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Evaluation Board for ADP2118

EVAL-ADP2118

Rev. 0

Evaluation boards are only intended for device evaluation and not for production purposes.

Evaluation boards are supplied “as is” and without warranties of any kind, express, implied, or

statutory including, but not limited to, any implied warranty of merchantability or fitness for a

particular purpose. No license is granted by implication or otherwise under any patents or other

intellectual property by application or use of evaluation boards. Information furnished by Analog

Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog

Devices for its use, nor for any infringements of patents or other rights of third parties that may result

from its use. Analog Devices reserves the right to change devices or specifications at any time

without notice. Trademarks and registered trademarks are the property of their respective owners.

Evaluation boards are not authorized to be used in life support devices or systems.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

www.analog.com

GENERAL DESCRIPTION

The evaluation (demo) board provides an easy way to evaluate

the ADP2118 buck regulator. This data sheet describes how to

quickly set up the board to begin collecting performance data. Full

details on the ADP2118 are available in the ADP2118 data

sheet, which is available from Analog Devices, Inc., and should

be consulted in conjunction with this data sheet when using the

evaluation board.

This data sheet also describes the design process for the

ADP2118 buck regulator, including external component

selection, and how to obtain the best dynamic performance.

Thermal performance is described, which provides a current

derating reference for the user when the ADP2118 is operating

at different ambient temperatures.

PRODUCT DESCRIPTION

The ADP2118 is a low quiescent current, synchronous,

step-down, dc-to-dc regulator in a compact 4 mm × 4 mm

LFCSP_WQ package. It uses a current mode, constant fre-

quency pulse width modulation (PWM) control scheme for

excellent stability and transient response. Under light loads,

the ADP2118 can be configured to operate in pulse frequency

modulation (PFM) mode that reduces switching frequency to

save power.

The ADP2118 runs from input voltages of 2.3 V to 5.5 V. The

ADP2118 requires minimal external parts and provides a high

efficiency solution with its integrated power switch, synchron-

ous rectifier, and internal compensation. Other key features

include undervoltage lockout (UVLO), integrated soft start to

limit inrush current at startup, overvoltage protection (OVP),

overcurrent protection (OCP), and thermal shutdown (TSD).

ADP2118 EVALUATION BOARD

08742-001

Figure 1.

Summary of content (16 pages)

