PART OBSOLETE CONTACT US AP65251 2A, 16V, 500KHz ACOT SYNCHRONOUS DC/DC BUCK CONVERTER Description Pin Assignments The AP65251 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, set-top-boxes, and network systems. The constant-on-time control scheme handles wide input/output BST 1 6 SW voltage ratios and provides low external component count. The internal proprietary circuit enables the device to adopt ultra-low ESR ceramic capacitors. 2 VIN GND 5 The adaptive on-time control supports seamless transition between continuous conduction mode (CCM) at higher load conditions and discontinuous conduction mode (DCM) at lighter load conditions. FB 3 4 EN DCM allows AP65251 to maintain high efficiency at light load conditions. The AP65251 also features UVLO, OTP, and OCP to TSOT26 protect the circuit. This IC is available in TSOT23-6 package. Features Applications V 4.5V to 16V IN Gaming Consoles 2A Continuous Output Current, 2.5A Valley Flat Screen TV sets and Monitors Efficiency Up to 95% Set Top Boxes Automated Light Load improvement Distributed power systems V Adjustable to 0.6 to 6V OUT Home Audio 500kHz Switching Frequency Consumer electronics Internal Soft-Start Network Systems Enable Pin FPGA, DSP and ASIC Supplies Over current Protection (OCP) with Hiccup Green Electronics Thermal Protection 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 AP65251 Pin Descriptions Pin Pin Number Function Name TSOT26 High-Side Gate Drive Boost Input. BST supplies the drive for the high-side N-Channel MOSFET a 0.01F or BST 1 greater capacitor from SW to BST to power the high side switch. GND 2 Power Ground. Feedback sensing terminal for the output voltage. Connect this pin to the resistive divider of the output. See FB 3 Setting the Output Voltage. Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the regulator low to EN 4 turn it off. Attach to IN with a 100k pull up resistor for automatic startup. Power Input. VIN supplies the power to the IC, as well as the step-down converter switches. Drive VIN with a VIN 5 4.5V to 16V power source. Bypass VIN to GND with a suitably large capacitor to eliminate noise on the input to the IC. See Input Capacitor. Power Switching Output. SW is the switching node that supplies power to the output. Connect the output LC SW 6 filter from SW to the output load. Note that a capacitor is required from SW to BST to power the high-side switch. Functional Block Diagram Logic 4 Control UVLO EN Internal 5V Vcc 5 VIN Reference Regulator Se + Soft Start 0.6V 5V SS SW OCP Ref + 3 - FB Q S SS + 1 BST Min Off SW R Q Time Digital Control Logic On Time 6 One Shot SW Compute Frequency VIN Lock Loop 2 GND Figure 2. Functional Block Diagram 2 of 19 March 2021 AP65251 Diodes Incorporated www.diodes.com Document number: DS39921 Rev. 3 - 4 OBSOLETE PART DISCONTINUED