Evaluates: MAX8556/MAX8557
MAX8556 Evaluation Kit
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Recommended Equipment
•One 4V, 5A variable-output power supply
•Dummy load capable of sinking 4A
•Digital multimeter (DMM)
Quick Start
The MAX8556 EV kit is fully assembled and tested.
Follow these steps to verify board operation:
1) Preset the power supply to 1.425V and turn off the
power supply. Do not turn on the power supply
until all connections are made.
2) Verify that the shunt is across pins 2 and 3 of JU1 to
enable the device.
3) Connect the positive lead of the power supply to the
VIN pad on the EV kit, and the negative lead of the
power supply to the GND pad on the EV kit.
4) Connect the positive input of the DMM to the VOUT
pad on the EV kit, and the negative input of the
DMM to the GND pad on the EV kit to measure the
output voltage.
5) Turn on the power supply and verify that the output
voltage is 1.2V ±1%.
6) Sweep the input voltage from +1.425V to +3.6V.
Verify that the output voltage is 1.2V ±1% over the
entire input range.
7) Set the power supply to 2V.
8) Connect the 4A load between the VOUT and GND
pads on the EV kit.
9) Verify that the output voltage is 1.2V ±1%.
Detailed Description
Adjusting the Output Voltage
R2 and R3 are used to adjust the output voltage for the
MAX8556. To adjust the output voltage, replace R2 with
a 0.1% resistor that is calculated as:
R2 = 1 x 103x ((VOUT / VFB) - 1)
where VFB is 0.5V and VOUT is the desired output voltage.
POK Output
The MAX8556 has an open-drain POK output that goes
high impedance after the output is within ±10% of the
regulation voltage. On the EV kit, R1 pulls up POK to
VIN. The MAX8556 EV kit can also be used to evaluate
the MAX8557. In this case, the POK output becomes
the POR output.
Shutdown
The MAX8556 features a shutdown mode to power
down the output and reduce input current. To shut
down the device, place the shunt between positions 1
and 2 of JU1. To operate normally, place the shunt
between positions 2 and 3 of JU1.
Jumper Settings