MIC49200 Datasheet, PDF (11/12 Pages) Micrel Semiconductor – 2A LOW VOLTAGE LDO WITH DUAL INPUT VOLTAGES

Micrel, Inc.
The heat sink may be significantly reduced in
applications where the maximum input voltage is
known and large compared with the dropout voltage.
Use a series input resistor to drop excessive voltage
and distribute the heat between this resistor and the
regulator. The low-dropout properties of the
MIC49200 allow significant reductions in regulator
power dissipation and the associated heat sink
without compromising performance. When this
technique is employed, a capacitor of at least 1µF is
needed directly between the input and regulator
ground. Refer to “Application Note 9” for further details
and examples on thermal design and heat sink
specification.
Minimum Load Current
The MIC49200, unlike most other high current
regulators, does not require a minimum load to
maintain output voltage regulation.
MIC49200
Adjustable Regulator Design
The MIC49200 adjustable version allows
programming the output voltage anywhere between
0.9V and 5V. Two resistors are used. The resistor
value between V_OUT and the adjust pin should not
exceed 10kΩ. Larger values can cause instability. The
resistor values are calculated by:
V_OUT
=
0.9 _{⎜⎜⎝⎛}
R₁
R₂
+ 1_{⎟⎟⎠⎞}
Where V_OUT is the desired output voltage.
Enable
The fixed output voltage versions of the MIC49200
feature an active high enable input (EN) that allows
on-off control of the regulator. Supply currents reduce
to “zero” when the device is in shutdown, with only
microamperes of leakage current. The EN input has
TTL/CMOS compatible thresholds for simple logic
interfacing. EN may be directly tied to V_IN and pulled
up to the maximum supply voltage.
January 2006
11
M9999-011306
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