EP5357XUI Datasheet, PDF (10/19 Pages) Altera Corporation – 600mA PowerSoC Synchronous Buck Regulator With Integrated Inductor

EP5357LUI/EP5357HUI
Detailed Description
Functional Overview
The EP5357xUI requires only 2 small MLCC
capacitors for a complete DC-DC converter
solution. The device integrates MOSFET
switches, PWM controller, Gate-drive,
compensation, and inductor into a tiny 2.5mm x
2.25mm x 1.1mm QFN package. Advanced
package design, along with the high level of
integration, provides very low output ripple and
noise. The EP5357xUI uses voltage mode
control for high noise immunity and load
matching to advanced ≤90nm loads. A 3-pin
VID allows the user to choose from one of 8
output voltage settings. The EP5357xUI
comes with two VID output voltage ranges.
The EP5357HUI provides V_OUT settings from
1.8V to 3.3V, the EP5357LUI provides VID
settings from 0.8V to 1.5V, and also has an
external resistor divider option to program
output setting over the 0.6V to V_IN-0.25V
range. The EP5357xUI provides the industry’s
highest power density of any 600mA DCDC
converter solution.
The key enabler of this revolutionary
integration is Altera 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 seem-less integration of all
switching, control, and compensation circuitry.
The proprietary magnetics design provides
high-density/high-value magnetics in a very
small footprint. Altera 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 EP5357xUI 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 conducted and radiated 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 input AC ripple currents that
are a major source of radiated emissions from
DC-DC converters. The integrated inductor
provides the optimal solution to the complexity,
output ripple, and noise that plague low power
DCDC converter design.
Voltage Mode Control
The EP5357xUI utilizes an integrated 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.
Light Load Mode (LLM) Operation
The EP5357xUI uses a proprietary light load
mode to provide high efficiency in the low load
operating condition. When the LLM pin is high,
the device is in automatic LLM/PWM mode.
When the LLM pin is low, the device is in PWM
mode. In automatic LLM/PWM mode, when a
light load condition is detected, the device will
(1) step V_OUT up by approximately 1.5% above
the nominal operating output voltage setting,
V_NOM, and then (2) shut down unnecessary
circuitry, and (3) monitor V_OUT. When V_OUT falls
below V_NOM, the device will repeat (1), (2), and
(3). The voltage step up, or pre-positioning,
improves transient droop when a load transient
causes a transition from LLM mode to PWM
mode. If a load transient occurs, causing V_OUT
to fall below the threshold V_MIN, the device will
03409
10
October 11, 2013
www.altera.com/enpirion
Rev E