AP65452 4A, 18V, 650kHz ADAPTIVE COT STEP-DOWN CONVERTER Description Pin Assignments The AP65452 is an adaptive, constant, on-time mode synchronous buck converter, providing high efficiency, excellent transient response ( Top View ) and high DC output accuracy for low-voltage regulation in digital TVs and monitors. EN 1 8 VIN BS FB 2 7 The constant on-time control scheme handles wide input/output voltage ratios and provides low external component count. The VREG5 3 6 SW internal proprietary circuit enables the device to adopt both low equivalent series resistance (ESR) output capacitors, such as SS 4 5 GND SP-CAP or POSCAP and ultra-low ESR ceramic capacitors. SO-8EP The AP65452 features programmable soft-start, UVLO, OTP and OCP to protect the circuit. Applications This IC is available in SO-8EP package. Gaming Consoles Flat Screen TV Sets and Monitors Features Set-Top Boxes Distributed Power Systems Fixed Frequency Emulated Constant On-Time Control Home Audio Good Stability Independent of the Output Capacitor ESR Consumer Electronics Fast Load Transient Response Network Systems Synchronous Rectification: 65m Internal High-Side Switch and FPGA, DSP and ASIC Supplies 36m Internal Low-Side Switch Green Electronics Wide Input Voltage Range: 4.5V to 18V Output Voltage Range: 0.76V to 6V 4A Continuous Output Current 650kHz Switching Frequency Built-in Overcurrent Limit Built-in Thermal Shutdown Protection Programmable Soft-Start Pre-biased Start-up 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 AP65452 Pin Descriptions Pin Pin Number Function Name SO-8EP Enable input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the regulator, drive it low EN 1 to turn off. Pull up with 100k resistor for automatic startup. Feedback Input. FB senses the output voltage and regulates it. Drive FB with a resistive voltage divider connected to FB 2 it from the output voltage. Internal power supply output pin to connect an additional capacitor. Connect a 1F (typical) capacitor as close as VREG5 3 possible to the VREG5 and GND. This pin is not active when EN is low. Soft-start control input pin. SS controls the soft start period. Connect a capacitor from SS to GND to set the soft-start SS 4 period. GND 5 Ground pin is the main power ground for the switching circuit. Power Switching Output. SW is the switching node that supplies power to the output. Connect the output LC filter SW 6 from SW to the output load. Note that a capacitor is required from SW to BS to power the high-side switch. Bootstrap pin. A bootstrap capacitor is connected between the BS pin and SW pin. The voltage across the bootstrap BS 7 capacitor drives the internal high-side NMOS switch. A 0.1F (typical) capacitor is required for proper operation. Supply input pin. A capacitor should be connected between the VIN pin and GND pin to keep the DC input voltage VIN 8 constant. EP Connect the exposed thermal pad to GND on the PCB. Functional Block Diagram Figure 2 Functional Block Diagram 2 of 13 AP65452 August 2015 Diodes Incorporated www.diodes.com Document number: DS37305 Rev. 3 - 2 ADVANCED INFORMATION