Evaluation Board for the AAT2784 Three-Channel Step-down DC/DC Converter

Transcription

1 Introduction EVALUATION BOARD DATA SHEET EV57 The AAT2784 evaluation board provides a platform for test and evaluation of the AAT2784 -channel.8mhz step-down converter. The input voltages (V P ) of the three channels are connected, while their outputs are separate. The evaluation board demonstrates suggested size and placement of external components to achieve the best performance. The external components are limited and selected for small size to suit portable device applications, while the layout has been optimized to achieve high efficiency and low output noise with the TDFN4-6 package. The design operates across an input voltage range from 2.7V to 5.5V. The AAT2784 evaluation board provides an adjustable output voltage from V to V IN at 500mA maximum output current for channel and 2, and.5a for channel. Resistors R and R2 program the channel output to regulate at a voltage higher than 0.6V. Similarity, resistors R and R4 program the channel 2 output, and resistors R5 and R6 program the channel output. The suggested value for R2 and R4 is 29.4kΩ, and the suggested value for R6 is 59kΩ. There are three enable pins: EN, EN2, and EN, corresponding to the three channels. Connecting each EN to V IN will turn on the channel, while connecting EN to GND will disable that channel. Schematic and BOM LX LX2 LX VIN R7 0 L2 4.7µH C7 00pF R k VOUT2 EN EN2 EN C5 0µF C4 0µF C 0µF PGND2 LX2 6 FB2 VP_2 5 EN LX 4 EN2 PGND GND FB 2 VIN VP EN LX 0 FB PGND 9 U AAT2784 C8 0µF L.5µH C9 56pF R5 59K R6 59K L 4.7µH VOUT C0 0µF C 00pF R K R2 29.4K VOUT C2 4.7µF R4 29.4k C6 4.7µF PGND PGND Figure : AAT2784 Evaluation Board Schematic. Symbol Description U AAT2784 TDFN4-6 C,C4, C5, C8,C0 0μF 0V 0805 C2, C6 4.7μF 0V 0805 C,C7 00pF 0V 0402(Optional) C9 56pF 0V 0402 (Optional) L, L2 4.7μH L.5μH R, R KΩ 0V 0402 R2, R4 29.4kΩ 0V 0402 R5, R6 59kΩ 0V 0402 R7 0Ω Table : AAT2784 Evaluation Board Build of Materials (BOM). Skyworks Solutions, Inc. Phone [78] Fax [78] sales@skyworksinc.com A Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice. August 22, 202

2 EV57 Test Equipment. Unit under test (UUT) is the AAT2784 evaluation board. 2. One () Keithley 240 A source meter or equivalent.. Two (2) XT0-2 power supplies or equivalent. 4. Two (2) 0Ω, 00W variable resistors, or DC electronic loads. 5. Two (2) Fluke 89 multi-meters or equivalent. 6. A HP20A 5MHz function/ aarbitrary waveform generator; set to PWM setting. 7. Oscilloscope: Tektronix TDS054B or equivalent, three () Tek P69A oscilloscope voltage probes or equivalent, and one Tektronix TCP202 00V 5A peak current probe. 8. A network analyzer. 9. Miscellaneous test leads (banana plug to clip lead type is recommended). Setup and Test Test: Line and Load Regulation Figure 2: AAT2784 Evaluation Board Connection Diagram for Line and Load Regulation Measurement.. Configure the specified test equipment as shown in Figure Enable channel by connecting the jumper to the ON position.. Turn on the input power supply and set to desired input voltage based on the DC voltmeter. 4. Vary the output load from 0 to 500mA and vary the input voltage from 2.7V to 5.5V while monitoring the output voltage. V OUT - V NOMINAL 5. % Error = % Error = 00%, where V NOMINAL is the output voltage at 0mA output current. V NOMINAL 6. Repeat steps 2 through 5 for channels 2 and (for channel, vary the output load from 0 to.5a). 2 Skyworks Solutions, Inc. Phone [78] Fax [78] sales@skyworksinc.com A Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice. August 22, 202

