Evaluates: MAX15038/MAX15039
Evaluating Other Switching
Frequencies (FREQ)
The EV kit comes preset at a 1MHz switching frequency.
To evaluate other frequencies, select a different value
for surface-mount 0603 resistor R7 using the following
equation:
where f
S
is the desired switching frequency in mega-
hertz and must be between 500kHz and 2MHz. Refer to
the MAX15038 IC data sheet for information on select-
ing output inductor, capacitor, and compensation com-
ponents to optimize the circuit for different switching
frequencies.
Power Good (PWRGD)
The MAX15038 PWRGD is an open-drain output that goes
to high impedance when V
FB
is above 0.925 x V
REFIN
and V
REFIN
is above 0.54V for at least 48 clock cycles.
PWRGD pulls low when V
FB
is below 90% of V
REFIN
or
V
REFIN
is below 0.54V for at least 48 clock cycles.
PWRGD is also low during shutdown. On the EV kit, the
PWRGD PCB pad is pulled up to VDD through resistor
R5. Use the GND PCB pad as a ground reference for this
signal.
Evaluating the MAX15039 IC
To evaluate the MAX15039ETG+ with the EV kit,
replace U1 with a MAX15039. The MAX15039 supports
up to 6A loads and comes in a 24-pin TQFN package
with an exposed pad. A 6A, 2.9V to 5.5V DC power
supply is needed. Refer to the MAX15039 IC data sheet
for more information.
.
.
.
*
Install a surface-mount 0603 8.06kΩ resistor at R8 and do not install a resistor at R9.
**
Install a surface-mount 0603 8.06kΩ resistor at R8 and a resistor at R9 (see the equation in the
Evaluating Other Output Voltages
section).
