EP5348UI Datasheet, PDF (7/12 Pages) Enpirion, Inc. – 400mA Synchronous Buck Regulator with Integrated Inductor

EP5348UI
Detailed Description
Functional Overview
The EP5348UI requires only 2 small MLCC
capacitors and a few small-signal components
for a complete DC-DC converter solution. The
device integrates MOSFET switches, PWM
controller, Gate-drive, part of the loop
compensation, and inductor into a tiny 2.0mm x
1.75mm x 0.9mm micro-QFN package.
Advanced package design, along with the high
level of integration, provides very low output
ripple and noise. The EP5348UI uses voltage
mode control for high noise immunity and load
matching to advanced ≤90nm loads. An
external resistor divider is used to program
output setting over the 0.6V to V_IN-V_DROPOUT as
specified in the Electrical Characteristics Table.
The EP5348UI provides the industry’s highest
power density of any 400mA DC-DC converter
solution.
The key enabler of this revolutionary
integration is Enpirion’s proprietary power
MOSFET technology. The advanced MOSFET
switches are implemented in deep-submicron
CMOS to supply very low switching loss at high
switching frequencies and to allow a high level
of integration. The semiconductor process
allows seamless integration of all switching,
control, and compensation circuitry.
The proprietary magnetics design provides
high-density/high-value magnetics in a very
small footprint. Enpirion magnetics are
carefully matched to the control and
compensation circuitry yielding an optimal
solution with assured performance over the
entire operating range.
Protection features include under-voltage lock-
out (UVLO), over-current protection (OCP),
short circuit protection, and thermal overload
protection.
Integrated Inductor
The EP5348UI utilizes a proprietary low loss
integrated inductor. The integration of the
inductor greatly simplifies the power supply
design process. The inherent shielding and
compact construction of the integrated inductor
reduces the noise that can couple into the
traces of the printed circuit board. Further, the
package layout is optimized to reduce the
electrical path length for the high di/dT currents
that are always present in DC-DC converters.
The integrated inductor provides the optimal
solution to the complexity, output ripple, and
noise that plague low power DC-DC converter
design.
Control Matched to sub 90nm Loads
The EP5348UI utilizes a type III compensation
network. Voltage mode control is inherently
impedance matched to the sub 90nm process
technology that is used in today’s advanced
ICs. Voltage mode control also provides a high
degree of noise immunity at light load currents
so that low ripple and high accuracy are
maintained over the entire load range. The
very high switching frequency allows for a very
wide control loop bandwidth and hence
excellent transient performance.
Soft Start
Internal soft start circuits limit the rate of output
voltage rise when the device starts up from a
power down condition, or when the “ENABLE”
pin is asserted “high”. Digital control circuitry
controls the V_OUT rise time to ensure a smooth
turn-on ramp.
The EP5348UI has a fixed V_OUT turn-on time.
Therefore, the ramp rate will vary with the
output voltage setting. Output voltage rise time
is given in the Electrical Characteristics Table.
Excess bulk capacitance on the output of the
device can cause an over-current condition at
startup. The maximum total capacitance on
the output, including the output filter capacitor,
and bulk and decoupling capacitance at the
load, is given as:
C_{OUT_TOTAL_MAX} = 9.333 x 10^-4 / V_OUT
The nominal value for the output filter capacitor
is 10uF. See the applications section for more
details.
Over Current/Short Circuit Protection
The current limit function is achieved by
sensing the current flowing through a sense P-
©Enpirion 2012 all rights reserved, E&OE
05721
7
September 12, 2012
www.enpirion.com
Rev: C