AP65352 3A, 18V, 650kHz ADAPTIVE COT STEP-DOWN CONVERTER Description Pin Assignments The AP65352 is an adaptive, constant on-time mode synchronous buck converter providing high efficiency, excellent transient response and high DC output accuracy for low-voltage regulation in digital ( Top View ) TVs and monitors. EN 1 8 VIN The constant-on-time control scheme handles wide input/output Exposed voltage ratios and provides low external component count. The Pad BS FB 2 7 internal proprietary circuit enables the device to adopt both low equivalent series resistance (ESR) output capacitors, such as VREG5 3 6 SW SP-CAP or POSCAP and ultra-low ESR ceramic capacitors. 9 SS 4 5 PGND The AP65352 also features programmable soft-start, UVLO, OTP, OVP and OCP to protect the circuit. SO-8EP AP65352 operates in continuous conduction mode (CCM) in light load conditions for better EMI performance. AP65353 and AP65355 are the options for light-load efficiency enhancement. This IC is available in SO-8EP package. Applications Features Fixed Frequency Emulated Constant On-Time Control Gaming Consoles Good Stability Independent of the Output Capacitor ESR Flat Screen TV Sets and Monitors Fast Load Transient Response Set-Top Boxes Synchronous Rectification: 90m Internal High-Side Switch and Distributed Power Systems 57m Internal Low-Side Switch Home Audio Wide Input Voltage Range: 4.5V to 18V Consumer Electronics Output Voltage Range: 0.76V to 6V Network Systems 3A Continuous Output Current FPGA, DSP and ASIC Supplies 650kHz Switching Frequency Green Electronics Built-in Overcurrent Limit Built-in Overvoltage Protection 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 AP65352 Typical Applications Circuit INPUT 7 V 8 IN BST L1 IN C5 12V OUTPUT 1.5 H 0.1F 6 V OUT ON 1 SW AP65352 1.05V EN OFF R1 2 8.25k C2 C1 FB R2 44F 20 F 3 4 22.1k VREG5 C4 SS 5 C3 GND 8.2nF 1F Figure 1 Typical Application Circuit 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. It can be safely connected to VIN directly 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 9 Connect the exposed thermal pad to GND on the PCB. 2 of 15 AP65352 December 2015 Diodes Incorporated www.diodes.com Document number: DS38482 Rev. 1 - 2