Click here for production status of specific part numbers. Evaluates: MAX17673 5V, 3.3V, 1.8V MAX17673EVKIT Evaluation Kit Output Applications General Description Features The MAX17673EVKIT evaluation kit (EV kit) provides a Three Synchronous DC-DC Buck Converter Outputs proven design to evaluate the MAX17673 60V, 1.5A high from a Single HV input efficiency, synchronous buck converter with integrated, Wide 7V to 60V Input Range for HV Converter dual 5V, 1A buck converters. The EV kit is preset for 5V Optional External Supply Input connections for LV output at a load current of up to 1.5A from the high volt- Converters (4.5V to 5.5V for LVA, and 2.7V to 5.5V age (HV) buck converter, and 3.3V and 1.8V outputs at for LVB) load currents up to 1A each from the low voltage (LV) Programmed 5V/1.5A Output for HV Buck and buck converters. The HV buck converter is programmed to operate at 400kHz, and the LV buck converters are 3.3V/1A & 1.8V/1A Output for LV Buck Converters programmed to operate at 2MHz, for optimum efficiency 400KHz Switching Frequency for HV Buck and 2MHz and component sizes. The output of the HV buck con- Switching Frequency for LV Buck verter is connected to the input of the LV buck converters. High 93% Efficiency (V = 12V, VOUT = 5V at INH The EV kit features adjustable input undervoltage lock- 0.45A) for HV Buck. 94% Efficiency for LV Buck out and soft-start for the HV buck converter, and Power Enable/UVLO Input, Resistor-Programmable UVLO OK (POK ) signals for all three buck converters. The Threshold for HV Buck Converter MAX17673 IC data sheet provides a complete descrip- tion of the part that should be read in conjunction with this Programmed 1ms Soft-Start Time for HV Buck data sheet prior to operating the EV kit. Converter, and Internal 4096 Clock Cycles Soft-Start Time for LV Buck Converters Selectable PWM and PFM Modes of Operation Independent Power OK (POK ) Outputs for the Three Converters Overcurrent and Overtemperature Protection Ordering Information appears at end of data sheet. Low-Profile, Surface-Mount Components Proven PCB Layout Fully Assembled and Tested EV kit specifications, settings, benefits and features are highlighted. For full MAX17673 features, benefits and parameters, refer to the MAX17673 data sheet. 319-1002782 Rev 0 11/18Evaluates: MAX17673 5V, 3.3V, 1.8V MAX17673EVKIT Evaluation Kit Output Applications to operate the MAX17673 in PWM mode or PFM mode, Quick Start based on light-load performance requirements. Jumpers Required Equipment JU2 and JU3 connect the LV Buck Converter inputs to One MAX17673EVKIT EV kit either the HV buck output (VOUT), or to external INA and INB Inputs. POKH, POKA, or POKB pads are available for One 0V to 60V DC, 3A power supply monitoring the status of output voltages. One load resistor capable of sinking up to 0.3A at 5V On the bottom layer of the EV Kit, additional footprints Two load resistors capable of sinking up to 1A at for optional components are included to ease board 3.3V and 1.8V, respectively modification for different input and output configurations. Digital multimeters (DMM) Placeholders are also available on the bottom layer for placement of EMI filter components. Equipment Setup and Procedure The EV kit is fully assembled and tested. Follow the steps Setting Switching Frequency below to verify board operation: Selection of the switching frequency must consider the input voltage range, desired output voltages, tON(MIN) Caution: Do not turn on power supply until all con- of the three buck converters in MAX17673, and ambient nections are completed. temperature. To optimize efficiency and component size, a 1) Set the input power supply at a voltage between 7V 400kHz switching frequency is chosen for the 5V HV buck and 60V. Disable the power supply. converter, and 2MHz switching frequency is chosen for the 2) Connect the positive terminal of the power supply to 3.3V and 1.8V LV buck converters. Resistor R5 connected the VIN EMI pad, and the negative terminal to the between the RT and SGND plane, programs the desired nearest PGND pad on the EV Kit. The output of the switching frequency of LV buck converters. The HV buck HV buck converter (VOUT) is connected to the LV converter switching frequency is derived as a fraction of buck input using Jumper JU2 and JU3 (see Table 1 the LV buck converters switching frequency by placing for details). Resistor R10 between the FDIV and SGND pins. Use the 3) Connect a 1A resistive load across OUTA (3.3V) and Switching Frequency Selection section of MAX17673 data its nearest PGND pad. sheet to choose different values of R5 and R10. In the EV kit, R5 is left open, and R10 is set to 0. 4) Connect a 1A resistive load across OUTB (1.8V) and its nearest PGND pad. Soft Start Programming 5) Connect a 0.3A resistive load across OUTA (5V) and The EV kit offers an adjustable soft-start function on the its nearest PGND pad. MAX17673 HV buck converter to limit inrush current dur- 6) Select the shunt position on jumper JU1 according ing startup. The soft-start time is adjusted by changing to the intended mode of operation (see Table 2 for the value of C13, the external capacitor from the SSH pin details). to SGND. The selected output capacitance (CSEL) and the HV buck converter output voltage (VOUT) determine 7) Connect digital multimeters (in voltage measurement the minimum value of C13, as shown by the following mode) across the VOUT, OUTA, OUTB pads and equation: their nearby PGND pads. C13 56 x 10-6 x C x V SEL OUT 8) Turn on the input power supply. Where C is the sum output capacitance, in F, con- SEL 9) Verify that the DMMs display 5V across the VOUT nected at the output of the HV buck converter (includes terminal, 3.3V across the OUTA terminal and 1.8V C21, C23, C4, C5, C6 and C7 on the EV kit), and V OUT across the OUTB terminal with respect to PGND. is the output voltage in Volts. Detailed Description The soft-start time (t ) is related to the soft-start capaci- SS tor C13 by the following equation: The MAX17673 EV kit is designed to demonstrate the salient features of the MAX17673 60V, 1.5A high effi- -6 t = C13 / (5.55 x 10 ) SS ciency, synchronous buck converter with integrated, dual For example, in order to program a 1ms soft-start time, 5V, 1A buck converters. The EV kit includes Jumper JU1 C13 should be 5600pF. Maxim Integrated 2 www.maximintegrated.com