Evaluates: MAX5025–MAX5028
MAX5026 Evaluation Kit
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Quick Start
The MAX5026 EV kit is a fully assembled and tested
surface-mount board. Follow the steps below to verify
board operation. Do not turn on the power supply
until all connections are completed.
Evaluating MAX5026
1) Verify that there is a shunt across JU1 (SHDN)
pins 1 and 2.
2) Connect a voltmeter and load (if any) to the VOUT
pad (and/or plug an oscilloscope probe into the
oscilloscope jack).
3) Connect a +3V to +11V power supply to the VIN
pad. Connect the power-supply ground to the
GND pad closest to VIN.
4) Turn on the power supply and verify that the out-
put voltage is approximately +30V.
To evaluate other output voltages, refer to the
Evaluating Other Output Voltages section.
Detailed Description
Shutdown Function
The MAX5026 EV kit contains a boost converter. The cir-
cuit provides a +30V output with less than 2mVp-p high-
frequency ripple from a +3V to +11V input voltage, and
delivers up to 6mA. The setting of jumper JU1 selects the
circuit operating modes. Table 1 shows the functions of
jumper JU1.
Noise Performance
The MAX5026 EV kit is specifically designed for low-
noise performance. An RC filter at the regulator’s output
reduces its noise further. To observe this filtered output,
monitor the signal at oscilloscope jack J1. The high-fre-
quency output ripple voltage is less than 1mVp-p at
2mA load current. Extra capacitor pads (C4 and C5)
are provided for further noise reduction. To reduce low-
frequency noise, add a 10µF electrolytic capacitor at
the pads labeled C5. Without the 10µF capacitor, the
peak-to-peak low-frequency noise is about 20mV. The
peak-to-peak low-frequency noise drops to 3mV when
the 10µF capacitor is included.
Evaluating Other Output Voltages
The default output for the MAX5026 EV kit is +30V. To
generate output voltages other than +30V with either
the MAX5025EUT or MAX5026EUT, change feedback
resistors R1 and R2. Limit the current through R1 and
R2 to about 200µA. R1 = R2 [(V
OUT
/1.25V) - 1].
Evaluating MAX5027/MAX5028
The MAX5026 EV kit can also be used to evaluate the
MAX5027/MAX5028 boost converters with fixed +30V
output. To evaluate MAX5027/MAX5028, remove the
feedback resistors R1 and R2, short the two pads of
R1, and replace the MAX5026EUT with a MAX5027EUT/
MAX5028EUT.
