ISL85403EVAL1Z

USERS MANUAL ISL85403EVAL1Z UG024 Rev 0.00 Evaluation Board March 4, 2015 Description Key Features The ISL85403EVAL1Z board allows quick evaluation of the Flexible design ISL85403 in the 2-stage boost-buck and the synchronous buck V range of 4V to 40V IN configurations. It is a cost effective solution for the low-power, Convenient power connection wide input voltage range point-of-load application where both stepping up and stepping down voltage capabilities are required. References ISL85403 Datasheet Specifications The design specifications of the ISL85403EVAL1Z are shown in Table 1. Ordering Information TABLE 1. SPECIFICATIONS PART NUMBER DESCRIPTION PARAMETERS VALUES ISL85403EVAL1Z ISL85403 Evaluation Board, 2-stage boost-buck configuration 5V output Input Voltage (V )4V to 40V IN Output Voltage (V)5.0V OUT Max. Output Current (IOUT MAX) 2.5A Switching Frequency 500kHz Output Ripple 40mV FIGURE 1. TOP VIEW FIGURE 2. BOTTOM VIEW UG024 Rev 0.00 Page 1 of 11 March 4, 2015ISL85403EVAL1Z 2. Connect the power supply to the input terminals VBAT(J5) and Functional Description GND (J6). Connect the load terminals to the output VOUT+ The ISL85403 is a flexible switching regulator with an integrated (J10) and GND (J11). Make sure the setup is correct prior to applying any power or load to the board. 127m high-side MOSFET. It can be used as a synchronous buck converter, a 2-stage boost-buck converter or a noninverting 3. Adjust the power supply to 4V to 40V and turn it on. buck-boost converter. 4. Verify the output voltage is 5V and use oscilloscope to monitor The ISL85403EVAL1Z board demonstrates the operations of the the phase node waveforms. ISL85403 in the 2-stage boost-buck configuration. It also allows the user to easily modify the board into synchronous buck Board Modification for the configuration. The ISL85403EVAL1Z board is shown in Figures 1 Synchronous Buck Configuration and 2. The following steps provide guidelines to modify the The schematic is shown on page 4, bill of materials on page 5, ISL85403EVAL1Z into the synchronous buck configuration. and PCB layers for reference start on page 9. Figures 6 through 25 show performance data taken from the evaluation board. 1. Populate Q1 with the desired MOSFET. 2. Remove the jumper on J16 to disconnect the boost power Operating Range stage from the buck power stage For the 2-stage boost-buck configuration, the board input voltage 3. Populate R with 0 resistor and R with 4.7kresistor. 32 5 range is 4V to 40V. The output voltage is set to 5V by default and 4. Remove resistor R . 22 and R , as can be changed by voltage feedback resistors R 3 4 5. Short EXT BOOST pin to ground by removing R and 31 shown in Equation 1: replacing R with 0 resistor 30 V ref (EQ. 1) R = R -------------------------------- 4 3 6. If V switch-over feature is needed, remove the resistors R V v CC 28 OUT ref and R and populate R with 0 resistor. 29 6 NOTE: In order to change to a higher output voltage, the output capacitors 7. Removing the diode D1 is optional. Generally the SS3P6 will have to be changed for the higher voltage rating. help reducing losses associated with the MOSFETs body The board is set to a default frequency of 500kHz (FS pin/R is 8 diode, yielding better efficiency. open). The switching frequency can be programmed to other 1. Connect the power supply to the input terminals VIN+ (J8) and values by a resistor at R . Refer to the ISL85403 datasheet for 8 GND (J9). Connect the load terminals to the output the resistor value and the switching frequency. The switching VOUT+ (J10) and GND (J11). Make sure the setup is correct frequency can also be synchronized to external clock by prior to applying any power or load to the board. connecting the external clock to the SYNC terminal (J13). 2. Adjust the power supply to 8V to 40V and turn it on. Quick Test Setup - LOAD + + - + - A - LOAD + A FIGURE 4. ISL85403EVAL1Z IN THE SYNCHRONOUS BUCK CONFIGURATION BOARD SET UP FIGURE 3. ISL85403EVAL1Z BOARD SETUP 1. Make sure that shunt is installed on J16. UG024 Rev 0.00 Page 2 of 11 March 4, 2015