MAX77231EVKIT# Analog Devices

Evaluates: MAX77231 MAX77231 Evaluation Kit General Description Quick Start The MAX77231 evaluation kit (EV kit) is a fully assembled Recommended Equipment and tested PCB for evaluating the MAX77231 low-noise MAX77231 EV kit step-up DC-DC converter. It is optimized for boost 2.5V to 6V 100mA bench power supply (PS1) applications requiring very low ripple/noise and small PCB space. The EV kit is set up to provide an 11.2V output Two digital multimeters (DMM1, DMM2) from an input voltage ranging from 2.7V to 4.8V, and can 050mA electronic load or appropriate load resistors deliver up to 10mA of current. The output ripple and noise are suppressed to 35V . Other output voltages up to Procedure RMS 16.2V can be factory set. Jumpers are provided to help The EV kit is a fully assembled and tested surface mount evaluate features of the MAX77231 IC. circuit board. Follow the steps below to set up and verify the IC and board operation: Features 1) Verify that the jumpers on the EV kit are configured 2 Ultra-Small Solution Circuit Area (< 7mm ) as shown in Table 1. 35V Typical Output Ripple/Noise RMS 2) If using an electronic load, set it to 6mA and turn it 2.7V to 4.8V Input Range off. Alternately, obtain a 2k resistor (values from 1.8k to 2.4k are also acceptable). 11.2V/10mA Output 3) Set the power supply to 3.6V and turn it off. Output Factory-Trimmable from 11.2V to 16.2V 4) Connect the MAX77231 evaluation board, bench 125A No-Load Supply CurrentOutput On power supply and DMMs as shown in Figure 1. < 1A Shutdown Supply Current 5) Turn on the power supply. True Shutdown Load Disconnect 6) Verify that voltage read by DMM1 is 3.6V. Selectable Active Discharge 7) Verify that voltage read by DMM2 is 11.2V. Proven PCB layout 8) Sweep the power supply down to 2.7V. Fully Assembled and Tested 9) Verify that voltage read by DMM2 is 11.2V. Ordering Information appears at end of data sheet. 10) Sweep the power supply up to 4.8V. 11) Verify that voltage read by DMM2 is 11.2V. 12) Disconnect RL (or electronic load). 13) Verify that voltage read by DMM2 is 11.2V. Table 1. Default Jumper Settings DEFAULT SHUNT JUMPER MODE POSITION JU1 1-2 Active Discharge Off JU2 1-2 Power On 19-7638 Rev 0 1/16Evaluates: MAX77231 MAX77231 Evaluation Kit DMM2 DMM1 PS1 - + - + 3.6V + - RL = 2k TEST LOAD (OR 6mA ELECTRONIC LOAD) MAX77231 EV KIT Figure 1. Quick-Start Connection Diagram Overload and Short Circuit Protection Detailed Description The MAX77231 is fully protected against output short circuits. The MAX77231 EV kit evaluates the MAX77231 low- In the case of a short circuit, off time is lengthened to prevent noise boost DC-DC converter IC. The IC utilizes a high- inductor current from climbing. The device will source frequency PFM boost followed by a low-noise pMOS current into the short indefinitely, without damage, until linear LDO regulator that reduces output noise and ripple the short is removed. to 35V in a 1MHz BW at V . RMS OUT Note, however, that only OUT (and not BST) is overload The step-up converter output is 11.7V at V , and 11.2V BST protected. A short at V to ground may cause inductor at V from an input voltage range from 2.7V to 4.8V. BST OUT and LX current to rise above guaranteed operating levels. Other output voltages up to 16.2V are available after replacing U1. Contact the factory for other ICs. Enable/Active Discharge The MAX77231 can be disabled with/without active discharge. See Table 2 for ENM and ENS control logic for active discharge. Table 2. MAX77231 Enable Truth Table JU1 JU2 ACTIVE POWER STATE DISCHARGE JUMPER POSITION ENM JUMPER POSITION ENS 2-3 0 X X Power Down ON 1-2 1 2-3 0 Power Down OFF 1-2 1 1-2 1 Active OFF Maxim Integrated 2 www.maximintegrated.com VIN ENM ENS VBST VOUT GND