NOT RECOMMENDED FOR NEW DESIGN CONTACT US AP65550 5A, 18V, 650kHz ADAPTIVE COT STEP-DOWN CONVERTER Description Pin Assignments The AP65550 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 2 7 BST FB The constant-on-time control scheme handles wide input/output voltage ratios and provides low external component count. The PGND VREG5 3 6 SW internal proprietary circuit enables the device to adopt both low 9 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 adaptive, on-time control supports seamless transition between continuous conduction mode (CCM) at higher load conditions and ( Top View ) discontinuous conduction mode (DCM) at lighter load conditions. 1 10 EN VIN DCM allows AP65550 to maintain high efficiency at light load FB 2 9 VIN conditions. The AP65550 also features programmable soft-start, Exposed 3 Pad 8 SW UVLO, OTP and OCP to protect the circuit. VREG5 7 BST 4 SW 11 This regulator is available in SO-8EP and U-DFN3030-10 packages. PGND 5 6 GND SS U-DFN3030-10 Applications Features Applications Gaming Consoles Fixed Frequency Emulated Constant On-Time Control Flat Screen TV Sets and Monitors Good Stability Independent of the Output Capacitor ESR Set-Top Boxes Fast Load Transient Response Distributed Power Systems Synchronous Rectification: 65m Internal High-Side Switch and Home Audio 36m Internal Low-Side Switch Consumer Electronics Wide Input Voltage Range: 4.5V to 18V Network Systems Output Voltage Range: 0.765V to 6V FPGA, DSP and ASIC Supplies 5A Continuous Output Current Green Electronics 650kHz Switching Frequency Built-in Over Current 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) & 2015/863/EU (RoHS 3) compliant. 2. See AP65550 Typical Applications Circuit INPUT V VIN IN BST L1 C5 12V OUTPUT 1.5 H 0.1F V OUT ON SW EN AP65550 1.05V R1 OFF 8.25k C2 C1 FB 44F 20 F R2 VREG5 SS C4 C3 22.1k PGND 8.2nF 1F Figure 1 Typical Application Circuit Pin Descriptions Pin Number Pin Function Name SO-8EP U-DFN3030-10 Enable input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on EN 1 1 the regulator, drive it low to turn off. Pull up with 100k resistor to VIN for automatic startup. Feedback Input. FB senses the output voltage and regulates it. Drive FB with a resistive FB 2 2 voltage divider connected to it from the output voltage. Internal power supply output pin to connect an additional capacitor. Connect a 1F (typical) VREG5 3 3 capacitor as close as possible to the VREG5 and PGND. 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 SS 4 5 GND to set the soft-start period. GND 5 6 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. SW 6 7, 8 Connect the output LC filter from SW to the output load. Note that a capacitor is required from SW to BST to power the high-side switch. Bootstrap pin. A bootstrap capacitor is connected between the BST pin and SW pin. The BST 7 4 voltage across the bootstrap 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 PGND pin to VIN 8 9, 10 keep the DC input voltage constant. 9 11 Power ground. Exposed pad must be connected to a single point GND and as large of PGND (Exposed (Exposed Pad) PGND plane as possible for maximum thermal performance. Pad) 2 of 16 AP65550 February 2020 Diodes Incorporated www.diodes.com Document number: DS36336 Rev. 7 - 3