3 EV57 Test: Line Transient Response. Configure the specified test equipment as shown in Figure. 2. Enable channel by connecting the jumper to the ON position.. Use the Line Transient Response Board to generate the step input voltage by setting the first power supplies to.6v and the second one to 4.2V. 4. Toggle the input voltage from.6v to 4.2 V by setting the magnitude of the PWM to 5V PP at 5MHz while monitoring the AC input voltage and the AC output voltage on the oscilloscope. 5. Repeat step 4 for different input voltage steps and over the range of V OUT and I LOAD. 6. Repeat the procedure for channels 2 and. Figure : AAT2784 Evaluation Board Connection Diagram for Line Transient Response Measurement. Skyworks Solutions, Inc. Phone [78] Fax [78] sales@skyworksinc.com A Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice. August 22, 202

4 EV57 Test: Load Transient Response. Configure the specified test equipment as shown in Figure Enable channel by connecting the jumper to the ON position.. Generate the step output load using a PWM (set V PP = 5V at 5KHz), a Power MOSFET, and adjustable resistors (R7, R8). 4. Adjust R7 and R8 to get the designed output current while monitoring the step output current and the output voltage response (AC coupling) on the oscilloscope. 5. Repeat step 4 for different output current steps and over the ranges of V IN and V OUT. 6. Repeat the same procedure for channel and then channel 2 with the step output load connected to V OUT, then to V OUT2. Figure 4: AAT2784 Evaluation Board Connection Diagram for Load Transient Response Measurement. 4 Skyworks Solutions, Inc. Phone [78] Fax [78] sales@skyworksinc.com A Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice. August 22, 202

5 EV57 Test: Quiescent Current vs. Input Voltage. Configure the specified test equipment as shown in Figure Enable channel by connecting the jumper to the ON position.. Remove the output loads (open circuit). 4. Replace the input power supply by Keithley 2400 A Source meter or equivalent. Set V SRC to the designed input voltage (V SRC = V OUT + V), and set I COM to 200µA. 5. Turn on the Keithley and read the compliance current (quiescent current). 6. Vary the input voltage V SRS = V OUT + V while monitoring the corresponding compliance current. Figure 5: AAT2784 Evaluation Board Connection Diagram for Quiescent Current. Skyworks Solutions, Inc. Phone [78] Fax [78] sales@skyworksinc.com A Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice. August 22, 202 5

6 EV57 Test: Startup using Enable. Configure the specified test equipment as shown in Figure Set the oscilloscope to single sequence, and trigger the rising edge of V OUT.. Turn on input power supply and toggle EN to ON position while monitoring the EN, V OUT, LX, and I LOAD on the oscilloscope. 4. Repeat steps 2 and for different I OUT, V IN, and V OUT. 5. Repeat the same procedure for channels 2 and. Test: Startup using V IN. Configure the specified test equipment as shown in Figure Enable channel by connecting the jumper to the ON position.. Set the oscilloscope to single sequence, and trigger the rising edge of V OUT. 4. Disconnect V IN from the input power supply. 5. Turn on the input power supply and toggle V IN by plugging the banana clip to the power supply while monitoring the V IN, V OUT, LX, and I LOAD on the oscilloscope. 6. Repeat steps through 5 for different I OUT, V IN, and V OUT. 7. Repeat the same procedure for channels 2 and. Figure 6: AAT2784 Evaluation Board Connection Diagram for Startup. 6 Skyworks Solutions, Inc. Phone [78] Fax [78] sales@skyworksinc.com A Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice. August 22, 202

