Datasheet

Maxim Integrated │ 16
MAX17503 4.5V-60V, 2.5A, High-Efciency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
www.maximintegrated.com
Thejunctiontemperatureofthedevicecanbeestimated
at any given maximum ambient temperature (T
A_MAX
)
from the equation below:
( )
= +θ ×
J_MAX A _MAX JA LOSS
TT P
If the application has a thermal management system that
ensures that the exposed pad of the device is maintained
at a given temperature (T
EP_MAX
) by using proper heat
sinks,thenthejunctiontemperatureofthedevicecanbe
estimated at any given maximum ambient temperature
from the equation below:
( )
= +θ ×
J_MAX EP_MAX JC LOSS
TT P
PCB Layout Guidelines
All connections carrying pulsed currents must be very
short and as wide as possible. The inductance of these
connections must be kept to an absolute minimum due to
the high di/dt of the currents. Since inductance of a current
carrying loop is proportional to the area enclosed by the
loop, if the loop area is made very small, inductance is
reduced. Additionally, small-current loop areas reduce
radiated EMI.
A ceramic input filter capacitor should be placed close
to the V
IN
pins of the IC. This eliminates as much trace
inductance effects as possible and gives the IC a cleaner
voltage supply. A bypass capacitor for the V
CC
pin also
should be placed close to the pin to reduce effects of trace
impedance.
When routing the circuitry around the IC, the analog
small-signal ground and the power ground for switching
currents must be kept separate. They should be connected
together at a point where switching activity is at a
minimum, typically the return terminal of the V
CC
bypass
capacitor. This helps keep the analog ground quiet.
The ground plane should be kept continuous/unbroken
as far as possible. No trace carrying high switching
current should be placed directly over any ground plane
discontinuity.
PCB layout also affects the thermal performance of the
design. A number of thermal vias that connect to a large
ground plane should be provided under the exposed pad
of the part, for efficient heat dissipation.
For a sample layout that ensures first pass success,
refer to the MAX17503 evaluation kit layout available at
www.maximintegrated.com.