MIC94310 Evaluation Board
200mA LDO with
Ripple Blocker™ Technology
General Description
The MIC94310 is a 200mA Low Dropout (LDO)
regulator that provides high power supply ripple
rejection (PSRR). This is important for applications
where switching noise cannot be tolerated by sensitive
downstream circuits such as in RF applications. The
MIC94310 maintains high power supply ripple rejection
(PSRR) with input voltage operating near the output
voltage level to improve overall system efficiency.
The MIC94310 operates from an input voltage of 1.8V to
3.6V.
Datasheets and support documentation can be found on
Micrel’s web site at
www.micrel.com.
Requirements
The MIC94310 evaluation board requires an input power
supply that is capable of delivering greater than 400mA
at a voltage range of 1.8V to 3.6V. The output load can
be either active or passive.
Precautions
The MIC94310 evaluation board does not have reverse
polarity protection. Applying a negative voltage to the
V
IN
terminal may damage the device.
Getting Started
•
Connect an External Supply to V
IN
. Apply the
desired input voltage to the V
IN
and ground terminal
of the evaluation board, paying careful attention to
polarity and supply voltage (1.8V
≤
V
IN
≤
3.6V).
•
Enable/Disable the MIC94310.
The evaluation
board is supplied with 100kΩ pull-up resistor to V
IN
for default on state. To disable the output, simply
jumper the EN terminal to ground.
•
Connect the Load.
Connect the load to the V
OUT
terminal and the ground terminal. The load can be
either a passive (resistor) or active (electronic load).
Be sure to monitor the output voltage at the V
OUT
terminal.
Ordering Information
Part Number
MIC94310-GYCS EV
Description
200mA LDO Ripple Blocker™ CSP
Package Evaluation Board
V
OUT
=1.8V
200mA LDO Ripple Blocker™ Thin
MLF
®
Package Evaluation Board
V
OUT
=1.8V
MIC94310-GYMT EV
Ripple Blocker is a trademark of Micrel, Inc
MLF and MicroLeadFrame are registered trademarks of Amkor Technology, 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
February 2012
M9999-020912
(408) 944-0800
Micrel, Inc.
MIC94310 Evaluation Board
PSRR measurements may be made using either
dedicated PSRR test equipment or with 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
difficulty arises when trying to impose the network
analyzer’s AC signal with the DC input voltage to the
MIC94310. The circuit shown in Figure 3
accomplishes this by using the MIC911 as a summing
amplifier. The summing amplifier adds the V
SUPPLY
(DC voltage) and the network analyzers AC signal. As
the network analyzers source is 50Ω impedance it
may be neglected, the DC voltage seen at the non-
inverting side is half of the V
SUPPLY
voltage. The output
is gained up by 2 with the 1kΩ resistor divider to the
non-inverting side. This sums the AC and DC voltages
with an overall gain of 1.
Power Supply Ripple Rejection (PSRR)
Measurements
Figure 1 illustrates the frequency response of the
MIC94310.
PSRR C
OUT
= 1µF
0
-20
-40
-60
-80
-100
V
IN
= 2.5V + 40mVpp
I
OUT
= 200mA
I
OUT
= 100mA
PSRR (dB)
V
OUT
= 1.8V
I
OUT
= 10mA
-120
10
100
1K
10K
100K
1M
10M
1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07
FREQUENCY (Hz)
Figure 1. MIC94310 Ripple Blocker™
Frequency Response
For high-frequency measurements (above 1MHz),
careful attention must be made to the test set-up
configuration as it is easy to introduce noise into the
grounds which will give inaccurate measurements as
shown in Figure 2.
Figure 2. High-Frequency Noise on
Measurement System
The inductance of test probes connected to the
evaluation board at higher frequencies becomes a
factor which can create a differential between the
device under test and test measurement system
grounds. Adding a low-value resistor (2Ω) in series
with the input capacitor to ground and utilizing a test
measurement system capable of making differential
measurements will help to reduce these effects.
Figure 3. Network Analyzer Set-Up
February 2012
2
M9999-020912
(408) 944-0800
Micrel, Inc.
MIC94310 Evaluation Board
Evaluation Board Schematics
Bill of Materials
Item
C1, C2
R1
R2
U1
Notes:
1.
2.
3.
Samsung:
http://www.semlcr.com.
Vishay:
www.vishay.com.
Micrel, Inc::
www.micrel.com.
Part Number
CL10B105KA8NNNC
CRCW0402100KFKEA
CRCW04022R00FKED
MIC94310-xYCS
MIC94310-xYMT
Manufacturer
Samsung
Vishay
(1)
(2)
Description
1µF, 25V, X7R, Size 0603, ceramic capacitor
100KΩ, 1%, 1/16W, Size 0402 resistor
2Ω, 1%, 1/16W, Size 0402 resistor
200mA LDO with Ripple Blocker™ technology
Qty.
2
1
1
1
Vishay
(2)
Micrel, Inc.
(3)
February 2012
3
M9999-020912
(408) 944-0800
Micrel, Inc.
MIC94310 Evaluation Board
PCB Layout Recommendations (CS Package)
Top Layer
Bottom Layer
February 2012
4
M9999-020912
(408) 944-0800
Micrel, Inc.
MIC94310 Evaluation Board
PCB Layout Recommendations (MT Package)
Top Layer
Bottom Layer
February 2012
5
M9999-020912
(408) 944-0800
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