MIC5234YME Evaluation Board
Low-Quiescent Current
150mA LDO Regulator
General Description
The MIC5234 is a low-quiescent current,
μCap
low-
dropout regulator. A maximum operating input voltage of
30V and quiescent current of 20μA make it ideal for
supplying keep-alive power in systems with high-voltage
batteries.
Capable of 150mA output, the MIC5234 has a dropout
voltage of only 320mV. It can also survive an input
transient of –20V to +32V. The MIC5234 needs only a
2.2μF output capacitor for stable operation.
The MIC5234 is available in an 8-pin ePad SOIC
package with a junction operating range from –40°C to
+125°C.
Data sheets and support documentation are available
on the Micrel web site:
www.micrel.com.
Requirements
The MIC5234YME Evaluation Board requires a 2.3V to
30V power supply, and a test load. Make sure that the
power supply can provide the wattage needed for the
chosen test load. The load can be active (electronic
load) or passive (resistor). Additionally, monitor the
Power Good output (PG) with a multimeter or an
oscilloscope.
Precautions
There is no reverse input protection on this board. While
connecting supplies and signals, make sure that correct
polarities are observed.
Getting Started
1. V
IN
Supplies
Connect the V
IN
supply (2.3V to 30V) across the VIN
and GND terminals. Monitor V
IN
at the VIN and GND
terminals with a voltmeter. JP1 is a 2-pin header test
point provided for monitoring V
IN
.
2. Enable Inputs
The enable input EN is logic high active and needs pull
up to input or a voltage source. When EN is pulled low
the output is off; when EN is high the output is on.
3. Monitor Outputs
Monitor the output V
OUT
with a scope or DVM connected
across the VOUT and GND terminals.
4. Output Load
Connect a load across the VOUT and GND terminals.
Use an active or passive load.
5. Turn On the Power
Turn on the power supply and verify that V
OUT
= 1.8V.
Ordering Information
Part Number
MIC5234YME EV
Description
Evaluation Board for the MIC5234YME
Ramp Control 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
September 2012
M9999-092412-A
Micrel, Inc.
MIC5234 Evaluation Board
Reverse Current Protection
The MIC5234 is designed to limit the reverse current
flow from output to input if the MIC5234 output has been
tied to the output of another power supply.
Output Capacitor
The MIC5234 has been designed to minimize the effect
of the output capacitor ESR on the closed loop stability.
As a result, ceramic or film capacitors can be used at
the output. Stability can also be maintained throughout
the specified load and line conditions with 2.2μF film or
ceramic capacitors.
Input Capacitor
An input capacitor may be needed when the device is
not near the source power supply or when it is supplied
by a battery. Small, surface mount, ceramic capacitors
can be used for bypassing. Larger values may be
needed if the source supply has high ripple.
Evaluation Board Features
See the
MIC5234 Data Sheet
for detailed explanations
of these functions.
Enable (EN)
EN allows the MIC5234 to turn on/off. A logic low on EN
pin keeps MIC5234 in shutdown mode with a typical
0.1µA input current.
Output Adjust (ADJ)
The MIC5234 can be adjusted from 1.24V to 20V by
using two external resistors. The resistors set the output
voltage based on Equation 1:
⎛
R1
⎞
V
OUT
=
V
REF
× ⎜
1
+
⎟
⎝
R2
⎠
Eq. 1
Where V
REF
= 1.23V.
The evaluation board is provided with R2=120Ω and
jumper (JP3-JP6) to easily set the output voltage to 5V,
3.3V, 2.5V, and 1.8V.
September 2012
2
M9999-092412-A
Micrel, Inc.
MIC5234 Evaluation Board
Evaluation Board Schematic
Bill of Materials
Item
C1, C5
C2, C3
Part Number
EKY-500ELL101MHB5D
12065C475KAT2A
GRM31CR71H475KA12L
C3216X5R1H475K
0805YD225KAT2A
C4
R1
R2
R3
R4
R5
R6
U1
Notes:
Manufacturer
United Chemi-con
AVX
(2)
Murata
(3)
TDK
(4)
AVX
Murata
TDK
Vishay
(5)
Vishay
Vishay
Vishay
Vishay
Micrel
(5)
(1)
Description
Capacitor, Aluminum, 100µF, 50V, 20%, Radial
Capacitor, 4.7µF, 50V, X5R, size 1206
Qty.
2
2
GRM219R61C225KA88D
C2012X7R1C225K
CRCW060310K0FKEA
CRCW06031200FKEA
CRCW06033830FKEA
CRCW06032000FKEA
CRCW06031270FKEA
CRCW060356R0FKEA
MIC5234YME
Capacitor, 2.2µF, 16V, X7R, size 0805
Resistor, 10KΩ, 1%, size 0603
Resistor, 120Ω, 1%, size 0603
Resistor, 383Ω, 1%, size 0603
Resistor, 200Ω, 1%, size 0603
Resistor, 127Ω, 1%, size 0603
Resistor, 56Ω, 1%, size 0603
Low-Quiescent Current µCap LDO Regulator
1
1
1
1
1
1
1
1
Vishay
(6)
1. United Chemi-Con:
www.chemi-con.com.
2. AVX:
www.avx.com.
3. Murata:
www.murata.com.
4. TDK:
www.tdk.com.
5. Vishay:
www.vishay.com.
6.
Micrel, Inc.:
www.micrel.com.
September 2012
3
M9999-092412-A
Micrel, Inc.
MIC5234 Evaluation Board
Evaluation Board PCB Layout
MIC5234 Evaluation Board Top Layer
MIC5234 Evaluation Board Top Silk
September 2012
4
M9999-092412-A
Micrel, Inc.
MIC5234 Evaluation Board
Evaluation Board PCB Layout (Continued)
MIC5234 Evaluation Board Bottom Layer
MIC5234 Evaluation Board Bottom Silk
September 2012
5
M9999-092412-A
嵌入式系统
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