DIODES AP64502SP-EVM: 40V, 5A Synchronous DC-DC Buck Converter with Internal Compensation

Description

The AP64502 is a 5A, synchronous buck converter with a wide input voltage range of 3.8V to 40V. The device fully integrates a 45mΩ highside power MOSFET and a 20mΩ low side power MOSFET to provide high-efficiency step-down DC-DC conversion. The AP64502 device is easily used by minimizing the external component count due to its adoption of peak current mode control along with its integrated loop compensation network. The AP64502 design is optimized for Electromagnetic Interference (EMI) reduction. The device has a proprietary gate driver scheme to resist switching node ringing without sacrificing MOSFET turn-on and turn-off times, which reduces high-frequency radiated EMI noise caused by MOSFET switching. The AP64502 also features Frequency Spread Spectrum (FSS) with a switching frequency jitter of ±6%, which reduces EMI by not allowing emitted energy to stay in any one frequency for a significant period of time. The device is available in an SO-8EP package.

Features

• VIN: 3.8V to 40V
• Output Voltage (VOUT): 0.8V to VIN
• 5A Continuous Output Current
• 0.8V ± 1% Reference Voltage
• 25µA Low Quiescent Current (Pulse Frequency Modulation)
• Adjustable Switching Frequency: 100kHz to 2.2MHz
• External Clock Synchronization: 100kHz to 2.2MHz
• Adjustable Soft-Start Time
• Up to 85% Efficiency at 5mA Light Load
• Proprietary Gate Driver Design for Best EMI Reduction
• Frequency Spread Spectrum (FSS) to Reduce EMI
• Low-Dropout (LDO) Mode
• Precision Enable Threshold to Adjust UVLO
• Protection Circuitry (Undervoltage Lockout (UVLO), Output Overvoltage Protection (OVP), Cycle-by-Cycle Peak Current Limit, Thermal Shutdown)
• Totally Lead-Free & Fully RoHS Compliant
• Halogen and Antimony Free. "Green" Device
• For automotive applications requiring specific change control (i.e. parts qualified to AEC-Q100/101/104/200, PPAP capable, and manufactured in IATF 16949 certified facilities), please contact DIODES INCORPORATED or your local Diodes representative. Visit: https://www.diodes.com/quality/product-definitions/

Applications

• Distributed Power Bus Supplies
• Power Tools and Laser Printers
• White Goods and Small Home Appliances
• Home Audio
• Network Systems
• Consumer Electronics
• General Purpose Point of Load

Typical Application Circuit

This diagram illustrates the standard configuration for the AP64502 synchronous DC-DC buck converter. It shows the IC's pins (VIN, BST, EN, RT/CLK, FB, SS, GND, SW) connected to external components such as an inductor (L1), capacitors (C1, C2, C3, C4, Css), and resistors (R1, R2) to form a functional buck converter circuit. The input is labeled VIN, and the output is labeled VOUT.

Absolute Maximum Ratings

Recommended Operating Conditions

Evaluation Board

The AP64502SP-EVM evaluation board provides a simple layout and access to signals through test points for evaluating the AP64502SP. It shows the placement of the AP64502 IC, various passive components, and connectors/test points. Key connections like VIN, GND, VOUT, and EN are clearly marked. Jumpers (JH6) for enabling/disabling the IC are also visible.

Quick Start Guide

To evaluate the performance of the AP64502SP, follow the procedure below:

1. Connect a power supply to the input terminals VIN and GND. Set VIN to 12V.
2. Connect the positive terminal of the electronic load to VOUT and negative terminal to GND.
3. For Enable, to enable the IC, place a jumper at JH6 to the "ON" position to connect the EN pin to VIN through a 100kΩ resistor, or leave it OPEN. Jump to the "OFF" position to disable the IC.
4. The evaluation board should now power up with a 5.0V output voltage.
5. Check for the proper output voltage of 5.0V (±1%) at the output terminals VOUT and GND. Measurement can also be done with a multimeter with the positive and negative leads between VOUT and GND.
6. Set the load to 5A through the electronic load. Check for the stable operation of the SW signal on the oscilloscope. Measure the switching frequency.

Measurement/Performance Guidelines

1. When measuring the output voltage ripple, maintain the shortest possible ground lengths on the oscilloscope probe. Long ground leads can erroneously inject high-frequency noise into the measured ripple.
2. For efficiency measurements, connect an ammeter in series with the input supply to measure the input current. Connect an electronic load to the output for output current.

Setting Output Voltage

Table 1 shows a list of recommended component selections for common output voltages.

Evaluation Board Schematic

This schematic details the circuit design of the AP64502SP-EVM. It shows the AP64502 IC connected to various passive components, including resistors, capacitors, and an inductor, to achieve a specific output voltage (e.g., 5.0V). Component values and connections are clearly indicated.

PCB Layouts

PCB Top Layout

This figure displays the component placement and copper trace routing on the top layer of the AP64502SP-EVM printed circuit board. It shows the arrangement of the IC, passive components, and signal paths.

PCB Bottom Layout

This figure illustrates the component placement and copper trace routing on the bottom layer of the AP64502SP-EVM printed circuit board, including ground planes and connections.

Bill of Materials for AP64502SP-EVM for VOUT=5V

Typical Performance Characteristics

Efficiency vs Output Current

This graph plots the efficiency of the DC-DC converter against the output current (IOUT) for different input voltage (VIN) and output voltage (VOUT) configurations, showing efficiency percentages across a range of output currents.

Load Transient, 3A to 5A

This graph displays the transient response of the output voltage (VOUT) and output current (IOUT) when the load is stepped from 3A to 5A. It illustrates the voltage overshoot/undershoot and recovery time.

Output Voltage Ripple, IOUT=5A

This graph shows the output voltage ripple, the switching node voltage (VSW), and the inductor current (IL) under a 5A load condition. It helps assess the noise and stability of the output.

Output Short Protection, IOUT=5A

This graph illustrates the behavior of the output voltage (VOUT), output current (IOUT), and switching node voltage (VSW) when a short circuit is applied to the output at a 5A load. It demonstrates the device's protection mechanisms.

Important Notice

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