NOT RECOMMENDED FOR NEW DESIGN CONTACT US AP65450 4A, 18V, 650kHz ADAPTIVE COT STEP-DOWN CONVERTER Description Pin Assignments The AP65450 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 TV and monitor. ( Top View ) The constant-on-time control scheme handles wide input/output voltage ratios and provides low external component count. The EN 1 8 VIN internal proprietary circuit enables the device to adopt both low equivalent series resistance (ESR) output capacitors, such as SP- 2 7 BS CAP or POSCAP and ultra-low ESR ceramic capacitors. FB The adaptive on-time control supports seamless transition between VREG5 3 6 SW continuous conduction mode (CCM) at higher load conditions and discontinuous conduction mode (DCM) at lighter load conditions. SS 4 5 GND DCM allows AP65450 to maintain high efficiency at light load conditions. The AP65450 also features programmable soft-start, UVLO, OTP and OCP to protect the circuit. SO-8EP This IC is available in SO-8EP package. Features Applications 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: 65m Internal High-side Switch Distributed power systems and 36m 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 4A Continuous Output Current FPGA, DSP and ASIC Supplies 650kHz Switching Frequency Green Electronics 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 AP65450 Typical Applications Circuit INPUT 7 V IN 8 BS L1 VIN C5 12V OUTPUT 1.5 H 0.1F 6 V OUT ON 1 SW AP65450 1.05V EN OFF R1 2 8.25k C2 C1 FB R2 44F 20 F 3 4 22.1k C4 VREG5 SS 5 C3 GND 8.2nF 1F Figure 1. Typical Application Circuit Pin Descriptions Pin Number Pin 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. 2 of 15 AP65450 February 2020 Diodes Incorporated www.diodes.com Document number: DS37135 Rev. 4 - 3