7 EV57 Test: Efficiency vs. Output Current Figure 7: AAT2784 Evaluation Board Connection Diagram for Efficiency vs. Load Current Measurement.. Configure the specified test equipment as shown in Figure 7. Connect the voltmeter as closely as possible to the input and output capacitors (C4, C6) to avoid voltage drop along the trace resistance. 2. Enable channel 2 by connecting the jumper to the ON position.. Set Keithley load to 4 Wire Sensing Mode (the two sensing wires should connect as closely as possible to the output cap C6). 4. Vary the output current (I OUT = I SRC ) from -ma to -500mA and keep the input voltage the same while monitoring the input current (I IN ), and the output voltage (V OUT ). 5. Calculate the efficiency as the following equation: 00 (V OUT I OUT ) V IN I IN 6. Repeat steps 4 and 5 for different input and output voltages. 7. Repeat the same procedure for channels and. η = Skyworks Solutions, Inc. Phone [78] Fax [78] sales@skyworksinc.com A Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice. August 22, 202 7

8 EV57 Test: R DS(ON)H and R DS(ON)L Figure 8: AAT2784 Schematic Connection Diagram for R DS(ON) Measurement.. Configure the specified test equipment as shown in Figure Enable channel by connecting the jumper to the ON position, and connect the FB pin to GND to turn on the high side PMOS and turn off the low side NMOS.. Connect 4 wires (Force and Sense) from the Keithley power supply between VIN and LX node. The compliance set to V SRC = 40mV at Icomp = 00mA). 4. Power up and measure R DS(ON)H. V R SRC DS(ON)H = I COMP 5. To measure R DS(ON)L, repeat steps 2 through 4 with the FB pin connected to V CC (to turn on the low side NMOS) and connect the 4 wires (Force and Sense) from the Keithley power supply between LX and GND. V R SRC DS(ON)L = I COMP 6. Repeat the same procedure measurement for channels 2 and. 8 Skyworks Solutions, Inc. Phone [78] Fax [78] sales@skyworksinc.com A Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice. August 22, 202

9 EV57 Test: Gain and Phase Margin (Loop Gain) Analog Network Analyzer Oscilliscope SOURCE OUT CHA CHB Power Supply 5.00V 500mA L 4.7uH LOAD 00mA 50 VIN 5 VP_2 4 LX Isolation Transformer Broken Original Connection VOUT C4 0uF ON/OFF EN TDFN4-6 AAT2784 FB AGND 2 5 R K. R2 29.4K C 00pF (Optional) C 4.7uF PGND Figure 9: AAT2784 Schematic Connection Diagram for Gain and Phase Margin Measurement.. Break the feedback loop and insert a one-to-one isolation transformer between the broken original connection. A 50Ω resistor is connected in parallel with the secondary wire. 2. Configure the specified test equipment as shown in Figure 9.. Inject a signal from SOURCE OUT to the loop through the primary wire of the isolation transformer while monitoring the ratio of CHA and CHB on the network analyzer. 4. Set the output current to heavy load while monitoring the LX node of the converter on the Oscilloscope (to obtain a good result the converter must be in continuous PWM mode). 5. Sweep the frequency from SOURCE OUT of the network analyzer from 0Hz to MHz and adjust the magnitude of the injected signal (around 0mV to 00mV) in order to have a clean PWM waveform at the LX node. 6. Repeat the measurement for different V IN, V OUT, and I LOAD. 7. Repeat the same procedure for channels 2 and. Skyworks Solutions, Inc. Phone [78] Fax [78] sales@skyworksinc.com A Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice. August 22, 202 9

10 EV57 Printed Circuit Board Figure 0: Top Layer (not to scale). Figure : Bottom Layer (not to scale). Copyright 202 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. ( Skyworks ) products or services. These materials, including the information contained herein, are provided by Skyworks as a service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes. No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or information provided hereunder, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale. THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED AS IS WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. SKYWORKS DOES NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, IN- CLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or environmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper use or sale. Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of products outside of published parameters or design specifications. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifications or parameters. Skyworks, the Skyworks symbol, and Breakthrough Simplicity are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for identification purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at are incorporated by reference. 0 Skyworks Solutions, Inc. Phone [78] Fax [78] sales@skyworksinc.com A Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice. August 22, 202