MIC94325/45/55
500mA LDO with
Ripple Blocker Technology
General Description
The MIC943x5 Ripple Blocker is a monolithic integrated
circuit that provides low-frequency ripple attenuation
(switching noise rejection) to a regulated output voltage.
This is important for applications where a DC/DC switching
converter is required to lower or raise a battery voltage but
where switching noise cannot be tolerated by sensitive
downstream circuits such as in RF applications. The
MIC943x5 maintains high power supply ripple rejection
(PSRR) with input voltages operating near the output
voltage level to improve overall system efficiency. A low-
voltage logic enable pin facilitates ON/OFF control at
typical GPIO voltage levels.
The MIC943x5 operates from an input voltage of 1.8V to
3.6V. The MIC943x5 options include fixed (MIC94345/55)
or adjustable (MIC94325) output voltages. The MIC94355
version offers an auto-discharge to discharge the output
capacitor when the part is disabled.
Packaged in a 0.84mm x 1.32mm 6-ball CSP or a 6-pin
1.6mm x 1.6mm Thin DFN, the MIC943x5 has a junction
operating temperature range of –40C to +125C.
Data sheets and support documentation can be found on
Micrel’s web site at:
www.micrel.com.
Features
1.8V to 3.6V input voltage range
Active noise rejection over a wide frequency band
>50dB from 10Hz to 5MHz at 500mA load
Rated to 500mA output current
Fixed and adjustable output voltages
Optional output auto-discharge when disabled
Current-limit and thermal-limit protected
Ultra-small 0.84mm x 1.32mm 6-ball CSP
1.6mm x 1.6mm, 6-pin Thin DFN
Logic-controlled enable pin
40C
to +125C junction temperature range
Applications
Smart phones
Tablet PC/notebooks and webcams
Digital still and video cameras
Global positioning systems
Mobile computing
Automotive and industrial applications
_________________________________________________________________________________________________
MIC94355 PSRR
C
OUT
= 4.7µF
V
IN
= 2.8V + 40mVpp
-20
-40
-60
-80
10mA
V
OUT
= 1.8V
C
OUT
= 4.7µF
Typical Application
0
PSRR (dB)
500mA
-100
-120
10
100
1,000
1K
200mA
10,000 100,00 1,000,0 10,000,
10K
100K
1M
10M
0
00
000
FREQUENCY (Hz)
Ripple Blocker is a trademark of Micrel, Inc
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 •
http://www.micrel.com
October 2012
M9999-102512-A
Embedded System
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