Datasheet

www.maximintegrated.com
MaximIntegrated │ 18
MAX15062 60V, 300mA, Ultra-Small, High-Efciency,
Synchronous Step-Down DC-DC Converters
Adjusting the Output Voltage
The MAX15062C output voltage can be programmed
from 0.9V to 0.89 x V
IN
. Set the output voltage by con-
nectingaresistor-dividerfromoutputtoFBtoGND(see
Figure 2).
Forthe outputvoltagesless than6V, chooseR2in the
50kΩ to 150kΩ range. For the output voltages greater
than6V,chooseR2inthe25kΩto75kΩrangeandcalcu-
lateR1withthefollowingequation:
OUT
V
R1 R2 1
0.9
−

= ×


Power Dissipation
Ensure that the junction temperature of the device does
not exceed 125°C under the operating conditions speci-
fied for the power supply. At a particular operating condi-
tion, the power losses that lead to temperature rise of the
part are estimated as follows:
2
LOSS OUT OUT DCR
1
P P - 1 - (I R )


=××


η


OUT OUT OUT
P VI= ×
where P
OUT
 is the output power, η is the efficiency of
powerconversion,andR
DCR
is the DC resistance of the
output inductor. See the Typical Operating Characteristics
for the power-conversion efficiency or measure the effi-
ciency to determine the total power dissipation.
The junction temperature (T
J
) of the device can be esti-
mated at any ambient temperature (T
A
) from the following
equation:
( )
J A JA LOSS
TT P= +θ ×
whereθ
JA
is the junction-to-ambient thermal impedance
of the package.
PCB Layout Guidelines
Careful PCB layout is critical to achieve clean and stable
operation. The switching power stage requires particular
attention. Follow the guidelines below for good PCB layout.
● Placetheinputceramiccapacitorascloseaspossible
to the V
IN
andGNDpins.
● Connect the negative terminal of the V
CC
bypass
capacitortotheGNDpinwithshortestpossibletraceor
ground plane.
● MinimizetheareaformedbytheLXpinandtheinduc-
torconnectiontoreducetheradiatedEMI.
● PlacetheV
CC
decoupling capacitor as close as pos-
sible to the V
CC
pin.
● Ensure that all feedback connections are short and
direct.
● Routethehigh-speedswitchingnode(LX)awayfrom
the FB/V
OUT
, RESET, and MODE pins.
For a sample PCB layout that ensures the first-pass
success, refer to the MAX15062 evaluation kit layouts
available at www.maximintegrated.com.
Figure 2. Setting the Output Voltage
R2
R1
GND
MAX15062C
FB
V
OUT