EP53A8xQI Evaluation Board User Guide February 2012 Enpirion EP53A8xQI DC/DC Converter Module Evaluation Board Introduction Thank you for choosing Enpirion, the source for Ultra small foot print power converter products! This application note describes how to test the EP53A8LQI and the EP53A8HQI converters using the Enpirion EP53A8QI Eval Board shown in Fig. 1. In addition to this document you will also need the device datasheet for a thorough evaluation of the power converter module. The EP53A8xQI converters are a complete power system on chip or PowerSoC. * * * * * * * These devices are complete modules including magnetics, and require only ceramic input and output capacitors. The evaluation board is designed to offer a wide range of engineering evaluation capabilities. This includes the base configuration of a 0603 input capacitor and a 0805 output capacitor. Pads are available to add up to one additional input capacitor and one additional output capacitor for evaluation of performance over a wide range of input/output capacitor combinations. Pads are available to populate an external voltage divider (for feedback) if desired. The pads are labeled R1 and R2. Pads are also available for placing an optional feed-forward capacitor (labeled C9) across resistor R1 to modify the compensation. Jumpers are provided for easy programming of the following signals: o Enable o VS0-VS2 output voltage selection pins Test points are provided as well as clip leads for input and output connections The board comes with input decoupling, and input reverse polarity protection to safeguard the device from common setup mishaps. Page 1 of 7 www.enpirion.com EP53A8xQI Evaluation Board User Guide February 2012 Quick Start Guide STEP 1: Set the "ENABLE" jumper to the Disable Position. Set VS0, VS1 and VS2 pins for the desired output setting. Jumper CAUTION: The signal pins ENA, VS0, VS1 and VS2 must be Output Disabled connected to a logic "high", jumper to the left, or a logic "low", jumper to the right. If left floating the state is indeterminate. STEP 2: Connect a power supply to the input test points, TP8 (+) and TP5 (-) as indicated in Figure 1. The same test points can also be used to measure the input voltage. CAUTION: Be mindful of the polarity and the voltage magnitude. If VIN is greater than 6V, the board may get damaged. If the input voltage polarity is wrong, diode D1 will conduct, and draw excessive input current. STEP 3: Set the output voltage select pins for the desired output voltage. Refer to Tables 1 and 2 to determine the setting. CAUTION: The external resistor divider is not populated in the standard board configuration. Choosing the "EXT" option for the EP53A8LQI without the external resistors R1 and R2 will result in unpredictable behavior. "1" STEP 4: Connect the load to the output connectors TP7 (+) and TP6 (-), as indicated in Figure 1.The same test points are also used to measure the DC output voltage. CAUTION: Please note the polarity of the output terminals is opposite from the input terminals. STEP 5: Move the ENABLE jumper to the enabled position, and power up the board. The EP53A8xQI should now be operational. Page 2 of 7 www.enpirion.com "0" EP53A8xQI Evaluation Board User Guide February 2012 Figure 1. Evaluation Board Layout Output Voltage Select The EP53A8xQI utilizes a 3 pin output voltage select scheme. The output voltage is programmed by setting the VSx jumpers to either logic "1" or logic "0" as described in the Quick Start section. Tables 1 and 2 show the truth table for VOUT selection. There are seven preset output voltage levels for the EP53A8LQI, and eight preset levels for the EP53A8HQI. Table 1. EP53A8LQI Output Voltage Select Table VS2 0 0 0 0 1 1 1 1 VS1 0 0 1 1 0 0 1 1 VS0 0 1 0 1 0 1 0 1 VOUT 1.50 1.45 1.20 1.15 1.10 1.05 0.8 EXT Page 3 of 7 www.enpirion.com EP53A8xQI Evaluation Board User Guide February 2012 Table 2. EP53A8HQI Output Voltage Select Table VS2 0 0 0 0 1 1 1 1 VS1 0 0 1 1 0 0 1 1 VS0 0 1 0 1 0 1 0 1 VOUT 3.3 3.0 2.9 2.6 2.5 2.2 2.1 1.8 Test Recommendations Recommendations To guarantee measurement accuracy, the following precautions should be observed: 1. Make all input and output voltage measurements at the board using the test points provided. This will eliminate voltage drop across the line and load cables that can produce false readings. 