MAX20458EVKIT# Analog Devices

Click here for production status of specific part numbers. Evaluates: MAX20458 MAX20458 Evaluation Kit General Description Features The MAX20458 evaluation kit (EV kit) is a fully assembled High-Voltage Step-Down Converter with Integrated and tested application circuit that simplifies the evaluation Power FETs to Minimize Board-Area-Occupancy of the MAX20458 400kHz/2.1MHz, 36V boost controller Asynchronous Boost Controller and buck converter in a 28-pin side-wettable TQFN pack- 3.5V to 40V Input Supply Range age. All installed components are rated for the automotive temperature range. Various test points and jumpers are Input Supply Range Extended down to 2V with included for evaluation. Pre-Boost Enabled The standard EV kit comes with the MAX20458ATIA/VY+ 10V Fixed Boost Output Voltage (Separate Option installed (3.3V/ADJ, 2.1MHz) but can also be used to Provides Adjustable Output Voltage) evaluate other MAX20458 variants with minimal compo- Buck Provides 5V/3.3V Output up to 3.5A Output nent changes discussed in the Evaluating Other Variants Current section. Buck Output Voltages Adjustable between 1V and 10V using External Resistors 2% Buck Output Voltage Accuracy Table 1. Default Jumper Settings Frequency-Synchronization Input SHUNT JUMPER FUNCTION Independent Enable Inputs POSITION Voltage-Monitoring PGOOD1 Output JU3 EN1 PIN1-2 Buck1 controller enabled Jumpers and Test Points on Key Nodes for Simplified JU1 EN2 PIN1-2 Boost controller enabled Evaluation FSYNC is pulled to V BIAS JU4 FSYNC PIN1-2 Proven PCB Layout enabling FPWM mode Fully Assembled and Tested PGOOD1 is pulled up to V BIAS JU PGOOD1 Installed when OUT1 is in regulation JU5 EXTVCC PIN2-3 EXTVCC is connected to GND Ordering Information appears at end of data sheet. 319-100399 Rev 1 7/19Evaluates: MAX20458 MAX20458 Evaluation Kit Buck Output Monitoring (PGOOD1) Quick Start The EV kit provides output test points (PGOOD1) to Required Equipment monitor the status of the buck output voltage on V . OUT1 MAX20458 EV kit PGOOD1 is high impedance when the output voltage is Adjustable DC power supply (PS1) in regulation. PGOOD1 is low impedance when the output voltage drops below 93.5% (typ) of its nominal regulated One digital multimeter (DMM1) voltage. One electronic load (EL) To obtain logic signal, pull up PGOOD1 to V by BIAS Procedure installing the shunt on jumper JU PGOOD1. The EV kit is fully assembled and tested. Follow the steps Setting the Output Voltage in Buck below to verify board operation: Converter 1) Verify that all jumpers are in their default positions as The EV Kit comes pre-assembled to provide a fixed shown in Table 1. 3.3V voltage regulation on V . To externally adjust OUT1 2) Connect the positive and negative terminals of PS1 to the voltage at V , remove R1 and place appropriate OUT1 the V and GND test pads, respectively. resistors in positions R3 and R4 according to the follow- BATTF ing equation: 3) Connect the positive terminal of DMM1 to V OUT1 connect the negative terminal of DMM1 to PGND1. V OUT1 R3 = R4 1 4) Connect the positive terminal of EL to V OUT1 V FB1 connect the negative terminal of EL to PGND1. where V = 1V (typ) and R4 = 50k. 5) Set the power supply to 14V and 3A limit. FB1 6) The DMM1 voltmeter should display an output Selecting EXTVCC voltage of 3.3V when connected to V . OUT1 The MAX20458 IC provides an internal low-dropout linear regulator (LDO) that supplies voltage available on the Detailed Description BIAS pin. This LDO can be bypassed when a voltage The MAX20458 EV kit provides a fully developed and source is detected at the EXTVCC pin. The EV kit pro- proven layout for evaluating all variants of the MAX20458 vides jumper JU5 EXTVCC, which allows shunts to be family. The IC accepts input supply voltages as high as installed connecting EXTVCC to either V or ground. OUT1 36V and input supply transients up to 40V. Bypassing the internal LDO and using the switching converter output to supply V increases efficiency over CC Switching Frequency and enabling the LDO. As assembled, the default position for External Synchronization the JU5 EXTVCC shunt connects EXTVCC to ground, The IC can operate in two modes: forced-PWM or skip forcing the internal LDO to supply VCC at the BIAS pin. mode. Skip mode offers improved efficiency over PWM When the voltage source on EXTVCC drops below the during light-load conditions. When FSYNC is pulled low, detection level, the internal LDO is enabled to supply V CC the device operates in skip mode for light loads, and in and BIAS. PWM mode for larger loads. When FSYNC is pulled high, the device is forced to operate in PWM across all load conditions. The EV kit default configuration uses a shunt on JU4 FSYNC to hold FSYNC high, resulting in forced- PWM mode operation. The FSYNC pin can be used to synchronize the switching frequency of the IC to an external source by applying an external clock signal. The device is forced to operate in PWM when FSYNC is connected to a clock source. Maxim Integrated 2 www.maximintegrated.com