PAGE 1
Evaluation Board for ADP2118 EVAL-ADP2118 GENERAL DESCRIPTION PRODUCT DESCRIPTION The evaluation (demo) board provides an easy way to evaluate the ADP2118 buck regulator. This data sheet describes how to quickly set up the board to begin collecting performance data. Full details on the ADP2118 are available in the ADP2118 data sheet, which is available from Analog Devices, Inc., and should be consulted in conjunction with this data sheet when using the evaluation board.
PAGE 2
EVAL-ADP2118 TABLE OF CONTENTS General Description ......................................................................... 1 Performance Improvement ..........................................................7 Product Description ......................................................................... 1 Layout Guidelines..........................................................................9 ADP2118 Evaluation Board ............................................................
PAGE 3
EVAL-ADP2118 EVALUATION BOARD HARDWARE Output Load Connection POWERING UP THE EVALUATION BOARD The ADP2118 evaluation board is fully assembled and tested. Before applying power to the evaluation board, follow the setup procedures in this section. Jumper Settings Refer to Table 1 for selecting the jumper positions. Make sure the enable input, EN, is high.
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EVAL-ADP2118 MEASURING EVAULATION BOARD PERFORMANCE the positive (+) capacitor terminal. Set the oscilloscope to ac, 10 mV/division, 2 µs/division time base, and 20 MHz bandwidth. Measuring the Switching Waveform A standard oscilloscope probe has a long wire ground clip. For high frequency measurements, this ground clip picks up high frequency noise and injects it into the measured output ripple. Figure 2 shows an easy way to measure the output ripple properly.
PAGE 5
EVAL-ADP2118 ADP2118 DESIGN PROCESS For the ADP2118 design, X5R or X7R ceramic capacitors are recommended. When selecting the capacitor, the dc voltage rating and the rms current rating must be considered. EXTERNAL COMPONENT SELECTION This section describes how to select the external components for the ADP2118 application. Input Capacitor Selection The input decoupling capacitor is used to attenuate high frequency noise on the input.
PAGE 6
EVAL-ADP2118 Cross Frequency and Phase Margin with Different Output Filter and fS = 1.2 MHz Table 2. Cross Frequency and Phase Margin—VOUT = 1.0 V COUT (µF) 47 L (µH) 1 1.5 2.2 3.3 100 1 1.5 2.2 3.3 VIN fC (kHz) PM (Degrees) fC (kHz) PM (Degrees) fC (kHz) PM (Degrees) fC (kHz) PM (Degrees) fC (kHz) PM (Degrees) fC (kHz) PM (Degrees) fC (kHz) PM (Degrees) fC (kHz) PM (Degrees) 3.3 V 150 42 126 33 118 28 103 30 104 59 92 47 78 41 72 34 5V 150 39 133 31 124 27 112 25 105 55 91 50 63 42 77 35 Table 3.
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EVAL-ADP2118 Table 6. Cross Frequency and Phase Margin—VOUT = 1.8 V PERFORMANCE IMPROVEMENT COUT (µF) 47 The ADP2118 uses internal compensation for ease-of-use but limits optimization of the converter’s transient performance. This section describes how to use a feedforward capacitor in the feedback resistor divider to optimize the transient response. 1.5 2.2 3.3 100 1 1.5 2.2 3.
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EVAL-ADP2118 The feedforward capacitor can be used to improve dynamic response with the following conditions: VIN = 5 V, VOUT = 3.3 V, fS = 1.2 MHz, L = 1 µH, COUT = 100 µF, RTOP = 10 kΩ, RBOT = 2.21 kΩ. From Equation 8, Figure 5 and Figure 6 show the bode plot and load dynamic response without the CFF capacitor. Therefore, CFF = 1000 pF. C FF = 1 × 2 × π × 45 kHz (10 kΩ + 2.21 kΩ) = 831 pF (10 kΩ) × 2.21 kΩ 2 Figure 7 and Figure 8 show the bode plot and load dynamic response with CFF = 1000 pF.
PAGE 9
EVAL-ADP2118 LAYOUT GUIDELINES The input decoupling capacitor (CIN) should be as close as possible to the PVIN and PGND pins. Make the loop composed of PVIN, PGND, and CIN as small as possible. The VIN filter needs to be placed as close as possible to the VIN pin. A ground plane is recommended to minimize noise and maximize heat dissipation. If a ground plane layer is not used, the analog ground (GND) and the power ground (PGND) should be separated and tied together at the output capacitor terminal.
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EVAL-ADP2118 THERMAL PERFORMANCE 3.5 3.0 3.0 2.0 1.5 1.0 VIN = 2.3V 0.5 VIN = 5.0V 0 20 40 60 80 100 AMBIENT TEMPERATURE (°C) 1.0 0 –40 3.0 3.0 MAXIMUM OUTPUT CURRENT (A) 3.5 2.5 2.0 1.5 1.0 VIN = 2.3V 0 –40 VIN = 5.0V 0 20 40 60 80 100 AMBIENT TEMPERATURE (°C) Figure 10. Thermal Derating Performance at 110°C Case Temperature, VOUT = 1.5 V, fS = 1.2 MHz –20 0 20 40 60 1.5 1.0 0 –40 VIN = 2.3V MAXIMUM OUTPUT CURRENT (A) 1.0 VIN = 5.
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EVAL-ADP2118 EVALUATION BOARD SCHEMATIC AND ARTWORK T1 PVIN 1 1 J1 POK 10 R1 3 2 1 J5 EN J6 GND 13 PGND PGND 1 R5 NC 9 T4 SW 1 2 1uH 10 8 7 5 1 VIN PVIN 15 14 SW J11 TRK J13 EN SW FB PGND TRK GND 1 4 ADP2118 L1 11 C6 NC C3 C4 100uF/6.
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EVAL-ADP2118 08742-016 08742-018 EVALUATION BOARD LAYOUT Figure 16.Top Layer Figure 17. 3rd Layer Rev. 0 | Page 12 of 16 08742-019 08742-017 Figure 18. 2nd Layer Figure 19.
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Figure 20. Silkscreen Top 08742-021 08742-020 EVAL-ADP2118 Figure 21. Evaluation Board Rev.
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EVAL-ADP2118 ORDERING INFORMATION BILL OF MATERIALS Table 8. Qty 1 1 1 1 1 1 1 Reference Designator C1 C2 C3 C4 C5 C6 L1 Part Number GRM188F51H104ZA01 GRM32ER60J107ME20 Optional GRM32ER60J107ME20 Optional Optional MSS1038-102NL Type Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Inductor 1 1 1 1 1 1 R1 R2 R3 R4 R5 U1 CRCW060310R0FKEA CRCW060310K0JKTA CRCW060310K0FKEA CRCW060310K0FKEA Optional ADP2118 Resistor Resistor Resistor Resistor Resistor IC Description 0.1 µF, 50 V 100 µF, 6.
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EVAL-ADP2118 NOTES Rev.