en5360 Enpirion, en5360 Datasheet - Page 9

• Manufacturer Part Number: en5360
• Description: 6a Voltage Mode Synchronous Buck Pwm Dc-dc Converter
• Manufacturer: Enpirion

It is possible to raise the over-current set-point by
~50% by connecting a 4.99k Ω resistor between
ROCP and GND.
Over-Voltage Protection
When the output voltage exceeds 120% of the
programmed output voltage, the PWM operation
stops, the lower N-MOSFET is turned on and the
POK signal goes low. When the output voltage
drops below 95% of the programmed output
voltage, normal PWM operation resumes and
POK returns to its high state.
Thermal Overload Protection
Thermal shutdown will disable operation once
the Junction temperature exceeds approximately
160ºC. Once the junction temperature drops by
approx 25ºC, the converter will re-start with a
normal soft-start.
Input Under-voltage Operation
Circuitry is provided to ensure that when the
input voltage is below the specified voltage
range, the operation of the converter is controlled
and predictable. Circuits for hysteresis, input de-
glitch and output leading edge blanking are
included to ensure high noise immunity and
prevent false tripping.
Compensation
The EN5360 is internally compensated through
the use of a type 3 compensation network and is
optimized for use with about 50µF of output
capacitance and will provide excellent loop
bandwidth and transient performance for most
applications. (See the section on Capacitor
Selection for details on recommended capacitor
types.) In some cases modifications to the
compensation may be required. For more
information,
Engineering support.
Layout Considerations
The EN5360 Layout Guidelines application note
provides
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on
specific
Applications
layout
9
recommendations for this part. The following are
general layout guidelines to consider.
The CMOS chip inside the EN5360 has two
grounds: AGND for the controller, and PGND for
the power stage. These two grounds need to be
connected outside the package at one point
through a low-impedance trace. The connection
should be made such that the impedance
between the connection point and the AGND pad
on the package is minimized. Since the internal
voltage sensing circuit is based on AGND, the
connection of the two grounds should also be
made such that the best voltage regulation can
be achieved. The soft-start capacitor, the voltage
programming resistors, and any other external
control component should be tied to AGND.
The placement of the input decoupling capacitors
and output filter capacitors relative to their
respective pins is very critical. The input
capacitors should be placed such that they have
the lowest inductance traces to PVIN and PGND
pins 28-33. The output filter capacitors should
have the lowest inductance traces to VOUT and
PGND pins 10-15.
There are two thermal pads underneath the
device. The centrally located pad is PGND, and,
depending on the number of layers of the PC
board, it needs to be connected to a thermal
plane in order to conduct heat away from the
device. Note that if any of the thermal planes is
also connected to AGND, the impedance
between this point and the GND connection of
the load needs to be minimized in order to get
the best possible load regulation. The pad in
front of the V
This V
copper area as large as possible to conduct
more heat away from the package. This will also
help minimize the trace inductance to the output
filter caps.
Pin 17 is a connected to a noisy internal node
and is brought out for test purposes only. Keep
all sensitive signal traces as far as possible from
this pin. In order to minimize cross-talk to other
parts of the board, do not run any unrelated
traces
EN5360.
OUT
from
pad should be connected to a top layer
OUT
other
pins 22-24 is connected to V
circuits
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underneath
OUT
the
.