Evaluates: MAX8727
MAX8727 Evaluation Kit
2 _______________________________________________________________________________________
Recommended Equipment
•2.6V to 5.5V, 5A DC power supply (VIN)
•Voltmeter
Quick Start
The MAX8727 EV kit is fully assembled and tested.
Follow these steps to verify board operation. Do not
turn on the power supply until all connections are
completed:
1) Verify that there is no shunt placed across jumper
JU1 to enable the MAX8727.
2) Connect the positive terminal of the DC power supply
to the VIN pad. Connect the negative terminal of the
DC power supply to the GND pad above the VIN pad.
3) Connect the voltmeter across the VOUT and GND
pads.
4) Turn on the 2.6V to 5.5V DC power supply and verify
that the output is 15V.
Detailed Description
The MAX8727 EV kit contains a high-efficiency, PWM
step-up DC-DC converter. The MAX8727 features a
programmable soft-start, loop compensation pin, and
an internal MOSFET switch. The EV kit operates from a
2.6V to 5.5V DC power supply, provides a regulated
15V output, and is capable of providing a 600mA load
current with a 4.5V input. The EV kit is configured for a
5V input, a 15V output, and a 1.2MHz switching fre-
quency. Operation at a different input voltage, out-
put voltage, or switching frequency may require a
different inductor, output capacitor, and compensa-
tion components. Refer to the MAX8727 data sheet for
detailed information on loop compensation and compo-
nent selection.
Jumper Selection
Shutdown Mode (
SHDN
)
The EV kit features a shutdown mode that reduces the
MAX8727 quiescent current. JU1 selects the shutdown
mode. See Table 1 for jumper JU1 functions.
Switching-Frequency Selection (FREQ)
The MAX8727 EV kit provides the option to configure
the switching frequency of the step-up DC-DC convert-
er. Table 2 lists jumper JU2 settings for configuring the
switching frequency. The EV kit is configured and
shipped to operate at 1.2MHz. For operation at 640kHz,
cut the trace between pins 1 and 2 of jumper JU2 and
short pins 2 and 3. Refer to the MAX8727 data sheet for
selecting the proper components.
Evaluating Other
Output Voltages
The EV kit is configured to provide a 15V output voltage.
However, the output voltage can be adjusted from VIN to
24V by selecting appropriate R1 and R2 values. Select
R2 in the 10kΩto 50kΩrange. R1 is then given by:
where VFB = 1.24V. For significantly different operation
points, the EV kit may require a different inductor and
component changes. Refer to the MAX8727 data sheet
for proper component selection.