Click here for production status of specific part numbers. Evaluates: MAX17673A 5V, 3.3V, 1.8V MAX17673AEVKIT Evaluation Kit Output Applications General Description Features The MAX17673AEVKIT evaluation kit (EV kit) provides a Three Synchronous DC-DC Buck Converter Outputs proven design to evaluate the MAX17673A 60V, 1.5A high from a Single HV Input efficiency, synchronous buck converter with integrated, Wide 7V to 60V Input Range for HV Buck Converter dual 5.5V, 1A buck converters. The EV kit is preset for Optional External Supply Input Connections for LV 5V output at a load current of up to 1.5A from the high- Buck Converters (4.5V to 5.5V for LVA, and 2.7V to voltage (HV) buck converter, and 3.3V and 1.8V outputs 5.5V for LVB) at load currents up to 1A each from the low-voltage (LV) Programmed 5V/1.5A Output for HV Buck Converter buck converters. The HV buck converter is programmed to operate at 400kHz, and the LV buck converters are and 3.3V/1A and 1.8V/1A Output for LV Buck Converters programmed to operate at 2MHz, for optimum efficiency and component sizes. The output of the HV buck con- 400kHz Switching Frequency for HV Buck Converter verter is connected to the input of the LV buck converters. and 2MHz Switching Frequency for LV Buck Converters The EV kit features adjustable input undervoltage lockout High 93% Efficiency (V = 12V, V = 5V at INH OUT and soft-start for the HV buck converter, and power- 0.45A) for HV Buck Converter 94% Efficiency (V = IN OK (POK ) signals for all three buck converters. The 5V, V = 3.3V at 0.5A) for LV Buck Converters OUT MAX17673/MAX17673A IC data sheet provides a com- Enable/UVLO Input, Resistor-Programmable UVLO plete description of the part that should be read in con- Threshold for HV Buck Converter junction with this data sheet prior to operating the EV kit. Programmed 1ms Soft-Start Time for HV Buck Converter, and Internal 4096 Clock Cycles Soft-Start Time for LV Buck Converters Selectable PWM and PFM Modes of Operation External Clock Synchronization Ordering Information appears at end of data sheet. Independent Power-OK (POK ) Outputs for the Three Buck Converters Overcurrent and Overtemperature Protection Low-Profile, Surface-Mount Components Proven PCB Layout Fully Assembled and Tested Complies with CISPR 22 (EN 55022) Class B Conducted and Radiated Emissions Limits EV kit specifications, settings, benefits and features are highlighted. For full MAX17673A features, benefits and parameters, refer to the MAX17673/MAX17673A data sheet. 319-100498 Rev 0 1/20Evaluates: MAX17673A 5V, 3.3V, 1.8V MAX17673AEVKIT Evaluation Kit Output Applications INA and INB inputs. POKH, POKA, or POKB pads are Quick Start available for monitoring the status of output voltages. Required Equipment On the bottom layer of the EV kit, additional footprints One MAX17673AEVKIT EV kit for optional components are included to ease board One 0V to 60V DC, 3A power supply modification for different input and output configurations. Placeholders are also available on the bottom layer for One load resistor capable of sinking up to 0.3A at 5V placement of EMI filter components. Two load resistors capable of sinking up to 1A at 3.3V and 1.8V, respectively Setting Switching Frequency Digital multimeters (DMM) Selection of the switching frequency must consider the input voltage range, desired output voltages, t of ON(MIN) Equipment Setup and Procedure the three buck converters in the MAX17673A, and ambient The EV kit is fully assembled and tested. Follow the steps temperature. To optimize efficiency and component size, a below to verify board operation: 400kHz switching frequency is chosen for the 5V HV buck converter, and 2MHz switching frequency is chosen for the Caution: Do not turn on power supply until all con- 3.3V and 1.8V LV buck converters. Resistor R5 connected nections are completed. between the RT and SGND plane programs the desired 1) Set the input power supply at a voltage between 7V switching frequency of LV buck converters. The HV buck and 60V. Disable the power supply. converter switching frequency is derived as a fraction of 2) Connect the positive terminal of the power supply to the LV buck converters switching frequency by placing the VIN pad, and the negative terminal to the nearest resistor R10 between the FDIV and SGND pins. Use the PGND pad on the EV kit. The output of the HV buck Switching Frequency Selection section of the MAX17673/ converter (OUT) is connected to the LV buck input MAX17673A data sheet to choose different values of R5 using jumpers JU2 and JU3 (see Table 1 for details). and R10. In the EV kit, R5 is left open, and R10 is set to 0. 3) Connect a 1A resistive load across OUTA (3.3V) and Soft-Start Programming its nearest PGND pad. The EV kit offers an adjustable soft-start function on the 4) Connect a 1A resistive load across OUTB (1.8V) and MAX17673A HV buck converter to limit inrush current its nearest PGND pad. during startup. The soft-start time is adjusted by changing 5) Connect a 0.3A resistive load across OUT (5V) and the value of C13, the external capacitor from the SSH pin its nearest PGND pad. to SGND. The selected output capacitance (C ) and SEL 6) Select the shunt position on jumper JU1 according to the HV buck converter output voltage (V ) determine OUT the intended mode of operation (see Table 2 for details). the minimum value of C13, as shown by the following equation: 7) Connect digital multimeters (in voltage measurement mode) across the OUT, OUTA, OUTB pads and their C13 56 x 10-6 x C x V SEL OUT nearby PGND pads. Where C is the sum output capacitance, in F, con- SEL 8) Turn on the input power supply. nected at the output of the HV buck converter (includes C21, C23, C25, C27, C4, C5, C6, and C7 on the EV kit), 9) Verify that the DMMs display 5V across the OUT and V is the output voltage in volts. OUT terminal, 3.3V across the OUTA terminal, and 1.8V across the OUTB terminal with respect to PGND. The soft-start time (t ) is related to the soft-start capaci- SS tor C13 by the following equation: Detailed Description -6 t = C13 / (5.55 x 10 ) SS The MAX17673A EV kit is designed to demonstrate the For example, in order to program a 1ms soft-start time, salient features of the MAX17673A 60V, 1.5A high-effi- C13 should be 5600pF. ciency, synchronous buck converter with integrated, dual 5.5V, 1A buck converters. The EV kit includes jumper JU1 Enable/Undervoltage Lockout (ENH) to operate the MAX17673A in PWM mode or PFM mode, Programming based on light-load performance requirements. Jumpers The MAX17673A EV kit includes a resistive voltage-divid- JU2 and JU3 connect the LV buck converter inputs to er, formed by R18 and R19, connected from VIN to SGND either the HV buck converter output (OUT), or to external to turn on the device when the input voltage is more than Maxim Integrated 2 www.maximintegrated.com