AP3405 600mA Step-down DC/DC Converter with Synchronous Rectifier Description Pin Assignments The AP3405 is a 2.0MHz fixed frequency, current mode, PWM synchronous buck (step-down) DC-DC converter, capable of driving a (Top View) 600mA load with high efficiency, excellent line and load regulation. The high efficiency is easily configured by using an inductor, resistors Pin 1 Mark and capacitors as the external components. Current mode control provides fast transient response and cycle-by-cycle current limit. NC 1 8 EN The AP3405 employs complete protection to ensure system security, EP FB 7 2 NC including input Undervoltage Lockout, Over-Temperature Protection and hiccup mode Short Circuit Protection. AGND 3 6 VIN This IC is available in U-DFN2020-8 package. PGND 4 5 SW U-DFN2020-8 (Type E) Features Applications High-Efficiency Buck Power Converter Post DC-DC Voltage Regulation Input Voltage Range: 2.3V to 5.5V Mobile Phones and Wearable Devices Output Voltage Range: 0.7V to 5.5V Fixed 2.0MHz Oscillator Frequency Built-in Soft-Start Time Built-in Overcurrent Protection Built-in Thermal Shutdown Function Built-in UVLO Function Hiccup Mode SCP Output Current: 600mA Package: U-DFN2020-8 (Type E) Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. Green Device (Note 3) Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. 2. See AP3405 Pin Descriptions Pin Number Pin Name Function 1 , 2 NC No connection 3 AGND Signal Ground Pin 4 PGND Power Ground Pin 5 SW Power switch output pin. This pin is connected to the inductor. Supply power input pin. A capacitor should be connected between VIN pin and GND - to keep the input 6 VIN voltage constant. 7 FB Feedback pin. This pin is connected to an external resistor divider to program the system output voltage. Control input pin. EN is a digital input that turns the regulator on or off. Drive EN high to turn the regulator 8 EN on. Drive low to turn the regulator off. Functional Block Diagram EN VIN 6 8 Slope OCP Oscillator UVLO Compensation Comparator Current Shutdown Sensing Comparator Buffer & Bias Dead Time Generator Control Control 5 Logic Logic SW Soft PWM Start Comparator 7 Reverse Inductor FB Current Comparator Error 4 Amplifier PGND Vin OVP Comparator Bandgap 3 Reference AGND 2 of 9 AP3405 January 2016 Diodes Incorporated www.diodes.com Document number: DS38093 Rev. 1 - 2 ADVANCED INFORMATION