Diodes AP65550SP-EVM

Description

The AP65550 is an adaptive 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 monitors. Its constant-on-time control scheme handles wide input/output voltage ratios and requires a low external component count. The internal proprietary circuit allows the use of low equivalent series resistance (ESR) output capacitors, such as SP-CAP or POSCAP, and ultra-low ESR ceramic capacitors. The adaptive on-time control supports seamless transition between continuous conduction mode (CCM) at higher loads and discontinuous conduction mode (DCM) at lighter loads, maintaining high efficiency. The AP65550 also features programmable soft-start, UVLO, OTP, and OCP for circuit protection. This IC is available in an SO-8EP package.

Applications

• Gaming Consoles
• Flat Screen TV Sets and Monitors
• Set Top Boxes
• Distributed Power Systems
• Green Electronics
• Home Audio
• Consumer Electronics
• Network Systems
• FPGA, DSP and ASIC Supplies

Performance Specifications

Evaluation Board Overview

Quick Start Guide

The AP65550SP-EVM features a simple layout and provides access to necessary signals via test points. To evaluate the AP65550's performance, follow these steps:

1. Connect a power supply to the input terminals VIN and GND. Set VIN to 12V.
2. Connect the positive terminal of an electronic load to VOUT and the negative terminal to GND.
3. The EN pin has a 100K pull-up to VIN; no external supply is required for EN. To use the EN function, drive EN above 1.9V to start the converter and below 0.6V to stop it.
4. The evaluation board should now power up with a 1.05V output voltage.
5. Verify the output voltage is 1.05V (±1%) at the VOUT and GND terminals. This can also be measured with a multimeter.
6. Set the load to 5A using the electronic load. Observe the SW signal on an oscilloscope for stable operation and measure the switching frequency at the inductor test point.

Measurement/Performance Guidelines

1. When measuring output voltage ripple, use the shortest possible ground lengths on the oscilloscope probe to avoid injecting high-frequency noise.
2. For efficiency measurements, connect an ammeter in series with the input supply to measure input current and an electronic load to measure output current.

Evaluation Board Schematic

The evaluation board schematic shows the AP65550 DC/DC converter IC (U1) connected to input (IN, GND) and output (OUT, GND) terminals via connectors JH1-JH5. Key external components include inductor L1, capacitors C1-C9, resistors R1-R3, and a terminal turret T1 for test points. The EN pin is controlled via a pull-up resistor R3. The SW pin is connected to L1 and C6. The FB pin is connected to R1 and R2.

Bill of Materials

Important Notice

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A. Life support devices or systems are devices or systems which:

1. are intended to implant into the body, or
2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user.

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