DIODES AP64500SP-EVM Low IQ Synchronous Buck With Programmable Frequency User Guide

DIODES AP64500SP-EVM Low IQ Synchronous Buck With Programmable Frequency User Guide

DESCRIPTION

The AP64500 is 5A, synchronous buck converter with a wide input voltage range of 3.8V to 40V. The device fully integrates a 45mΩ high-side power MOSFET and a 20mΩ low-side power MOSFET to provide high-efficiency stepdown DC-DC conversion.

The AP64500 device is easily used by minimizing the external component count due to its adoption of peak current mode control.

The AP64500 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. AP64500 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 a SO-8EP package.

• 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

APPLICATIONS

• 5V, 12V, and 24V 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 APPLICATIONS CIRCUIT

Figure 1. Typical Application Circuit

ABSOLUTE MAXIMUM RATINGS

-0.3 to +45.0 (400ms)
VBST| Bootstrap Pin Voltage| VSW – 0.3 to VSW + 6.0| V
VEN| Enable/UVLO Pin Voltage| -0.3 to +42.0| V
VRT/CLK| RT/CLK Pin Voltage| -0.3 to +6.0| V
VFB| Feedback Voltage| -0.3V to +6.0| V
VCOMP| Compensation Pin Voltage| -0.3 to +6.0| V
VSW| Switch Node Voltage| -0.3 to VIN + 0.3 (DC)| V
-2.5 to VIN + 2.0 (20ns)
TJ| Junction Temperature| +160| °C
TL| Lead Temperature| +260| °C

RECOMMENDED OPERATING CONDITIONS

EVALUATION BOARD

Figure 2. AP64500SP-EVM

QUICK START GUIDE

The AP64500SP-EVM has a simple layout and allows access to the appropriate signals through test points. To evaluate the performance of the AP64500SP, 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 IC, place a jumper at JH6 to “ON” position to connect EN pin to VIN through 100KΩ resistor or leave it OPEN. Jump to “OFF” position to disable 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.

Table 1. Common Output Voltages

VOUT| R1| R2| L1| R7| C7| C1, C2| C5, C6, C13
---|---|---|---|---|---|---|---
1.2V| 4.99KΩ| 10KΩ| 1.5µH| 3.74KΩ| 2.7nF| 2×10µF| 3×22µF
1.5V| 8.66KΩ| 10KΩ| 2.2µH| 4.75KΩ| 2.7nF| 2×10µF| 3×22µF
1.8V| 12.4KΩ| 10KΩ| 2.2µH| 5.62KΩ| 2.7nF| 2×10µF| 3×22µF
2.5V| 21.5KΩ| 10KΩ| 3.3µH| 7.87KΩ| 2.7nF| 2×10µF| 3×22µF
3.3V| 31.6KΩ| 10KΩ| 3.3µH| 10.5KΩ| 2.7nF| 2×10µF| 3×22µF
5.0V| 52.3KΩ| 10KΩ| 3.6µH| 15.8KΩ| 2.7nF| 2×10µF| 3×22µF
12V| 140KΩ| 10KΩ| 10µH| 37.4KΩ| 2.7nF| 2×10µF| 3×22µF

EVALUATION BOARD SCHEMATIC

Figure 3. AP64500SP-EVM Schematic

PCB TOP LAYOUT

Figure 4. AP64500SP-EVM – Top Layer

PCB BOTTOM LAYOUT

Figure 5. AP64500SP-EVM – Bottom Layer

BILL OF MATERIALS for AP64500SP-EVM for VOUT=5V

**Ref| ****Value| ****Description| ****Qty| ****Size| ****Vendor Name| ****Manufacturer PN| PCB Layer
---|---|---|---|---|---|---|---
** C1, C2| 10µF| Ceramic Capacitor,50V, X7R, 10%| 2| 1206| Samsung| CL31B106KBHNNNE| Top
C3, C4,C9| 0.1µF| Ceramic Capacitor,50V, X7R, 10%| 2| 0603| WurthElectronics| 885012206095| Top
C5, C6,C13| 22µF| Ceramic Capacitor,16V, X7R| 3| 1210| Samsung| CL32B226KOJNNNE| Top
C7| 2.7nF| Ceramic Capacitor, 50V, X7R| 1| 0603| Murata| GRM1885C1H272JA01D| Top
R1| 52.3KΩ| SMD Resistor, 1%| 1| 0603| Panasonic| ERJ-3EKF5232V| Top
R2| 10KΩ| SMD Resistor, 1%| 1| 0603| Panasonic| ERJ-3EKF1002V| Top
**** R3| **** 0Ω| RES SMD 1% 1/10W| **** 1| **** 0603| **** Vishay| **** CRCW06030000Z0EAC| **** Top
**** R4| **** 100KΩ| RES SMD 1% 1/10W| **** 1| **** 0603| **** Vishay| **** CRCW0603100KFKEA| **** Top
R6| 200KΩ| RES SMD 1% 1/10W| 1| 0603| Yageo| RC0603FR-07200KL| Top
R7| 15.8KΩ| RES SMD 1% 1/10W| 1| 0603| Bourns Inc| CR0603-FX-1582ELF| Top
L1| 3.6µH| DCR=12.2mΩ, Ir=8.2A| 1| 10.2×10.2×4.5mm| Wurth Electronics| 7447797360| Top
JH6| | PCB Header, 40POS| 1| 1X3| 3M| 2340-6111TG| Top
VIN,VOUT, GNDx2| 1598| Terminal TurretTriple 0.094″ L (Test Points)| 4| Through- Hole| Keystone Electronics| 1598-2| Top
U1| AP64500| Sync DC-DC Converter| 1| SO-8EP| Diodes Incorporated (Diodes)| AP64500SP| Top

TYPICAL PERFORMANCE CHARACTERISTICS

Figure 6. Efficiency vs. Output Current

Figure 7. Load Transient 3A to 5A

Figure 8. Output Voltage Ripple, IOUT=5A

Figure 9. Output Short Protection, IOUT=5A

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