en5311 Enpirion, en5311 Datasheet - Page 7

• Manufacturer Part Number: en5311
• Description: 1a Synchronous Buck Regulator With Integrated Inductor
• Manufacturer: Enpirion

March 2008
Detailed Description
Functional Overview
The EN5311QI is a complete DCDC converter
solution requiring only two low cost MLCC
capacitors.
controller,
inductor are integrated into the tiny 5mm x
4mm x 1.1mm package to provide the smallest
footprint
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 high
switching
frequency allows for a wide control loop
bandwidth
performance. The high switching frequency
enables the use of very small components
making possible this unprecedented level of
integration.
Enpirion’s
technology provides very low switching loss at
frequencies of 4 MHz and higher, allowing for
the use of very small internal components, and
very wide control loop bandwidth.
magnetic design allows for integration of the
inductor into the very low profile 1.1mm
package. Integration of the inductor virtually
eliminates the design/layout issues normally
associated
converters.
and faster integration into various applications
to meet demanding EMI requirements.
Output voltage is chosen from seven preset
values via a three pin VID voltage select
scheme.
the selection of any voltage in the 0.6V to V
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.
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possible
An external divider option enables
frequency.
Gate-drive,
proprietary
All of this enables much easier
providing
with
MOSFET
while
switch-mode
The
compensation,
excellent
power
maintaining
switches,
high
MOSFET
switching
transient
Unique
DCDC
PWM
high
and
IN
-
7
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 use of an internal inductor localizes the
noises
currents. The inherent shielding and compact
construction of the integrated inductor reduces
the radiated noise that couples into the traces
of the circuit board.
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.
significantly reduces parasitic effects that can
harm loop stability, and makes layout very
simple.
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
the Power MOSFETS and the integrated
inductor. The soft start ramp rate is nominally
1.65V/mS.
Over Current/Short Circuit Protection
The current limit function is achieved by
sensing the current flowing through a sense P-
MOSFET which is compared to a reference
current. When this level is exceeded the P-
FET is turned off and the N-FET is turned on,
pulling V
OUT
OUT
associated
ramp rate to levels that are safe for
low. This condition is maintained
The
with
Further, the package
integrated
www.enpirion.com
the
output
EN5311QI
inductor
loop