2. Measure input and output current with series ammeters or accurate shunt resistors. This is especially important when measuring efficiency. 3. Use a low-loop-inductance probe tip as shown in Figure 2, and through-hole test point pair TP2 to measure the output voltage ripple to avoid noise coupling into the probe ground lead. For more accurate ripple measurement, please refer to Enpirion Output Ripple Measurement Methods Application Note. Figure 2: Balanced-impedance oscilloscope probe. Wrap bare wire around the ground shaft and bring the wire close to the probe tip. This minimizes probe loop inductance and stray noise pickup by the probe. Please contact techsupport@enpirion.com for any questions regarding this evaluation board. Page 4 of 7 www.enpirion.com EP53A8xQI Evaluation Board User Guide February 2012 Using the External Voltage Divider The EP53A8xQI evaluation board is designed to provide a great deal of flexibility in evaluating the performance of the Enpirion DC/DC module. Pre-tinned pads are provided to place 0805 sized resistors on the board to implement an external resistor divider for the EP53A8LQI to choose an output voltage other than one of the pre-set voltages available on the VID. See Figure 3 for the basic circuit. 100 Ohms VIN VSense AVIN ENABLE VS0 VS1 VS2 EP53A8L 4.7uF 0603 PVIN VOUT VOUT Ra 10F 0805 VFB Rb PGND AGND Figure 3. External divider schematic for the EP53A8LQI The output voltage is selected by the following formula: ) VOUT = 0.6V (1 + Ra Rb Ra must be chosen as 237k to maintain control loop stability. Then Rb is given as: R2 = 142.2 x10 3 VOUT - 0.6 The external voltage divider option is chosen by setting the jumpers VS0 - VS3 to logic "high". Page 5 of 7 www.enpirion.com EP53A8xQI Evaluation Board User Guide February 2012 Dynamically Adjustable Output The EP53A8xQI is designed to allow for dynamic switching between the predefined voltage levels by toggling the VID pins. The inter-voltage slew rate is optimized to prevent excess undershoot or overshoot as the output voltage levels transition. The slew rate is defined in the datasheet. This feature can be tested by connecting the VSx jumper center pins to logic driver to toggle between the various VOUT states. Evaluation Board Schematic VS1 VS2 17 18 19 U2 N/U 13 14 15 D1 S2A VS0 ENABLE 5 6 7 + 9 10 11 N/U Vin C8 47u J1 ASP12192002 1 2 3 Input Protection FB1 Vin 742792012 C10 0805 10u X5R 1 2 TP1 1 C1 N/U 0603 TP8 Vin 3 TP6 1 4 5 PVIN AVIN Enable Vf b VS0 Vsense VS1 AGND VS2 C10 0805 10u X5R 1206 C4 N/U 14 R1 N/U R3 100 0402 13 12 11 10 9 U1 EP53A8xQI NOTE: Input/Output capacitors must be X5R or X7R dielectric formulations. Do not use Y5V or any similar dielectric. 0805 1 TP7 Vout 2 1 0805 C9 N/U 15 PGND 7 6 PGND NC(SW)15 2 1 VOUT TP4 TP5 NC(SW)1 VOUT 1 TP3 8 R2 N/U 0805 Place TP3 and TP4 around 100 mil apart NC(SW)16 16 C2 4.7u 0603 X5R TP2 Schematic PCB Figure 4: EP53A8QI Evaluation Board Schematic Page 6 of 7 www.enpirion.com 03400 03401 EP53A8xQI Evaluation Board User Guide February 2012 Contact Information Enpirion, Inc. Perryville III 53 Frontage Road Suite 210 Hampton, NJ 08827 Tel.908.894.6000 Fax: 908-894-6090 Enpirion reserves the right to make changes in circuit design and/or specifications at any time without notice. Information furnished by Enpirion is believed to be accurate and reliable. Enpirion assumes no responsibility for its use or for infringement of patents or other third party rights, which may result from its use. Enpirion products are not authorized for use in nuclear control systems, as critical components in life support systems or equipment used in hazardous environment without the express written authority from Enpirion. Page 7 of 7 www.enpirion.com