Datasheet
Evaluates: MAX15039
Evaluating Other Switching
Frequencies (FREQ)
The EV kit comes preset at a 1MHz switching frequen-
cy. To evaluate other frequencies, select a different
value for surface-mount 0603 resistor R7 using the fol-
lowing equation:
where f
S
is the desired switching frequency in mega-
hertz and must be between 500kHz and 2MHz. Refer to
the MAX15039 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 MAX15039 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 refe-
rence for this signal.
R
s
s7
49 9
095
1
005k
k
f
MHz
S
Ω
Ω
[]
=×
[]
⎛
⎝
⎜
⎞
⎠
⎟
−
.
.
.
µ
µ
MAX15039 Evaluation Kit
4 _______________________________________________________________________________________
Table 4. Mode Selection (JU5)
SHUNT
POSITION
MODE PIN
CONNECTION
MAX15039 IC
FUNCTIONAL MODE
2-3 GND Forced PWM
Not installed Unconnected
Forced PWM, monotonic
startup into prebiased
output
1-2 VDD
Skip, monotonic startup
into prebiased output
SHUNT
POSITION
(JU3)
CTL1 PIN
CONNECTION
SHUNT
POSITION
(JU4)
CTL2 PIN
CONNECTION
V
OUT
(V)
V
OUT
(V) WHEN USING
EXTERNAL V
REFIN
2-3 GND 2-3 GND
0.6V* or 0.6V < V
OUT
≤
0.9 x V
IN
**
V
REFIN
* or V
REFIN
<
V
OUT
≤ 0.9 x V
IN
**
1-2 VDD 1-2 VDD 0.7 V
REFIN
x (7/6)
2-3 GND Not installed Unconnected 0.8 V
REFIN
x (4/3)
2-3 GND 1-2 VDD 1.0 V
REFIN
x (5/3)
Not installed Unconnected 2-3 GND 1.2 V
REFIN
x 2
Not installed Unconnected Not installed Unconnected 1.5 V
REFIN
x 2.5
Not installed Unconnected 1-2 VDD 1.8 V
REFIN
x 3
1-2 VDD 2-3 GND 2.0 V
REFIN
x (10/3)
1-2 VDD Not installed Unconnected 2.5 V
REFIN
x (25/6)
*
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).
Table 3. Output-Voltage Selection (JU3, JU4)