EP5388QI Datasheet, PDF (8/14 Pages) Enpirion, Inc. – 800mA Synchronous Buck Regulator With Integrated Inductor 3mm x 3mm x 1.1mm Package

July 2008
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 0.603V to
V_IN-0.5V 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 between any two of
the seven preset VID voltage levels.
Protection features include under-voltage lock-
out (UVLO), over-current protection (OCP),
short circuit protection, and thermal overload
protection.
Integrated Inductor
Enpirion 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.
EP5388QI
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 V_OUT ramp rate to levels that are safe for
the Power MOSFETS and the integrated
inductor. The soft start ramp rate is nominally
1.5V/mS.
Over Current/Short Circuit Protection
When an over current condition occurs, V_OUT is
pulled low. This condition is maintained for a
period of approximately 1.2 ms and then a
normal soft start cycle is initiated. If the over
current condition still persists, this cycle will
repeat.
Under Voltage Lockout
During initial power up an under voltage
lockout circuit will hold-off the switching
circuitry until the input voltage reaches a
sufficient level to insure proper operation. If
the voltage drops below the UVLO threshold
the lockout circuitry will again disable the
switching. Hysteresis is included to prevent
chattering between states.
Enable
The ENABLE pin provides a means to shut
down the converter or enable normal
operation. Transitioning from low to high will
cause the converter to go through a soft start
cycle. Transitioning from high to a low will
cause the device to discharge the output and
then shutdown. In shutdown mode, the device
quiescent current will be less than 1 uA.
NOTE: This pin must not be left floating.
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