MIC94325/45/55
Evaluati on B oar d
500mA LDO with
Ripple Blocker Technol ogy
Ripple Block er is a trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • US A • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
June 11, 2013
Revision 1.0
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 f or applications, such as RF app lica tions,
where switching noise cannot be tolerated by sensitive
downstream circuits. The MIC94325/45/55 maintains high
power supply ripple rejection (PSRR) with input voltage
operating near the output voltage level to improve overall
system efficiency.
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.
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Requirements
The MIC94325/45/55 evaluation board requires an input
power supply that can deliver greater than 800mA at a
voltage range of 1.8V to 3.6V. The output load can be
either active or passive.
Precautions
The MIC94325/45/55 evaluation board does not have
reverse polarity protection. Applying a negative voltage to
the VIN terminal may damage the device.
Getting Started
1. Connect an Ex ternal Supply to VIN.
Apply the desired input voltage to the VIN and ground
terminal of the evaluation board, paying careful
attention to polarity and supply voltage (1.8V ≤ VIN ≤
3.6V).
2. Enable/Disable the MIC94325/45/55.
The evaluation board is supplied with a 100kΩ pull-up
resistor to VIN, which makes the on state the default.
To disable the output, jumper the EN terminal to
ground.
3. Connect the Load.
Connect the load to the VOUT terminal and the ground
terminal. The load can be either passive (resistor) or
active (electronic load). Be sure to monitor the output
voltage at the VOUT terminal.
Ordering Information
Part Number Description
MIC94325YMT EV 500mA LDO Ripple Blocker
Evaluation Board
MIC94355-4YMT EV 500mA LDO Ripple Blocker
Evaluation Board (VOUT = 1.2V)
MIC94355-FYMT EV 500mA LDO Ripple Blocker
Evaluation Board (VOUT = 1.5V)
MIC94355-GYMT EV 500mA LDO Ripple Blocker
Evaluation Board (VOUT = 1.8V)
MIC94355-MYMT EV 500mA LDO Ripple Blocker
Evaluation Board (VOUT = 2.8V)
MIC94355-SYMT EV 500mA LDO Ripple Blocker
Evaluation Board (VOUT = 3.3V)
Micrel, Inc.
MIC94325/45/55 Evaluation Board
June 11, 2013
2 Revision 1.0
Power Supply Ripple Rejection (PSRR)
Measurements
Figure 1 shows the frequency response of the MIC94325.
Figure 1. MIC94325 Rippled Blocker Frequency Response
For high-frequency measurements (above 1MHz), pay
careful attention to the test set-up configuration because it
is easy to introduce noise into the grounds. That gives
inaccurate measurements, as shown in Figure 2.
Figure 2. High-Frequency Noise on Measurement System
The induc tance of tes t probes con nected to th e evaluation
board at higher frequencies is a factor that can create a
differential between the device under test and test
meas ur em ent system grou nds. Adding a lo w-value resistor
(2Ω) in series with the input capacitor to ground and using
a test measurement system that can make differential
measurements will help to reduce these effects.
PSRR m easurements can be made us ing either dedicated
PSRR test equipment or a PSRR interface board and a
network analyzer. The network analyzer can sweep the AC
frequency and perform a comparison measurement of the
amplitude on the input and output. With this method, the
network analyzer is configured for an A/R measurement.
The problem comes when trying to impose the network
analyzer’s AC signal with the DC input voltage to the
MIC94325/45/55. The circuit shown in Figure 3 solves this
problem by using the MIC911 as a summing amplifier.
Figure 3. Network Analyzer Set-Up
The summ ing amplifier adds the VSUPPLY (DC voltage) and
the network analyzer’s AC signal. Because the network
analyzer’s source is 50Ω impedance, it may be neglected.
The DC voltage see n at th e non-in verting side is half of the
VSUPPLY voltage. T he output is gained up b y 2 with the 1k Ω
resistor divider to t he n on-invert ing side . This sum s the AC
and DC voltages with an overall gain of 1.
( )
LYZERNETWORKANASUPPLYOUT
LYZERNETWORKANASUPPLYOUT
LYZERNETWORKANASUPPLYOUT
VVV
2V
2
1
V
2
1
V
k1k1
1V
k1k1 k1
V
k1k1 k1
V
+=
+=
Ω
Ω
+
Ω+Ω
Ω
+
Ω+Ω
Ω
=
Eq. 1
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
10 100 1,000 10,000 100,00
01,000,0
00 10,000,
000
FREQUENCY (Hz)
PSRR (d B)
VIN = 2. 7V
COUT = 4. 7µF
CFF = 3. 3nF
500mA
10 100 1K 10K 100K 1M 10M
300mA
10mA
Micrel, Inc.
