DIODES AP64351QSP-EVM 3.5A Synchronous Buck Converter Owner’s Manual

AP64351QSP-EVM
AUTOMOTIVE-COMPLIANT, 40V, 3.5A SYNCHRONOUS
BUCK WITH PROGRAMMABLE SOFT-START TIME

DESCRIPTION

The AP64351Q is an automotive-compliant, 3.5A, synchronous buck converter with a wide input voltage range of 3.8V to 40V. The device fully integrates a 75mΩ high-side power MOSFET and a 45mΩ low-side power MOSFET to provide high- efficiency step-down DC-DC conversion.
The AP64351Q device is easily used by minimizing the external component count due to its adoption of peak current mode control.
The AP64351Q 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 AP64351Q 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

**

• AEC-Q100 Qualified with the Following Results

• Device Temperature Grade 1: -40°C to +125°C TA Range

•  Device HBM ESD Classification Level H2

• Device CDM ESD Classification Level C5

• VIN: 3.8V to 40V

• 3.5A Continuous Output Current

• 0.8V ±1% Reference Voltage

• 22µA Ultralow Quiescent Current (Pulse Frequency Modulation)

• 570kHz Switching Frequency

• Programmable 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
  o Undervoltage Lockout (UVLO)
  o Output Overvoltage Protection (OVP)
  o Cycle-by-Cycle Peak Current Limit
  o Thermal Shutdown

• Totally Lead-Free & Fully RoHS Compliant

• Halogen and Antimony Free. “Green” Device

APPLCATIONS

• 12V Automotive Power Systems
• Automotive Infotainment
• Automotive Instrument Clusters
• Automotive Telematics
• Advanced Driver Assistance Systems

TYPICAL APPLICATIONS CIRCUIT

-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
VSS| Soft-Start 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

QUICK START GUIDE
The AP64351QSP-EVM has a simple layout and allows access to the appropriate signals through test points. To evaluate the performance of the AP64351QSP, 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, place a jumper at JH6 to “ON” position to connect EN pin to VIN through 100KΩ resistor to enable IC. 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 3.5A 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.

VOUT| R1| R2| L1| R7| C7| C1, C2| C5, C6
---|---|---|---|---|---|---|---
1.2V| 4.99KΩ| 10KΩ| 3.3µH| 3.32KΩ| 3.3nF| 2×10µF| 2×22µF
1.5V| 8.66KΩ| 10KΩ| 3.3µH| 4.22KΩ| 3.3nF| 2×10µF| 2×22µF
1.8V| 12.4KΩ| 10KΩ| 3.3µH| 4.99KΩ| 3.3nF| 2×10µF| 2×22µF
2.5V| 21.5KΩ| 10KΩ| 4.7µH| 6.98KΩ| 3.3nF| 2×10µF| 2×22µF
3.3V| 31.6KΩ| 10KΩ| 4.7µH| 9.31KΩ| 3.3nF| 2×10µF| 2×22µF
5.0V| 52.3KΩ| 10KΩ| 6.8µH| 14KΩ| 3.3nF| 2×10µF| 2×22µF
12V| 140KΩ| 10KΩ| 10µH| 33.2KΩ| 3.3nF| 2×10µF| 2×22µF

Table 1. Common Output Voltages

EVALUATION BOARD SCHEMATIC

PCB TOP LAYOUT
PCB BOTTOM LAYOUT

AUTOMOTIVE BILL OF MATERIALS for AP64351QSP-EVM @Vout=5V

**Ref| ****Value| ****Description| ****Qty| ****Size| ****Vendor Name| ****Manufacturer PN
---|---|---|---|---|---|---
C1, C2| 10µF| Ceramic Capacitor, 50V| 2| 1206| TDK| CGA5L1X7R1H106K160AC
C3, C4, C9| 0.1µF| Ceramic Capacitor, 50V| 3| 0603| TDK| CGA3E3X8R1H104K080AB
C5, C6| 22µF| Ceramic Capacitor, 16V| 2| 1210| TDK| CGA6P1X8L1C226M250AC
C7| 3.3nF| Ceramic Capacitor, 50V| 1| 0603| TDK| CGA3E2NP01H332J080AA
** C8| 10nF| Ceramic Capacitor, 50V| 1| 0603| TDK| CGA3E2NP01H103J080AA
R1| 52.3KΩ| SMD Resistor, 1%| 1| 0603| Panasonic| ERJ-3EKF5232V
R2| 10KΩ| SMD Resistor, 1%| 1| 0603| Panasonic| ERJ-3EKF1002V
R3, R8| 0Ω| RES SMD| 2| 0603| Panasonic| ERJ-3GEY0R00V
R4| 100KΩ| RES SMD| 1| 0603| Panasonic| ERJ-3RBD104V
R7| 14KΩ| RES SMD| 1| 0603| Panasonic| ERJ-3EKF1402V
L1| 6.8µH| DCR=18.5mΩ, Ir=8.9A| 1| 10.0×10.7x 4mm| Panasonic| ETQP4M6R8KVC
JH6| | PCB Header, 36 POS| 1| 1X3| Amphenol| 78511-136HLF
JH13, JH14, JH15, JH16| 1598| Terminal Turret Triple 0.094″ L (Test Points)| 4| Through-Hole| Keystone Electronics| 1598-2
U1| AP64351Q| Sync DC-DC Buck Converter| 1| SO-8EP| Diodes Inc| AP64351QSP

TYPICAL PERFORMANCE CHARACTERISTICS IMPORTANT NOTICE

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