EP5388QI
www.altera.com/enpirion Page 8
Detailed Description
Functional Overview
The EP5388QI is a complete DCDC converter
solution requiring only two low cost MLCC
capacitors. MOSFET switches, PWM controller,
Gate-drive, compensation, and inductor are
integrated into the tiny 3mm x 3mm x 1.1mm
package to provide the smallest footprint possible
while maintaining high efficiency, low ripple, and
high performance. The converter uses voltage
mode control to provide the simplest
implementation and high noise immunity. The
device operates at a 4MHz switching frequency.
The high switching frequency allows for a wide
control loop bandwidth providing excellent transient
performance. The high switching frequency further
enables the use of very small components making
possible this unprecedented level of integration.
Altera’s proprietary power MOSFET technology
provides very low switching loss at frequencies of 4
MHz and higher, allowing for the use of very small
internal components, and high performance.
Integration of the magnetics virtually eliminates the
design/layout issues normally associated with
switch-mode DCDC converters. All of this enables
much easier and faster incorporation into various
applications to meet demanding EMI requirements.
Output voltage is chosen from seven preset values
via a three pin VID voltage select scheme. An
external divider option enables the selection of any
voltage in VIN to 0.6V range. This reduces the
number of components that must be qualified and
reduces inventory burden. The VID pins can be
toggled on the fly to implement glitch free dynamic
voltage scaling.
Protection features include under-voltage lock-out
(UVLO), over-current protection (OCP), short circuit
protection, and thermal overload protection.
Integrated Inductor
Altera has introduced the world’s first product family
featuring integrated inductors. The EP5388QI
utilizes a proprietary low loss integrated inductor.
The use of an internal inductor localizes the noises
associated with the output loop currents. The
inherent shielding and compact construction of the
integrated inductor reduces the radiated noise that
couples into the traces of the circuit board. Further,
the package layout is optimized to reduce the
electrical path length for the AC ripple currents that
are a major source of radiated emissions from
DCDC converters. The integrated inductor
significantly reduces parasitic effects that can harm
loop stability, and makes layout very simple.
Stable Over Wide Range of Operating
Conditions
The EP5388QI utilizes an internal type III
compensation network and is designed to provide a
high degree of stability over a wide range of
operating conditions. The device operates over the
entire input and output voltage range with no
external modifications required. The very high
switching frequency allows for a very wide control
loop bandwidth.
Soft Start
Internal soft start circuits limit in-rush current when
the device starts up from a power down condition or
when the “ENABLE” pin is asserted “high”. Digital
control circuitry limits the VOUT ramp rate to levels
that are safe for the Power MOSFETS and the
integrated inductor.
The EP5388QI has two soft start operating modes.
When VOUT is programmed using a preset voltage
in VID mode, the device has a constant slew rate.
When the EP5388QI is configured in external
resistor divider mode, the device has a constant
VOUT ramp time. Output voltage slew rate and
ramp 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. Maximum allowable output capacitance
depends on the device’s minimum current limit, the
output current at startup, the minimum soft-start
time and the output voltage (all are listed in the
Electrical Characteristics Table). The total
maximum capacitance on the output rail is
estimated by the equation below:
COUT_MAX = 0.7 * (ILIMIT - IOUT) * tSS / VOUT
COUT_MAX = maximum allowable output capacitance
ILIMIT = minimum current limit = 0.8A
IOUT = output current at startup
VOUT = output voltage
0.7 = margin factor
tSS(VFB) = min soft-start time
= 0.784ms External feedback setting
tSS(VID) = VOUT [V] / 2.025 [V/ms] VID setting
02377 Decemeber 11, 2017 Rev G