EN5337QI Evaluation Board Application Note August 2008 V1.0 Enpirion EN5337QI 3A DCDC Converter w/Integrated Inductor Evaluation Board Introduction Thank you for choosing Enpirion, the source for Ultra small foot print power converter products The EN5337QI features integrated inductor, power MOSFETS, Controller, a bulk of the compensation Network, and protection circuitry against system faults. This level of integration delivers a substantial reduction in footprint and part count over competing solutions. However, the evaluation board is not optimized for minimum footprint rather for engineering ease of evaluation through programming options, clip leads, test points etc. The EN5337QI features a customer programmable output voltage by means of a resistor divider. The resistor divider allows the user to set the output voltage to any value within the range 0.75V to (V -V ). The IN DROPOUT evaluation board, as shipped is populated with a 4 resistor divider option. The upper resistor is fixed (150k) and has a phase lead capacitor (27pF) in parallel. One of 4 lower resistors is selected with the jumper option for output voltages of 1.0V, 1.2V, 1.55V and 2.5V. We recommend the user to retain the upper resistor and capacitor values and change only the lower resistor to program the output to the desired voltage. This device has no over-voltage protection feature. We strongly recommend the customer to ensure the feedback loop is truly closed before powering up the device especially if the load can not withstand the input voltage. The input capacitor is a 10V rated 2X10uF X5R MLCC. The output filter section is populated with 1 x 10uF and 1 x 47uF, 6.3V rated X5R MLC capacitors to achieve the required ~50uF of output capacitance. This combination of output caps yields very low ESR and hence low output ripple. A single 47uF capacitor may be substituted if minimizing footprint is important. The Soft-start capacitor is a small 10V rated 15nF X5R MLCC. Pads are available to add an additional input capacitor and there are a total of 5 pads to accommodate the output capacitor(s). This allows for evaluation of performance over a wide range of input/output capacitor combinations. Page 1 of 9 EN5337QI Evaluation Board Application Note August 2008 V1.0 Clip on terminals are provided for ENA, SS, POK, VIN and VOUT. Other test points are also made available. A jumper is provided for controlling the Enable signal. Enable may also be controlled using an external switching source by removing the jumper and applying the enable signal to the middle pin and ground. A jumper is also provided to connect a resistor load to POK pin. This jumper is especially useful to measure the disable current and eliminates having to subtract the current drawn by this load. Foot print is also provided for a SMA connector to SYNC input. The SYNC input allows the device switching to be phase locked to an external clock signal. This external clock synchronization allows for moving any offending beat frequency to be moved out-of-band. A swept frequency applied to this pin results in spread spectrum operation and reduces the peaks in the noise spectrum of emitted EMI. Numerous test points are provided as well as banana plugs for input and output connections. Input / Output ripple are best measured at test points J12 / J11. The switching waveform may be viewed between test points labeled SW and GND. The board comes with input decoupling and reverse polarity protection to guard the device against common setup mishaps. Page 2 of 9