input Under-voltage Lockout MAX UNIT 5.5 V 2.2 V Threshold VUVLO Output voltage adjustable 2.5 5.5 V range VOUT 4.95 5.05 5.15 V Feedback voltage VFB 490 500 510 mV Oscillator frequency fOSC 640 800 960 KHz Fixed Output Voltage FB=GND NCH Switch Current Limit VOUT= 5V 5.5 A NCH Switch on resistance VOUT= 5V 75 mΩ PCH Switch on resistance VOUT= 5V 75 mΩ Shutdown Current VEN = 0V, VIN = 3.6V 0.1 1 µA Quiescent Current(V IN) VFB=0.55V, VOUT=5V 125 200 uA 0.4 V EN Logic Low Voltage 1.4 EN Logic High Voltage EN Leakage Current Clamped on GND or VIN V -1 1 uA Thermal Shutdown 150 ℃ Thermal Shutdown Hysteresis 20 ℃ E-CMOS Corp. (www.ecmos.com.tw) Page 4 of 8 4E02N-Rev.P001 800KHz Synchronous Step-up Converter with 5.5A Switches EC3689 Functional Block Diagram Figure 2. EC3689 Functional Block Diagram E-CMOS Corp. (www.ecmos.com.tw) Page 5 of 8 4E02N-Rev.P001 800KHz Synchronous Step-up Converter with 5.5A Switches EC3689 Detailed Description The EC3689 is based on a fixed frequency current mode pulse width modulation topology. The peak current of the NMOS switch is sensed to limit the maximum current flowing through the switch and the inductor. The typical peak current limit is set to 5.5A. An internal temperature sensor prevents the device from getting overheated in case of excessive power dissipation. Application Information Because of the high integration of EC3689, the application circuit is simple. Only input capacitor CIN, output Capacitor COUT, inductor L, output feedback resistors R3, R4 need to be selected for the targeted applications specifications. Setting the Output Voltage The EC3689 output voltage can be adjusted with an external resistor divider (See Figure 1). The typical value of the voltage on the FB pin is 500mV. The maximum allowed value for the output voltage is 5.5 V. Choose the bottomresistor R4 in the 100kΩ~500kΩ range to set the divider current at 1 µA or higher. The value of resistor R3, depending on the needed output voltage VOUT, can be calculated using Equation 1: Inductor Selection The inductor DC current rating should be greater (by some margin) than the maximum input average current. The highest peak current through the inductor and the switch depends on the output load, converter efficiency η, the input voltage (VIN), and the output voltage (VOUT). Estimation of the maximum average inductor current can be done using Equation 2: For example, for an output current of 2A at 5V with 90% efficiency, at least 3.8A of average current flows through the inductor at a minimum input voltage of 2.9V. The EC3689 step-up converters have been optimized to operate with an effective inductance in the range of 1µH to 2.2µH and with output capacitors in the range of 20µF to 100µF. The internal compensation is optimized for an output filter of L = 1.5µH and COUT = 20µF. Larger or smaller inductor values can be used to optimize the performance of the device for specific operating conditions. Input Capacitor Place at least a 10 µF input ceramic capacitor close to the IC is to improve transient behavior of the regulator and EMI behavior of the total power supply circuit. E-CMOS Corp. (www.ecmos.com.tw) Page 6 of 8 4E02N-Rev.P001 800KHz Synchronous Step-up Converter with 5.5A Switches EC3689 Output Capacitor The output capacitor must completely supply the load during the charging phase of the inductor. A reasonable value of the output capacitance depends on the speed of the load transients and the load current during the load change. It is recommended to use X7R ceramic capacitors placed as close as possible to the VOUT and PGND pins of the IC. A recommended output capacitance value is around 20~100µF. Note that high capacitance ceramic capacitors have a DC Bias effect, which will have a strong influence on the final effective capacitance. A 10 V rated 0805 capacitor with 10µF can have an effective capacitance of less 5µF at an output voltage of 5V. Layout consideration Use wide and short traces for the main current path and for the power ground tracks. The input capacitor, output capacitor, and the inductor should be placed as close as possible to the IC. Use a common ground node for power ground and a different one for analog ground to minimize the effects of ground noise. Connect these ground nodes at any place close to the ground pins of the IC. Thermal information Implementation of integrated circuits in low-profile and fine-pitch surface-mount packages typically requires special attention to power dissipation. Many system-dependent issues such as thermal coupling, airflow, added heat sinks and convection surfaces, and the presence of other heat-generating components affect the power-dissipation limits of a given component. Three basic approaches for enhancing thermal performance are listed below: ● Improving the power dissipation capability of the PCB design ● Improving the thermal coupling of the component to the PCB ● Introducing airflow in the system The maximum junction temperature (TJ) of the EC3689 devices is 125℃.The thermal resistance of the SOP8 (Exposed PAD) package is RθJA = 38.2℃/W, if the Exposed PAD is soldered. Specified regulator operation is assured to a maximum ambient temperature TA of +50℃. Therefore, the maximum power dissipation for the SOP8(Exposed PAD) package it is about 1.96W. More power can be dissipated if the maximum ambient temperature of the application is lower. E-CMOS Corp. (www.ecmos.com.tw) Page 7 of 8 4E02N-Rev.P001 800KHz Synchronous Step-up Converter with 5.5A Switches EC3689 Package Information SOP-8(Exposed PAD) SYMBOLS Package Outline Dimension MILLIMETERS INCHES MIN. MAX. MIN. MAX. A 1.35 1.75 0.053 0.069 A1 0.10 0.25 0.004 0.010 D 4.90 0.193 E1 3.90 0.153 D1 2.00 0.081 E2 2.00 0.081 E 5.80 6.20 0.228 0.244 L 0.40 1.27 0.016 0.050 b 0.31 0.51 0.012 0.020 e E-CMOS Corp. (www.ecmos.com.tw) 1.27 0.050 Page 8 of 8 4E02N-Rev.P001