MIC94325/45/55 Evaluation Board
June 11, 2013
3 Revision 1.0
Evaluation Board Schematic (Adjustable)
Bill of Materials
Item Part Number Manufacturer Description Qty.
C1, C2 CL10A475K08NNNC Samsung(1) Capacitor, 4.7µF Ceramic, 16V, X5R, Size 0603 2
C3 C1608X7R2AP/NK TDK(2) Capacitor, 10nF Ceramic, 50V, X7R, Size 0603 1
R1, R2, R4 CRCW0402100KFKED Vishay(3) Resistor, 100kΩ, Size 0402 3
R3 CRCW04022R00FKED Vishay(3) Resistor, 2.0Ω, Si ze 0402 1
U1 MIC943X5YMT Micrel, Inc.
(4)
500mA LDO with Ripple Blocker Technology 1
Notes:
1. Samsung: www.samsung.com.
2. TDK: www.tdk.com.
3. Vishay: www.vishay.com.
4. Micrel, Inc.: www.micrel.com.
Micrel, Inc.
MIC94325/45/55 Evaluation Board
June 11, 2013
4 Revision 1.0
Evaluation Board Schematic (Fixed)
Bill of Materials
Item Part Number Manufacturer Description Qty.
C1, C2 CL10A475K08NNNC Samsung(5) Capacitor, 4. 7µF Ceramic, 16V, X5R, Size 0603 2
R1 CRCW04022R0FKED Vishay(6) Resistor, 2.0Ω, Size 0402
R2 CRCW0402100KFKED Vishay(6) Resistor , 100 kΩ, Size 0402 2
U1 MIC94355-XYMT Micrel, Inc.
(7)
500mA LDO with Ripple Blocker Technology 1
Notes:
5. Samsung: www.samsung.com.
6. Vishay: www.vishay.com.
7. Micrel, Inc.: www.micrel.com.
Micrel, Inc.
MIC94325/45/55 Evaluation Board
June 11, 2013
5 Revision 1.0
PCB Layout Recommendations (MIC94325)
Top Layer
Bottom Layer
Micrel, Inc.
MIC94325/45/55 Evaluation Board
June 11, 2013
6 Revision 1.0
PCB Layout Recommendations (MIC94345/55)
Top Layer
Bottom Layer
Micrel, Inc.
MIC94325/45/55 Evaluation Board
June 11, 2013
7 Revision 1.0
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
Micrel makes no represent ations or warranties with respec t t o the accuracy or completeness of the information furnis hed in this data sheet. This
informat i on is not intended as a warranty and Micrel does not assume responsibilit y for its use. Micrel reserves the right to change circuitry,
specificat i ons and descript i ons at any time without notice. No license, whether express , implied, arising by estoppel or otherwise, to any intellectual
property rights is granted by this document. Except as provided in Micrel’s term s and condit i ons of sale for such products, Micrel assumes no liabil ity
whatsoever, and Micrel disclaims any express or impli ed warranty relati ng to t he sale and/or use of Micrel products including liabil ity or warranties
relating to fitness for a partic ular purpose, merchant abi lit y, or inf ri ngem ent of any patent, copyright or other intel l ect ual propert y right.
Micrel Products are not designed or authorized for use as components in life support applianc es, devic es or syst ems where malf unct i on of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or syst em s t hat (a) are intended for surgical
implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a
significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life
support appliances, devices or syst ems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Mic rel for any damages resulting from such use or sale.
© 2013 Micrel, Incorporated.
Mouser Electronics
Authorized Distributor
Click to View Pricing, Inventory, Delivery & Lifecycle Information:
Micrel:
MIC94355-MYMT EV MIC94355-SYMT EV MIC94355-FYMT EV MIC94325YMT EV MIC94355-4YMT EV
MIC94355-GYMT EV MIC94355-SYMT-EV MIC94325YMT-EV MIC94355-FYMT-EV MIC94355-4YMT-EV
MIC94355-GYMT-EV MIC94355-MYMT-EV